Neuronetics (STIM) 10-K 7 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 01, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2022
Document Transition Report	false
Entity File Number	001-38546
Entity Registrant Name	NEURONETICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-1051425
Entity Address, Address Line One	3222 Phoenixville Pike
Entity Address, City or Town	Malvern
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19355
City Area Code	610
Local Phone Number	640-4202
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	STIM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		28,363,420
Entity Central Index Key	0001227636
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Ex Transition Period	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 67.7
Document Annual Report	true
ICFR Auditor Attestation Flag	false
Auditor Name	KPMG LLP
Auditor Firm ID	185
Auditor Location	Philadelphia, Pennsylvania
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE ​ Portions of the Registrant’s Definitive Proxy Statement relating to the 2023 Annual Meeting of Stockholders, which will be filed with the Securities and Exchange Commission within 120 days after the end of the Registrant’s fiscal year ended December 31, 2022, are incorporated by reference into Part III of this Report.

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 70,340	$ 94,141
Accounts receivable, net	13,591	7,706
Inventory	8,899	6,563
Current portion of net investments in sales-type leases	1,538	2,198
Current portion of prepaid commission expense	1,997	1,559
Current portion of note receivables	230	74
Prepaid expenses and other current assets	2,174	3,090
Total current assets	98,769	115,331
Property and equipment, net	1,991	1,220
Operating lease right-of-use assets	3,327	3,884
Net investments in sales-type leases	1,222	1,697
Prepaid commission expense	7,568	6,763
Long-term note receivable	362	10,110
Other assets	3,645	2,218
Total Assets	116,884	141,223
Current liabilities:
Accounts payable	2,433	4,299
Accrued expenses	14,837	8,233
Deferred revenue	1,980	2,501
Current portion of operating lease liabilities	824	670
Current portion of long-term debt, net	13,125
Total current liabilities	33,199	15,703
Long-term debt, net	22,829	35,335
Deferred revenue	829	1,471
Operating lease liabilities	2,967	3,539
Total Liabilities	59,824	56,048
Commitments and contingencies (Note 18)
Stockholders' Equity:
Preferred stock, $0.01 par value: 10,000 shares authorized; no shares issued or outstanding on December 31, 2022, and December 31, 2021
Common stock, $0.01 par value: 200,000 shares authorized; 27,268 and 26,395 shares issued and outstanding on December 31, 2022, and December 31, 2021, respectively	273	264
Additional paid-in capital	402,679	393,644
Accumulated deficit	(345,892)	(308,733)
Total Stockholders' Equity	57,060	85,175
Total Liabilities and Stockholders' Equity	$ 116,884	$ 141,223

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheets
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	27,268	26,395
Common stock, shares outstanding	27,268	26,395

Statements of Operations

Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statements of Operations
Revenues	$ 65,206	$ 55,312	$ 49,244
Cost of revenues	15,483	11,653	11,554
Gross Profit	49,723	43,659	37,690
Operating expenses:
Sales and marketing	49,982	37,746	32,562
General and administrative	25,516	25,554	18,236
Research and development	9,336	7,923	9,201
Total operating expenses	84,834	71,223	59,999
Loss from operations	(35,111)	(27,564)	(22,309)
Other (income) expense:
Interest expense	4,251	4,019	4,522
Loss on extinguishment of debt			924
Other income, net	(2,203)	(390)	(302)
Net Loss	$ (37,159)	$ (31,193)	$ (27,453)
Net loss per share of common stock outstanding, basic	$ (1.38)	$ (1.22)	$ (1.46)
Net loss per share of common stock outstanding, diluted	$ (1.38)	$ (1.22)	$ (1.46)
Weighted-average common shares outstanding, basic	26,900	25,479	18,835
Weighted-average common shares outstanding, diluted	26,900	25,479	18,835

Statements of Changes in Stockh

Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2019	$ 186	$ 297,753	$ (250,087)	$ 47,852
Beginning balance, shares at Dec. 31, 2019	18,645
Share-based awards and options exercises	$ 5	685		690
Share-based awards and options exercises, shares	469
Share-based compensation expense		4,404		4,404
Net Loss			(27,453)	(27,453)
Ending balance at Dec. 31, 2020	$ 191	302,842	(277,540)	25,493
Ending balance, shares at Dec. 31, 2020	19,114
Issuance of common stock	$ 56	80,515		80,571
Issuance of common stock (in shares)	5,566
Share-based awards and options exercises	$ 17	2,418		2,435
Share-based awards and options exercises, shares	1,715
Share-based compensation expense		7,869		7,869
Net Loss			(31,193)	(31,193)
Ending balance at Dec. 31, 2021	$ 264	393,644	(308,733)	85,175
Ending balance, shares at Dec. 31, 2021	26,395
Share-based awards and options exercises	$ 9	289		298
Share-based awards and options exercises, shares	873
Share-based compensation expense		8,746		8,746
Net Loss			(37,159)	(37,159)
Ending balance at Dec. 31, 2022	$ 273	$ 402,679	$ (345,892)	$ 57,060
Ending balance, shares at Dec. 31, 2022	27,268

Statements of Changes in Stoc_2

Statements of Changes in Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Statements of Changes in Stockholders' Equity (Deficit)
Issuance of common stock, issuance costs	$ 401

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash Flows from Operating Activities:
Net loss	$ (37,159)	$ (31,193)	$ (27,453)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,648	1,060	941
Share-based compensation	8,746	7,869	4,404
Non-cash interest expense	709	715	1,192
Cost of rental units purchased by customers	92	203	179
Loss on extinguishment of debt			622
Changes in certain assets and liabilities:
Accounts receivable, net	(6,317)	(3,054)	(597)
Inventory	(2,587)	(3,444)	(945)
Net investments in sales-type leases	1,114	324	(1,609)
Leasehold reimbursement			836
Prepaid commission expense	(1,243)	(1,926)	(1,928)
Prepaid expenses and other assets	786	62	(641)
Accounts payable	(1,968)	276	(1,085)
Accrued expenses	6,604	910	(1,733)
Deferred revenue	(1,164)	215	(573)
Net Cash Used in Operating Activities	(30,739)	(27,983)	(28,390)
Cash Flows from Investing Activities:
Purchases of property and equipment and capitalized software	(3,269)	(2,353)	(730)
Repayment (Issuance) of promissory note	10,000
Repayment (Issuance) of promissory note		(7,486)
Net Cash provided by (used in) Investing Activities	6,731	(9,839)	(730)
Cash Flows from Financing Activities:
Payments of debt issuance costs	(91)		(821)
Proceeds from issuance of long-term debt			41,360
Repayment of long-term debt			(38,860)
Proceeds from exercises of stock options	298	2,435	690
Proceeds from the issuance of common stock		80,972
Payments of common stock offering issuance costs		(401)
Net Cash Provided by Financing Activities	207	83,006	2,369
Net (Decrease) Increase in Cash and Cash Equivalents	(23,801)	45,184	(26,751)
Cash and Cash Equivalents, Beginning of Period	94,141	48,957	75,708
Cash and Cash Equivalents, End of Period	70,340	94,141	48,957
Supplemental disclosure of cash flow information:
Cash paid for interest	3,543	3,304	3,892
Transfer of inventory to property and equipment	250	601
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property and equipment and capitalized software in accounts payable and accrued expenses	103	273	$ 208
Reduction of accounts receivable in current and long-term note receivable	$ 432	$ 2,514

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2022
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	1. DESCRIPTION OF BUSINESS Neuronetics, Inc., or the Company, is a commercial stage medical technology company focused on designing, developing and marketing products that improve the quality of life for patients who suffer from neurohealth disorders. The Company’s first commercial product, the NeuroStar Advanced Therapy System, is a non-invasive and non-systemic office-based treatment that uses transcranial magnetic stimulation, (“TMS”), to create a pulsed, MRI-strength magnetic field that induces electrical currents designed to stimulate specific areas of the brain associated with mood. The system was cleared in 2008 by the United States Food and Drug Administration, (the “FDA”), to treat adult patients with major depressive disorder, (“MDD”), who have failed to achieve satisfactory improvement from prior antidepressant medication in the current episode. The Company intends to continue to pursue development of its NeuroStar Advanced Therapy System for additional indications. COVID-19 The Company is monitoring the impact of the COVID-19 pandemic on all aspects of its business and geographies, including how it will impact the Company’s customers, supply chain, employees and other business partners. While the Company experienced significant disruptions in the first quarter of 2022 and through the end of December 2021, from the COVID-19 pandemic, it is unable to predict the full impact that the COVID-19 pandemic may have on its financial condition, results of operations and cash flows due to numerous uncertainties. These uncertainties include the scope, severity and duration of the pandemic, the actions taken to contain the pandemic or mitigate its impact and the direct and indirect economic effects of the pandemic and containment measures, among others. The outbreak of COVID-19 in many countries, including the United States, has significantly adversely impacted global economic activity and has contributed to significant volatility and negative pressure in financial markets. The Company applied for and received a $6.4 million loan in April 2020 under the Paycheck Protection Program (the “PPP”) established by the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) on March 27, 2020. Due to questions concerning the eligibility of public companies similarly situated to the Company, on May 7, 2020, the Company repaid the loan in full, including interest accrued to date. Liquidity As of December 31, 2022, the Company had cash and cash equivalents of $70.3 million and an accumulated deficit of $345.9 million. The Company incurred negative cash flows from operating activities of $30.7 million, $28.0 million and $28.4 million for the years ended December 31, 2022, 2021 and 2020, respectively. The Company has incurred operating losses since its inception, and management anticipates that its operating losses will continue in the near term as the Company seeks to expand its sales and marketing initiatives to support its growth into existing and new markets and invest in additional research and development activities. The Company’s primary sources of capital to date have been from its initial public offering, private placements of its convertible preferred securities, borrowings under its credit facility, proceeds from its secondary public offering of common stock, and revenues from sales of its products. As of December 31, 2022, the Company had $35.0 million of borrowings outstanding under its credit facility, which matures in February 2025

