<PAGE>   1
                                                                 EXHIBIT 10.29


                              EMPLOYMENT AGREEMENT

            THIS EMPLOYMENT AGREEMENT (the "Agreement") is made and entered
into as of the ninth day of April, 1998, by and between Advanced Neuromodulation
Systems, Inc. ("ANS"), Quest Medical, Inc. (the "Parent"), (the Parent, ANS,
and, in the event of a merger of the two companies, any surviving entity,
hereinafter referred to as "the Companies," "either Company," or "each Company"
according to the context) and Christopher G. Chavez ("Employee").

                                 R E C I T A L S

            The Companies have special expertise in their businesses that has
enabled them to provide unique career opportunities for their employees.

            The Companies' growth depends, to a significant degree, on their
possession of more and better information than that available to their
competitors concerning a number of matters, including but not limited to,
research, systems, development, marketing, management and other information not
generally known to others in each Company's industry. To obtain such information
and use it successfully, the Companies have made significant investments in
research, business development, customer satisfaction methods and techniques,
business process improvements and other developments in marketing methods and
providing services to their customers. This unique and special expertise in
pooling this information has enabled the Companies to conduct their businesses
successfully and thus provide potential employment opportunities for their
employees.

            The parties acknowledge that Employee has his own valuable knowledge
and training in certain of the areas in which the Companies conduct their
businesses but that his knowledge will be enhanced by this employment.

            Employee recognizes that unless the Companies impart to him their
special expertise, he would be less effective and of less benefit to the
Companies. Employee further acknowledges that without the additional knowledge
to be imparted to him by the Companies, he will be less valuable than would
otherwise be the case in their businesses.

            Employee understands and acknowledges that a covenant not to compete
and a restriction on disclosure of confidential information is essential to the
continued growth and stability of each Company's businesses and to the
continuing viability of such businesses in the event the Employee's employment
is terminated as expressly permitted under the terms and limitations of this
Agreement.

            The Employee desires employment as an Employee of the Companies
under the terms and conditions of this Agreement and further desires to be given
access to each Company's proprietary information.

            The Companies desire to employ Employee under the terms and
conditions of this Agreement.
<PAGE>   2

            NOW, THEREFORE, in consideration of the mutual covenants and 
agreements set forth in this Agreement, the parties agree as follows:

         1. Employment. Subject to the terms and conditions set forth in this
Agreement, the Companies employ Employee, and Employee hereby accepts such
employment by the Companies.

         2. Duties of Employee.

            (a) Employee shall serve in the capacities of President and Chief
Executive Officer of Quest/ANS, and shall be subject to supervision by the Board
of Directors of Quest/ANS. In the event of a merger of Quest and ANS, Employee
shall serve as President and Chief Executive Officer of the surviving entity. In
such capacities, Employee shall have all necessary powers to discharge his
responsibilities, including general supervision of the affairs of the Companies
and active control of their businesses. Employee shall have all powers granted
by the Bylaws of the Companies to the President and/or Chief Executive Officer,
as applicable, and Employee shall report to the Board of Directors of such
corporation. For so long as Employee serves in the foregoing capacities, the
Companies shall nominate and support the election of Employee as a member of the
Board of Directors of each corporation.

            (b) During the term of this Agreement, and thereafter so long as
Employee is employed by either Company, Employee shall devote his full business
time and effort to the performance of his duties and responsibilities as an
officer of ANS and the Parent. Notwithstanding the foregoing, Employee may spend
reasonable amounts of time on personal civic and charitable activities that do
not interfere with the performance of his duties and responsibilities to ANS and
the Parent. In addition, Employee may, subject to prior approval by the Board of
Directors of Quest/ANS, spend reasonable amounts of time serving on boards of
directors for other companies, provided that such service does not, in the sound
discretion of the Board of Directors of Quest/ANS, constitute or create a
conflict of interest.

            (c) Employee shall observe and comply with the written rules and
regulations of each Company respecting their businesses and shall carry out and
perform the directives and policies of the Companies as they may from time to
time be stated to Employee in writing by the Chairman of the Board or the Board
of Directors.

            (d) Employee shall maintain accurate business records as may from
time to time be required by the Companies. Such records may be examined by the
Companies, at all reasonable times after written request is delivered to
Employee. Any such document shall be delivered to each Company promptly upon
request.

