Neuronetics (STIM) 10-Q 6 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	STIM
Entity Registrant Name	NEURONETICS, INC.
Entity Central Index Key	0001227636
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		18,484,544
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38546
Entity Tax Identification Number	331051425
Entity Address, Address Line One	3222 Phoenixville Pike
Entity Address, City or Town	Malvern
Entity Address, State or Province	PA
Entity Address, Country	US
Entity Address, Postal Zip Code	19355
City Area Code	610
Local Phone Number	640-4202
Entity Listing, Description	Common Stock ($0.01 par value)
Entity Listing, Par Value Per Share	$ 0.01

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 89,644	$ 104,583
Accounts receivable, net	7,563	5,620
Inventory	2,552	2,432
Current portion of net investments in sales-type leases	240
Current portion of prepaid commission expense	237
Prepaid expenses and other current assets	1,061	1,838
Total current assets	101,297	114,473
Property and equipment, net	1,105	1,378
Operating lease right-of-use assets	3,998
Net investments in sales-type leases	400
Prepaid commission expense	1,342
Other assets	1,284	1,171
Total Assets	109,426	117,022
Current liabilities:
Accounts payable	3,659	3,756
Accrued expenses	6,476	7,548
Deferred revenue	2,206	2,255
Current portion of operating lease liabilities	516
Current portion of long-term debt, net	3,750
Total current liabilities	16,607	13,559
Long-term debt, net	27,007	30,395
Deferred revenue	2,351	1,940
Operating lease liabilities	3,642
Deferred rent		86
Total Liabilities	49,607	45,980
Commitments and contingencies (Note 16)
Stockholders’ Equity:
Preferred stock, $0.01 par value: 10,000 shares authorized; no shares issued or outstanding at June 30, 2019 and December 31, 2018
Common stock, $0.01 par value: 200,000 shares authorized; 18,445 and 17,744 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	184	177
Additional paid-in capital	295,301	291,908
Accumulated deficit	(235,666)	(221,043)
Total Stockholders' Equity	59,819	71,042
Total Liabilities and Stockholders’ Equity	$ 109,426	$ 117,022

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	18,445,000	17,744,000
Common stock, shares outstanding	18,445,000	17,744,000

Statements of Operations

Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 16,572	$ 13,252	$ 29,300	$ 23,404
Cost of revenues	4,171	3,245	6,978	5,702
Gross Profit	12,401	10,007	22,322	17,702
Operating expenses:
Sales and marketing	11,523	9,835	21,115	17,944
General and administrative	4,261	3,078	8,860	5,714
Research and development	3,224	2,330	6,010	3,885
Total operating expenses	19,008	15,243	35,985	27,543
Loss from Operations	(6,607)	(5,236)	(13,663)	(9,841)
Other (income) expense:
Interest expense	931	900	1,850	1,821
Other expense (income), net	(444)	1,360	(890)	1,331
Net Loss	$ (7,094)	$ (7,496)	$ (14,623)	$ (12,993)
Net loss per share of common stock outstanding, basic and diluted	$ (0.39)	$ (30.60)	$ (0.80)	$ (55.29)
Weighted-average common shares outstanding, basic and diluted	18,351	245	18,189	235

Statement of Changes in Convert

Statement of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ (192,652)		$ 2	$ 4,292	$ (196,946)
Beginning balance, shares at Dec. 31, 2017		304,958
Beginning balance at Dec. 31, 2017		$ 187,136
Beginning balance, shares at Dec. 31, 2017			231
Share-based awards and options exercises	31		$ 1	30
Share-based awards and options exercises, shares			20
Share-based compensation expense	144			144
Net loss	(5,497)				(5,497)
Ending balance at Mar. 31, 2018	(197,974)		$ 3	4,466	(202,443)
Ending balance, shares at Mar. 31, 2018		304,958
Ending balance at Mar. 31, 2018		$ 187,136
Ending balance, shares at Mar. 31, 2018			251
Beginning balance at Dec. 31, 2017	(192,652)		$ 2	4,292	(196,946)
Beginning balance, shares at Dec. 31, 2017		304,958
Beginning balance at Dec. 31, 2017		$ 187,136
Beginning balance, shares at Dec. 31, 2017			231
Net loss	(12,993)
Ending balance at Jun. 30, 2018	(205,271)		$ 3	4,665	(209,939)
Ending balance, shares at Jun. 30, 2018		304,958
Ending balance at Jun. 30, 2018		$ 187,136
Ending balance, shares at Jun. 30, 2018			257
Beginning balance at Mar. 31, 2018	(197,974)		$ 3	4,466	(202,443)
Beginning balance, shares at Mar. 31, 2018		304,958
Beginning balance at Mar. 31, 2018		$ 187,136
Beginning balance, shares at Mar. 31, 2018			251
Share-based awards and options exercises	7			7
Share-based awards and options exercises, shares			6
Share-based compensation expense	192			192
Net loss	(7,496)				(7,496)
Ending balance at Jun. 30, 2018	(205,271)		$ 3	4,665	(209,939)
Ending balance, shares at Jun. 30, 2018		304,958
Ending balance at Jun. 30, 2018		$ 187,136
Ending balance, shares at Jun. 30, 2018			257
Beginning balance at Dec. 31, 2018	71,042		$ 177	291,908	(221,043)
Beginning balance, shares at Dec. 31, 2018			17,744
Share-based awards and options exercises	1,407		$ 5	1,402
Share-based awards and options exercises, shares			483
Share-based compensation expense	501			501
Net loss	(7,529)				(7,529)
Ending balance at Mar. 31, 2019	65,421		$ 182	293,811	(228,572)
Ending balance, shares at Mar. 31, 2019			18,227
Beginning balance at Dec. 31, 2018	71,042		$ 177	291,908	(221,043)
Beginning balance, shares at Dec. 31, 2018			17,744
Net loss	(14,623)
Ending balance at Jun. 30, 2019	59,819		$ 184	295,301	(235,666)
Ending balance, shares at Jun. 30, 2019			18,445
Beginning balance at Mar. 31, 2019	65,421		$ 182	293,811	(228,572)
Beginning balance, shares at Mar. 31, 2019			18,227
Share-based awards and options exercises	470		$ 2	468
Share-based awards and options exercises, shares			218
Share-based compensation expense	1,022			1,022
Net loss	(7,094)				(7,094)
Ending balance at Jun. 30, 2019	$ 59,819		$ 184	$ 295,301	$ (235,666)
Ending balance, shares at Jun. 30, 2019			18,445

Statements of Cash Flows (Unaud

Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Cash Flows from Operating Activities:
Net loss	$ (14,623)	$ (12,993)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	457	463
Share-based compensation	1,523	336
Non-cash interest expense	362	441
Change in fair value of convertible preferred stock warrant liability		1,415
Cost of rental units purchased by customers	77	79
Changes in certain assets and liabilities:
Accounts receivable, net	(1,216)	(457)
Inventory	(82)	(378)
Net investment in sales-type leases	(640)
Prepaid commission expense	(1,579)
Prepaid expenses and other assets	941	380
Accounts payable	(228)	(89)
Accrued expenses	(1,044)	(2,130)
Deferred revenue	(366)	(435)
Deferred rent		(29)
Net Cash Used in Operating Activities	(16,418)	(13,397)	$ (20,600)
Cash Flows from Investing Activities:
Purchases of property and equipment and capitalized software	(398)	(513)
Net Cash Used in Investing Activities	(398)	(513)
Cash Flows from Financing Activities:
Payments of public offering costs		(731)
Proceeds from exercises of stock options	1,877	38
Net Cash Provided by (Used in) Financing Activities	1,877	(693)
Net Decrease in Cash and Cash Equivalents	(14,939)	(14,603)
Cash and Cash Equivalents, Beginning of Period	104,583	29,147	29,147
Cash and Cash Equivalents, End of Period	89,644	14,544	$ 104,583
Supplemental disclosure of cash flow information:
Cash paid for interest	1,494	1,334
Transfer of inventory to property and equipment	37	261
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property and equipment and capitalized software in accounts payable and accrued expenses	$ 13
Deferred initial public offering costs included in accounts payable and accrued expenses		$ 2,542

Description of Business

Description of Business	6 Months Ended
	Jun. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
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 psychiatric 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, or 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, or the FDA, to treat adult patients with major depressive disorder, or MDD, who have failed to achieve satisfactory improvement from prior antidepressant medication in the current episode. NeuroStar Advanced Therapy is also available in other parts of the world, including Japan, where it is listed under Japan’s national health insurance. The Company intends to continue to pursue development of its NeuroStar Advanced Therapy System for additional indications. Liquidity As of June 30, 2019, the Company had cash and cash equivalents of $89.6 million and an accumulated deficit of $235.7 million. The Company incurred negative cash flows from operating activities of $20.6 million for the year ended December 31, 2018 and $16.4 million for the six months ended June 30, 2019. 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 proceeds from its IPO, private placements of its convertible preferred securities, borrowings under its credit facilities and revenues from sales of its products. As of June 30, 2019, the Company had $30.0 million of borrowings outstanding under its credit facility, which matures in March 2022. Management believes that the Company’s cash and cash equivalents as of June 30, 2019 and anticipated revenues from sales of its products are sufficient to fund the Company’s operations for at least the next 24 months after June 30, 2019.