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	2. BASIS OF PRESENTATION The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”), and Accounting Standards Updates (“ASUs”), promulgated by the Financial Accounting Standards Board (“FASB”). Use of Estimates The preparation of financial statements in accordance with GAAP and the rules and regulations of the United States Securities and Exchange Commission (“SEC”), requires the use of estimates and assumptions, based on judgments considered reasonable, which affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates and assumptions on historical experience, known trends and events and various other factors that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Although management believes its estimates and assumptions are reasonable when made, they are based upon information available at the time they are made. Management evaluates the estimates and assumptions on an ongoing basis and, if necessary, makes adjustments. Due to the risks and uncertainties involved in the Company’s business and evolving market conditions and given the subjective element of the estimates and assumptions made, actual results may differ from estimated results.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. As of December 31, 2022 and 2021, cash equivalents consisted of money market funds. Concentrations of Credit Risk The Company’s cash is held on deposit in demand accounts at a large financial institution in amounts in excess of the Federal Deposit Insurance Corporation (“FDIC”), insurance coverage limit of $250,000 per depositor, per FDIC-insured bank, per ownership category. Financial instruments that potentially subject the Company to concentrations of credit risk principally consist of cash equivalents and accounts receivable. The Company limits its credit risk associated with cash equivalents by placing investments in highly-rated money market funds. The Company limits its credit risk with respect to accounts receivable by performing credit evaluations when deemed necessary, but it does not require collateral to secure amounts owed by its customers. Allowance for Doubtful Accounts The Company maintains allowances for doubtful accounts for estimated losses resulting from amounts deemed to be uncollectible from its customers. These allowances are for specific amounts on certain customer accounts based on facts and circumstances determined on a case-by-case basis. Leases The Company accounts for leases in accordance with ASC Topic 842, Leases The Company leases warehouse, office space, a training facility and office equipment pursuant to net operating leases. Operating leases where the Company is the lessor are included in revenue on the Statements of Operations. From time to time the Company enters into sales-type lease arrangements that include a lessee obligation to purchase the leased equipment at the end of the lease term, automatic transfer of ownership of the leased equipment at the end of the lease, a lessee purchase option reasonably certain to be exercised, or provides for minimum lease payments with a present value equal to or exceeding substantially all of the fair value of the underlying leased equipment at the date of lease inception. Sales-type leases where the Company is the lessor are included in revenue on the Statements of Operations. Operating leases where the Company is the lessee are included in operating lease right-of-use assets and operating lease liabilities on the Balance Sheets. The lease liabilities are initially measured at the present value of the unpaid lease payments at the lease commencement date. The Company uses the following inputs in its lease calculations under Topic 842: (1) the discount rate the Company uses to discount the unpaid lease payments to present value, (2) lease term, and (3) lease payments. (1) Topic 842 requires a lessor to discount its unpaid lease payments using the interest rate implicit in the lease and a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most leases where the Company is the lessee do not provide an implicit rate, the Company uses the incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The incremental borrowing rate for a lease is the rate of interest the Company would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The Company uses the implicit rate when readily determinable. (2) The lease term for all leases includes the noncancelable period of the lease plus any additional periods covered by either a lessee option to extend (or not to terminate) the lease that the lessee is reasonably certain to exercise, or an option to extend (or not to terminate) the lease controlled by the lessor. (3) Lease payments included in the measurement of the lease asset or liability comprise the following: fixed payments (including in-substance fixed payments), and the exercise price of a lessee option to purchase the underlying asset if the lessee is reasonably certain to exercise. For operating leases where the Company is the lessor, the Company continues recognizing the underlying asset and depreciating it over its estimated useful life. Lease income from lessees is recognized on a straight-line basis over the terms of the relevant lease agreement in revenue. Operating leases for equipment with fixed rentals and step rentals are recognized on a straight-line basis over the term of the lease, assuming no renewals, in revenue. Revenue is not recognized when collection is not reasonably assured. When collectability is not reasonably assured, the customer is placed on non-accrual status and revenue is recognized when cash payments are received. The lease asset for sales-type leases is initially measured as the total net investment in the lease, which comprises the initial amount of the lease receivable plus the deferred initial direct costs. The lease asset for sales-type leases is subsequently measured throughout the lease term at the carrying amount of the net investment in the lease which is increased by interest income and reduced by lease payments collected. The lease payments are segregated into principal and interest components similar to a loan. Equipment leasing revenues are recognized on an effective interest method over the lease term. The principal component of the lease payment is reflected as a reduction to the net investment in the lease. For operating leases where the Company is the lessee, the right-of-use (“ROU”), asset is initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred less any lease incentives received. The ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, plus (minus) any prepaid (accrued) lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Lease assets for sales-type leases where the Company is the lessor and ROU assets for operating leases where the Company is the lessee are periodically reduced by impairment losses. The Company uses the loans impairment guidance in ASC Subtopic 330-10, Receivables, and the long-lived assets impairment guidance in ASC Subtopic 360-10, Property, Plant, and Equipment – Overall, to determine whether a lease asset or a ROU asset, respectively, is impaired, and if so, the amount of the impairment loss to recognize. For the years ended December 31, 2022, and 2020 the Company did not recognize any impairment losses. The Company recognized $0.1 million in impairment losses which is included within Sales and marketing expense on the statement of operations for the year ended December 31, 2021. The Company monitors for events or changes in circumstances that require a reassessment of its leases. When a reassessment results in the remeasurement of a lease liability, a corresponding adjustment is made to the carrying amount of the corresponding ROU asset unless doing so would reduce the carrying amount of the ROU asset to an amount less than zero. In that case, the amount of the adjustment that would result in a negative ROU asset balance is recorded in profit or loss. The Company has elected not to recognize ROU assets and lease liabilities for all short-term leases that have a lease term of 12 months or less. The Company recognizes the lease payments associated with the short-term leases as an expense on a straight-line basis over the lease term. Variable lease payments associated with these leases are recognized and presented in the same manner as for all other leases. The Company has elected to exclude sales and other similar taxes from lease payments in arrangements where the Company is a lessor. Inventory Inventory is stated at the lower of cost and net realizable value, with cost being determined on a first in, first out basis. The Company’s inventory is primarily comprised of finished goods. Property and Equipment and Capitalized Software Property and equipment are recorded at cost. Maintenance and repairs are charged to expense as incurred and costs of improvements and renewals are capitalized. Depreciation and amortization are recognized using the straight-line method based on the estimated useful lives of the related assets. The Company uses an estimated useful life of three years for computers and software, five years for laboratory and office equipment, six years for devices in the rental agreement program and the lesser of five years or the remaining life of the underlying facility lease for leasehold improvements. Software development costs relating to assets to be sold in the normal course of business are included in research and development and are expensed as incurred until technological feasibility is established. After technological feasibility is established, software development costs are capitalized. The Company uses an estimated useful life of two years for capitalized software and amortizes these costs beginning at the product release. Impairment of Long-Lived Assets Long-lived assets, such as property and equipment, are tested for impairment when events or changes in circumstances indicate that the carrying value of the asset may not be recoverable. Impairment testing requires management to estimate the future net undiscounted cash flows of an asset using assumptions believed to be reasonable. Actual cash flows may differ from the estimates used in the impairment testing. If such assets are considered to be impaired, the Company recognizes an impairment loss when and to the extent that the estimated fair value of an asset is less than its carrying value. The Company has not recorded any impairment of its long-lived assets for the years ended December 31, 2022, 2021 and 2020. Note Receivables Note receivables are reported on the Company’s balance sheet at amortized cost basis. The Company recognizes interest income within other income, net within the statements of operations. Note receivables are periodically reviewed to determine whether a note receivable is impaired, and if so, the amount of the impairment loss to recognize. For the year ended December 31, 2021, the Company recognized $0.1 million in impairment charges which is included within “Sales and marketing expense” on the statements of operations. For the year ended December 31, 2022 there were no impairment charges. Deferred Debt Issuance Costs The Company capitalizes direct costs incurred to obtain debt financing and amortizes these costs to interest expense over the term of the debt using the effective interest method. These costs are recorded as a debt discount and are netted against the related debt on the Company’s balance sheets. Revenue Recognition ASC Topic 606, Revenue from Contracts with Customers Sales and usage-based taxes are excluded from revenues. Contract Formation The Company accounts for a contract with a customer when there is a legally enforceable contract between the Company and the customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. For all sales, the Company uses either a signed agreement or a binding purchase order as evidence of an arrangement. Performance Obligations The unit of account for Topic 606 is the performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer or a series of distinct goods or services that are substantially the same and have the same pattern of transfer. A contract’s transaction price is allocated to each performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of the Company’s contracts are comprised of the following performance obligations: (1) The NeuroStar TMS Therapy System (the “System”) which includes a chair, an electromagnet coil, a monitoring console and accessories. The various components are inputs that function together to deliver a combined output and together form one performance obligation (a NeuroStar Advanced Therapy System). Revenues from the sale of the System are satisfied at the point-in-time when shipped from our premises. (2) NeuroStar Treatment Session (the “Treatment Session”) is a single use consumable that is delivered via an encrypted activation code and is required in order for a clinician to perform TMS therapy. Revenues from the sale of the Treatment Sessions are satisfied at the point-in-time when delivered to the customer. The Company determined that sales of Treatment Sessions are not part of the enforceable rights and obligations of the System sales, except when sold with System sales. (3) Separately priced extended warranties and when-and-if-available upgrade rights are considered service-type warranties. Warranty services are considered stand-ready obligations satisfied over-time and recognized using a straight-line time-based measurement toward completion. (4) The System clinical and reimbursement training enable the clinician to provide patient treatment. The trainings are not required in order to operate the System but are required in order to receive a certification from the Company and accordingly are not essential to the functionality of other performance obligations. Training services are recognized at a point-in-time when training is complete, typically simultaneous to or near the time of delivery of the System. In addition, the Company has determined that there are various perfunctory deliverables such as installation of the System, the technical support hotline and marketing materials which the Company does not separately recognize as revenue nor does the Company accrue the estimated cost of providing these goods and services because they are not material. The Company provides a one-year warranty on all new System sales which were determined to be assurance-type warranties and thus not considered a separate performance obligation. The Company accrues the cost of providing these warranties. There is no right of return or refund for any of the Company’s products or services and the Company has elected to treat shipping and handling as a fulfillment activity and expenses the costs as incurred. Rent-to-Own The System is typically purchased but the Company does offer certain customers the option to lease instead. The Company accounts for these leases under Topic 842, Leases Distribution Agreement The Company has an exclusive distribution agreement that began in October 2017 with a foreign entity for a period of 7 ● Exclusive distribution and intellectual property license ● NeuroStar TMS Therapy System ● NeuroStar Treatment Session The distribution agreement contains pricing for the Company’s products and services. The contractual purchase prices were determined to be at the standalone selling prices based on the expected sales volumes of this customer type and thus the Company concluded that this agreement did not contain a separate performance obligation for the material right to discounted Systems and Treatments Sessions. The Company allocated the transaction price through a combination of the cost plus a margin approach and the residual method. For the System and Treatment Sessions the Company maximized the use of observable inputs by beginning with average historical contractual selling prices and adjusting on a consistent and rational basis for pricing trends, the customer type and expected sales volumes and the Company’s changing cost and margins. Since it was determined that the contractual selling prices for the Company’s products and services in the distribution agreement were at the standalone selling prices, the residual consideration which is made up of the fixed and variable milestone payments was allocated to the exclusive distribution and intellectual property license. The exclusive distribution and intellectual property rights were determined to be symbolic IP and thus recognized over time. The System and Treatment Sessions were determined to be performance obligations recognized at a point-in-time when delivered to the distributor. Contract Estimates Accounting for the Company’s contracts involves the use of significant judgments and estimates including determining the separate performance obligations, allocating the transaction price to the different performance obligations and determining the method to measure the entity’s performance toward satisfaction of performance obligations that most faithfully depicts when control is transferred to the customer. The Company allocates the contract’s transaction price to each performance obligation using the Company’s best estimate of the standalone selling price for each distinct good or service in the contract. The Company maximizes the use of observable inputs by beginning with average historical contractual selling prices and adjusting as necessary and on a consistent and rational basis for other inputs such as pricing trends, customer types, volumes and changing cost and margins. Contract Balances Payment terms typically require payment upon shipment of the System and additional payments as access codes are delivered, which can span several years after the System is first delivered and installed. The timing of revenue recognition compared to billings and cash collections typically results in accounts receivable. However, sometimes customer advances and deposits might be required for certain customers and are recorded as contract liabilities. Changes in the contract asset and liability balances during the years ended December 31, 2022 and 2021 were not materially impacted by any other factors. ​ ​ ​ As of December 31, 2022, the Company expects to recognize approximately the following percentages of deferred revenue by year: ​ ​ ​ ​ ​ ​ Revenue Year: ​ Recognition 2023 67 % 2024 25 % 2025 8 % 2026 — % 2027 — % Thereafter — % Total 100 % ​ ​ ​ ​ ​ Revenue recognized for the years ended December 31, 2022 and 2021 that was included in the contract liability balance at the beginning of the year was $2.5 million and $1.9 million, respectively, and primarily represented revenue earned from separately priced extended warranties, rent-to-own revenue, milestone revenue, and clinical training. Customers Significant customers are those which represent more than 10% of the Company’s total revenue. For the years ended December 31, 2022, 2021 and 2020, one customer accounted for 17%, 20% and 22% respectively, of the Company’s revenue. Accounts receivable outstanding related to the customer was $5.2 million and $2.5 million as of December 31, 2022 and 2021, respectively. Geographical Information The following geographic data includes revenue generated from the Company’s third-party distributors. The Company’s revenue was generated in the following geographic regions and by product line for the periods indicated (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues by Geography ​ ​ ​ Year Ended December 31, ​ ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ ​ ​ Amount ​ Revenues ​ Amount ​ Revenues ​ ​ ​ (in thousands, except percentages) ​ ​ United States $ 63,406 97 % $ 53,447 97 % ​ International ​ 1,800 3 % 1,865 3 % ​ Total revenues ​ $ 65,206 100 % $ 55,312 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Revenues by Product Category ​ ​ ​ Year Ended December 31, ​ ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ ​ % of ​ ​ ​ % of ​ ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) ​ ​ NeuroStar Advanced Therapy System ​ $ 16,575 ​ 26 % $ 9,760 ​ 18 % ​ Treatment sessions ​ 45,077 71 % 41,933 78 % ​ Other ​ 1,754 3 % 1,754 4 % ​ Total U.S. revenues ​ $ 63,406 100 % $ 53,447 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ International Revenues by Product Category ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ (in thousands, except percentages) ​ NeuroStar Advanced Therapy System ​ $ 811 45 % $ 1,108 59 % Treatment sessions ​ 354 20 % 264 14 % Other ​ 635 35 % 493 27 % Total International revenues ​ $ 1,800 100 % $ 1,865 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues by Geography ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) ​ United States ​ $ 53,447 97 % $ 47,519 96 % International ​ 1,865 3 % 1,725 4 % Total revenues ​ $ 55,312 100 % $ 49,244 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Revenues by Product Category ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ % of ​ ​ % of ​ ​ Amount ​ Revenues ​ Amount ​ Revenues ​ (in thousands, except percentages) ​ NeuroStar Advanced Therapy System ​ $ 9,760 18 % $ 11,094 23 % Treatment sessions ​ 41,933 78 % 34,852 73 % Other ​ 1,754 4 % 1,573 4 % Total U.S. revenues ​ $ 53,447 100 % $ 47,519 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ International Revenues by Product Category ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) NeuroStar Advanced Therapy System ​ $ 1,108 59 % $ 856 50 % Treatment sessions ​ 264 14 % 449 26 % Other ​ 493 27 % 420 24 % Total International revenues ​ $ 1,865 100 % $ 1,725 100 % ​ ​ ​ ​ ​ ​ Research and Development Expenses Research and development activities are expensed as incurred. Costs incurred in obtaining technology licenses are charged immediately to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future uses. Share-based Compensation The Company recognizes the grant-date fair value of share-based awards issued as compensation as expense on a straight-line basis over the requisite service period, which is generally the vesting period of the award. The fair value of restricted stock awards and restricted stock units is estimated at the time of grant, based on the grant date fair value of the Company’s common stock. The fair value of performance restricted stock units is estimated at the time of grant and is determined using a risk neutral Monte Carlo simulation valuation model, which requires the use of inputs and assumptions such as the fair value of the underlying common stock, risk free interest rate, and expected volatility. The performance restricted stock units generally vest based on appreciation of the Company’s common stock to a certain price as determined by the Company’s board of directors measured using a trailing 30-day volume weighted average price of a share of the Company’s common stock. The fair value of stock options is estimated at the time of grant using the Black-Scholes option pricing model, which requires the use of inputs and assumptions such as the fair value of the underlying common stock, exercise price of the option, expected term, risk-free interest rate, expected volatility and dividend yield. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes the enactment date. A valuation allowance is recorded to the extent it is more likely than not that some portion or all of the deferred tax assets will not be realized. Unrecognized income tax benefits represent income tax positions taken on income tax returns that have not been recognized in the financial statements. The Company recognizes the benefit of an income tax position only if it is more likely than not (greater than 50%) that the tax position will be sustained upon tax examination, based solely on the technical merits of the tax position. Otherwise, no benefit is recognized. The tax benefits recognized are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The Company accrues interest and related penalties are classified as income tax expense in the statements of operations. The Company does not anticipate significant changes in the amount of unrecognized income tax benefits over the next year.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2022
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Recent Accounting Pronouncements	4. RECENT ACCOUNTING PRONOUNCEMENTS New Accounting Standards Not Yet Adopted by the Company In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments “Topic 326” ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging (Topic 815) Topic 825, Financial Instruments ASU 2019-11 Codification Improvements to Topic 326 Financial Instruments - Credit Losses ASU 2019-05, Financial Instruments - Credit Losses (Topic 326) Targeted Transition Relief ASC 825-10, Financial Instruments - Overall The ASUs 15, 2022 for entities that are eligible to be defined by the SEC as a smaller reporting company. The Company is a smaller reporting company. The Company does not anticipate a material impact on its financial statements based on the instruments currently held and its historical trend of bad debt expense relating to trade accounts receivable. ​ Other than the items noted above, there have been no new accounting pronouncements not yet effective or adopted in the current year that we believe have a material impact, or potential material impact, to our financial statements.

Fair Value Measurement and Fina

Fair Value Measurement and Financial Instruments	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurement and Financial Instruments	5. FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS The carrying values of cash equivalents, accounts receivable, prepaids and other current assets, and accounts payable on the Company’s balance sheets approximated their fair values as of December 31, 2022 and 2021 due to their short-term nature. The carrying values of the Company’s current credit facility approximated its fair value as of December 31, 2022 and 2021 due to its variable interest rate. The carrying value of the Company’s note receivable approximated its fair value as of December 31, 2022 and 2021 due to its variable interest rate. Certain of the Company’s financial instruments are measured at fair value using a three-level hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 : Inputs are quoted prices for identical instruments in active markets. Level 2: Inputs are quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; or model-derived valuations whose inputs are observable or whose significant value drivers are observable. Level 3 : Inputs are unobservable and reflect the Company’s own assumptions, based on the best information available, including the Company’s own data. The following tables set forth the carrying amounts and fair values of the Company’s financial instruments as December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement Based on ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices In ​ other ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Observable ​ Unobservable ​ ​ Carrying ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ Amount Fair Value (Level 1) (Level 2) (Level 3) Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (cash equivalents) ​ $ 68,002 ​ $ 68,002 ​ $ 68,002 ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement Based on ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices In ​ other ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Observable ​ Unobservable ​ ​ Carrying ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ ​ Amount ​ Fair Value ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets ​ ​ ​ ​ ​ Money market funds (cash equivalents) ​ $ 91,236 ​ $ 91,236 ​ $ 91,236 ​ $ — ​ $ — ​

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2022
Receivables [Abstract]
Accounts Receivable	6. ACCOUNTS RECEIVABLE The following table presents the composition of accounts receivable, net as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2021 Gross accounts receivable - trade ​ $ 15,239 ​ $ 9,168 Less: Allowances for doubtful accounts ​ (1,648) ​ (1,462) Accounts receivable, net ​ $ 13,591 ​ $ 7,706 ​ ​ The following table presents a rollforward of the allowance for doubtful accounts (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Bad Debt ​ Write-offs of ​ Balance at ​ ​ Beginning of ​ Expense ​ Uncollectible ​ End of ​ Period Recognized Balances Period Year ended December 31, 2020 ​ $ (548) ​ (897) ​ 433 ​ $ (1,012) Year ended December 31, 2021 ​ $ (1,012) (763) 313 ​ $ (1,462) Year ended December 31, 2022 ​ $ (1,462) (341) 155 ​ $ (1,648) ​

Property and Equipment and Capi

Property and Equipment and Capitalized Software	12 Months Ended
	Dec. 31, 2022
Property Plant And Equipment [Abstract]
Property and Equipment and Capitalized Software	7. PROPERTY AND EQUIPMENT AND CAPITALIZED SOFTWARE The following table presents the composition of property and equipment, net as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2021 Laboratory equipment ​ $ 462 ​ $ 249 Office equipment ​ 508 ​ 497 Computer equipment and software ​ 1,758 ​ 1,598 Manufacturing equipment ​ 343 ​ 341 Leasehold improvements ​ 1,435 ​ 471 Rental equipment ​ 542 ​ 601 Property and equipment, gross ​ 5,048 ​ 3,757 Less: Accumulated depreciation ​ (3,057) ​ (2,537) Property and equipment, net ​ $ 1,991 ​ $ 1,220 ​ As of December 31, 2022 and 2021, the Company had capitalized software costs, net of $3.6 million and $2.5 million, respectively, which are included in “Other assets” on the balance sheet. Depreciation and amortization expense was $1.6 million, $1.1 million, and $0.9 million for the years ended December 31, 2022, 2021 and 2020, respectively.