            (e) Employee agrees not to solicit or receive any income or other
compensation from any third party in connection with his employment with the
Companies. Employee agrees, upon written request by either Company, to render an
accounting of all transactions relating to his business endeavors during the
term of this employment hereunder.
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         3. Term. The term of this Agreement (the "Term") shall commence
effective as of April ninth, 1998 (the "Effective Date") and continue until the
second anniversary of the Effective Date, unless Employee's employment is
earlier terminated in accordance with Section 10 of this Agreement. Upon
expiration of the term of this Agreement, Employee shall remain an "at will"
employee of the Companies but shall still be subject to and bound by the terms
of this Agreement. In the event of a merger of Quest and ANS, this Agreement
shall remain in full force and effect, with all rights and obligations of the
Companies hereunder passing to the surviving entity.

         4. Salary. Commencing on the Effective Date, the Companies will pay
Employee a minimum base annual salary during the term of this Agreement for his
services as an officer of $200,000.00, which shall be payable in accordance with
the Companies' standard payroll practice, but not less than monthly. Such base
salary shall not include any benefits made available to Employee or any
contributions or payments made on his behalf pursuant to any employee benefit
plan or program of the Companies, including any health, disability or life
insurance plan or program, 401-K plan, cash bonus plan, stock incentive plan,
retirement plan or similar plan or program of any nature. The Companies shall
review Employee's salary on a semi-annual basis, and shall increase the annual
salary of Employee from time to time as may be warranted in accordance with the
Companies' compensation policies. ANS shall have no separate salary obligation
to Employee.

         5. Bonus Compensation. The Companies may pay Employee an annual
performance-based cash bonus in accordance with Company policy established by
the board from time to time, as described in Exhibit "A" to this Agreement. ANS
shall have no separate bonus obligation to Employee.

         6. Stock Options: The Companies shall, upon execution of this
Agreement, grant Employee a total of 200,000 non-transferable stock options to
purchase shares of Quest Common Stock. A total of 50,000 options (25%) shall
vest immediately upon execution of this Agreement. An additional 50,000 options
(25%) shall vest on each of the first, second, and third anniversaries of the
grant, respectively. All options conferred through this grant shall expire in
ten years, and shall be granted at the market price for the Companies' Common
Stock as of the date of the grant.

         7. Relocation Expenses: The Companies shall reimburse Employee for all
expenses reasonably incurred by Employee in connection with relocating his
family to a residence in reasonable proximity to the Companies' location. Such
expenses shall include direct costs associated with sale of the Employee's
current residence (e.g., commissions, title, other direct costs); direct costs
associated with purchase of a new residence (e.g., inspections, closing costs
and up to one point on a purchase money mortgage); direct costs of packing and
moving Employee's household goods. During the interim period between the
Effective Date of this Agreement and the completion of Employee's relocation,
the Companies agree to reimburse Employee for costs associated with commuting
from Employee's current residence in Arlington, Texas, to Company offices in
Allen, Texas.

            In the event that the Companies' reimbursement of costs associated
with Employee's relocation are deemed taxable income, the Companies agree to
make an additional
<PAGE>   4

"gross up" payment to Employee at the conclusion of the relocation process for
the purposes of making Employee whole for any tax liability incurred as a result
of reimbursements contemplated in this section, provided that the Companies'
total obligation to Employee for reimbursement of costs pursuant to this Section
shall not exceed $50,000.00.

         8. Employee Benefits. During the term of this Agreement, the Companies
shall provide Employee with all benefits made available from time to time by the
Companies to their employees and/or officers generally and to employees who hold
positions similar to that of Employee (including benefits granted to other
officers of the Companies), such benefits to be in accordance with the
Companies' policies except that if Employee's employment with the Companies is
terminated, Employee's cash severance payments shall be in accordance with
Section 10 of this Agreement, in lieu of cash severance payments provided by the
policies of the Companies. Specifically, Employee's benefits shall include
participation in medical, dental and vision plans or programs (providing
coverage for Employee's immediate family); disability insurance; 401-K plans;
life insurance payable to Employee's designated beneficiary and paid vacation
(up to four weeks). ANS shall have no separate obligations to Employee with
respect to employee benefits. In the event that Employee's employment with the
Companies is terminated, the Companies agree to pay in full all premiums
associated with Employee's election to continue health benefits provided
hereunder.