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	2. The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles, or GAAP. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Updates, or ASUs, promulgated by the Financial Accounting Standards Board, or FASB. Interim Financial Statements The accompanying unaudited interim financial statements have been prepared from the books and records of the Company in accordance with GAAP for interim financial information and Rule 10-01 of Regulation S-X promulgated by the United States Securities and Exchange Commission, or SEC, which permit reduced disclosures for interim periods. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying balance sheets and statements of operations, changes in convertible preferred stock and stockholders’ deficit and cash flows have been made. Although these interim financial statements do not include all of the information and footnotes required for complete annual financial statements, management believes the disclosures are adequate to make the information presented not misleading. Unaudited interim results of operations and cash flows for the three and six months ended June 30, 2019 are not necessarily indicative of the results that may be expected for the full year. Unaudited interim financial statements and footnotes should be read in conjunction with the audited financial statements and footnotes included in the Company’s Form 10-K filed with the SEC on March 5, 2019, wherein a more complete discussion of significant accounting policies and certain other information can be found. Use of Estimates The preparation of financial statements in accordance with GAAP and the rules and regulations of the 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. The most significant estimates and judgments impact share-based compensation prior to the initial public offering (IPO).

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. The Company’s complete summary of significant accounting policies can be found in “Note 3. Summary of Significant Accounting Policies” in the audited financial statements included in the Company’s Form 10-K filed with the SEC on March 5, 2019. As of January 1, 2019, the Company adopted ASU 2014-09, “Revenue from Contracts with Customers” (Topic 606) “Leases” (Topic 842) Revenue Recognition Adoption of ASC Topic 606, "Revenue from Contracts with Customers" On January 1, 2019, the Company adopted Topic 606 using the modified retrospective method applying the open contract practical expedient and accounted for those contracts which were not completed as of January 1, 2019 under Topic 606. Results for reporting periods beginning after January 1, 2019 are presented under Topic 606, while prior period amounts are not adjusted and continue to be reported in accordance with the Company’s historic accounting under Topic 605. Impact of Topic 606 on Financial Statement Line Items The adoption of ASC 606 had no impact to retained earnings or revenue as of January 1, 2019. In accordance with the new revenue standard requirements, the disclosure of the impact of adoption on prepaid commissions expense on the balance sheet as of June 30, 2019 and the statement of operations for the three and six months ended June 30, 2019 is as follows: As of June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Balance Sheet Current portion of prepaid commission expense $ 237 $ - $ 237 Prepaid commission expense 1,342 - 1,342 For the three months ended June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Income Statement Sales and marketing $ 11,523 $ 12,587 $ (1,064 ) Net loss (7,094 ) (8,158 ) 1,064 Six Months ended June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Income Statement Sales and marketing $ 21,115 $ 22,694 $ (1,579 ) Net loss (14,623 ) (16,202 ) 1,579 Topic 606 is principles-based and provides a five-step model to determine when and how revenue is recognized. The core principle is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Sales and usage-based taxes are excluded from revenues. Other than the revenue recognized under the distribution agreement disclosed below, all but an immaterial amount of the Company’s revenue is recognized at a point in time. 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 delivered to the customer’s 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 trans-cranial magnetic stimulation (“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 two-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 with a foreign entity for a period of 7 ½ years with two 2 year renewal options. As consideration for the right to be the sole distributor of the Company’s products and use of the Company’s intellectual property in the foreign territory, the distributor is required to make certain fixed milestone payments upon contract execution and regulatory approval. In addition, the distributor is required to make variable milestone payments depending upon regulatory reimbursement rates. Furthermore, the distributor is required to make certain minimum purchases based upon sales history and forecasts subject to a ceiling and floor. The Company assessed the potential performance obligations in this contract and concluded that the contract contained the following performance obligations: • Exclusive distribution and intellectual property license • NeuroStar TMS Therapy System (the “System”) • NeuroStar Treatment Session (the “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 three months ended June 30, 2019, were not materially impacted by any other factors. As of June 30, 2019, the Company expects to recognize approximately the following percentages of deferred revenue by year: Year: Revenue Recognition 2019 37 % 2020 16 % 2021 11 % 2022 11 % 2023 11 % Thereafter 14 % Total 100 % Revenue recognized for the six months ended June 30, 2019 that was included in the contract liability balance at the beginning of the year was $1.7 million, and primarily represented revenue earned from separately priced extended warranties and clinical training. Leases Adoption of ASC Topic 842, "Leases" The Company accounts for leases in accordance with ASC Topic 842, Leases, (“Topic 842”). The Company determines if an arrangement is a lease at contract inception. A lease exists when a contract conveys to the customer the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. The definition of a lease embodies two conditions: (1) there is an identified asset in the contract that is land or a depreciable asset (i.e., property, plant, and equipment), and (2) the customer has the right to control the use of the identified asset. The Company leases warehouse and office space, 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, a bargain purchase option, or provides for minimum lease payments with a present value 90% or more of the fair value of the 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 and subsequently 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. As of June 30, 2019, the Company has not encountered any impairment losses. The Company monitors for events or changes in circumstances that require a reassessment of a lease. 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. The Company adopted ASU 2016-02 using a modified retrospective transition approach as of the effective date as permitted by the amendments in ASU 2018-11, which provides an alternative modified retrospective transition method. As a result, the Company was not required to adjust comparative period financial information for effects of the standard or make the new required lease disclosures for periods before the date of adoption (i.e. January 1, 2019). The Company has elected to adopt the package of transition practical expedients and, therefore, has not reassessed (1) whether existing or expired contracts contain a lease, (2) lease classification for existing or expired leases or (3) the accounting for initial direct costs that were previously capitalized. The Company did not elect the practical expedient to use hindsight for leases existing at the adoption date. Further, the Company does not expect the amendments in ASU 2018-01: Land Easement Practical Expedient to have an effect on us because the Company does not enter into land easement arrangements. There was no effect of the adoption of Topic 842 on retained earnings and other components of equity as of December 31, 2018.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2019
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Recent Accounting Pronouncements	4. The Company’s discussion of recently issued accounting pronouncements can be found in “Note 4. Recent Accounting Pronouncements” in the audited financial statements included in the Company’s Form 10-K filed with the SEC on March 5, 2019. Additionally, refer to “Note 3. Summary of Significant Accounting Policies” appearing on this Form 10-Q for additional information.

Fair Value Measurement and Fina

Fair Value Measurement and Financial Instruments	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurement and Financial Instruments	5. 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 June 30, 2019 and December 31, 2018 due to their short-term nature. The carrying values of the Company’s credit facility approximated its fair value as of June 30, 2019 and December 31, 2018 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 of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 Fair Value Measurement Based on Carrying Amount Fair Value Quoted Prices In Active Markets (Level 1) Significant other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market funds (cash equivalents) $ 70,992 $ 70,992 $ 70,992 $ - $ - December 31, 2018 Fair Value Measurement Based on Carrying Amount Fair Value Quoted Prices In Active Markets (Level 1) Significant other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market funds (cash equivalents) $ 87,062 $ 87,062 $ 87,062 $ - $ - The fair value of the convertible preferred stock warrant liability was estimated using the Black-Scholes option pricing model and the following inputs and assumptions as of June 30, 2018: June 30, 2018 Series E Series F Estimated fair value of convertible preferred stock $ 26.67 $ 26.67 Exercise price $ 19.55 $ 9.73 Remaining term (in years) 4.5 2.6 - 6.5 Risk-free interest rate 2.7% 2.6% - 2.8% Expected volatility 43% 43% Dividend yield 0% 0% The following table presents the changes in the Company’s Level 3 instrument, the then outstanding convertible preferred stock warrant liability, measured on a recurring basis for the six months ended June 30, 2018 (in thousands): Balance at December 31, 2017 $ 478 Change in fair value 1,415 Balance at June 30, 2018 $ 1,893

Accounts Receivable

Accounts Receivable	6 Months Ended
	Jun. 30, 2019
Receivables [Abstract]
Accounts Receivable	6. The following table presents the composition of accounts receivable, net as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Gross accounts receivable - trade $ 8,074 $ 6,120 Less: Allowances for doubtful accounts (511 ) (500 ) Accounts receivable, net $ 7,563 $ 5,620

Property and Equipment and Capi

Property and Equipment and Capitalized Software	6 Months Ended
	Jun. 30, 2019
Property Plant And Equipment [Abstract]
Property and Equipment and Capitalized Software	7. The following table presents the composition of property and equipment, net as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Laboratory equipment $ 150 $ 150 Office equipment 487 487 Computer equipment and software 1,115 1,050 Manufacturing equipment 273 273 Leasehold improvements 172 172 Rental equipment 1,055 1,262 Property and equipment, gross 3,252 3,394 Less: Accumulated depreciation (2,147 ) (2,016 ) Property and equipment, net $ 1,105 $ 1,378 As of June 30, 2019 and December 31, 2018, the Company had capitalized software costs, net of $1.1 million and $1.0 million, respectively, which are included in “Other assets” on the balance sheet. Depreciation and amortization expense was $0.3 million and $0.3 million for the three months ended June 30, 2019 and 2018, respectively and $0.5 million and $0.5 million for the six months ended June 30, 2019 and June 30, 2018, respectively.