Note Receivables

Note Receivables	12 Months Ended
	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Note Receivables	8. NOTE RECEIVABLES ​ On September 29, 2021, the Company entered into an exclusive, five-year master sales agreement with Check Five, LLC d/b/a Success TMS (“Success TMS”). In connection with the Commercial Agreement, the Company agreed to loan Success TMS the principal amount of $10.0 million for a period of five years pursuant to a secured promissory note (the “Note”). The Note included interest at a floating rate equal to the prime rate plus 6.00% per annum and interest-only period through October 1, 2022, after which time Success TMS was required to make monthly payments of principal and interest. On July 14, 2022, Success TMS repaid in full the Note with a cash payment of $10.5 million, which included all outstanding principal, prepayment premium and accrued but unpaid interest. The repayment extinguished the Note in its entirety and terminated the Subordination Agreement entered into by the Company. Interest income recognized by the Company was $1.0 million and $0.2 million for the years ended December 31, 2022 and 2021, respectively, and included within other income, net on the statement of operations.

Leases

Leases	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Leases	9. LEASES Lessee: The Company has operating leases for its corporate headquarters, a training facility and office equipment, including copiers. The Company leases an approximately 32,000 square foot facility in Malvern, Pennsylvania for its corporate headquarters, which includes office and warehouse space. In the first quarter of 2019, the Company signed a lease modification for its Malvern facility that extended the lease through February 2028 and included approximately 10,000 square foot of additional premises. The Company has an option to extend The Company leases an approximately 9,600 square foot facility in Charlotte, North Carolina as a training facility for its NeuroStar Advanced Therapy Systems. The lease ends in September 2027. The Company has an option Operating lease rent expense was $0.8 million, $0.7 million, and $0.6 million for the years ended December 31, 2022, 2021 and 2020, respectively. As of December 31, 2022, the weighted-average remaining lease term of operating leases was 5.0 years and the weighted-average discount rate was 7.2%. The following table presents the supplemental cash flow information as a lessee related to leases for the years ended December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended Year ended ​ ​ December 31, 2022 ​ December 31, 2021 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 892 ​ $ 822 Right-of-use assets obtained in exchange for lease obligations: ​ ​ ​ ​ ​ ​ Operating leases ​ $ — ​ $ 866 ​ The following table sets forth by year the required future payments of operating lease liabilities as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2022 ​ 2023 ​ $ 853 ​ 2024 ​ ​ 875 ​ 2025 ​ 898 ​ 2026 ​ 921 ​ 2027 ​ 882 ​ Thereafter ​ 116 ​ Total lease payments ​ 4,545 ​ Less imputed interest ​ (754) ​ Present value of operating lease liabilities ​ $ 3,791 ​ ​ Lessor sales-type leases: Certain costumers have purchased NeuroStar Advanced Therapy Systems on a rent-to-own basis. The lease term is three The following table sets forth the profit recognized on sales-type leases (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2022 ​ 2021 Profit recognized at commencement, net ​ $ 478 ​ $ 807 Interest income ​ — ​ — Total sales-type lease income ​ $ 478 ​ $ 807 ​ The following table sets forth a maturity analysis of the undiscounted lease receivables related to sales-type leases as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2023 ​ $ 1,538 2024 ​ ​ 824 2025 ​ 358 2026 ​ 40 2027 ​ ​ — Total sales-type lease receivables ​ $ 2,760 ​ As of December 31, 2022 and 2021, the carrying amount of the lease receivables is $2.8 million and $3.9 million, respectively. The Company does not have any unguaranteed residual assets. Lessor operating leases: NeuroStar Advanced Therapy Systems sold on a rent-to-own basis prior to January 1, 2019 are accounted for as operating leases. NeuroStar Advanced Therapy Systems sold subsequent to January 1, 2019 for which collection is not probable are also accounted for as operating leases. For the years ended December 31, 2022, 2021 and 2020, the Company recognized operating lease income of $0.2 million, $0.3 million and $0.4 million, respectively. ​ The Company maintained Rental Equipment, net of $0.5 million and $0.6 million, as of December 31, 2022 and 2021, respectively, which are included in “Property and equipment, net” on the balance sheet. Rental equipment depreciation expense was $0.10 million, $0.05 million and $0.1 million for the years ended December 31, 2022, 2021 and 2020, respectively.

Prepaid Commission Expense

Prepaid Commission Expense	12 Months Ended
	Dec. 31, 2022
Amortization Of Deferred Charges [Abstract]
Prepaid Commission Expense	10. PREPAID COMMISSION EXPENSE The Company pays a commission on both NeuroStar Advanced Therapy System sales and Treatment Session sales. Since the commission paid for NeuroStar Advanced Therapy System sales is not commensurate with the commission paid for Treatment Sessions, the Company capitalizes commission expense associated with NeuroStar Advanced Therapy System commissions paid that is incremental to specifically anticipated future Treatment Session orders. In developing this estimate, the Company considered its historical Treatment Session sales and customer retention rates, as well as technology development life cycles and other industry factors. These costs are periodically reviewed for impairment. NeuroStar Advanced Therapy System commissions are deferred and amortized on a straight-line basis over a seven year period equal to the average customer term, which the Company deems to be the expected period of benefit for these costs. On the Company’s balance sheets, the current portion of capitalized contract costs is represented by the current portion of prepaid commission expense, while the long-term portion is included in prepaid commission expense. Amortization expense was $1.8 million and $1.3 million for the years ended December 31, 2022 and December 31, 2021, respectively, and presented within sales and marketing in the statements of operations.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2022
Payables And Accruals [Abstract]
Accrued Expenses	11. ACCRUED EXPENSES The following table presents the composition of accrued expenses as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, ​ ​ 2022 ​ 2021 Compensation and related benefits ​ $ 11,201 ​ $ 5,090 Consulting and professional fees ​ 761 ​ 537 Research and development expenses ​ 678 ​ 388 Sales and marketing expenses ​ ​ 410 ​ ​ 268 Warranty ​ 328 ​ 306 Sales and other taxes payable ​ 659 ​ 664 Other ​ 800 ​ 980 Accrued expenses ​ $ 14,837 ​ $ 8,233 ​

Debt

Debt	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Debt	12. DEBT The following table presents the composition of debt as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ ​ 2022 2021 ​ Outstanding principal ​ $ 35,000 ​ $ 35,000 ​ Accrued final payment fees ​ 1,925 ​ 1,925 ​ Less debt discounts ​ (971) ​ (1,590) ​ Total debt, net ​ 35,954 ​ 35,335 ​ Less current portion ​ (13,125) ​ — ​ Long-term debt, net ​ $ 22,829 ​ $ 35,335 ​ ​ For the year ended December 31, 2022, the Company recognized interest expense of $4.3 million, of which $3.6 million was cash and $0.7 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. For the year ended December 31, 2021, the Company recognized interest expense of $4.0 million, of which $3.3 million was cash and $0.7 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. For the year ended December 31, 2020, the Company recognized interest expense of $4.5 million, of which $3.9 million was cash and $0.6 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. The following table sets forth by year our required future principal payments under the term loan portion of the Solar Facility: ​ ​ ​ ​ ​ ​ Principal Year: ​ Payments 2023 ​ $ 13,125 2024 ​ 17,500 2025 ​ 4,375 2026 ​ — 2027 ​ — Total principal payments ​ $ 35,000 ​ Solar Credit Facility On March 2, 2020, the Company entered into a loan and security agreement with SLR Investment Corp. (formerly known as Solar Capital Ltd.), or (“Solar”), as collateral agent, and other lenders defined in the agreement, for a credit facility, or the Solar Facility, that replaced the Company’s previous $35.0 million credit facility with Oxford Finance LLC, or Oxford, and such facility, the Oxford Facility. On March 2, 2020, the Company borrowed an aggregate amount of $35.0 million, which was the aggregate amount available under the term loan portion of the Solar Facility. The term loan portion of the Solar Facility matures, and all amounts borrowed thereunder are due, on February 28, 2025. The term loan accrues interest from the date of borrowing through the date of repayment at a floating per annum rate of interest, which resets monthly and is equal to 7.65% plus the greater of (a) 1.66% or (b) the rate per annum rate published by the Intercontinental Exchange Benchmark Administration Ltd but was amended on February 15, 2022. The 2022 Solar Amendment (i) waived any default under the Solar Facility and Solar Amendment that resulted from the Company’s failure to comply with the minimum monthly trailing twelve months net product revenue financial covenant, beginning with the testing period for the calendar month ending December 31, 2021 and continuing to the execution date of the 2022 Solar Amendment; (ii) decreased the amount of trailing twelve months net product revenue that the Company is required to achieve for testing periods on and from the calendar month ending January 31, 2022 and (iii) modified the definition of interest only extension conditions to allow commencement of loan principal amortization under the Solar Facility to be extended to March 1, 2023. In addition to the principal and interest payments due under the Solar Facility, the Company is required to pay a final payment fee to Solar due upon the earlier of prepayment, acceleration or the maturity date of the loan portion of the Solar Facility equal to 5.50% of the principal amount of the term loan actually funded. The Company is accruing the final payment fees using the effective interest rate, with a charge to non-cash interest expense, over the term of borrowing. If the Company prepays the loan prior to its scheduled maturity, the Company will also be required to pay prepayment fees to Solar equal to 1% of the principal amount of such term loan then-prepaid if prepaid after the second anniversary of funding of the principal amounts borrowed. The Company is also required to pay Solar an exit fee upon the occurrence, prior to March 2, 2030, of (a) any liquidation, dissolution or winding up of the Company, (b) transaction that results in a person obtaining control over the Company, (c) the Company achieving $100 million in trailing twelve month net product revenue or (d) the Company achieving $125 million in trailing twelve month net product revenue. The exit fee for liquidation, dissolution, winding up or change of control of the Company is equal to 4.50% of the principal amount of the term loans actually funded. The exit fee for achieving either $100 million or $125 million in trailing twelve-month net product revenue is equal to 2.25% of the principal amount of the term loans actually funded or, if both net product revenue milestones are achieved, 4.50% of the principal amount of the term loans actually funded. The exit fee is capped at 4.50% of the principal amount of the term loans actually funded. The Company’s obligations under the Solar Facility are secured by a first priority security interest in substantially all of its assets, including its intellectual property. The loan and security agreement requires the Company to comply with certain financial covenants as well as customary affirmative and negative covenants. The Solar Facility contains events of default, including, without limitation, events of default upon: (i) failure to make payment pursuant to the terms of the agreement; (ii) violation of covenants; (iii) material adverse changes to the Company’s business; (iv) attachment or levy on the Company’s assets or judicial restraint on its business; (v) insolvency; (vi) material cross-defaults; (vii) significant judgments, orders or decrees for payments by the Company not covered by insurance; (viii) incorrectness of representations and warranties; (ix) incurrence of subordinated debt; (x) a termination or breach of a guaranty; (xi) revocation of governmental approvals necessary for the Company to conduct its business; and (xii) failure by the Company to maintain a valid and perfected lien on the collateral securing the borrowing. As of December 31, 2022, the Company is in compliance with all covenants in the Solar Facility. Oxford Credit Facility Prior to March 2020, the Company had a $35.0 million credit facility in place with Oxford, which it entered into in March 2017 and that allowed it to borrow up to $35.0 million in three tranches of term loans: a Term A Loan in the amount of $25 million, which was drawn immediately upon closing in March 2017, a Term B Loan in the amount of $5.0 million, which was drawn down in December 2017, and a Term C Loan in the amount of $5.0 million which was never drawn down. Each term loan accrued interest from the date of borrowing through the date of repayment at a floating per annum rate of interest, which reset monthly and was equal to the greater of (a) 8.15% or (b) the 30 day U.S. LIBOR on the last business day of the month plus 7.38%. This facility featured an interest-only period on all tranches through March 2019. The Company evaluated whether the Solar Facility entered into in March 2020 represented a debt modification or extinguishment in accordance with ASC 470-50, Debt—Modifications and Extinguishments and determined that the existing debt was extinguished as a result of the full repayment of the existing facility and concurrent issuance of a new credit facility with a new lender. The unamortized balance of the Company’s combined debt discount and deferred issuance costs of $0.6 million related to the Oxford facility were accounted for as a loss on extinguishment of debt in March 2020.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Stockholders' Equity	13. STOCKHOLDERS’ EQUITY Common Stock Offering On February 2, 2021, the Company closed on their secondary public offering and sale (the “Offering) of their common stock in which the Company issued and sold 5,566,000 shares of our common stock, which included shares pursuant to an option granted to underwriters to purchase additional shares, at a public offering price of $15.50 per share. The Company received net proceeds of $80.6 million after deducting underwriting discounts, commissions and offering expenses. Common Stock The Company’s amended and restated certificate of incorporation as of December 31, 2020 authorized the issuance of 200.0 million shares of common stock, $0.01 par value per share, of which 27.3 million were issued and outstanding The following table summarizes the total number of shares of the Company’s common stock issued and reserved for issuance as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 December 31, 2021 ​ Shares of common stock issued 27,268 26,395 ​ Shares of common stock reserved for issuance for: ​ Common stock warrants outstanding 61 75 ​ Stock options outstanding 1,301 1,499 ​ Restricted stock units outstanding 3,901 2,124 ​ Shares available for grant under stock incentive plan 1,140 2,037 ​ Shares available for sale under employee stock purchase plan 1,063 799 ​ Total shares of common stock issued and reserved for issuance 34,734 32,929 ​ ​ Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Holders of common stock are entitled to receive any dividends that the Company’s board of directors may declare out of funds legally available for that purpose on a non-cumulative basis. The Company has never paid, and for the foreseeable future does not expect to pay, a dividend on its common stock. Common Stock Warrants The following table summarizes the Company’s outstanding common stock warrants as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ Warrants ​ Outstanding ​ ​ ​ ​ ​ (in thousands) ​ Exercise Price ​ Expiration Date 20 ​ $ 9.73 Aug-2023 20 ​ $ 9.73 Mar-2024 21 ​ $ 9.73 Dec-2024 61 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ Warrants ​ Outstanding ​ ​ ​ ​ ​ (in thousands) ​ Exercise Price ​ Expiration Date 14 ​ $ 19.55 ​ Dec-2022 20 ​ $ 9.73 Aug-2023 20 ​ $ 9.73 Mar-2024 21 ​ $ 9.73 Dec-2024 75 ​ ​