     9. Reimbursement of Expenses. ANS and/or Parent shall reimburse Employee 
for all expenses actually and reasonably incurred by him in the business 
interests of ANS and/or Parent. Such reimbursement shall be made to Employee 
upon appropriate documentation of such expenditures in accordance with the 
Companies' written policies.

     10. Early Termination. It is the desire and expectation of each party that
the employer-employee relationship shall continue for the full term specified 
herein and be a pleasant and rewarding experience for the parties hereto. The
Companies shall, however, be entitled to terminate Employee's employment at any
time before or after the Effective Date with or without Cause (as defined in 
this Section 10). Termination shall require approval by majority vote of the
board of directors of the Parent.

         If Employee's employment is terminated without Cause, the Companies
shall pay Employee severance compensation pursuant to the following formulas:

         (a)      In the event of a termination without Cause occurring prior to
                  the one-year anniversary of this Agreement, Employee shall
                  receive severance payments equivalent to twenty-four (24)
                  months' salary.

         (b)      In the event of a termination without Cause occurring at any
                  time after the one-year anniversary of this Agreement,
                  Employee will receive twelve (12) months' salary as severance.

         In each case, severance payments shall be made in equal installments on
the Companies' semi-monthly payroll dates.
<PAGE>   5

         If Employee dies, is unable to perform his duties and responsibilities
as a result of disability that continues for 90 consecutive days or more
("Disability"), voluntarily resigns from the Companies, or is terminated for
"Cause," ANS shall pay Employee (or his estate, executor or legal
representative, as appropriate) any salary and bonus that has accrued to the
date employment ceases, and ANS' obligations to pay additional salary or cash
compensation or benefits shall terminate as of such date.

         "Cause," for the purpose of this Agreement, shall mean the occurrence
of any of the following events:

         (a) Performance by Employee of illegal or fraudulent acts, criminal
conduct or willful misconduct relating to the activities of the Companies;

         (b) A conviction of or nolo contendere plea by Employee for any
criminal acts involving moral turpitude having or reasonably likely to have a
material adverse effect upon each Company, including, without limitation, upon
their profitability, reputation or goodwill;

         (c) Willful or grossly negligent failure by Employee to perform his
duties in a manner consistent with the Companies' best interests;

         (d) Willful refusal by Employee to carry out reasonable written
instructions of the Companies' Boards of Directors not inconsistent with the
provisions of this Agreement;

         (e) Violation by Employee of any of Employee's covenants and agreements
contained in Sections 11, 12 or 13 of this Agreement;

         (f) Any other material breach of Employee's obligations hereunder,
which he fails to cure within thirty (30) days after receiving written notice
thereof.

     11. Non-Competition Agreement.

         (a) Employee understands and each Company promises that during the
course of his employment by the Companies, Employee will have access to and the
benefit of the information referred to in the Recitals above, specifically Trade
Secrets and Confidential Information, and will represent each Company and
develop contacts and relationships with other persons and entities, including
but not limited to customers, potential customers and other employees of such
entities. To protect the Companies' interest in preserving their Trade Secrets,
Confidential and other protected information and in the Business Good Will
generated by new contacts and relationships, and as a direct inducement and
consideration for the Companies' promises to provide new Trade Secrets, new
Confidential Information and new contacts, the Employee agrees and covenants to
the duties and obligations created by this covenant not to compete.

         (b) The Employee agrees that all duties assumed by this covenant not to
compete include any actions taken by the Employee directly or indirectly, either
as an individual or as an employee, partner, officer, director, shareholder,
advisor, or consultant or in any other 
<PAGE>   6
capacity whatsoever, of any person (other than ownership of less than 1% of the
issued and outstanding voting securities of a publicly held corporation).