Leases

Leases	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Leases	8. LEASES Lessee: The Company has operating leases for its corporate headquarters and office equipment, including copiers. The Company leases approximately 32,000 square foot facility in Malvern, Pennsylvania for its corporate headquarters, which includes office and warehouse space. In Q1 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 additional premises. The Company has an option to extend the lease on its combined 42,000 square foot facility for an additional five-year term; however, the Company has determined it is not reasonably certain to exercise the option at this time due to on-going personnel expansion efforts. The Company also maintains operating leases on office equipment, including copiers, which end in March 2023. The Company does not currently have any finance leases or executed leases that have not yet commenced. Operating lease rent expense was $0.2 million for the three months ended June 30, 2019 and $0.3 million for the six months ended June 30, 2019. As of June 30, 2019 the weighted-average remaining lease term of operating leases was 8.6 years and the weighted-average discount rate was 6.5%. The following table presents the supplemental cash flow information as a lessee related to leases (in thousands): June 30, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 175 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 4,164 The following table sets forth by year the required future payments of operating lease liabilities (in thousands): June 30, 2019 Remainder of 2019 $ 271 2020 584 2021 613 2022 637 2023 634 Thereafter 2,791 Total lease payments 5,530 Less imputed interest (1,372 ) Present value of operating lease liabilities $ 4,158 The following table sets forth by year the minimum expected lease payments under non-cancelable operating leases (in thousands) as of December 31, 2018: December 31, 2018 2019 $ 547 2020 560 2021 88 Total lease payments $ 1,195 Lessor sales-type leases: Certain costumers have purchased NeuroStar Advanced Therapy Systems on a rent-to-own basis. The lease term is three years with a customer option to purchase the NeuroStar Advanced Therapy System at the end of the lease. The following table sets forth the profit recognized on sales-type leases (in thousands): Three Months ended June 30, Six Months ended June 30, 2019 2018 2019 2018 Profit recognized at commencement, net $ 118 $ - $ 262 $ - Interest Income - - - - Total sales-type lease income $ 118 $ - $ 262 $ - The following table sets forth a maturity analysis of the undiscounted lease receivables related to sales-type leases (in thousands): June 30, 2019 Remainder of 2019 $ - 2020 240 2021 240 2022 160 Total sales-type lease receivables $ 640 As of June 30, 2019, the carrying amount of the lease receivables is $0.6 million. 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. For the three months ended June 30, 2019 and 2018, the Company recognized operating lease income of $0.1 million and $0.2 million, respectively. For the six months ended June 30, 2019 and June 30, 2018, the Company recognized operating lease income of $0.3 million and $0.4 million, respectively. The following table sets forth a maturity analysis of its undiscounted lease receivables related to operating leases: June 30, 2019 Remainder of 2019 $ 245 2020 365 2021 150 Total lease receivables $ 760 The Company maintained Rental Equipment, net of $0.7 million and $0.9 million, as of June 30, 2019 and December 31, 2018, respectively, which are included in “Property and equipment, net” on the balance sheet. Rental equipment depreciation expense was $0.05 million and $0.2 million for the three months ended June 30, 2019 and 2018, respectively, and $0.1 million and $0.3 million for the six months ended June 30, 2019 and June 30, 2018, respectively.

Prepaid Commission Expense

Prepaid Commission Expense	6 Months Ended
	Jun. 30, 2019
Amortization Of Deferred Charges [Abstract]
Prepaid Commission Expense	9. 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. As result of modified retrospective adoption method applied to open contracts only, the beginning balance as of January 1, 2019 did not include prepaid commission expense for those contracts that were substantially complete as of December 31, 2018. 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 prepaid commission expense. Amortization expense was $0.04 million for the three months ended June 30, 2019 and $0.06 million for the six months ended June 30, 2019.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2019
Payables And Accruals [Abstract]
Accrued expenses	10 . The following table presents the composition of accrued expenses as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Compensation and related benefits $ 3,638 $ 4,909 Consulting and professional fees 516 342 Research and development expenses 329 191 Sales and marketing expenses 96 127 Warranty 716 629 Sales and other taxes payable 470 606 Interest payable 245 251 Other 466 493 Accrued expenses $ 6,476 $ 7,548

Debt

Debt	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Debt	11 . The following table presents the composition of debt as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Outstanding principal $ 30,000 $ 30,000 Accrued final payment fees 1,646 1,468 Less debt discounts (889 ) (1,073 ) Total long-term debt, net 30,757 30,395 Less current portion of long-term debt (3,750 ) - Long-term debt, net $ 27,007 $ 30,395 For the three months ended June 30, 2019, the Company recognized interest expense of $0.9 million, of which $0.7 million was cash and $0.2 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. For the three months ended June 30, 2018, the Company recognized interest expense of $0.9 million, of which $0.7 million was cash and $0.2 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. For the six months ended June 30, 2019, the Company recognized interest expense of $1.9 million, of which $1.5 million was cash and $0.4 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. For the six months ended June 30, 2018, the Company recognized interest expense of $1.8 million, of which $1.4 million was cash and $0.4 million was non-cash interest expense related to the amortization of deferred debt issuance costs and accrual of final payment fees. Credit Facility In March 2017, the Company entered into a loan and security agreement with Oxford Finance LLC, or Oxford, for a credit facility that replaced its previous $25.0 million credit facility with Oxford and which allowed it to borrow up to $35.0 million in three tranches of term loans: a Term A Loan in the amount of $25.0 million, which was drawn down 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 became available to the Company upon the achievement of $45.0 million of trailing twelve month revenues during the second quarter of 2018. Upon achieving the required revenue milestone, the Company had 60 days to notify Oxford if it elected to borrow the Term C Loan. As a result of completing its IPO on July 2, 2018 and receiving the net proceeds therefrom, the Company elected not to borrow the additional $5.0 million, and it is no longer available to the Company. Each 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 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%. The Company was also required to issue to Oxford at the date of each borrowing warrants to purchase its Series F or later series of convertible preferred stock with a seven-year term and in an amount equal to 3.95% of the first $5.0 million of each tranche borrowed. The credit facility matures and all amounts borrowed thereunder are due on March 1, 2022. As of June 30, 2019, the Company had borrowed and had outstanding an aggregate of $30.0 million of principal under the credit facility. The Term A Loan featured an interest-only period through March 2019, during which time the Company was required to make monthly interest payments, after which time the Company was required to make monthly payments of principal and interest based on a 36-month amortization schedule. However, due to the achievement of $45.0 million of revenues during fiscal year 2018, the interest-only period was extended for an additional 12 months through March 2020, after which time the Company will be required to make monthly payments of principal and interest based on a 24-month amortization schedule. In connection with the drawdown of the Term A Loan, the Company issued to Oxford a warrant to purchase shares of its Series F convertible preferred stock. On July 2, 2018, this convertible preferred stock warrant converted into a warrant to purchase 20,303 shares of the Company’s common stock at an exercise price of $9.73 per share. The warrant will expire in March 2024. The Term B Loan featured an interest-only period through March 2019, during which time the Company was required to make monthly interest payments, after which time the Company was required to make monthly payments of principal and interest based on a 36-month amortization schedule. However, due to the achievement of $45.0 million of revenues during the fiscal year 2018, the interest-only period was extended for an additional 12 months through March 2020, after which time the Company will be required to make monthly payments of principal and interest based on a 24-month amortization schedule. In connection with the drawdown of the Term B Loan, the Company issued to Oxford a warrant to purchase shares of its Series F convertible preferred stock. On July 2, 2018, this convertible preferred stock warrant converted into a warrant to purchase 20,303 shares of the Company’s common stock at an exercise price of $9.73 per share. The warrant will expire in December 2024. In addition to principal and interest payments due under the credit facility, the Company is required to make final payment fees to Oxford due upon the earlier of prepayment or maturity of each tranche, which increased as a result the extension of the interest-only period and are now equal to 8.5% and 7.5% of the principal amounts of the Term A and Term B Loans, respectively. The Company accrues the estimated final payment fees using the effective interest rate, with a charge to non-cash interest expense, over the term of borrowing for each tranche. As of December 31, 2018, the effective interest rates for the Term A and Term B Loans were 11.87% and 12.14%, respectively. If the Company prepays its term loans prior to their respective scheduled maturities, it will also be required to make prepayment fees to Oxford equal to 3% if prepaid on or before the first anniversary of funding, 2% if prepaid after the first and on or before the second anniversary of funding, or 1% if prepaid after the second anniversary of funding of the principal amounts borrowed. The Company’s obligations under the credit facility are secured by a first priority security interest in substantially all of its assets, other than its intellectual property. The Company has agreed not to pledge or otherwise encumber any of its intellectual property. The loan and security agreement related to the credit facility includes a financial maintenance covenant that requires the Company to achieve at least 75% of its trailing 12-month forecasted revenues, as measured each month in accordance with a forecast that the Company provided to Oxford upon signing the agreement and future forecasts that the Company is required to deliver to Oxford each year for the life of the credit facility, as well as customary affirmative and negative covenants. The Company was in compliance with all of the covenants under its credit facility as of June 30, 2019. The loan and security agreement related to the credit 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) significant judgments, orders or decrees for payments by the Company not covered by insurance; (vii) incorrectness of representations and warranties; (viii) incurrence of subordinated debt; (ix) revocation of governmental approvals necessary for the Company to conduct its business; and (x) failure by the Company to maintain a valid and perfected lien on the collateral securing the borrowing. Based on a 24-month amortization of the outstanding principal amounts of the Term A and Term B Loans beginning on April 1, 2020 as discussed above, the following table sets forth by year the Company’s required future principal payments (in thousands): Year: Principal Payments 2019 $ - 2020 11,250 2021 15,000 2022 3,750 Total principal payments $ 30,000

