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                                                                   EXHIBIT 10.18


                            FOURTH AMENDMENT TO LEASE

         THIS FOURTH AMENDMENT TO LEASE AGREEMENT (hereinafter the "Fourth
Amendment") is made and entered into this 11th day of March, 1999, by and
between W. FRED WILLIAMS, TRUSTEE FOR THE BENEFIT OF HIGHWOODS/TENNESSEE
HOLDINGS, L.P. (successor-in-interest to 3401 Associates, L.P., a Tennessee
limited partnership, successor-in-interest to The Equitable Life Assurance
Society of the United States) as "Landlord", and CHILDREN'S COMPREHENSIVE
SERVICES, INC. (successor-in-interest to Vendell Healthcare, Inc.,
successor-in-interest to Rivendell of America, Inc.) as "Tenant".

         WHEREAS, Landlord and Tenant entered into a certain Lease dated
September 26, 1989, and as subsequently amended on February 21,1990, by that
"First Amendment to Lease" and on March 1, 1993, by that "Second Amendment to
Lease" and on October 26, 1993 by that "Third Amendment to Lease" (all
hereinafter referred to as the "Lease"), providing for the demise by Landlord to
Tenant of office space in a certain office building now commonly known and
designated as 3401 West End Avenue, Nashville, Tennessee (the "Building"), all
as more specifically set forth in the Lease; and

         WHEREAS, Landlord and Tenant desire to renew the Lease, amend the
rental rate, and expand the premises by 4,056 rentable square feet; and

         WHEREAS, Tenant will now occupy 18,551 rentable square feet on the 4th
floor of the East wing and 4,635 rentable square feet on the 5th floor of the
East wing as described in Exhibit A-1

         NOW, THEREFORE, in consideration of mutual covenants and undertakings
hereinafter set forth by and between the parties hereto, the Lease is hereby
Amended as follows:

1.       Amendment of Article I. "Lessee" Section. Line 5 of the Section
         captioned "Lessee" in Article I of the Lease shall be amended to
         provide the following:

                  "approximately 23,186 rentable square feet"

2.       Amendment of Article I, "Term" Section. The Section captioned "Term" of
         Article I of the Lease shall be deleted and the following substituted:

                  "The term of this Lease shall commence on June 1, 1999 and
                  shall end on December 31, 2004 unless sooner terminated as
                  provided herein, to be occupied and used by the Tenant for
                  general offices and for no other purposes whatsoever."

3.       Amendment of Article II, "Base Rental" Section. The Section captioned
         "Base Rental (a)" of Article II of the Lease shall be deleted and the
         following substituted:


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                  "The Tenant shall pay to the Landlord as Base Rent according
                  to the following schedule:"



                  (18,551 rsf on 4th floor)
                   From        To          Rate       Monthly        Annually
                  ------    --------      ------     ----------    -----------
                                                       
                  6/1/99     5/31/00      $19.95     $30,841.04    $370,092.48
                  6/1/00     5/31/01      $20.55     $31,768.59    $381,223.08
                  6/1/01     5/31/02      $21.17     $32,727.06    $392,724.72
                  6/1/02     5/31/03      $21.80     $33,700.98    $404,411.76
                  6/1/03     5/31/04      $22.45     $34,705.83    $416,469.96
                  6/1/04    12/31/04      $23.13     $35,757.05    $250,299.35(7 mos)





                  (4,635 rsf on the 5th floor)
                   From        To          Rate       Monthly        Annually
                  ------    --------      ------     ----------    -----------
                                                       
                  6/1/99    12/31/99      $16.00     $ 6,180.00    $ 43,260.00(7 mos)
                  1/1/00     5/31/00      $19.95     $ 7,705.69    $ 38,528.45(5 mos)
                  6/1/00     5/31/01      $20.55     $ 7,937.44    $ 95,249.28
                  6/1/01     5/31/02      $21.17     $ 8,176.91    $ 98,122.92
                  6/1/02     5/31/03      $21.80     $ 8,420.25    $101,043.00
                  6/1/03     5/31/04      $22.45     $ 8,671.31    $104,055.72
                  6/1/04    12/31/04      $23.13     $ 8,933.96    $ 62,537.72(7 mos)


                  *        Current base year for this space will remain the same
                           through 12/31/99



                  (Storage Rent)
                  Suite              Size               Monthly Rent
                  -----              ----               ------------
                                                   
                  4B               281 rsf               $187.33 p/m
                  5A               112 rsf               $ 74.67 p/m


4.       Amendment of Article II, "Net Rentable Area" Section. The Section
         captioned "Net Rentable Area" of Article II of the Lease shall be
         deleted and the following substituted:

                  "The Net Rentable Area of the Building shall, for all
                  purposes, be deemed to be 254,442 square feet, and the Net
                  Rentable Area of the Premises shall be deemed to be 23,186
                  square feet."