Loss Per Share

Loss Per Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Loss Per Share	14. LOSS PER SHARE The Company’s basic loss per common share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. The Company’s restricted stock awards (non-vested shares) are issued and outstanding at the time of grant but are excluded from the Company’s computation of weighted-average shares outstanding in the determination of basic loss per share until vesting occurs. A net loss cannot be diluted, so when the Company is in a net loss position, basic and diluted loss per common share are the same. If in the future the Company achieves profitability, the denominator of a diluted earnings per common share calculation will include both the weighted-average number of shares outstanding and the number of common stock equivalents, if the inclusion of such common stock equivalents would be dilutive. Dilutive common stock equivalents potentially include warrants, stock options, non-vested restricted stock awards and non-vested performance restricted stock units using the treasury stock method, along with the effect, if any, from the potential conversion of outstanding securities, such as convertible preferred stock. The following potentially dilutive securities outstanding as of December 31, 2022, 2021 and 2020 have been excluded from the denominator of the diluted loss per share of common stock outstanding calculation (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2021 2020 Stock options ​ 1,301 ​ 1,499 ​ 2,365 Non-vested performance restricted stock units ​ 395 395 — Non-vested restricted stock units ​ 3,506 1,729 1,860 Common stock warrants ​ 61 75 105 ​

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2022
Disclosure Of Compensation Related Costs Share-based Payments [Abstract]
Share-Based Compensation	15. SHARE-BASED COMPENSATION The amount of share-based compensation expense recognized by the Company by location in its statements of operations for the years ended December 31, 2022, 2021 and 2020 is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years ended December 31, ​ ​ ​ ​ 2022 ​ 2021 ​ 2020 Cost of revenues ​ ​ ​ $ 130 ​ $ 79 ​ $ 66 Sales and marketing ​ ​ ​ 4,286 ​ 2,096 ​ 1,813 General and administrative ​ ​ ​ 3,868 ​ 5,496 ​ 2,076 Research and development ​ ​ ​ 462 ​ 198 ​ 449 Total ​ ​ ​ $ 8,746 ​ $ 7,869 ​ $ 4,404 ​ 2018 Equity Incentive Plan In June 2018, the Company adopted the 2018 Equity Incentive Plan, or 2018 Plan, which authorized the issuance of up to 1.4 million shares, subject to an annual 4% increase based on the number of shares of common stock outstanding, in the form of restricted stock, stock appreciation rights and stock options to the Company’s directors, employees and consultants. The amount and terms of grants are determined by the Company’s board of directors. All stock options granted to date have had exercise prices equal to the fair value, as determined by the closing price as reported by the Nasdaq Global Market, of the underlying common stock on the date of grant. The contractual term of stock options is up to 10 years, and stock options are exercisable in cash or as otherwise determined by the board of directors. Generally, stock options vest 25% upon the first anniversary of the date of grant and the remainder ratably monthly thereafter for 36 months. Restricted stock units generally vest ratably in three equal installments on the first, second and third anniversaries of the grant date. Performance restricted stock units (“PRSUs”) generally vest based on appreciation of the Company’s common stock to a certain price as determined by the Company’s board of directors measured using a trailing 30-day volume weighted average price of a share of the Company’s common stock. The fair value of the PRSU awards are determined using a risk neutral Monte Carlo simulation valuation model. As of December 31, 2022, there were 0.7 million shares available for future issuance under the 2018 Plan. 2020 Inducement Incentive Plan In December 2020, the Company adopted the 2020 Inducement Incentive Plan, which authorized the issuance of up to 0.4 million shares in the form of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards and other stock awards to eligible employees who satisfy the standards for inducement grants under Nasdaq global market rules. In March 2022, the Company’s board of directors approved an additional 0.5 million shares for issuance under the plan. An individual who previously served as an employee or director of the Company is not eligible to receive awards under this plan. The amount and terms of grants are determined by the Company’s board of directors. As of December 31, 2022, there were 0.4 million shares available for future issuance under the 2020 Inducement Incentive Plan. Stock Options The following table summarizes the Company’s stock option activity for the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aggregate ​ ​ Number of ​ Weighted- ​ Weighted- ​ average ​ ​ Shares under ​ average ​ Remaining ​ Intrinsic ​ ​ Option ​ Exercise Price ​ Contractual ​ Value ​ ​ (in thousands) ​ per Option ​ Life (in years) ​ (in thousands) Outstanding at December 31, 2019 2,415 ​ $ 7.11 ​ Granted 1,028 ​ 2.01 ​ Exercised (371) ​ 1.86 ​ Forfeited (707) ​ 10.76 ​ Outstanding at December 31, 2020 2,365 ​ 4.62 ​ Granted — ​ — ​ Exercised (698) ​ 4.01 ​ Forfeited (168) ​ 14.32 ​ Outstanding at December 31, 2021 1,499 ​ $ 4.01 ​ ​ ​ Granted — ​ $ — ​ Exercised (168) ​ $ 1.77 ​ ​ Forfeited (30) ​ $ 13.81 ​ Outstanding at December 31, 2022 1,301 ​ $ 4.07 7.0 $ 5,001 Exercisable at December 31, 2022 869 ​ $ 4.82 6.7 $ 3,022 Vested and expected to vest at December 31, 2022 1,301 ​ $ 4.07 7.0 $ 5,001 ​ The Company recognized share-based compensation expense related to stock options of $0.7 million, $0.8 million and $1.7 million for the years ended December 31, 2022, 2021 and 2020, respectively. As of December 31, 2022, there was $0.6 million of total unrecognized compensation cost related to non-vested stock options which the Company expects to recognize over a weighted-average period of 1.3 years. The weighted-average grant-date fair value of stock options granted during the year ended December 31, 2020 was estimated at $1.09 per option. The Company did not grant stock options during the years ended December 31, 2022 and 2021. The total intrinsic value of stock options exercised during the years ended December 31, 2022, 2021 and 2020 was $0.2 million, $8.2 million, and $1.4 million, respectively. For the year ended December 31, 2020 the grant-date fair value of stock options was estimated at the time of grant using the following weighted-average inputs and assumptions in the Black-Scholes option pricing model: ​ ​ ​ ​ ​ ​ ​ 2020 Estimated fair value of common stock ​ $ 2.01 ​ Exercise price ​ $ 2.01 ​ Expected term (in years) ​ 6.1 ​ Risk-free interest rate ​ 0.4 % Expected volatility ​ 59.5 % Dividend yield ​ — % ​ Restricted Stock Awards and Restricted Stock Units The following table summarizes the Company’s restricted stock award, restricted stock unit and performance restricted stock unit activity for the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-vested ​ Weighted- Non-vested ​ Weighted- ​ ​ Restricted ​ ​ average ​ Performance Restricted ​ ​ average ​ ​ Stock Units ​ ​ Grant-date ​ Stock Units ​ ​ Grant-date ​ ​ (in thousands) ​ ​ Fair Value ​ (in thousands) ​ ​ Fair Value Non-vested at December 31, 2019 245 ​ $ 15.23 — ​ $ — Granted 2,307 ​ 3.18 500 ​ 1.71 Vested (98) ​ 13.24 — ​ — Forfeited ​ (594) ​ ​ 5.24 ​ — ​ ​ ​ Non-vested at December 31, 2020 1,860 ​ 3.58 500 ​ 1.71 Granted 1,008 ​ 11.51 145 ​ 15.59 Vested (780) ​ 3.63 (250) ​ 1.77 Forfeited (359) ​ 7.86 — ​ — Non-vested at December 31, 2021 ​ 1,729 ​ $ 7.29 395 ​ $ 6.77 Granted 2,902 ​ $ 3.36 — ​ $ — Vested (705) ​ $ 7.32 — ​ $ — Forfeited (420) ​ $ 5.35 — ​ $ — Non-vested at December 31, 2022 3,506 ​ $ 4.29 395 ​ $ 6.77 ​ The Company recognized share-based compensation expense related to restricted stock awards, restricted stock units and performance restricted stock units of $8.1 million, $7.1 million, and $2.7 million during the years ended December 31, 2022, 2021 and 2020, respectively. As of December 31, 2022, there was $8.7 million of unrecognized compensation cost related to non-vested restricted stock units and performance restricted stock units that the Company expects to recognize over a weighted-average period of 1.8 years. The total fair value at the vesting date of restricted stock awards, restricted stock units and performance restricted stock units vested during the years ended December 31, 2022, 2021 and 2020 was $2.5 million, $14.1 million, and $0.3 million, respectively. ​ The Company did not grant performance restricted stock units during the year ended December 31, 2022. For the years ended December 31, 2021 and 2020, the grant-date fair value of the performance restricted stock units was estimated at the time of grant using the following inputs and assumptions in the Monte Carlo simulation valuation model: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Closing price of common stock ​ ​ ​ $ 15.92 ​ $ 1.98 ​ Risk-free interest rate ​ ​ ​ 1.15 % 0.63 % Expected volatility ​ ​ ​ 99.7 % 87.4 % ​

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2022
Employee Benefit Plans
Employee Benefit Plans	16. EMPLOYEE BENEFIT PLANS Defined Contribution Plan The Company maintains a 401(k) defined contribution retirement plan which covers all of its employees. Employees are eligible to participate on the first of the month following their date of hire. Under the 401(k) plan, participating employees may defer up to 100% of their pre-tax salary but not more than statutory limits. As of December 31, 2022, the Company contributes 3% of employee salary to the participant’s defined contribution plan, which vests immediately. Employee contributions also vest immediately. 2018 Employee Stock Purchase Plan In July 2018, the Company adopted the 2018 Employee Stock Purchase Plan, or 2018 ESPP, with an initial 0.2 million share reserve, subject to automatic annual increases on January 1st of each year for a period of up to ten years, as defined in the plan document. The purpose of the 2018 ESPP is to enhance employee interest in the success and progress of the Company by encouraging employee ownership of common stock of the Company. The 2018 ESPP provides the opportunity to purchase the Company’s common stock at a 15% discount to the market price through payroll deductions or lump sum cash investments. As of December 31, 2022, the Company had not yet approved any offering under the plan and 1.1 million shares were reserved for issuance.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	17. INCOME TAXES The Company’s loss before income taxes was $37.2 million, $31.2 million, $27.5 million for the years ended December 31, 2022, 2021, and 2020, respectively, and was generated entirely in the United States. The Company did A reconciliation of the statutory United States federal income tax rate to the Company’s effective tax rate is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Tax Year ended December 31, ​ 2022 2021 2020 U.S. federal statutory income tax rate ​ 21.0 % 21.0 % 21.0 % State and local taxes, net of federal benefit (0.9) % 5.5 % 3.5 % Nondeductible expenses (2.3) % 10.6 % (0.8) % Research and development credits - % — % — % Tax rate change and true-up (1.5) % 0.8 % (1.6) % Change in valuation allowance (16.3) % (37.9) % (22.1) % Effective income tax rate — % — % — % ​ ​ The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 ​ 2021 Deferred tax assets: ​ ​ Net operating loss carryforwards ​ $ 76,013 ​ $ 72,620 Research and development credits ​ 3,008 ​ 3,008 Share-based compensation ​ 2,273 ​ 2,111 Accruals ​ 1,379 ​ 786 Interest expense ​ 3,807 ​ 3,308 Lease Liability ​ 929 ​ 1,024 Capitalized start-up costs ​ 215 ​ 479 Capitalized R&D costs ​ ​ 2,165 ​ ​ — Other temporary differences ​ 1,000 ​ 1,050 Gross deferred tax assets ​ 90,789 ​ 84,386 Less: Valuation allowance ​ (86,733) ​ (80,663) Total deferred tax assets ​ $ 4,056 ​ $ 3,723 ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ Capitalized software ​ $ (894) ​ $ (753) Right-of-use asset ​ (816) ​ (945) Prepaid commission ​ (2,346) ​ (2,025) Gross deferred tax liabilities ​ (4,056) ​ (3,723) Net deferred taxes ​ $ — ​ $ — ​ In assessing the realizability of the net deferred tax asset, the Company considers all relevant positive and negative evidence in determining whether it is more likely than not that some portion or all of the deferred income tax assets will not be realized. The realization of the gross deferred tax assets is dependent on several factors, including the generation of sufficient taxable income prior to the expiration of the net operating loss carryforwards. The Company believes that it is more likely than not that the Company’s deferred income tax asset associated with its net operating losses will not be realized in the immediate future. As such, there is a full valuation allowance against the net deferred tax assets as of December 31, 2022 and 2021. The valuation allowance increased by ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2022 2021 Balance at the beginning of the year ​ $ 80,663 ​ $ 68,856 Amounts charged to expense ​ 6,070 ​ 11,807 Balance at the end of the year ​ $ 86,733 ​ $ 80,663 ​ The following table summarizes carryforwards of federal net operating losses and tax credits as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Expiration ​ ​ Amount ​ Beginning in Federal net operating losses ​ $ 312,721 2023 State net operating losses ​ $ 197,281 2023 Research and development credits ​ $ 3,008 2023 ​ Under the Tax Reform Act of 1986 (the “Act”), the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has not done an analysis to determine whether or not ownership changes, as defined by the Act, have occurred since inception. The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2022, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s statements of operations. Due to net operating loss and tax credit carry forwards that remain unutilized, income tax returns for tax years from inception through 2021 remain subject to examination by the taxing jurisdictions.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	18. COMMITMENTS AND CONTINGENCIES Executive Employment Agreements The Company has entered into an employment agreement and offer letters with certain key executives, providing for compensation and severance in certain circumstances, as defined in the agreements. Legal Matters The Company is subject from time to time to various claims and legal actions arising during the ordinary course of its business. Management believes that there are currently no claims or legal actions that would reasonably be expected to have a material adverse effect on the Company’s results of operations, financial condition or cash flows.

Distribution Agreement with Tei

Distribution Agreement with Teijin Pharma Limited	12 Months Ended
	Dec. 31, 2022
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Distribution Agreement with Teijin Pharma Limited	19 . In October 2017, the Company entered into a seven-and-a-half-year In 2017, under the distribution agreement with Teijin, the Company received an upfront payment of $0.75 million and a milestone payment of $2.0 million following the Japanese Ministry of Health, Labour and Welfare’s, or JMHLW, approval of marketing the NeuroStar Advanced Therapy System for the treatment of MDD in Japan. In the second quarter of 2019, under the distribution agreement with Teijin, the Company earned a second milestone payment of $0.7 million, following Japan’s Central Social Insurance Medical Council (Chuikyo) approval of the recommendation by JMHLW’s expert review panel to provide reimbursement for NeuroStar Advanced Therapy for the treatment of MDD in adults. The reimbursement went into effect on June 1, 2019 and covers patients who are treated in the largest inpatient and outpatient psychiatric facilities in Japan at the rate of JPY12,000 per treatment session. These upfront and subsequent milestone payments have been deferred and are being recognized as revenue over the seven-and one-half year In May 2019, the Company and Teijin entered into an amendment to the distribution agreement, which among other things finalized transfer prices, forecasting and minimum purchases, and made certain clarifications to the agreement. The distribution agreement is scheduled to expire on March 31, 2025, subject to earlier termination if the Company or Teijin breach the agreement, Teijin fails to maintain distributor-level permits and approvals, Teijin fails to purchase from the Company specified dollar values of its sales forecasts, reimbursement for treatment of MDD using the NeuroStar Advanced Therapy System is not obtained from JMHLW by specified dates or such reimbursement is below specified minimums, Teijin reasonably believes that it is not commercially reasonable to continue distributing the NeuroStar Advanced Therapy System in Japan or bankruptcy related events occur. The term of the distribution agreement will be automatically extended for two years unless either party gives the other party at least two years’ prior written of notice of non-renewal, except that the Company cannot decline to renew the agreement if Teijin has purchased 100% of its sales forecasts over the term of the agreement.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2022
Segments Geographical Areas [Abstract]
Segment Information	20. SEGMENT INFORMATION Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company currently operates in one business segment as it is managed and operated as one business. A single management team that reports to the chief operating decision maker comprehensively manages the entire business. The Company does not operate any material separate lines of business or separate business entities with respect to its products or product development.