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Common Stock	1 2 . Common Stock The Company’s amended and restated certificate of incorporation as of June 30, 2019 authorized the issuance of 200.0 million shares of common stock, $0.01 par value per share, of which 18.4 million were issued and outstanding as of June 30, 2019. The following table summarizes the total number of shares of the Company’s common stock issued and reserved for issuance as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Shares of common stock issued 18,445 17,744 Shares of common stock reserved for issuance for: Common stock warrants outstanding 105 105 Stock options outstanding 2,507 2,711 Restricted stock units outstanding 184 43 Shares available for grant under stock incentive plan 1,383 1,312 Shares available for sale under employee stock purchase plan 421 244 Total shares of common stock issued and reserved for issuance 23,045 22,159 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. Immediately prior to the closing of the Company’s IPO on July 2, 2018, all of the Company’s outstanding shares of convertible preferred stock converted into an aggregate of 11.0 million shares of common stock, resulting in the elimination of the Company’s outstanding liquidation preferences. Common Stock Warrants The following table summarizes the Company’s outstanding common stock warrants as of June 30, 2019 and December 31, 2018: Warrants Outstanding (in thousands) Exercise Price Expiration Date 14 $ 19.55 Dec-2022 30 $ 9.73 Feb-2021 20 $ 9.73 Aug-2023 20 $ 9.73 Mar-2024 21 $ 9.73 Dec-2024 105

Loss Per Share

Loss Per Share	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Loss Per Share	1 3 . 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 and non-vested restricted stock awards and 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 June 30, 2019 and 2018 have been excluded from the denominator of the diluted loss per share of common stock outstanding calculation (in thousands): June 30, 2019 2018 Stock options 2,507 2,855 Non-vested restricted stock awards - 10 Non-vested restricted stock units 184 - Convertible preferred stock warrants - 105 Common stock warrants 105 - Shares of convertible preferred stock “as-converted” - 10,994

Share-based Compensation

Share-based Compensation	6 Months Ended
	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based Compensation	1 4 . The amount of share-based compensation expense recognized by the Company by location in its statements of operations for the three and six months ended June 30, 2019 and 2018 is as follows (in thousands): Three Months ended June 30, Six Months ended June 30, 2019 2018 2019 2018 Cost of revenues $ 19 $ 5 $ 29 $ 9 Sales and marketing 404 65 608 119 General and administrative 479 87 697 142 Research and development 120 35 189 66 Total $ 1,022 $ 192 $ 1,523 $ 336 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% evergreen increase, 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. As of June 30, 2019, there were 1.4 million shares available for future issuance under the 2018 Plan. Stock Options The following table summarizes the Company’s stock option activity for the six months ended June 30, 2019: Number of Shares under Option (in thousands) Weighted- average Exercise Price per Option Weighted- average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2018 2,711 $ 3.59 Granted 588 $ 16.08 Exercised (687 ) $ 2.82 Forfeited (105 ) $ 8.86 Outstanding at June 30, 2019 2,507 $ 6.51 7.6 $ 17,741 Exercisable at June 30, 2019 1,204 $ 2.39 6.2 $ 12,221 Vested and expected to vest at June 30, 2019 2,507 $ 6.51 7.6 $ 17,741 The Company recognized share-based compensation expense related to stock options of $0.7 million and $0.2 million for the three months ended June 30, 2019 and 2018, respectively, and $1.0 million and $0.3 million for the six months ended June 30, 2019 and June 30, 2018, respectively. As of June 30, 2019, there was $6.8 million of total unrecognized compensation cost related to non-vested stock options which the Company expects to recognize over a weighted-average period of 3.3 years. The weighted-average grant-date fair value of stock options granted during the six months ended June 30, 2019 was estimated at $8.70 per option. The total intrinsic value of stock options exercised during the six months ended June 30, 2019 was $9.4 million. For the six months ended June 30, 2019, 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: Estimated fair value of common stock $ 16.08 Exercise price $ 16.08 Expected term (in years) 6.1 Risk-free interest rate 2.4 % Expected volatility 55.3 % Dividend yield 0 % Restricted Stock Awards and Restricted Stock Units The following table summarizes the Company’s restricted stock award and restricted stock unit activity for the six months ended June 30, 2019: Non-vested Restricted Stock Awards (in thousands) Weighted- average Grant-date Fair Value Non-vested Restricted Stock Units (in thousands) Weighted- average Grant-date Fair Value Non-vested at December 31, 2018 4 $ 2.32 43 $ 25.21 Granted - $ - 155 $ 15.77 Vested (4 ) $ 2.32 (14 ) $ 22.23 Non-vested at June 30, 2019 - $ - 184 $ 17.41 The Company recognized approximately $0.3 million and minimal in share-based compensation expense related to restricted stock awards and restricted stock units for the three months ended June 30, 2019 and 2018, respectively, and $0.5 million and minimal for the six months ended June 30, 2019 and June 30, 2018, respectively. As of June 30, 2019, there was $2.9 million of unrecognized compensation cost related to non-vested restricted stock awards and restricted stock units, which the Company expects to recognize over a weighted-average period of 2.6 years. The total fair value at the vesting date of restricted stock awards and restricted stock units vested during the six months ended June 30, 2019 was $0.3 million.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	1 5 . 401(k) 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. There is currently no employer matching of employee contributions and employee contributions 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 June 30, 2019, the Company had not yet approved any offering under the 2018 ESPP.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 6 . 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	6 Months Ended
	Jun. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Distribution Agreement with Teijin Pharma Limited	17. DISTRIBUTION AGREEMENT WITH TEIJIN PHARMA LIMITED In October 2017, the Company entered into a seven-and-a-half-year distribution agreement with Teijin Pharma Limited, or Teijin, for the exclusive distribution of its NeuroStar Advanced Therapy System to customers who will treat patients with MDD in Japan. Under the distribution agreement, Teijin is generally restricted from selling competing products in Japan. The distribution agreement provides that the Company will have primary responsibility for obtaining reimbursement approval for use of NeuroStar Advanced Therapy System for the treatment of MDD in Japan, and Teijin will promote the sales of NeuroStar Advanced Therapy System for treatment of MDD in Japan. The Company has agreed to provide sales and technical support training to Teijin for its NeuroStar Advanced Therapy Systems. Teijin is required to purchase minimum dollar values of NeuroStar Advanced Therapy Systems and treatment sessions from the Company. 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 term of the agreement. 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.

Geographical Segment Informatio

Geographical Segment Information	6 Months Ended
	Jun. 30, 2019
Segments Geographical Areas [Abstract]
Geographical Segment Information	1 8 . 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. 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 Three Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues United States $ 15,890 96 % $ 12,898 97 % International 682 4 % 354 3 % Total revenues $ 16,572 100 % $ 13,252 100 % U.S. Revenues by Product Category Three Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 4,628 29 % $ 3,568 28 % Treatment sessions 10,847 68 % 8,920 69 % Other 415 3 % 410 3 % Total U.S. revenues $ 15,890 100 % $ 12,898 100 % International Revenues by Product Category Three Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 465 68 % $ 219 62 % Treatment sessions 114 17 % 56 16 % Other 103 15 % 79 22 % Total International revenues $ 682 100 % $ 354 100 % Revenues by Geography Six Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues United States $ 28,436 97 % $ 22,870 98 % International 864 3 % 534 2 % Total revenues $ 29,300 100 % $ 23,404 100 % U.S. Revenues by Product Category Six Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 7,978 28 % $ 5,941 26 % Treatment sessions 19,625 69 % 16,160 71 % Other 833 3 % 769 3 % Total U.S. revenues $ 28,436 100 % $ 22,870 100 % International Revenues by Product Category Six Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 537 62 % $ 219 41 % Treatment sessions 133 15 % 81 15 % Other 194 23 % 234 44 % Total International revenues $ 864 100 % $ 534 100 %