5.       Operating Expenses. The Base Year for taxes and operating expenses
         shall be the full calendar year of 1999. The 1999 Base Year will be
         effective June 1, 1999 for the 4th floor space and January 1, 2000 for
         the 5th floor space.

6.       Option to Renew. Tenant shall have the option to renew this Lease for
         one (1) successive five (5) year term under the same terms and
         conditions of the Lease, except that Base Rent for the renewal term
         shall be calculated at the then current market rate for the Premises,
         provided however, that: 1) the Tenant shall have notified the Landlord
         in writing of its election to renew the term at least six (6) months
         prior to the commencement of such term,


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         and 2) at the time of such election and at the time of commencement of
         such term, the Tenant shall not be in default under any of the terms,
         covenants or conditions of the Lease with respect to a matter as to
         which notice of default has been given hereunder and which has not been
         remedied within the time limited in this Lease and this Lease has not
         been terminated.

7.       Amendment of Article II, "Operating Expense" Section Paragraph (g).
         Paragraph (g) of the Section captioned "Operating Expense" in Article
         II of the Lease shall be amended as follows:

                  "Landlord will provide Tenant with a total of seventy-seven
                  (77) parking spaces at no cost. Seventy-one spaces will be
                  non-reserved and six (6) spaces will be reserved."

8.       Amendment of Article V. "Brokerage" Section. The Section captioned
         "Brokerage" of Article V of the Lease shall be amended by deleting the
         reference to any Broker other than Grubb and Ellis/Centennial.

9.       Tenant Improvements. Landlord will provide an allowance of up to
         $248,555 to be used solely for improvements to the Premises. The tenant
         improvement allowance is inclusive of all architectural and engineering
         costs. There will be no rental abatement or refund to the tenant for
         any unused portion of the allowance.

10.      Termination Option. Tenant shall have a one (1) time option to
         terminate the Lease on December 31, 2002 by providing at least six (6)
         months written notice to Landlord. Prior to termination of Lease,
         Tenant will pay in a lump sum an amount of all unamortized costs
         associated with tenant improvements (5 year amortization at an interest
         rate of 12%) and the total of the unamortized real estate brokers
         commission and will pay a termination fee equal to three (3) months
         rent at the rental rate of $21.80 per rentable square foot as outlined
         in the Lease.

11.      Definitions. Definitions and terms used in this Fourth Amendment shall
         have the same definitions set forth in the Lease.

12.      Incorporation. This Fourth Amendment shall be incorporated into and
         made a part of the Lease and all provisions of this Lease not expressly
         modified or amended shall remain in full force and effect.


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         IN WITNESS WHEREOF, the parties hereto have executed this Fourth
Amendment to Lease Agreement by proper person thereunto authorized to do so on
the day and year first written above.

LANDLORD:

W. FRED WILLIAMS, TRUSTEE FOR THE
BENEFIT OF HIGHWOODS/TENNESSEE HOLDINGS, L.P.

By: /s/ W. Brian Reames
   ---------------------------------------
   W. Brian Reames, as Authorized Agent for
   W. Fred Williams, Trustee, under that
   certain Amended and Restated Trust
   Agreement effective as of November 27,
   1996 by and between Highwoods/Tennessee
   Holdings, L.P. and W. Fred Williams


Title: Vice President

Date: 3-12-99
     --------------------

TENANT:

CHILDREN'S COMPREHENSIVE SERVICES, INC.
(Assignee of Vendell Healthcare, Inc.)

By: /s/ Donald B Whitfield
   ---------------------------------------

Title: VP-Finance/CFO
       -----------------------------------

Date:    March 11, 1999
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