Severance

Severance	12 Months Ended
	Dec. 31, 2022
Restructuring And Related Activities [Abstract]
Severance	21. SEVERANCE On April 8, 2020, the Company took action to reduce expenses through a reduction in force (“RIF”). As part of this action the Company terminated 95 employees who received separation benefits upon their termination. During the second quarter of 2020, the Company recorded a separation-related charge for the RIF equal to the fair value of the terminated employees benefits as of the communication date in the amount of $2.1 million. This amount was paid out during the quarter with the final payoff occurring on June 15, 2020. The Company entered into transition agreements outlining the separation with its former chief executive officer in March 2020, the vice president of medical operations in September 2020, and the chief commercial officer, vice president of commercial access and director of medical operations in December 2020, the VP of sales and five business development managers in January 2021, the director of strategic clinical development in February 2021, and the vice president of marketing in August 2021 and vice president of marketing in December 2022. In connection with these agreements, the Company recorded $0.6 million and $0.5 million of charges in salary, payroll tax and bonus expenses for the years ended December 31, 2022 and 2021, respectively. For the year ended December 31, 2022 and 2021, $0.5 million and $1.3 million of termination benefits were paid associated with the termination of the employees and charged against this liability. As of December 31, 2022 and December 31, 2021, $0.3 million and $0.1 million, respectively, remain in accrued liabilities for the unpaid portion of the separation benefits.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with GAAP and the rules and regulations of the United States Securities and Exchange Commission (“SEC”), requires the use of estimates and assumptions, based on judgments considered reasonable, which affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates and assumptions on historical experience, known trends and events and various other factors that management believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Although management believes its estimates and assumptions are reasonable when made, they are based upon information available at the time they are made. Management evaluates the estimates and assumptions on an ongoing basis and, if necessary, makes adjustments. Due to the risks and uncertainties involved in the Company’s business and evolving market conditions and given the subjective element of the estimates and assumptions made, actual results may differ from estimated results.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. As of December 31, 2022 and 2021, cash equivalents consisted of money market funds.
Concentration of Credit Risk	Concentrations of Credit Risk The Company’s cash is held on deposit in demand accounts at a large financial institution in amounts in excess of the Federal Deposit Insurance Corporation (“FDIC”), insurance coverage limit of $250,000 per depositor, per FDIC-insured bank, per ownership category. Financial instruments that potentially subject the Company to concentrations of credit risk principally consist of cash equivalents and accounts receivable. The Company limits its credit risk associated with cash equivalents by placing investments in highly-rated money market funds. The Company limits its credit risk with respect to accounts receivable by performing credit evaluations when deemed necessary, but it does not require collateral to secure amounts owed by its customers.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company maintains allowances for doubtful accounts for estimated losses resulting from amounts deemed to be uncollectible from its customers. These allowances are for specific amounts on certain customer accounts based on facts and circumstances determined on a case-by-case basis.
Leases	Leases The Company accounts for leases in accordance with ASC Topic 842, Leases The Company leases warehouse, office space, a training facility and office equipment pursuant to net operating leases. Operating leases where the Company is the lessor are included in revenue on the Statements of Operations. From time to time the Company enters into sales-type lease arrangements that include a lessee obligation to purchase the leased equipment at the end of the lease term, automatic transfer of ownership of the leased equipment at the end of the lease, a lessee purchase option reasonably certain to be exercised, or provides for minimum lease payments with a present value equal to or exceeding substantially all of the fair value of the underlying leased equipment at the date of lease inception. Sales-type leases where the Company is the lessor are included in revenue on the Statements of Operations. Operating leases where the Company is the lessee are included in operating lease right-of-use assets and operating lease liabilities on the Balance Sheets. The lease liabilities are initially measured at the present value of the unpaid lease payments at the lease commencement date. The Company uses the following inputs in its lease calculations under Topic 842: (1) the discount rate the Company uses to discount the unpaid lease payments to present value, (2) lease term, and (3) lease payments. (1) Topic 842 requires a lessor to discount its unpaid lease payments using the interest rate implicit in the lease and a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most leases where the Company is the lessee do not provide an implicit rate, the Company uses the incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The incremental borrowing rate for a lease is the rate of interest the Company would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The Company uses the implicit rate when readily determinable. (2) The lease term for all leases includes the noncancelable period of the lease plus any additional periods covered by either a lessee option to extend (or not to terminate) the lease that the lessee is reasonably certain to exercise, or an option to extend (or not to terminate) the lease controlled by the lessor. (3) Lease payments included in the measurement of the lease asset or liability comprise the following: fixed payments (including in-substance fixed payments), and the exercise price of a lessee option to purchase the underlying asset if the lessee is reasonably certain to exercise. For operating leases where the Company is the lessor, the Company continues recognizing the underlying asset and depreciating it over its estimated useful life. Lease income from lessees is recognized on a straight-line basis over the terms of the relevant lease agreement in revenue. Operating leases for equipment with fixed rentals and step rentals are recognized on a straight-line basis over the term of the lease, assuming no renewals, in revenue. Revenue is not recognized when collection is not reasonably assured. When collectability is not reasonably assured, the customer is placed on non-accrual status and revenue is recognized when cash payments are received. The lease asset for sales-type leases is initially measured as the total net investment in the lease, which comprises the initial amount of the lease receivable plus the deferred initial direct costs. The lease asset for sales-type leases is subsequently measured throughout the lease term at the carrying amount of the net investment in the lease which is increased by interest income and reduced by lease payments collected. The lease payments are segregated into principal and interest components similar to a loan. Equipment leasing revenues are recognized on an effective interest method over the lease term. The principal component of the lease payment is reflected as a reduction to the net investment in the lease. For operating leases where the Company is the lessee, the right-of-use (“ROU”), asset is initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred less any lease incentives received. The ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, plus (minus) any prepaid (accrued) lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Lease assets for sales-type leases where the Company is the lessor and ROU assets for operating leases where the Company is the lessee are periodically reduced by impairment losses. The Company uses the loans impairment guidance in ASC Subtopic 330-10, Receivables, and the long-lived assets impairment guidance in ASC Subtopic 360-10, Property, Plant, and Equipment – Overall, to determine whether a lease asset or a ROU asset, respectively, is impaired, and if so, the amount of the impairment loss to recognize. For the years ended December 31, 2022, and 2020 the Company did not recognize any impairment losses. The Company recognized $0.1 million in impairment losses which is included within Sales and marketing expense on the statement of operations for the year ended December 31, 2021. The Company monitors for events or changes in circumstances that require a reassessment of its leases. When a reassessment results in the remeasurement of a lease liability, a corresponding adjustment is made to the carrying amount of the corresponding ROU asset unless doing so would reduce the carrying amount of the ROU asset to an amount less than zero. In that case, the amount of the adjustment that would result in a negative ROU asset balance is recorded in profit or loss. The Company has elected not to recognize ROU assets and lease liabilities for all short-term leases that have a lease term of 12 months or less. The Company recognizes the lease payments associated with the short-term leases as an expense on a straight-line basis over the lease term. Variable lease payments associated with these leases are recognized and presented in the same manner as for all other leases. The Company has elected to exclude sales and other similar taxes from lease payments in arrangements where the Company is a lessor.
Inventory	Inventory Inventory is stated at the lower of cost and net realizable value, with cost being determined on a first in, first out basis. The Company’s inventory is primarily comprised of finished goods.
Property and Equipment and Capitalized Software	Property and Equipment and Capitalized Software Property and equipment are recorded at cost. Maintenance and repairs are charged to expense as incurred and costs of improvements and renewals are capitalized. Depreciation and amortization are recognized using the straight-line method based on the estimated useful lives of the related assets. The Company uses an estimated useful life of three years for computers and software, five years for laboratory and office equipment, six years for devices in the rental agreement program and the lesser of five years or the remaining life of the underlying facility lease for leasehold improvements. Software development costs relating to assets to be sold in the normal course of business are included in research and development and are expensed as incurred until technological feasibility is established. After technological feasibility is established, software development costs are capitalized. The Company uses an estimated useful life of two years for capitalized software and amortizes these costs beginning at the product release.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets, such as property and equipment, are tested for impairment when events or changes in circumstances indicate that the carrying value of the asset may not be recoverable. Impairment testing requires management to estimate the future net undiscounted cash flows of an asset using assumptions believed to be reasonable. Actual cash flows may differ from the estimates used in the impairment testing. If such assets are considered to be impaired, the Company recognizes an impairment loss when and to the extent that the estimated fair value of an asset is less than its carrying value. The Company has not recorded any impairment of its long-lived assets for the years ended December 31, 2022, 2021 and 2020.
Note Receivables	Note Receivables Note receivables are reported on the Company’s balance sheet at amortized cost basis. The Company recognizes interest income within other income, net within the statements of operations. Note receivables are periodically reviewed to determine whether a note receivable is impaired, and if so, the amount of the impairment loss to recognize. For the year ended December 31, 2021, the Company recognized $0.1 million in impairment charges which is included within “Sales and marketing expense” on the statements of operations. For the year ended December 31, 2022 there were no impairment charges.
Deferred Debt Issuance Costs	Deferred Debt Issuance Costs The Company capitalizes direct costs incurred to obtain debt financing and amortizes these costs to interest expense over the term of the debt using the effective interest method. These costs are recorded as a debt discount and are netted against the related debt on the Company’s balance sheets.
Revenue Recognition	Revenue Recognition ASC Topic 606, Revenue from Contracts with Customers Sales and usage-based taxes are excluded from revenues. Contract Formation The Company accounts for a contract with a customer when there is a legally enforceable contract between the Company and the customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. For all sales, the Company uses either a signed agreement or a binding purchase order as evidence of an arrangement. Performance Obligations The unit of account for Topic 606 is the performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer or a series of distinct goods or services that are substantially the same and have the same pattern of transfer. A contract’s transaction price is allocated to each performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of the Company’s contracts are comprised of the following performance obligations: (1) The NeuroStar TMS Therapy System (the “System”) which includes a chair, an electromagnet coil, a monitoring console and accessories. The various components are inputs that function together to deliver a combined output and together form one performance obligation (a NeuroStar Advanced Therapy System). Revenues from the sale of the System are satisfied at the point-in-time when shipped from our premises. (2) NeuroStar Treatment Session (the “Treatment Session”) is a single use consumable that is delivered via an encrypted activation code and is required in order for a clinician to perform TMS therapy. Revenues from the sale of the Treatment Sessions are satisfied at the point-in-time when delivered to the customer. The Company determined that sales of Treatment Sessions are not part of the enforceable rights and obligations of the System sales, except when sold with System sales. (3) Separately priced extended warranties and when-and-if-available upgrade rights are considered service-type warranties. Warranty services are considered stand-ready obligations satisfied over-time and recognized using a straight-line time-based measurement toward completion. (4) The System clinical and reimbursement training enable the clinician to provide patient treatment. The trainings are not required in order to operate the System but are required in order to receive a certification from the Company and accordingly are not essential to the functionality of other performance obligations. Training services are recognized at a point-in-time when training is complete, typically simultaneous to or near the time of delivery of the System. In addition, the Company has determined that there are various perfunctory deliverables such as installation of the System, the technical support hotline and marketing materials which the Company does not separately recognize as revenue nor does the Company accrue the estimated cost of providing these goods and services because they are not material. The Company provides a one-year warranty on all new System sales which were determined to be assurance-type warranties and thus not considered a separate performance obligation. The Company accrues the cost of providing these warranties. There is no right of return or refund for any of the Company’s products or services and the Company has elected to treat shipping and handling as a fulfillment activity and expenses the costs as incurred. Rent-to-Own The System is typically purchased but the Company does offer certain customers the option to lease instead. The Company accounts for these leases under Topic 842, Leases Distribution Agreement The Company has an exclusive distribution agreement that began in October 2017 with a foreign entity for a period of 7 ● Exclusive distribution and intellectual property license ● NeuroStar TMS Therapy System ● NeuroStar Treatment Session The distribution agreement contains pricing for the Company’s products and services. The contractual purchase prices were determined to be at the standalone selling prices based on the expected sales volumes of this customer type and thus the Company concluded that this agreement did not contain a separate performance obligation for the material right to discounted Systems and Treatments Sessions. The Company allocated the transaction price through a combination of the cost plus a margin approach and the residual method. For the System and Treatment Sessions the Company maximized the use of observable inputs by beginning with average historical contractual selling prices and adjusting on a consistent and rational basis for pricing trends, the customer type and expected sales volumes and the Company’s changing cost and margins. Since it was determined that the contractual selling prices for the Company’s products and services in the distribution agreement were at the standalone selling prices, the residual consideration which is made up of the fixed and variable milestone payments was allocated to the exclusive distribution and intellectual property license. The exclusive distribution and intellectual property rights were determined to be symbolic IP and thus recognized over time. The System and Treatment Sessions were determined to be performance obligations recognized at a point-in-time when delivered to the distributor. Contract Estimates Accounting for the Company’s contracts involves the use of significant judgments and estimates including determining the separate performance obligations, allocating the transaction price to the different performance obligations and determining the method to measure the entity’s performance toward satisfaction of performance obligations that most faithfully depicts when control is transferred to the customer. The Company allocates the contract’s transaction price to each performance obligation using the Company’s best estimate of the standalone selling price for each distinct good or service in the contract. The Company maximizes the use of observable inputs by beginning with average historical contractual selling prices and adjusting as necessary and on a consistent and rational basis for other inputs such as pricing trends, customer types, volumes and changing cost and margins. Contract Balances Payment terms typically require payment upon shipment of the System and additional payments as access codes are delivered, which can span several years after the System is first delivered and installed. The timing of revenue recognition compared to billings and cash collections typically results in accounts receivable. However, sometimes customer advances and deposits might be required for certain customers and are recorded as contract liabilities. Changes in the contract asset and liability balances during the years ended December 31, 2022 and 2021 were not materially impacted by any other factors. ​ ​ ​ As of December 31, 2022, the Company expects to recognize approximately the following percentages of deferred revenue by year: ​ ​ ​ ​ ​ ​ Revenue Year: ​ Recognition 2023 67 % 2024 25 % 2025 8 % 2026 — % 2027 — % Thereafter — % Total 100 % ​ ​ ​ ​ ​ Revenue recognized for the years ended December 31, 2022 and 2021 that was included in the contract liability balance at the beginning of the year was $2.5 million and $1.9 million, respectively, and primarily represented revenue earned from separately priced extended warranties, rent-to-own revenue, milestone revenue, and clinical training. Customers Significant customers are those which represent more than 10% of the Company’s total revenue. For the years ended December 31, 2022, 2021 and 2020, one customer accounted for 17%, 20% and 22% respectively, of the Company’s revenue. Accounts receivable outstanding related to the customer was $5.2 million and $2.5 million as of December 31, 2022 and 2021, respectively. Geographical Information The following geographic data includes revenue generated from the Company’s third-party distributors. The Company’s revenue was generated in the following geographic regions and by product line for the periods indicated (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues by Geography ​ ​ ​ Year Ended December 31, ​ ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ ​ ​ Amount ​ Revenues ​ Amount ​ Revenues ​ ​ ​ (in thousands, except percentages) ​ ​ United States $ 63,406 97 % $ 53,447 97 % ​ International ​ 1,800 3 % 1,865 3 % ​ Total revenues ​ $ 65,206 100 % $ 55,312 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Revenues by Product Category ​ ​ ​ Year Ended December 31, ​ ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ ​ % of ​ ​ ​ % of ​ ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) ​ ​ NeuroStar Advanced Therapy System ​ $ 16,575 ​ 26 % $ 9,760 ​ 18 % ​ Treatment sessions ​ 45,077 71 % 41,933 78 % ​ Other ​ 1,754 3 % 1,754 4 % ​ Total U.S. revenues ​ $ 63,406 100 % $ 53,447 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ International Revenues by Product Category ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ (in thousands, except percentages) ​ NeuroStar Advanced Therapy System ​ $ 811 45 % $ 1,108 59 % Treatment sessions ​ 354 20 % 264 14 % Other ​ 635 35 % 493 27 % Total International revenues ​ $ 1,800 100 % $ 1,865 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues by Geography ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) ​ United States ​ $ 53,447 97 % $ 47,519 96 % International ​ 1,865 3 % 1,725 4 % Total revenues ​ $ 55,312 100 % $ 49,244 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Revenues by Product Category ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ % of ​ ​ % of ​ ​ Amount ​ Revenues ​ Amount ​ Revenues ​ (in thousands, except percentages) ​ NeuroStar Advanced Therapy System ​ $ 9,760 18 % $ 11,094 23 % Treatment sessions ​ 41,933 78 % 34,852 73 % Other ​ 1,754 4 % 1,573 4 % Total U.S. revenues ​ $ 53,447 100 % $ 47,519 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ International Revenues by Product Category ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) NeuroStar Advanced Therapy System ​ $ 1,108 59 % $ 856 50 % Treatment sessions ​ 264 14 % 449 26 % Other ​ 493 27 % 420 24 % Total International revenues ​ $ 1,865 100 % $ 1,725 100 % ​ ​ ​ ​ ​ ​
Research and Development Expenses	Research and Development Expenses Research and development activities are expensed as incurred. Costs incurred in obtaining technology licenses are charged immediately to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future uses.
Share-based Compensation	Share-based Compensation The Company recognizes the grant-date fair value of share-based awards issued as compensation as expense on a straight-line basis over the requisite service period, which is generally the vesting period of the award. The fair value of restricted stock awards and restricted stock units is estimated at the time of grant, based on the grant date fair value of the Company’s common stock. The fair value of performance restricted stock units is estimated at the time of grant and is determined using a risk neutral Monte Carlo simulation valuation model, which requires the use of inputs and assumptions such as the fair value of the underlying common stock, risk free interest rate, and expected volatility. The performance restricted stock units generally vest based on appreciation of the Company’s common stock to a certain price as determined by the Company’s board of directors measured using a trailing 30-day volume weighted average price of a share of the Company’s common stock. The fair value of stock options is estimated at the time of grant using the Black-Scholes option pricing model, which requires the use of inputs and assumptions such as the fair value of the underlying common stock, exercise price of the option, expected term, risk-free interest rate, expected volatility and dividend yield.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes the enactment date. A valuation allowance is recorded to the extent it is more likely than not that some portion or all of the deferred tax assets will not be realized. Unrecognized income tax benefits represent income tax positions taken on income tax returns that have not been recognized in the financial statements. The Company recognizes the benefit of an income tax position only if it is more likely than not (greater than 50%) that the tax position will be sustained upon tax examination, based solely on the technical merits of the tax position. Otherwise, no benefit is recognized. The tax benefits recognized are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The Company accrues interest and related penalties are classified as income tax expense in the statements of operations. The Company does not anticipate significant changes in the amount of unrecognized income tax benefits over the next year.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Summary of Percentages of Deferred Revenue by Year	​ ​ ​ ​ ​ ​ Revenue Year: ​ Recognition 2023 67 % 2024 25 % 2025 8 % 2026 — % 2027 — % Thereafter — % Total 100 % ​ ​ ​ ​ ​
Summary of Revenue Generated in Geographic Regions for Years Indicated	The following geographic data includes revenue generated from the Company’s third-party distributors. The Company’s revenue was generated in the following geographic regions and by product line for the periods indicated (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues by Geography ​ ​ ​ Year Ended December 31, ​ ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ ​ ​ Amount ​ Revenues ​ Amount ​ Revenues ​ ​ ​ (in thousands, except percentages) ​ ​ United States $ 63,406 97 % $ 53,447 97 % ​ International ​ 1,800 3 % 1,865 3 % ​ Total revenues ​ $ 65,206 100 % $ 55,312 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues by Geography ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) ​ United States ​ $ 53,447 97 % $ 47,519 96 % International ​ 1,865 3 % 1,725 4 % Total revenues ​ $ 55,312 100 % $ 49,244 100 % ​
United States
Summary of Revenue Generated in Product Category for Years Indicated	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Revenues by Product Category ​ ​ ​ Year Ended December 31, ​ ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ ​ % of ​ ​ ​ % of ​ ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) ​ ​ NeuroStar Advanced Therapy System ​ $ 16,575 ​ 26 % $ 9,760 ​ 18 % ​ Treatment sessions ​ 45,077 71 % 41,933 78 % ​ Other ​ 1,754 3 % 1,754 4 % ​ Total U.S. revenues ​ $ 63,406 100 % $ 53,447 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Revenues by Product Category ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ % of ​ ​ % of ​ ​ Amount ​ Revenues ​ Amount ​ Revenues ​ (in thousands, except percentages) ​ NeuroStar Advanced Therapy System ​ $ 9,760 18 % $ 11,094 23 % Treatment sessions ​ 41,933 78 % 34,852 73 % Other ​ 1,754 4 % 1,573 4 % Total U.S. revenues ​ $ 53,447 100 % $ 47,519 100 %
International
Summary of Revenue Generated in Product Category for Years Indicated	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ International Revenues by Product Category ​ ​ Year Ended December 31, ​ ​ 2022 ​ 2021 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ (in thousands, except percentages) ​ NeuroStar Advanced Therapy System ​ $ 811 45 % $ 1,108 59 % Treatment sessions ​ 354 20 % 264 14 % Other ​ 635 35 % 493 27 % Total International revenues ​ $ 1,800 100 % $ 1,865 100 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ International Revenues by Product Category ​ ​ Year ended December 31, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ % of ​ ​ ​ ​ % of ​ Amount Revenues Amount Revenues ​ ​ (in thousands, except percentages) NeuroStar Advanced Therapy System ​ $ 1,108 59 % $ 856 50 % Treatment sessions ​ 264 14 % 449 26 % Other ​ 493 27 % 420 24 % Total International revenues ​ $ 1,865 100 % $ 1,725 100 % ​