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Interim Financial Statements	Interim Financial Statements The accompanying unaudited interim financial statements have been prepared from the books and records of the Company in accordance with GAAP for interim financial information and Rule 10-01 of Regulation S-X promulgated by the United States Securities and Exchange Commission, or SEC, which permit reduced disclosures for interim periods. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying balance sheets and statements of operations, changes in convertible preferred stock and stockholders’ deficit and cash flows have been made. Although these interim financial statements do not include all of the information and footnotes required for complete annual financial statements, management believes the disclosures are adequate to make the information presented not misleading. Unaudited interim results of operations and cash flows for the three and six months ended June 30, 2019 are not necessarily indicative of the results that may be expected for the full year. Unaudited interim financial statements and footnotes should be read in conjunction with the audited financial statements and footnotes included in the Company’s Form 10-K filed with the SEC on March 5, 2019, wherein a more complete discussion of significant accounting policies and certain other information can be found.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with GAAP and the rules and regulations of the 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. The most significant estimates and judgments impact share-based compensation prior to the initial public offering (IPO).
Revenue Recognition	Revenue Recognition Adoption of ASC Topic 606, "Revenue from Contracts with Customers" On January 1, 2019, the Company adopted Topic 606 using the modified retrospective method applying the open contract practical expedient and accounted for those contracts which were not completed as of January 1, 2019 under Topic 606. Results for reporting periods beginning after January 1, 2019 are presented under Topic 606, while prior period amounts are not adjusted and continue to be reported in accordance with the Company’s historic accounting under Topic 605. Impact of Topic 606 on Financial Statement Line Items The adoption of ASC 606 had no impact to retained earnings or revenue as of January 1, 2019. In accordance with the new revenue standard requirements, the disclosure of the impact of adoption on prepaid commissions expense on the balance sheet as of June 30, 2019 and the statement of operations for the three and six months ended June 30, 2019 is as follows: As of June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Balance Sheet Current portion of prepaid commission expense $ 237 $ - $ 237 Prepaid commission expense 1,342 - 1,342 For the three months ended June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Income Statement Sales and marketing $ 11,523 $ 12,587 $ (1,064 ) Net loss (7,094 ) (8,158 ) 1,064 Six Months ended June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Income Statement Sales and marketing $ 21,115 $ 22,694 $ (1,579 ) Net loss (14,623 ) (16,202 ) 1,579 Topic 606 is principles-based and provides a five-step model to determine when and how revenue is recognized. The core principle is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Sales and usage-based taxes are excluded from revenues. Other than the revenue recognized under the distribution agreement disclosed below, all but an immaterial amount of the Company’s revenue is recognized at a point in time. 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 delivered to the customer’s 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 trans-cranial magnetic stimulation (“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 two-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 with a foreign entity for a period of 7 ½ years with two 2 year renewal options. As consideration for the right to be the sole distributor of the Company’s products and use of the Company’s intellectual property in the foreign territory, the distributor is required to make certain fixed milestone payments upon contract execution and regulatory approval. In addition, the distributor is required to make variable milestone payments depending upon regulatory reimbursement rates. Furthermore, the distributor is required to make certain minimum purchases based upon sales history and forecasts subject to a ceiling and floor. The Company assessed the potential performance obligations in this contract and concluded that the contract contained the following performance obligations: • Exclusive distribution and intellectual property license • NeuroStar TMS Therapy System (the “System”) • NeuroStar Treatment Session (the “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 three months ended June 30, 2019, were not materially impacted by any other factors. As of June 30, 2019, the Company expects to recognize approximately the following percentages of deferred revenue by year: Year: Revenue Recognition 2019 37 % 2020 16 % 2021 11 % 2022 11 % 2023 11 % Thereafter 14 % Total 100 % Revenue recognized for the six months ended June 30, 2019 that was included in the contract liability balance at the beginning of the year was $1.7 million, and primarily represented revenue earned from separately priced extended warranties and clinical training.
Leases	Leases Adoption of ASC Topic 842, "Leases" The Company accounts for leases in accordance with ASC Topic 842, Leases, (“Topic 842”). The Company determines if an arrangement is a lease at contract inception. A lease exists when a contract conveys to the customer the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. The definition of a lease embodies two conditions: (1) there is an identified asset in the contract that is land or a depreciable asset (i.e., property, plant, and equipment), and (2) the customer has the right to control the use of the identified asset. The Company leases warehouse and office space, 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, a bargain purchase option, or provides for minimum lease payments with a present value 90% or more of the fair value of the 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 and subsequently 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. As of June 30, 2019, the Company has not encountered any impairment losses. The Company monitors for events or changes in circumstances that require a reassessment of a lease. 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. The Company adopted ASU 2016-02 using a modified retrospective transition approach as of the effective date as permitted by the amendments in ASU 2018-11, which provides an alternative modified retrospective transition method. As a result, the Company was not required to adjust comparative period financial information for effects of the standard or make the new required lease disclosures for periods before the date of adoption (i.e. January 1, 2019). The Company has elected to adopt the package of transition practical expedients and, therefore, has not reassessed (1) whether existing or expired contracts contain a lease, (2) lease classification for existing or expired leases or (3) the accounting for initial direct costs that were previously capitalized. The Company did not elect the practical expedient to use hindsight for leases existing at the adoption date. Further, the Company does not expect the amendments in ASU 2018-01: Land Easement Practical Expedient to have an effect on us because the Company does not enter into land easement arrangements. There was no effect of the adoption of Topic 842 on retained earnings and other components of equity as of December 31, 2018.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Summary of Impact of Adoption on Prepaid Commissions Expense on Balance Sheet and Statement of Operations	In accordance with the new revenue standard requirements, the disclosure of the impact of adoption on prepaid commissions expense on the balance sheet as of June 30, 2019 and the statement of operations for the three and six months ended June 30, 2019 is as follows: As of June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Balance Sheet Current portion of prepaid commission expense $ 237 $ - $ 237 Prepaid commission expense 1,342 - 1,342 For the three months ended June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Income Statement Sales and marketing $ 11,523 $ 12,587 $ (1,064 ) Net loss (7,094 ) (8,158 ) 1,064 Six Months ended June 30, 2019 As Reported Balance Without Adoption of ASC 606 Effect of Change Higher/(Lower) Income Statement Sales and marketing $ 21,115 $ 22,694 $ (1,579 ) Net loss (14,623 ) (16,202 ) 1,579
Summary of Percentages of Deferred Revenue by Year	As of June 30, 2019, the Company expects to recognize approximately the following percentages of deferred revenue by year: Year: Revenue Recognition 2019 37 % 2020 16 % 2021 11 % 2022 11 % 2023 11 % Thereafter 14 % Total 100 %

Fair Value Measurement and Fi_2

Fair Value Measurement and Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2019
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 of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 Fair Value Measurement Based on Carrying Amount Fair Value Quoted Prices In Active Markets (Level 1) Significant other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market funds (cash equivalents) $ 70,992 $ 70,992 $ 70,992 $ - $ - December 31, 2018 Fair Value Measurement Based on Carrying Amount Fair Value Quoted Prices In Active Markets (Level 1) Significant other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market funds (cash equivalents) $ 87,062 $ 87,062 $ 87,062 $ - $ -
Summary of Fair Value Inputs and Assumptions	The fair value of the convertible preferred stock warrant liability was estimated using the Black-Scholes option pricing model and the following inputs and assumptions as of June 30, 2018: June 30, 2018 Series E Series F Estimated fair value of convertible preferred stock $ 26.67 $ 26.67 Exercise price $ 19.55 $ 9.73 Remaining term (in years) 4.5 2.6 - 6.5 Risk-free interest rate 2.7% 2.6% - 2.8% Expected volatility 43% 43% Dividend yield 0% 0%
Summary of Changes in Instruments and Outstanding Convertible Preferred Stock Warrant Liability Measured on Recurring Basis	The following table presents the changes in the Company’s Level 3 instrument, the then outstanding convertible preferred stock warrant liability, measured on a recurring basis for the six months ended June 30, 2018 (in thousands): Balance at December 31, 2017 $ 478 Change in fair value 1,415 Balance at June 30, 2018 $ 1,893

Accounts Receivable (Tables)

Accounts Receivable (Tables)	6 Months Ended
	Jun. 30, 2019
Receivables [Abstract]
Composition of Accounts Receivable, Net	The following table presents the composition of accounts receivable, net as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Gross accounts receivable - trade $ 8,074 $ 6,120 Less: Allowances for doubtful accounts (511 ) (500 ) Accounts receivable, net $ 7,563 $ 5,620

Property and Equipment and Ca_2

Property and Equipment and Capitalized Software (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Laboratory equipment $ 150 $ 150 Office equipment 487 487 Computer equipment and software 1,115 1,050 Manufacturing equipment 273 273 Leasehold improvements 172 172 Rental equipment 1,055 1,262 Property and equipment, gross 3,252 3,394 Less: Accumulated depreciation (2,147 ) (2,016 ) Property and equipment, net $ 1,105 $ 1,378

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2019
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 (in thousands): June 30, 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 175 Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 4,164
Schedule of Future Payments of Operating Lease Liabilities	The following table sets forth by year the required future payments of operating lease liabilities (in thousands): June 30, 2019 Remainder of 2019 $ 271 2020 584 2021 613 2022 637 2023 634 Thereafter 2,791 Total lease payments 5,530 Less imputed interest (1,372 ) Present value of operating lease liabilities $ 4,158
Summary of Minimum Expected Lease Payments Under Non-Cancelable Operating Leases	The following table sets forth by year the minimum expected lease payments under non-cancelable operating leases (in thousands) as of December 31, 2018: December 31, 2018 2019 $ 547 2020 560 2021 88 Total lease payments $ 1,195
Schedule of Profit Recognized on Sales-type Leases	The following table sets forth the profit recognized on sales-type leases (in thousands): Three Months ended June 30, Six Months ended June 30, 2019 2018 2019 2018 Profit recognized at commencement, net $ 118 $ - $ 262 $ - Interest Income - - - - Total sales-type lease income $ 118 $ - $ 262 $ -
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 (in thousands): June 30, 2019 Remainder of 2019 $ - 2020 240 2021 240 2022 160 Total sales-type lease receivables $ 640
Schedule of Maturity Analysis of Undiscounted Lease Receivable Related to Operating Leases	The following table sets forth a maturity analysis of its undiscounted lease receivables related to operating leases: June 30, 2019 Remainder of 2019 $ 245 2020 365 2021 150 Total lease receivables $ 760

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2019
Payables And Accruals [Abstract]
Summary of Composition of Accrued Expenses	The following table presents the composition of accrued expenses as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Compensation and related benefits $ 3,638 $ 4,909 Consulting and professional fees 516 342 Research and development expenses 329 191 Sales and marketing expenses 96 127 Warranty 716 629 Sales and other taxes payable 470 606 Interest payable 245 251 Other 466 493 Accrued expenses $ 6,476 $ 7,548

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Summary of Composition of Debt	The following table presents the composition of debt as of June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Outstanding principal $ 30,000 $ 30,000 Accrued final payment fees 1,646 1,468 Less debt discounts (889 ) (1,073 ) Total long-term debt, net 30,757 30,395 Less current portion of long-term debt (3,750 ) - Long-term debt, net $ 27,007 $ 30,395
Summary of Future Principal Payments	Based on a 24-month amortization of the outstanding principal amounts of the Term A and Term B Loans beginning on April 1, 2020 as discussed above, the following table sets forth by year the Company’s required future principal payments (in thousands): Year: Principal Payments 2019 $ - 2020 11,250 2021 15,000 2022 3,750 Total principal payments $ 30,000

Common Stock (Tables)

Common Stock (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 and December 31, 2018 (in thousands): June 30, 2019 December 31, 2018 Shares of common stock issued 18,445 17,744 Shares of common stock reserved for issuance for: Common stock warrants outstanding 105 105 Stock options outstanding 2,507 2,711 Restricted stock units outstanding 184 43 Shares available for grant under stock incentive plan 1,383 1,312 Shares available for sale under employee stock purchase plan 421 244 Total shares of common stock issued and reserved for issuance 23,045 22,159
Summary of Outstanding Common Stock Warrants	The following table summarizes the Company’s outstanding common stock warrants as of June 30, 2019 and December 31, 2018: Warrants Outstanding (in thousands) Exercise Price Expiration Date 14 $ 19.55 Dec-2022 30 $ 9.73 Feb-2021 20 $ 9.73 Aug-2023 20 $ 9.73 Mar-2024 21 $ 9.73 Dec-2024 105

Loss Per Share (Tables)

Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 and 2018 have been excluded from the denominator of the diluted loss per share of common stock outstanding calculation (in thousands): June 30, 2019 2018 Stock options 2,507 2,855 Non-vested restricted stock awards - 10 Non-vested restricted stock units 184 - Convertible preferred stock warrants - 105 Common stock warrants 105 - Shares of convertible preferred stock “as-converted” - 10,994

Share-Based Compensation (Table

Share-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased 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 three and six months ended June 30, 2019 and 2018 is as follows (in thousands): Three Months ended June 30, Six Months ended June 30, 2019 2018 2019 2018 Cost of revenues $ 19 $ 5 $ 29 $ 9 Sales and marketing 404 65 608 119 General and administrative 479 87 697 142 Research and development 120 35 189 66 Total $ 1,022 $ 192 $ 1,523 $ 336
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity for the six months ended June 30, 2019: Number of Shares under Option (in thousands) Weighted- average Exercise Price per Option Weighted- average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2018 2,711 $ 3.59 Granted 588 $ 16.08 Exercised (687 ) $ 2.82 Forfeited (105 ) $ 8.86 Outstanding at June 30, 2019 2,507 $ 6.51 7.6 $ 17,741 Exercisable at June 30, 2019 1,204 $ 2.39 6.2 $ 12,221 Vested and expected to vest at June 30, 2019 2,507 $ 6.51 7.6 $ 17,741
Summary of Weighted-average Inputs and Assumptions used to Estimate Grant-date Fair Value of Stock Options	For the six months ended June 30, 2019, 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: Estimated fair value of common stock $ 16.08 Exercise price $ 16.08 Expected term (in years) 6.1 Risk-free interest rate 2.4 % Expected volatility 55.3 % Dividend yield 0 %
Summary of Restricted Stock Award and Restricted Stock Unit Activity	The following table summarizes the Company’s restricted stock award and restricted stock unit activity for the six months ended June 30, 2019: Non-vested Restricted Stock Awards (in thousands) Weighted- average Grant-date Fair Value Non-vested Restricted Stock Units (in thousands) Weighted- average Grant-date Fair Value Non-vested at December 31, 2018 4 $ 2.32 43 $ 25.21 Granted - $ - 155 $ 15.77 Vested (4 ) $ 2.32 (14 ) $ 22.23 Non-vested at June 30, 2019 - $ - 184 $ 17.41

Geographical Segment Informat_2

Geographical Segment Information (Tables)	6 Months Ended
	Jun. 30, 2019
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 Three Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues United States $ 15,890 96 % $ 12,898 97 % International 682 4 % 354 3 % Total revenues $ 16,572 100 % $ 13,252 100 % Revenues by Geography Six Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues United States $ 28,436 97 % $ 22,870 98 % International 864 3 % 534 2 % Total revenues $ 29,300 100 % $ 23,404 100 %
United States
Summary of Revenue Generated in Product Category for Years Indicated	U.S. Revenues by Product Category Three Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 4,628 29 % $ 3,568 28 % Treatment sessions 10,847 68 % 8,920 69 % Other 415 3 % 410 3 % Total U.S. revenues $ 15,890 100 % $ 12,898 100 % U.S. Revenues by Product Category Six Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 7,978 28 % $ 5,941 26 % Treatment sessions 19,625 69 % 16,160 71 % Other 833 3 % 769 3 % Total U.S. revenues $ 28,436 100 % $ 22,870 100 %
International
Summary of Revenue Generated in Product Category for Years Indicated	International Revenues by Product Category Three Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 465 68 % $ 219 62 % Treatment sessions 114 17 % 56 16 % Other 103 15 % 79 22 % Total International revenues $ 682 100 % $ 354 100 % International Revenues by Product Category Six Months ended June 30, 2019 2018 Amount % of Revenues Amount % of Revenues (in thousands, except percentages) NeuroStar Advanced Therapy System $ 537 62 % $ 219 41 % Treatment sessions 133 15 % 81 15 % Other 194 23 % 234 44 % Total International revenues $ 864 100 % $ 534 100 %

Description of Business - Addit

Description of Business - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Description Of Business [Line Items]
Cash and cash equivalents	$ 89,644		$ 104,583
Accumulated deficit	235,666		221,043
Cash flows from operating activities	16,418	$ 13,397	$ 20,600
$35.0 Million Credit Facility | Oxford Finance LLC
Description Of Business [Line Items]
Borrowings outstanding under credit facility	$ 30,000
Credit facility maturity date	Mar. 1, 2022

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Jan. 01, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit		$ (235,666,000)		$ (235,666,000)			$ (221,043,000)
Impact to revenue		16,572,000	$ 13,252,000	$ 29,300,000	$ 23,404,000
Revenue, performance obligation, description of warranty				The Company provides a two-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
Distribution agreement, renewal period				2 years		2 years
Revenue recognized				$ 1,700,000
ASU 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ 0
Impact to revenue	$ 0
Topic 842
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit							$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Impact of Adoption on Prepaid Commissions Expense on Balance Sheet and Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Current portion of prepaid commission expense	$ 237				$ 237
Prepaid commission expense	1,342				1,342
Sales and marketing	11,523		$ 9,835		21,115	$ 17,944
Net loss	(7,094)	$ (7,529)	$ (7,496)	$ (5,497)	(14,623)	$ (12,993)
ASC 606 | Income Statement
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales and marketing	11,523				21,115
Net loss	(7,094)				(14,623)
ASC 606 | Income Statement | Balance Without Adoption of ASC 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales and marketing	12,587				22,694
Net loss	(8,158)				(16,202)
ASC 606 | Income Statement | Effect of Change Higher/(Lower)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Sales and marketing	(1,064)				(1,579)
Net loss	1,064				1,579
ASC 606 | Balance Sheet
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Current portion of prepaid commission expense	237				237
Prepaid commission expense	1,342				1,342
ASC 606 | Balance Sheet | Effect of Change Higher/(Lower)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Current portion of prepaid commission expense	237				237
Prepaid commission expense	$ 1,342				$ 1,342

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Percentages of Deferred Revenue by Year (Details)	Jun. 30, 2019
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	100.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	37.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	16.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	11.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	11.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	11.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	14.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Percentages of Deferred Revenue by Year 1 (Details)	Jun. 30, 2019
Revenue Performance Obligation Satisfied Over Time [Abstract]
Revenue, remaining performance obligation	100.00%

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	Jun. 30, 2019	Dec. 31, 2018
Carrying Amount
Assets
Total assets	$ 70,992	$ 87,062
Fair Value
Assets
Total assets	70,992	87,062
Quoted Prices In Active Markets (Level 1)
Assets
Total assets	$ 70,992	$ 87,062

Fair Value Measurement and Fi_4

Fair Value Measurement and Financial Instruments - Summary of Fair Value Inputs and Assumptions (Details)	6 Months Ended
	Jun. 30, 2018$ / shares
Estimated Fair Value of Convertible Preferred Stock | Series E
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumption	$ 26.67
Estimated Fair Value of Convertible Preferred Stock | Series F
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumption	26.67
Exercise Price | Series E
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Exercise price	19.55
Exercise Price | Series F
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Exercise price	$ 9.73
Remaining Term (in years) | Series E
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	4 years 6 months
Remaining Term (in years) | Series F | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	2 years 7 months 6 days
Remaining Term (in years) | Series F | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Remaining term (in years)	6 years 6 months
Risk-free Interest Rate | Series E
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	2.7
Risk-free Interest Rate | Series F | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	2.6
Risk-free Interest Rate | Series F | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	2.8
Expected Volatility | Series E
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	43
Expected Volatility | Series F
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	43
Dividend Yield | Series E
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	0
Dividend Yield | Series F
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Risk-free interest rate	0

Fair Value Measurement and Fi_5

Fair Value Measurement and Financial Instruments - Summary of Changes in Instruments and Outstanding Convertible Preferred Stock Warrant Liability Measured on Recurring Basis (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Balance at December 31, 2017	$ 478
Change in fair value	1,415
Balance at June 30, 2018	$ 1,893

Accounts Receivable - Compositi

Accounts Receivable - Composition of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Receivables [Abstract]
Gross accounts receivable - trade	$ 8,074	$ 6,120
Less: Allowances for doubtful accounts	(511)	(500)
Accounts receivable, net	$ 7,563	$ 5,620