Fair Value Measurement and Fi_2

Fair Value Measurement and Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of Carrying Amounts and Fair Values of Financial Instruments	The following tables set forth the carrying amounts and fair values of the Company’s financial instruments as December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement Based on ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices In ​ other ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Observable ​ Unobservable ​ ​ Carrying ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ Amount Fair Value (Level 1) (Level 2) (Level 3) Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (cash equivalents) ​ $ 68,002 ​ $ 68,002 ​ $ 68,002 ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement Based on ​ ​ ​ ​ ​ ​ ​ ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prices In ​ other ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ Active ​ Observable ​ Unobservable ​ ​ Carrying ​ ​ ​ ​ Markets ​ Inputs ​ Inputs ​ ​ Amount ​ Fair Value ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets ​ ​ ​ ​ ​ Money market funds (cash equivalents) ​ $ 91,236 ​ $ 91,236 ​ $ 91,236 ​ $ — ​ $ —

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2022
Receivables [Abstract]
Composition of Accounts Receivable, Net	The following table presents the composition of accounts receivable, net as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2021 Gross accounts receivable - trade ​ $ 15,239 ​ $ 9,168 Less: Allowances for doubtful accounts ​ (1,648) ​ (1,462) Accounts receivable, net ​ $ 13,591 ​ $ 7,706 ​
Allowance for Doubtful Accounts	​ The following table presents a rollforward of the allowance for doubtful accounts (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Bad Debt ​ Write-offs of ​ Balance at ​ ​ Beginning of ​ Expense ​ Uncollectible ​ End of ​ Period Recognized Balances Period Year ended December 31, 2020 ​ $ (548) ​ (897) ​ 433 ​ $ (1,012) Year ended December 31, 2021 ​ $ (1,012) (763) 313 ​ $ (1,462) Year ended December 31, 2022 ​ $ (1,462) (341) 155 ​ $ (1,648)

Property and Equipment and Ca_2

Property and Equipment and Capitalized Software (Tables)	12 Months Ended
	Dec. 31, 2022
Property Plant And Equipment [Abstract]
Summary of Composition of Property and Equipment, Net	The following table presents the composition of property and equipment, net as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2021 Laboratory equipment ​ $ 462 ​ $ 249 Office equipment ​ 508 ​ 497 Computer equipment and software ​ 1,758 ​ 1,598 Manufacturing equipment ​ 343 ​ 341 Leasehold improvements ​ 1,435 ​ 471 Rental equipment ​ 542 ​ 601 Property and equipment, gross ​ 5,048 ​ 3,757 Less: Accumulated depreciation ​ (3,057) ​ (2,537) Property and equipment, net ​ $ 1,991 ​ $ 1,220 ​

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Schedule of Supplemental Cash Flow Information as Lessee Related to Leases	The following table presents the supplemental cash flow information as a lessee related to leases for the years ended December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended Year ended ​ ​ December 31, 2022 ​ December 31, 2021 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 892 ​ $ 822 Right-of-use assets obtained in exchange for lease obligations: ​ ​ ​ ​ ​ ​ Operating leases ​ $ — ​ $ 866 ​
Schedule of Future Payments of Operating Lease Liabilities	The following table sets forth by year the required future payments of operating lease liabilities as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2022 ​ 2023 ​ $ 853 ​ 2024 ​ ​ 875 ​ 2025 ​ 898 ​ 2026 ​ 921 ​ 2027 ​ 882 ​ Thereafter ​ 116 ​ Total lease payments ​ 4,545 ​ Less imputed interest ​ (754) ​ Present value of operating lease liabilities ​ $ 3,791 ​ ​
Schedule of Profit Recognized on Sales-type Leases	The following table sets forth the profit recognized on sales-type leases (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ ​ 2022 ​ 2021 Profit recognized at commencement, net ​ $ 478 ​ $ 807 Interest income ​ — ​ — Total sales-type lease income ​ $ 478 ​ $ 807 ​
Schedule of Maturity Analysis of Undiscounted Lease Receivables Related to Sales-type Leases	The following table sets forth a maturity analysis of the undiscounted lease receivables related to sales-type leases as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2023 ​ $ 1,538 2024 ​ ​ 824 2025 ​ 358 2026 ​ 40 2027 ​ ​ — Total sales-type lease receivables ​ $ 2,760 ​

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2022
Payables And Accruals [Abstract]
Summary of Composition of Accrued Expenses	The following table presents the composition of accrued expenses as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, ​ ​ 2022 ​ 2021 Compensation and related benefits ​ $ 11,201 ​ $ 5,090 Consulting and professional fees ​ 761 ​ 537 Research and development expenses ​ 678 ​ 388 Sales and marketing expenses ​ ​ 410 ​ ​ 268 Warranty ​ 328 ​ 306 Sales and other taxes payable ​ 659 ​ 664 Other ​ 800 ​ 980 Accrued expenses ​ $ 14,837 ​ $ 8,233

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Summary of Composition of Debt	The following table presents the composition of debt as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, ​ ​ 2022 2021 ​ Outstanding principal ​ $ 35,000 ​ $ 35,000 ​ Accrued final payment fees ​ 1,925 ​ 1,925 ​ Less debt discounts ​ (971) ​ (1,590) ​ Total debt, net ​ 35,954 ​ 35,335 ​ Less current portion ​ (13,125) ​ — ​ Long-term debt, net ​ $ 22,829 ​ $ 35,335 ​
Summary of Future Principal Payments	​ ​ ​ ​ ​ ​ Principal Year: ​ Payments 2023 ​ $ 13,125 2024 ​ 17,500 2025 ​ 4,375 2026 ​ — 2027 ​ — Total principal payments ​ $ 35,000

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Summary of Common Stock Issued and Reserved for Issuance	The following table summarizes the total number of shares of the Company’s common stock issued and reserved for issuance as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 December 31, 2021 ​ Shares of common stock issued 27,268 26,395 ​ Shares of common stock reserved for issuance for: ​ Common stock warrants outstanding 61 75 ​ Stock options outstanding 1,301 1,499 ​ Restricted stock units outstanding 3,901 2,124 ​ Shares available for grant under stock incentive plan 1,140 2,037 ​ Shares available for sale under employee stock purchase plan 1,063 799 ​ Total shares of common stock issued and reserved for issuance 34,734 32,929 ​ ​
Summary of Outstanding Warrants	The following table summarizes the Company’s outstanding common stock warrants as of December 31, 2022 and 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ Warrants ​ Outstanding ​ ​ ​ ​ ​ (in thousands) ​ Exercise Price ​ Expiration Date 20 ​ $ 9.73 Aug-2023 20 ​ $ 9.73 Mar-2024 21 ​ $ 9.73 Dec-2024 61 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ Warrants ​ Outstanding ​ ​ ​ ​ ​ (in thousands) ​ Exercise Price ​ Expiration Date 14 ​ $ 19.55 ​ Dec-2022 20 ​ $ 9.73 Aug-2023 20 ​ $ 9.73 Mar-2024 21 ​ $ 9.73 Dec-2024 75 ​

Loss Per Share (Tables)

Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Securities Outstanding Excluded from Diluted Loss Per Share Calculation	The following potentially dilutive securities outstanding as of December 31, 2022, 2021 and 2020 have been excluded from the denominator of the diluted loss per share of common stock outstanding calculation (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 2021 2020 Stock options ​ 1,301 ​ 1,499 ​ 2,365 Non-vested performance restricted stock units ​ 395 395 — Non-vested restricted stock units ​ 3,506 1,729 1,860 Common stock warrants ​ 61 75 105