Property and Equipment and Ca_3

Property and Equipment and Capitalized Software - Summary of Composition of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 3,252	$ 3,394
Less: Accumulated depreciation	(2,147)	(2,016)
Property and equipment, net	1,105	1,378
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	150	150
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	487	487
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,115	1,050
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	273	273
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	172	172
Rental Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,055	1,262
Property and equipment, net	$ 700	$ 900

Property and Equipment and Ca_4

Property and Equipment and Capitalized Software - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 0.3	$ 0.3	$ 0.5	$ 0.5
Other Assets [Member]
Property Plant And Equipment [Line Items]
Capitalized software cost, net	$ 1.1		$ 1.1		$ 1

Leases - Additional Information

Leases - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)ft²	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)ft²	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Leases [Line Items]
Lessee, finance lease, lease not yet commenced, description			The Company does not currently have any finance leases or executed leases that have not yet commenced.
Operating lease, rent expense, net	$ 200,000		$ 300,000
Operating lease, weighted-average remaining lease term	8 years 7 months 6 days		8 years 7 months 6 days
Operating lease, weighted-average discount rate	6.50%		6.50%
Carrying amount of lease receivables	$ 600,000		$ 600,000
Unguaranteed residual assets	0		0
Operating lease income	100,000	$ 200,000	300,000	$ 400,000
Property and equipment, net	$ 1,105,000		$ 1,105,000		$ 1,378,000
NeuroStar Advanced Therapy Systems
Leases [Line Items]
Lessor sales-type lease, Term	3 years		3 years
Headquarters and Office Equipment, Including Copiers
Leases [Line Items]
Area of lease facility | ft²	32,000		32,000
Lessee, operating lease, extended maturity period			2028-02
Additional lease facility area acquired | ft²	10,000		10,000
Lessee, operating lease, existence of option to extend			true
Combined area of lease facility | ft²	42,000		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		5 years
Office Equipment, Including Copiers
Leases [Line Items]
Lessee, operating lease, maturity period			2023-03
Rental Equipment
Leases [Line Items]
Property and equipment, net	$ 700,000		$ 700,000		$ 900,000
Rental equipment depreciation expense	$ 50,000	$ 200,000	$ 100,000	$ 300,000

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information as Lessee Related to Leases (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 175
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 4,164

Leases - Schedule of Future Pay

Leases - Schedule of Future Payments of Operating Lease Liabilities (Details) $ in Thousands	Jun. 30, 2019USD ($)
Operating Lease Liabilities Payments Due [Abstract]
Remainder of 2019	$ 271
2020	584
2021	613
2022	637
2023	634
Thereafter	2,791
Total lease payments	5,530
Less imputed interest	(1,372)
Present value of operating lease liabilities	$ 4,158

Leases - Summary of Minimum Exp

Leases - Summary of Minimum Expected Lease Payments Under Non-Cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2019	$ 547
2020	560
2021	88
Total lease payments	$ 1,195

Leases - Schedule of Profit Rec

Leases - Schedule of Profit Recognized on Sales-type Leases (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Sales Type Lease Lease Income [Abstract]
Profit recognized at commencement, net	$ 118	$ 262
Total sales-type lease income	$ 118	$ 262

Leases - Schedule of Maturity A

Leases - Schedule of Maturity Analysis of Undiscounted Lease Receivables Related to Sales-type Leases (Details) $ in Thousands	Jun. 30, 2019USD ($)
Sales Type And Direct Financing Leases Lease Receivable Fiscal Year Maturity [Abstract]
2020	$ 240
2021	240
2022	160
Total sales-type lease receivables	$ 640

Leases - Schedule of Maturity_2

Leases - Schedule of Maturity Analysis of Undiscounted Lease Receivable Related to Operating Leases (Details) $ in Thousands	Jun. 30, 2019USD ($)
Lessor Operating Lease Payments Fiscal Year Maturity [Abstract]
Remainder of 2019	$ 245
2020	365
2021	150
Total lease receivables	$ 760

Prepaid Commission Expense - Ad

Prepaid Commission Expense - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Amortization Of Deferred Charges [Abstract]
Amortization period of deferred commissions		7 years
Amortization expense	$ 40	$ 60

Accrued Expenses - Summary of C

Accrued Expenses - Summary of Composition of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Compensation and related benefits	$ 3,638	$ 4,909
Consulting and professional fees	516	342
Research and development expenses	329	191
Sales and marketing expenses	96	127
Warranty	716	629
Sales and other taxes payable	470	606
Interest payable	245	251
Other	466	493
Accrued expenses	$ 6,476	$ 7,548

Debt - Summary of Composition o

Debt - Summary of Composition of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Outstanding principal	$ 30,000	$ 30,000
Accrued final payment fees	1,646	1,468
Less debt discounts	(889)	(1,073)
Total long-term debt, net	30,757	30,395
Less current portion of long-term debt	(3,750)
Long-term debt, net	$ 27,007	$ 30,395

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands	Jul. 02, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Mar. 31, 2017	Feb. 28, 2017
Debt Instrument [Line Items]
Interest expense		$ 900,000	$ 900,000	$ 1,900,000	$ 1,800,000
Cash interest expense		700,000	700,000	1,500,000	1,400,000
Non-cash interest expense		200,000	$ 200,000	$ 400,000	$ 400,000
$35.0 Million Credit Facility
Debt Instrument [Line Items]
Percentage of forecasted revenue to be achieved				75.00%
$35.0 Million Credit Facility | Prepaid on or Before First Anniversary of Funding
Debt Instrument [Line Items]
Prepayment fees percentage				3.00%
$35.0 Million Credit Facility | Prepaid After First and on or Before Second Anniversary of Funding
Debt Instrument [Line Items]
Prepayment fees percentage				2.00%
$35.0 Million Credit Facility | Prepaid After Second Anniversary of Funding
Debt Instrument [Line Items]
Prepayment fees percentage				1.00%
$35.0 Million Credit Facility | Oxford Finance LLC
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							$ 35,000,000	$ 25,000,000
Borrowings outstanding under credit facility		$ 30,000,000		$ 30,000,000
Available borrowing achievement of trailing twelve month revenues							45,000,000
Debt instrument, interest rate		8.15%		8.15%
Warrants term		7 years		7 years
Percentage of borrowing capacity of tranche				3.95%
Borrowing capacity of tranche		$ 5,000,000		$ 5,000,000
Credit facility maturity date				Mar. 1, 2022
$35.0 Million Credit Facility | Oxford Finance LLC | LIBOR
Debt Instrument [Line Items]
Debt instrument, description of variable rate basis				30-day U.S. LIBOR
Basis spread on variable rate				7.38%
$35.0 Million Credit Facility | Term A Loan
Debt Instrument [Line Items]
Available borrowing achievement of trailing twelve month revenues						$ 45,000,000
Interest-only period				2019-03
Amortization period without interest-only period extension				36 months
Extension of interest-only period upon achievement of revenues				12 months
Interest-only period upon achievement of revenues				2020-03
Amortization period upon extension of interest-only period				24 months
Increase in final payment fees percentage upon extension interest only periods				8.50%
Effective interest rates						11.87%
$35.0 Million Credit Facility | Term A Loan | Common Stock
Debt Instrument [Line Items]
Warrants to purchase shares	20,303
Warrants, exercise price	$ 9.73
Warrants expiration period	2024-03
$35.0 Million Credit Facility | Term A Loan | Oxford Finance LLC
Debt Instrument [Line Items]
Borrowings outstanding under credit facility							25,000,000
$35.0 Million Credit Facility | Term B Loan
Debt Instrument [Line Items]
Available borrowing achievement of trailing twelve month revenues						$ 45,000
Interest-only period				2019-03
Amortization period without interest-only period extension				36 months
Extension of interest-only period upon achievement of revenues				12 months
Interest-only period upon achievement of revenues				2020-03
Amortization period upon extension of interest-only period				24 months
Increase in final payment fees percentage upon extension interest only periods				7.50%
Effective interest rates						12.14%
$35.0 Million Credit Facility | Term B Loan | Common Stock
Debt Instrument [Line Items]
Warrants to purchase shares	20,303
Warrants, exercise price	$ 9.73
Warrants expiration period	2024-12
$35.0 Million Credit Facility | Term B Loan | Oxford Finance LLC
Debt Instrument [Line Items]
Borrowings outstanding under credit facility							5,000,000
$35.0 Million Credit Facility | Term C Loan | Oxford Finance LLC
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity							$ 5,000,000
Notification period for lenders to borrow loan upon achieving required revenue milestone				60 days
Line of credit facility additional borrowing capacity		$ 5,000,000		$ 5,000,000

Debt - Schedule of Future Princ

Debt - Schedule of Future Principal Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total principal payments	$ 30,000	$ 30,000
Term A and Term B Loans
Debt Instrument [Line Items]
2020	11,250
2021	15,000
2022	3,750
Total principal payments	$ 30,000

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - $ / shares	Jul. 02, 2018	Jun. 30, 2019	Dec. 31, 2018
Stockholders Deficit [Line Items]
Common stock, par value per share		$ 0.01	$ 0.01
Common stock, shares authorized for issuance		200,000,000	200,000,000
Common stock, shares issued		18,445,000	17,744,000
Common stock, shares outstanding		18,445,000	17,744,000
Initial Public Offering | Common Stock
Stockholders Deficit [Line Items]
Convertible preferred stock converted into common stock	11,000,000