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Disclosure Of Compensation Related Costs Share-based Payments [Abstract]
Summary of Share-Based Compensation Expense	The amount of share-based compensation expense recognized by the Company by location in its statements of operations for the years ended December 31, 2022, 2021 and 2020 is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years ended December 31, ​ ​ ​ ​ 2022 ​ 2021 ​ 2020 Cost of revenues ​ ​ ​ $ 130 ​ $ 79 ​ $ 66 Sales and marketing ​ ​ ​ 4,286 ​ 2,096 ​ 1,813 General and administrative ​ ​ ​ 3,868 ​ 5,496 ​ 2,076 Research and development ​ ​ ​ 462 ​ 198 ​ 449 Total ​ ​ ​ $ 8,746 ​ $ 7,869 ​ $ 4,404 ​
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity for the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aggregate ​ ​ Number of ​ Weighted- ​ Weighted- ​ average ​ ​ Shares under ​ average ​ Remaining ​ Intrinsic ​ ​ Option ​ Exercise Price ​ Contractual ​ Value ​ ​ (in thousands) ​ per Option ​ Life (in years) ​ (in thousands) Outstanding at December 31, 2019 2,415 ​ $ 7.11 ​ Granted 1,028 ​ 2.01 ​ Exercised (371) ​ 1.86 ​ Forfeited (707) ​ 10.76 ​ Outstanding at December 31, 2020 2,365 ​ 4.62 ​ Granted — ​ — ​ Exercised (698) ​ 4.01 ​ Forfeited (168) ​ 14.32 ​ Outstanding at December 31, 2021 1,499 ​ $ 4.01 ​ ​ ​ Granted — ​ $ — ​ Exercised (168) ​ $ 1.77 ​ ​ Forfeited (30) ​ $ 13.81 ​ Outstanding at December 31, 2022 1,301 ​ $ 4.07 7.0 $ 5,001 Exercisable at December 31, 2022 869 ​ $ 4.82 6.7 $ 3,022 Vested and expected to vest at December 31, 2022 1,301 ​ $ 4.07 7.0 $ 5,001 ​
Summary of Weighted-Average Inputs and Assumptions used to Estimate Grant-date Fair Value of Stock Options	For the year ended December 31, 2020 the grant-date fair value of stock options was estimated at the time of grant using the following weighted-average inputs and assumptions in the Black-Scholes option pricing model: ​ ​ ​ ​ ​ ​ ​ 2020 Estimated fair value of common stock ​ $ 2.01 ​ Exercise price ​ $ 2.01 ​ Expected term (in years) ​ 6.1 ​ Risk-free interest rate ​ 0.4 % Expected volatility ​ 59.5 % Dividend yield ​ — % ​
Summary of Restricted Stock Units and Performance Restricted Stock Units Activity	The following table summarizes the Company’s restricted stock award, restricted stock unit and performance restricted stock unit activity for the years ended December 31, 2022, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-vested ​ Weighted- Non-vested ​ Weighted- ​ ​ Restricted ​ ​ average ​ Performance Restricted ​ ​ average ​ ​ Stock Units ​ ​ Grant-date ​ Stock Units ​ ​ Grant-date ​ ​ (in thousands) ​ ​ Fair Value ​ (in thousands) ​ ​ Fair Value Non-vested at December 31, 2019 245 ​ $ 15.23 — ​ $ — Granted 2,307 ​ 3.18 500 ​ 1.71 Vested (98) ​ 13.24 — ​ — Forfeited ​ (594) ​ ​ 5.24 ​ — ​ ​ ​ Non-vested at December 31, 2020 1,860 ​ 3.58 500 ​ 1.71 Granted 1,008 ​ 11.51 145 ​ 15.59 Vested (780) ​ 3.63 (250) ​ 1.77 Forfeited (359) ​ 7.86 — ​ — Non-vested at December 31, 2021 ​ 1,729 ​ $ 7.29 395 ​ $ 6.77 Granted 2,902 ​ $ 3.36 — ​ $ — Vested (705) ​ $ 7.32 — ​ $ — Forfeited (420) ​ $ 5.35 — ​ $ — Non-vested at December 31, 2022 3,506 ​ $ 4.29 395 ​ $ 6.77 ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Statutory Federal Income Tax Rate	A reconciliation of the statutory United States federal income tax rate to the Company’s effective tax rate is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Tax Year ended December 31, ​ 2022 2021 2020 U.S. federal statutory income tax rate ​ 21.0 % 21.0 % 21.0 % State and local taxes, net of federal benefit (0.9) % 5.5 % 3.5 % Nondeductible expenses (2.3) % 10.6 % (0.8) % Research and development credits - % — % — % Tax rate change and true-up (1.5) % 0.8 % (1.6) % Change in valuation allowance (16.3) % (37.9) % (22.1) % Effective income tax rate — % — % — % ​
Schedule of Deferred Tax Assets	The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ ​ 2022 ​ 2021 Deferred tax assets: ​ ​ Net operating loss carryforwards ​ $ 76,013 ​ $ 72,620 Research and development credits ​ 3,008 ​ 3,008 Share-based compensation ​ 2,273 ​ 2,111 Accruals ​ 1,379 ​ 786 Interest expense ​ 3,807 ​ 3,308 Lease Liability ​ 929 ​ 1,024 Capitalized start-up costs ​ 215 ​ 479 Capitalized R&D costs ​ ​ 2,165 ​ ​ — Other temporary differences ​ 1,000 ​ 1,050 Gross deferred tax assets ​ 90,789 ​ 84,386 Less: Valuation allowance ​ (86,733) ​ (80,663) Total deferred tax assets ​ $ 4,056 ​ $ 3,723 ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ Capitalized software ​ $ (894) ​ $ (753) Right-of-use asset ​ (816) ​ (945) Prepaid commission ​ (2,346) ​ (2,025) Gross deferred tax liabilities ​ (4,056) ​ (3,723) Net deferred taxes ​ $ — ​ $ — ​
Summary of Changes in Valuation Allowance	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, ​ 2022 2021 Balance at the beginning of the year ​ $ 80,663 ​ $ 68,856 Amounts charged to expense ​ 6,070 ​ 11,807 Balance at the end of the year ​ $ 86,733 ​ $ 80,663
Summary of Net Operating Loss Carryforwards and Tax Credits	The following table summarizes carryforwards of federal net operating losses and tax credits as of December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Expiration ​ ​ Amount ​ Beginning in Federal net operating losses ​ $ 312,721 2023 State net operating losses ​ $ 197,281 2023 Research and development credits ​ $ 3,008 2023 ​

Description of Business - Addit

Description of Business - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Apr. 30, 2020
Description Of Business [Line Items]
Cash and cash equivalents	$ 70,340	$ 94,141
Accumulated deficit	345,892	308,733
Cash flows from operating activities	30,739	$ 27,983	$ 28,390
Paycheck Protection Program (the "PPP") | Silicon Valley Bank
Description Of Business [Line Items]
Unsecured debt				$ 6,400
$35.0 Million Credit Facility | Oxford Finance LLC
Description Of Business [Line Items]
Borrowings outstanding under credit facility	$ 35,000
Credit facility maturity date	Feb. 28, 2025

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	1 Months Ended	12 Months Ended				24 Months Ended
	Oct. 31, 2017	Dec. 31, 2022 USD ($) customer	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) customer	Dec. 31, 2017	Dec. 31, 2022 USD ($) customer
Summary Of Significant Accounting Policies [Line Items]
Cash held on deposits at financial institution in excess of FDIC Insured limit		$ 250,000				$ 250,000
Accumulated deficit		(345,892,000)	$ (308,733,000)			(345,892,000)
Impairment of long-lived assets		0	0	$ 0
Impact to revenue		$ 65,206,000	55,312,000	$ 49,244,000
Revenue, performance obligation, description of warranty		The Company provides a one-year warranty on all new System sales which were determined to be assurance-type warranties and thus not considered a separate performance obligation. The Company accrues the cost of providing these warranties.
Right of return or refund		$ 0				$ 0
Term of distribution agreement	7 years 6 months	7 years 6 months			7 years 6 months
Distribution agreement, renewal period		2 years			2 years
Revenue recognized		$ 2,500,000	1,900,000
Number of customer accounted for more than 10% of revenues | customer		1		1		1
Accounts receivable		$ 13,591,000	$ 7,706,000			$ 13,591,000
Dividend yield percentage		17	20	22		17
Credit concentration risk
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable			$ 2,500,000
Credit concentration risk | Customer 1
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable		$ 5,200,000				$ 5,200,000
Sales and Marketing
Summary Of Significant Accounting Policies [Line Items]
Impairment losses		0	100,000	$ 0
Impairment charges		$ 0	$ 100,000
Computers and Software
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life		3 years
Laboratory and Office Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life		5 years
Devices in Rental Agreement Program
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life		6 years
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life		5 years
Capitalized Software
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life		2 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Percentages of Deferred Revenue by Year (Details)	Dec. 31, 2022
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	100%
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	67%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	25%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	8%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]: 2026-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]: 2027-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]: 2028-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Revenue Generated in Geographic Regions for Years Indicated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 65,206	$ 55,312	$ 49,244
Revenue | Geographic Concentration
Segment Reporting Information [Line Items]
Revenues	$ 65,206	$ 55,312	$ 49,244
Percentage of Revenues	100%	100%	100%
Revenue | United States | Geographic Concentration
Segment Reporting Information [Line Items]
Revenues	$ 63,406	$ 53,447	$ 47,519
Percentage of Revenues	97%	97%	96%
Revenue | International | Geographic Concentration
Segment Reporting Information [Line Items]
Revenues	$ 1,800	$ 1,865	$ 1,725
Percentage of Revenues	3%	3%	4%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Revenue Generated in Product Category for Years Indicated (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 65,206	$ 55,312	$ 49,244
Product Category | United States | Revenue
Segment Reporting Information [Line Items]
Revenues	$ 63,406	$ 53,447	$ 47,519
Percentage of Revenues	100%	100%	100%
Product Category | United States | Revenue | NeuroStar Advanced Therapy System
Segment Reporting Information [Line Items]
Revenues	$ 16,575	$ 9,760	$ 11,094
Percentage of Revenues	26%	18%	23%
Product Category | United States | Revenue | Treatment Sessions
Segment Reporting Information [Line Items]
Revenues	$ 45,077	$ 41,933	$ 34,852
Percentage of Revenues	71%	78%	73%
Product Category | United States | Revenue | Other
Segment Reporting Information [Line Items]
Revenues	$ 1,754	$ 1,754	$ 1,573
Percentage of Revenues	3%	4%	4%
Product Category | International | Revenue
Segment Reporting Information [Line Items]
Revenues	$ 1,800	$ 1,865	$ 1,725
Percentage of Revenues	100%	100%	100%
Product Category | International | Revenue | NeuroStar Advanced Therapy System
Segment Reporting Information [Line Items]
Revenues	$ 811	$ 1,108	$ 856
Percentage of Revenues	45%	59%	50%
Product Category | International | Revenue | Treatment Sessions
Segment Reporting Information [Line Items]
Revenues	$ 354	$ 264	$ 449
Percentage of Revenues	20%	14%	26%
Product Category | International | Revenue | Other
Segment Reporting Information [Line Items]
Revenues	$ 635	$ 493	$ 420
Percentage of Revenues	35%	27%	24%

Fair Value Measurement and Fi_3

Fair Value Measurement and Financial Instruments - Schedule of Carrying Amounts and Fair Values of Financial Instruments (Details) - Money market funds - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Carrying Amount
Assets
Total assets	$ 68,002	$ 91,236
Fair Value
Assets
Total assets	68,002	91,236
Quoted Prices In Active Markets (Level 1)
Assets
Total assets	$ 68,002	$ 91,236

Accounts Receivable - Compositi

Accounts Receivable - Composition of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Gross accounts receivable - trade	$ 15,239	$ 9,168
Less: Allowances for doubtful accounts	(1,648)	(1,462)	$ (1,012)	$ (548)
Accounts receivable, net	$ 13,591	$ 7,706

Accounts Receivable - Allowance

Accounts Receivable - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Receivables [Abstract]
Balance at Beginning of Period	$ (1,462)	$ (1,012)	$ (548)
Bad Debt Expense Recognized	(341)	(763)	(897)
Write-offs of Uncollectible Balances	155	313	433
Balance at End of Period	$ (1,648)	$ (1,462)	$ (1,012)

Property and Equipment and Ca_3

Property and Equipment and Capitalized Software - Summary of Composition of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 5,048	$ 3,757
Less: Accumulated depreciation	(3,057)	(2,537)
Property and equipment, net	1,991	1,220
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	462	249
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	508	497
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,758	1,598
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	343	341
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,435	471
Rental Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	542	601
Property and equipment, net	$ 500	$ 600

Property and Equipment and Ca_4

Property and Equipment and Capitalized Software - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 1.6	$ 1.1	$ 0.9
Other assets
Property Plant And Equipment [Line Items]
Capitalized software cost, net	$ 3.6	$ 2.5

Note Receivables (Details)

Note Receivables (Details) - Success T M S - USD ($) $ in Millions			12 Months Ended
	Jul. 14, 2022	Sep. 29, 2021	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Repayment of notes issued	$ 10.5
Secured Promissory Note
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of master sales agreement		5 years
Term of notes receivable			5 years
Principal amount of notes receivable		$ 10
Secured Promissory Note | Other income, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized			$ 1	$ 0.2
Secured Promissory Note | Prime Rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest rate (as a percent)		6%

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Leases [Line Items]
Operating lease, rent expense, net	$ 800	$ 700	$ 600
Operating lease, weighted-average remaining lease term	5 years
Operating lease, weighted-average discount rate	7.20%
Carrying amount of lease receivables	$ 2,800	3,900
Unguaranteed residual assets	0
Operating lease income	$ 200	$ 300	$ 400
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue From Contract With Customer Excluding Assessed Tax	Revenue From Contract With Customer Excluding Assessed Tax	Revenue From Contract With Customer Excluding Assessed Tax
Property and equipment, net	$ 1,991	$ 1,220
NeuroStar Advanced Therapy Systems | Minimum
Leases [Line Items]
Lessor sales-type lease, Term	3 years
NeuroStar Advanced Therapy Systems | Maximum
Leases [Line Items]
Lessor sales-type lease, Term	4 years
Headquarters and Office Equipment, Including Copiers
Leases [Line Items]
Area of lease facility | ft²	32,000
Lessee, operating lease, extended maturity period	2028-02
Additional lease facility area acquired | ft²	10,000
Lessee, operating lease, existence of option to extend	true
Combined area of lease facility | ft²	42,000
Description of option to extend lease facility	The Company has an option to extend the lease on its combined 42,000 square foot facility for an additional five-year term
Lessee, operating lease, renewal term	5 years
Rental Equipment
Leases [Line Items]
Property and equipment, net	$ 500	600
Rental equipment depreciation expense	$ 100	$ 50	$ 100
Charlotte, North Carolina
Leases [Line Items]
Area of lease facility | ft²	9,600
Description of option to extend lease facility	True
Lessee, operating lease, renewal term	1 year

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information as Lessee Related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 892	$ 822
Right-of-use assets obtained in exchange for lease obligations:
Operating leases		$ 866

Leases - Schedule of Future Pay

Leases - Schedule of Future Payments of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2023	$ 853
2024	875
2025	898
2026	921
2027	882
Thereafter	116
Total lease payments	4,545
Less imputed interest	(754)
Present value of operating lease liabilities	$ 3,791

Leases - Schedule of Profit Rec

Leases - Schedule of Profit Recognized on Sales-type Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Sales Type Lease Lease Income [Abstract]
Profit recognized at commencement, net	$ 478	$ 807
Total sales-type lease income	$ 478	$ 807
Sales-Type Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue From Contract With Customer Excluding Assessed Tax	Revenue From Contract With Customer Excluding Assessed Tax