Common Stock - Summary of Commo

Common Stock - Summary of Common Stock Issued and Reserved for Issuance (Details) - shares	Jun. 30, 2019	Dec. 31, 2018	Jul. 31, 2018
Stockholders Deficit [Line Items]
Shares of common stock issued	18,445,000	17,744,000
Shares of common stock reserved for issuance for:
Total shares of common stock issued and reserved for issuance	23,045,000	22,159,000
Common Stock Warrants Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	105,000	105,000
Stock Options Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	2,507,000	2,711,000
Restricted Stock Units Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	184,000	43,000
Shares Available for Grant Under Stock Incentive Plan
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	1,383,000	1,312,000
Shares Available for Sales Under Employee Stock Purchase Plan
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	421,000	244,000	200,000

Common Stock - Summary of Outst

Common Stock - Summary of Outstanding Common Stock Warrants (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	105
Exercise Price $19.55
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	14
Exercise Price | $ / shares	$ 19.55
Expiration Date	2022-12
Exercise Price $9.73
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	30
Exercise Price | $ / shares	$ 9.73
Expiration Date	2021-02
Exercise Price $9.73
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	20
Exercise Price | $ / shares	$ 9.73
Expiration Date	2023-08
Exercise Price $9.73
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	20
Exercise Price | $ / shares	$ 9.73
Expiration Date	2024-03
Exercise Price $9.73
Class Of Warrant Or Right [Line Items]
Warrants Outstanding	21
Exercise Price | $ / shares	$ 9.73
Expiration Date	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	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Stock Options Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	2,507	2,855
Non-vested Restricted Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share		10
Non-vested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	184
Convertible Preferred Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share		105
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share	105
Shares of Convertible Preferred Stock "as-converted"
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding excluded from diluted loss per share		10,994

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 1,022	$ 192	$ 1,523	$ 336
Cost of Revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	19	5	29	9
Sales and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	404	65	608	119
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	479	87	697	142
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 120	$ 35	$ 189	$ 66

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses	$ 1,022,000	$ 192,000	$ 1,523,000	$ 336,000
Weighted-average grant-date fair value of stock options granted			$ 8.70
Intrinsic value of stock options exercised			$ 9,400,000
Stock Options Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses	700,000	200,000	1,000,000	300,000
Unrecognized compensation cost related to non-vested stock options	6,800,000		$ 6,800,000
Non-vested awards not yet recognized weighted-average period for recognition			3 years 3 months 18 days
Restricted Stock Awards and Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested awards not yet recognized weighted-average period for recognition			2 years 7 months 6 days
Unrecognized compensation cost related to non-vested restricted stock	2,900,000		$ 2,900,000
Fair value of restricted stock vested			300,000
Maximum | Restricted Stock Awards and Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses	$ 300,000	$ 300,000	$ 500,000	$ 500,000
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual percentage increase in number of shares authorized for issuance			4.00%
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
Shares available for future issuance	1,400,000		1,400,000
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			25.00%
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		1,400,000
Maximum contractual term of stock options			10 years

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options Outstanding - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares under Option, Outstanding, Beginning balance	2,711
Number of Shares under Option, Granted	588
Number of Shares under Option, Exercised	(687)
Number of Shares under Option, Forfeited	(105)
Number of Shares under Option, Outstanding, Ending balance	2,507
Number of Shares under Option, Exercisable	1,204
Number of Shares under Option, Vested and expected to vest	2,507
Weighted-average Exercise Price per Option, Outstanding, Beginning balance	$ 3.59
Weighted-average Exercise Price per Option, Granted	16.08
Weighted-average Exercise Price per Option, Exercised	2.82
Weighted-average Exercise Price per Option, Forfeited	8.86
Weighted-average Exercise Price per Option, Outstanding, Ending balance	6.51
Weighted-average Exercise Price per Option, Exercisable	2.39
Weighted-average Exercise Price per Option, Vested and expected to vest	$ 6.51
Weighted-average Remaining Contractual Life, Outstanding	7 years 7 months 6 days
Weighted-average Remaining Contractual Life, Exercisable	6 years 2 months 12 days
Weighted-average Remaining Contractual Life, Vested and expected to vest	7 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding	$ 17,741
Aggregate Intrinsic Value, Exercisable	12,221
Aggregate Intrinsic Value, Vested and expected to vest	$ 17,741

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Weighted-average Inputs and Assumptions used to Estimate Grant-date Fair Value of Stock Options (Details)	6 Months Ended
	Jun. 30, 2019$ / shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Estimated fair value of common stock	$ 16.08
Exercise price	$ 16.08
Expected term (in years)	6 years 1 month 6 days
Risk-free interest rate	2.40%
Expected volatility	55.30%
Dividend yield	0.00%

Share-Based Compensation - Su_4

Share-Based Compensation - Summary of Restricted Stock Award and Restricted Stock Unit Activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Restricted Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested, Beginning balance | shares	4
Vested | shares	(4)
Weighted-average Grant-date Fair Value, Non-vested, Beginning balance | $ / shares	$ 2.32
Weighted-average Grant-date Fair Value, Vested | $ / shares	$ 2.32
Restricted Stock Units Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-vested, Beginning balance | shares	43
Granted | shares	155
Vested | shares	(14)
Non-vested, Ending balance | shares	184
Weighted-average Grant-date Fair Value, Non-vested, Beginning balance | $ / shares	$ 25.21
Weighted-average Grant-date Fair Value, Granted | $ / shares	15.77
Weighted-average Grant-date Fair Value, Vested | $ / shares	22.23
Weighted-average Grant-date Fair Value, Non-vested, Ending balance | $ / shares	$ 17.41

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - shares shares in Thousands	1 Months Ended	6 Months Ended
	Jul. 31, 2018	Jun. 30, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined contribution retirement plan, plan name		401(k) plan
2018 ESPP
Defined Benefit Plan Disclosure [Line Items]
Shares of common stock reserved for issuance	200	421	244
Common stock purchase price, discount rate	15.00%
Maximum | 2018 ESPP
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 retirement plan, maximum employee contribution deferred		100.00%

Distribution Agreement with T_2

Distribution Agreement with Teijin Pharma Limited - Additional Information (Details) $ in Thousands	Jun. 01, 2019JPY (¥)	Jun. 30, 2019USD ($)	Jun. 30, 2019	Dec. 31, 2017USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Term of distribution agreement			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 Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Agreement expiry date				Mar. 31, 2025
Extended term of agreement				2 years
Related party purchased percentage of sales forecasts over agreement term.				100.00%
Upfront Payment
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received				$ 750
Milestone Payment
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment received		$ 700		$ 2,000

Geographical Segment Informat_3

Geographical Segment Information - Additional Information (Details)	6 Months Ended
	Jun. 30, 2019Segment
Segments Geographical Areas [Abstract]
Number of operating business segment	1

Geographical Segment Informat_4

Geographical Segment Information - Summary of Revenue Generated in Geographic Regions for Years Indicated (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 16,572	$ 13,252	$ 29,300	$ 23,404
Revenues | Geographic Concentration
Segment Reporting Information [Line Items]
Revenues	$ 16,572	$ 13,252	$ 29,300	$ 23,404
Percentage of Revenues	100.00%	100.00%	100.00%	100.00%
Revenues | United States | Geographic Concentration
Segment Reporting Information [Line Items]
Revenues	$ 15,890	$ 12,898	$ 28,436	$ 22,870
Percentage of Revenues	96.00%	97.00%	97.00%	98.00%
Revenues | International | Geographic Concentration
Segment Reporting Information [Line Items]
Revenues	$ 682	$ 354	$ 864	$ 534
Percentage of Revenues	4.00%	3.00%	3.00%	2.00%

Geographical Segment Informat_5

Geographical Segment Information - Summary of Revenue Generated in Product Category for Years Indicated (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 16,572	$ 13,252	$ 29,300	$ 23,404
Product Category | United States | Revenues
Segment Reporting Information [Line Items]
Revenues	$ 15,890	$ 12,898	$ 28,436	$ 22,870
Percentage of Revenues	100.00%	100.00%	100.00%	100.00%
Product Category | United States | Revenues | NeuroStar Advanced Therapy System
Segment Reporting Information [Line Items]
Revenues	$ 4,628	$ 3,568	$ 7,978	$ 5,941
Percentage of Revenues	29.00%	28.00%	28.00%	26.00%
Product Category | United States | Revenues | Treatment Sessions
Segment Reporting Information [Line Items]
Revenues	$ 10,847	$ 8,920	$ 19,625	$ 16,160
Percentage of Revenues	68.00%	69.00%	69.00%	71.00%
Product Category | United States | Revenues | Other
Segment Reporting Information [Line Items]
Revenues	$ 415	$ 410	$ 833	$ 769
Percentage of Revenues	3.00%	3.00%	3.00%	3.00%
Product Category | International | Revenues
Segment Reporting Information [Line Items]
Revenues	$ 682	$ 354	$ 864	$ 534
Percentage of Revenues	100.00%	100.00%	100.00%	100.00%
Product Category | International | Revenues | NeuroStar Advanced Therapy System
Segment Reporting Information [Line Items]
Revenues	$ 465	$ 219	$ 537	$ 219
Percentage of Revenues	68.00%	62.00%	62.00%	41.00%
Product Category | International | Revenues | Treatment Sessions
Segment Reporting Information [Line Items]
Revenues	$ 114	$ 56	$ 133	$ 81
Percentage of Revenues	17.00%	16.00%	15.00%	15.00%
Product Category | International | Revenues | Other
Segment Reporting Information [Line Items]
Revenues	$ 103	$ 79	$ 194	$ 234
Percentage of Revenues	15.00%	22.00%	23.00%	44.00%