Leases - Schedule of Maturity A

Leases - Schedule of Maturity Analysis of Undiscounted Lease Receivables Related to Sales-type Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Sales Type And Direct Financing Leases Lease Receivable Fiscal Year Maturity [Abstract]
2023	$ 1,538
2024	824
2025	358
2026	40
Total sales-type lease receivables	$ 2,760

Prepaid Commission Expense - Ad

Prepaid Commission Expense - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Amortization Of Deferred Charges [Abstract]
Amortization period of deferred commissions	7 years
Amortization expense	$ 1.8	$ 1.3

Accrued Expenses - Summary of C

Accrued Expenses - Summary of Composition of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables And Accruals [Abstract]
Compensation and related benefits	$ 11,201	$ 5,090
Consulting and professional fees	761	537
Research and development expenses	678	388
Sales and marketing expenses	410	268
Warranty	328	306
Sales and other taxes payable	659	664
Other	800	980
Accrued expenses	$ 14,837	$ 8,233

Debt - Summary of Composition o

Debt - Summary of Composition of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
Outstanding principal	$ 35,000	$ 35,000
Accrued final payment fees	1,925	1,925
Less debt discounts	(971)	(1,590)
Total debt, net	35,954	35,335
Less current portion	(13,125)
Long-term debt, net	$ 22,829	$ 35,335

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($) $ in Millions			12 Months Ended
	Mar. 02, 2020	Mar. 02, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Feb. 29, 2020	Mar. 31, 2017
Debt Instrument [Line Items]
Interest expense			$ 4.3	$ 4	$ 4.5
Cash interest expense			3.6	3.3	3.9
Non-cash interest expense			0.7	$ 0.7	0.6
Solar Capital Ltd | Term A Loan and Term B Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.66%
Interest rate	7.65%	7.65%
Solar Capital Ltd | $35.0 Million Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							$ 35
Solar Capital Ltd | $35.0 Million Credit Facility | Term A Loan
Debt Instrument [Line Items]
Borrowings outstanding under credit facility	$ 35	$ 35
Solar Capital Ltd | $50.0 Million Credit Facility
Debt Instrument [Line Items]
Increase in final payment fees percentage upon extension interest only periods	5.50%
Trailing twelve month net product revenue first threshold limit to pay exit fee	$ 100
Trailing twelve month net product revenue Second threshold limit to pay exit fee	$ 125
Percentage of exit fee for liquidation, dissolution, winding up or change of control of the Company	4.50%
Percentage of exit fee upon achievement of any trailing twelve month revenues	2.25%
Percentage of exit fee upon achievement of both trailing twelve month revenues	4.50%
Capped exit fee percentage on term loan principal amount	4.50%
Solar Capital Ltd | $50.0 Million Credit Facility | Prepaid After Second Anniversary of Funding
Debt Instrument [Line Items]
Prepayment fees percentage	1%
Solar Capital Ltd | $50.0 Million Credit Facility | Term A Loan
Debt Instrument [Line Items]
Credit facility maturity date		Feb. 28, 2025
Oxford Finance LLC
Debt Instrument [Line Items]
Combined debt discount and deferred issuance costs					$ 0.6
Oxford Finance LLC | $35.0 Million Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 35
Borrowings outstanding under credit facility			$ 35
Credit facility maturity date			Feb. 28, 2025
Debt instrument, interest rate					8.15%
Oxford Finance LLC | $35.0 Million Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					7.38%
Debt instrument, description of variable rate basis					30 day U.S. LIBOR
Oxford Finance LLC | $35.0 Million Credit Facility | Term A Loan
Debt Instrument [Line Items]
Borrowings outstanding under credit facility						25
Oxford Finance LLC | $35.0 Million Credit Facility | Term B Loan
Debt Instrument [Line Items]
Borrowings outstanding under credit facility						5
Oxford Finance LLC | $35.0 Million Credit Facility | Term C Loan
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity						$ 5

Debt - Schedule of Future Princ

Debt - Schedule of Future Principal Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
2023	$ 13,125
2024	17,500
2025	4,375
Total principal payments	$ 35,000	$ 35,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 02, 2021	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2020
Equity [Abstract]
Common stock shares issued and sold	5,566,000
Public offering price	$ 15.50
Net proceeds from initial public offering	$ 80,600	$ 80,972
Common stock, shares authorized		200,000,000	200,000,000	200,000,000
Common stock, par value		$ 0.01	$ 0.01	$ 0.01
Common stock, shares outstanding		26,395,000	27,268,000
Common stock, shares issued		26,395,000	27,268,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Common Stock Issued and Reserved for Issuance (Details) - shares shares in Thousands	Dec. 31, 2022	Dec. 31, 2021	Jul. 31, 2018
Stockholders Deficit [Line Items]
Shares of common stock issued	27,268	26,395
Shares of common stock reserved for issuance for:
Total shares of common stock issued and reserved for issuance	34,734	32,929
Common stock warrants
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	61	75
Stock options
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	1,301	1,499
Restricted Stock Units and Awards Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	3,901	2,124
Shares available for grant under stock incentive plan
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	1,140	2,037
Shares available for sale under employee stock purchase plan
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	1,063	799	200

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Outstanding Common Stock Warrants (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	61	75
Exercise Price $19.55
Class Of Warrant Or Right [Line Items]
Warrants Outstanding		14
Exercise Price		$ 19.55
Expiration Date		2022-12
Exercise Price $9.73.
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	20	20
Exercise Price	$ 9.73	$ 9.73
Expiration Date	2023-08	2023-08
Exercise Price $9.73
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	20	20
Exercise Price	$ 9.73	$ 9.73
Expiration Date	2024-03	2024-03
Exercise Price. $9.73
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	21	21
Exercise Price	$ 9.73	$ 9.73
Expiration Date	2024-12	2024-12

Loss Per Share - Schedule of Po

Loss Per Share - Schedule of Potentially Dilutive Securities Outstanding Excluded from Diluted Loss Per Share Calculation (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	1,301	1,499	2,365
Non-vested performance restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	395	395
Restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	3,506	1,729	1,860
Common stock warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	61	75	105

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 8,746	$ 7,869	$ 4,404
Cost of Revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	130	79	66
Sales and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	4,286	2,096	1,813
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	3,868	5,496	2,076
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 462	$ 198	$ 449

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual percentage increase in number of shares authorized for issuance		4%
Share-based compensation expenses		$ 8,746	$ 7,869	$ 4,404
Weighted-average grant-date fair value of stock options granted				$ 1.09
Intrinsic value of stock options exercised		200	8,200	$ 1,400
Expected volatility				59.50%
Risk-free interest rate				0.40%
Expected term (in years)				6 years 1 month 6 days
Stock options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses		700	800	$ 1,700
Unrecognized compensation cost related to non-vested stock options		$ 600
Non-vested awards not yet recognized weighted-average period for recognition		1 year 3 months 18 days
Restricted Stock Awards and Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses		$ 8,100	7,100	2,700
Non-vested awards not yet recognized weighted-average period for recognition		1 year 9 months 18 days
Unrecognized compensation cost related to non-vested restricted stock		$ 8,700
Fair value of restricted stock vested		$ 2,500	$ 14,100	$ 300
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting terms of stock options		stock options vest 25% upon the first anniversary of the date of grant and the remainder ratably monthly thereafter for 36 months. Restricted stock units generally vest ratably in three equal installments on the first, second and third anniversaries of the grant date.
Shares available for future issuance		700,000
2018 Equity Incentive Plan | PRSUs | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average price, number of days trailing		30 days
2018 Equity Incentive Plan | First Anniversary of Date of Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage of stock options		25%
2018 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance		1,400,000
Maximum contractual term of stock options		10 years
2020 Inducement Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of additional shares authorized for issuance	500,000
Shares available for future issuance		400,000
2020 Inducement Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance				0.4

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Stock Option Activity (Details) - Stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares under Option, Outstanding, Beginning balance	1,499	2,365	2,415
Number of Shares under Option, Granted			1,028
Number of Shares under Option, Exercised	(168)	(698)	(371)
Number of Shares under Option, Forfeited	(30)	(168)	(707)
Number of Shares under Option, Outstanding, Ending balance	1,301	1,499	2,365
Number of Shares under Option, Exercisable	869
Number of Shares under Option, Vested and expected to vest	1,301
Weighted-average Exercise Price per Option, Outstanding, Beginning balance	$ 4.01	$ 4.62	$ 7.11
Weighted-average Exercise Price per Option, Granted			2.01
Weighted-average Exercise Price per Option, Exercised	1.77	4.01	1.86
Weighted-average Exercise Price per Option, Forfeited	13.81	14.32	10.76
Weighted-average Exercise Price per Option, Outstanding, Ending balance	4.07	$ 4.01	$ 4.62
Weighted-average Exercise Price per Option, Exercisable	4.82
Weighted-average Exercise Price per Option, Vested and expected to vest	$ 4.07
Weighted-average Remaining Contractual Life, Outstanding	7 years
Weighted-average Remaining Contractual Life, Exercisable	6 years 8 months 12 days
Weighted-average Remaining Contractual Life, Vested and expected to vest	7 years
Aggregate Intrinsic Value, Outstanding	$ 5,001
Aggregate Intrinsic Value, Exercisable	3,022
Aggregate Intrinsic Value, Vested and expected to vest	$ 5,001

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Restricted Stock Units and Performance Restricted Stock Unit Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested, Beginning balance	1,729	1,860	245
Granted	2,902	1,008	2,307
Vested	(705)	(780)	(98)
Forfeited	(420)	(359)	(594)
Non-vested, Ending balance	3,506	1,729	1,860
Weighted-average Grant-date Fair Value, Non-vested, Beginning balance	$ 7.29	$ 3.58	$ 15.23
Weighted-average Grant-date Fair Value, Granted	3.36	11.51	3.18
Weighted-average Grant-date Fair Value, Vested	7.32	3.63	13.24
Weighted-average Grant-date Fair Value, Forfeited	5.35	7.86	5.24
Weighted-average Grant-date Fair Value, Non-vested, Ending balance	$ 4.29	$ 7.29	$ 3.58
Performance Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested, Beginning balance	395	500
Granted		145	500
Vested		(250)
Non-vested, Ending balance	395	395	500
Weighted-average Grant-date Fair Value, Non-vested, Beginning balance	$ 6.77	$ 1.71
Weighted-average Grant-date Fair Value, Granted		15.59	$ 1.71
Weighted-average Grant-date Fair Value, Vested		1.77
Weighted-average Grant-date Fair Value, Non-vested, Ending balance	$ 6.77	$ 6.77	$ 1.71

Share-Based Compensation - Su_4

Share-Based Compensation - Summary of Inputs and Assumptions used to Estimated Grant-date Fair Value of Performance Restricted Stock Unit (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Feb. 02, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated fair value of common stock		$ 2.01
Exercise price		$ 2.01
Expected term (in years)		6 years 1 month 6 days
Closing price of common stock			$ 15.50
Risk-free interest rate		0.40%
Expected volatility		59.50%
Performance Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Closing price of common stock	$ 15.92	$ 1.98
Risk-free interest rate	1.15%	0.63%
Expected volatility	99.70%	87.40%

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - shares shares in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2018	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, plan name		401(k) plan
Defined contribution plan, employee salary contribution		3%
Shares available for sale under employee stock purchase plan
Defined Benefit Plan Disclosure [Line Items]
Shares of common stock reserved for issuance	200	1,063	799
Common stock purchase price, discount rate	15%
Maximum | Shares available for sale under employee stock purchase plan
Defined Benefit Plan Disclosure [Line Items]
Period of automatic annual increase in the share reserve	10 years
401(k) Plan
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, maximum employee contribution deferred		100%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Net loss	$ 37,159	$ 31,193	$ 27,453
Deferred income tax expense or benefit	0	0	0
Current income tax expense (benefit)	0	0	$ 0
Increase in valuation allowance	6,100	$ 11,800
Accrued interest or penalties related to uncertain tax positions	0
Interest or penalties related to uncertain tax positions recognized in statements of operations and comprehensive loss	$ 0

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Statutory Federal Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	21%	21%	21%
State and local taxes, net of federal benefit	(0.90%)	5.50%	3.50%
Nondeductible expenses	(2.30%)	10.60%	(0.80%)
Research and development credits
Tax rate change and true-up	(1.50%)	0.80%	(1.60%)
Change in valuation allowance	(16.30%)	(37.90%)	(22.10%)

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 76,013	$ 72,620
Research and development credits	3,008	3,008
Share-based compensation	2,273	2,111
Accruals	1,379	786
Interest expense	3,807	3,308
Lease Liability	929	1,024
Capitalized start-up costs	215	479
Capitalized R&D costs	2,165
Other temporary differences	1,000	1,050
Gross deferred tax assets	90,789	84,386
Less: Valuation allowance	(86,733)	(80,663)
Total deferred tax assets	4,056	3,723
Deferred tax liabilities:
Capitalized software	(894)	(753)
Right-of-use asset	(816)	(945)
Prepaid commission	(2,346)	(2,025)
Gross deferred tax liabilities	$ (4,056)	$ (3,723)

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Balance at the beginning of the year	$ 80,663	$ 68,856
Amounts charged to expense	6,070	11,807
Balance at the end of the year	$ 86,733	$ 80,663

Income Taxes - Summary of Net O

Income Taxes - Summary of Net Operating Loss Carryforwards and Tax Credits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Federal
Income Taxes [Line Items]
Net operating losses, Amount	$ 312,721
Net operating loss carryforwards, Expiration beginning	2023
State
Income Taxes [Line Items]
Net operating losses, Amount	$ 197,281
Net operating loss carryforwards, Expiration beginning	2023
Research and Development Credits
Income Taxes [Line Items]
Net operating losses, Amount	$ 3,008
Net operating loss carryforwards, Expiration beginning	2023

Distribution Agreement with T_2

Distribution Agreement with Teijin Pharma Limited - Additional Information (Details) $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 01, 2019 JPY (¥)	Oct. 31, 2017	Jun. 30, 2019 USD ($)	Dec. 31, 2022	Dec. 31, 2017 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Term of distribution agreement		7 years 6 months		7 years 6 months	7 years 6 months
Reimbursement of rate per treatment session | ¥	¥ 12,000
Distribution agreement, renewal period				2 years	2 years
Distribution term agreement				The term of the distribution agreement will be automatically extended for two years unless either party gives the other party at least two years’ prior written of notice of non-renewal, except that the Company cannot decline to renew the agreement if Teijin has purchased 100% of its sales forecasts over the term of the agreement.
Teijin | Distribution Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Agreement expiry date					Mar. 31, 2025
Extended term of agreement					2 years
Related party purchased percentage of sales forecasts over agreement term.					100%
Upfront Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment received					$ 750
Milestone Payment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment received			$ 700		$ 2,000

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 segment
Segments Geographical Areas [Abstract]
Number of operating business segment	1

Severance - Additional Informat

Severance - Additional Information (Details) $ in Thousands		3 Months Ended	12 Months Ended
	Apr. 08, 2020 employee	Jun. 30, 2020 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Restructuring Cost And Reserve [Line Items]
Accrued liabilities			$ 14,837	$ 8,233
Transition Separation Agreement
Restructuring Cost And Reserve [Line Items]
Restructuring charges			600	500
Accrued liabilities			300	100
Reduction in Force
Restructuring Cost And Reserve [Line Items]
Number of employees terminated | employee	95
Restructuring charges		$ 2,100
Termination Benefits | Transition Separation Agreement
Restructuring Cost And Reserve [Line Items]
Payments for restructuring			$ 500	$ 1,300