         (c) The employee covenants he:

             (1) will not recruit, hire, assist others in recruiting or hiring,
discuss employment with, or refer to others for employment any person who is, or
within the 12 month period immediately preceding the date of any such activity
was, an employee of either Company or any of their affiliates;

             (2) Employee agrees that during the term of his employment with the
Companies and for a period of one (1) year thereafter, without regard to the
party terminating such employment or the reason for termination, if any,
Employee will not, without prior written approval by the Board of Directors for
Quest/ANS, in the United States or in any foreign country in which either
Company is then marketing its products or services, directly or indirectly
engage in or own or control an interest in (except as to those investments held
at the effective date of this agreement or as a passive investor in publicly
held companies, i.e., Employee and Employee's relatives do not own of record, or
beneficially, an aggregate of more than one percent [1%] of any class of
outstanding securities) or act as an officer, director, or employee of, or
consultant or adviser to, any firm, corporation, institution or entity, directly
or indirectly in competition with or engaged in a business substantially similar
to that of Employer, including the research, development, manufacture, sale or
marketing of products, devices, instruments, methods or techniques (or any
related services or activities) similar to any products, devices, instruments,
methods or techniques which either Company is engaged in the research of,
development of, manufacture, selling, or marketing, or has under consideration
to do the same (whether or not such products, devices, instruments, methods or
techniques or the technology related thereto were obtained from Employee),
during the term of the Employee's employment. This provision 11(c)(2) is not
intended to, and shall not be construed in such a manner as to, prevent Employee
from securing gainful employment within the health care industry except with
those entities whose products, devices, instruments, methods or techniques (or
any related services or activities) substantially compete with those of the
Companies.

         (d) It is understood and agreed that the scope of the foregoing
covenant is reasonable as to time, scope and geography and is necessary to
protect the legitimate business interests of the Companies, in the Confidential
Information and Trade Secrets the Companies have promised to share with
Employee. It is further agreed that such covenant will be regarded as divisible
and will be operative as to time, area and persons to the extent that it may be
so operative, and if any part of such covenant is declared invalid,
unenforceable, or void as to time, area or persons, the validity and
enforceability of the remainder will not be affected.

         (e) If Employee violates the restrictive covenants of this Section 11
and the Companies bring legal action for injunctive or other relief, neither
Company shall be deprived of the benefit of the full period of the restrictive
covenant, as a result of the time involved in obtaining the relief. Accordingly,
to the extent allowed by law, the Employee agrees that the restricted period
following the term of employment shall have a duration of two years, and the
regularly 
<PAGE>   7

scheduled expiration date of such covenant shall be extended by the same amount
of time that Employee is determined to have violated such covenant.

         12. Confidentiality. Employee acknowledges that he has learned and will
learn Confidential Information (as defined herein) relating to the business
conducted and to be conducted by the Companies. The Companies promise to provide
all needed Confidential Information to the Employee. Employee agrees that he
will not during the term of employment with the Companies or at any time after
the termination of such employment, without regard to the party terminating such
employment, except in the normal and proper course of his duties hereunder,
disclose or use or authorize any third party to disclose or use any such
Confidential Information, without prior written approval of the Companies. As
used in this Section 12, "Confidential Information" shall mean information
disclosed to or known to Employee as a direct or indirect consequence of or
through his employment with the Companies, about the Companies' business,
methods, business plans, operations, products, processes, and services,
including, but not limited to, information relating to research, development,
inventions, recommendations, programs, systems, and systems analyses, flow
charts, finances, and financial statements, marketing plans and strategies,
merchandising, pricing strategies, merchandise sources, client sources, system
designs, procedure manuals, automated data programs, financing methods,
financial projections, terms and conditions of arrangements of any business,
computer software, terms and conditions of business arrangements with customers
or suppliers, reports, personnel procedures, supply and services resources,
names and addresses of clients, the Companies' contacts, names of professional
advisors, and all other information pertaining to customers and suppliers,
including, but not limited to assets, business interests, personal data and all
other information pertaining to the Companies, clients or suppliers whatsoever,
including all accompanying documentation therefor. All information disclosed to
Employee, or to which Employee has access during the period of his employment,
for which there is any reasonable basis to be believed is, or which appears to
be treated by the Companies as Confidential Information, shall be presumed to be
Confidential Information hereunder. Confidential Information shall not, however,
include information that (i) is publicly known or becomes publicly known through
no fault of Employee, or (ii) is generally or readily obtainable by the public,
or (iii) constitutes general skills, knowledge and experience acquired by
Employee before and/or during his employment with ANS and the Parent.

             Employee agrees that all documents of any nature pertaining to
activities of the Companies or their affiliates, or that include any
Confidential Information, in his possession now or at any time during the term
of his employment, including without limitation, memoranda, notebooks, notes,
data sheets, records and computer programs, are and shall be the property of
such entity and that all copies thereof shall be surrendered to the appropriate
entity upon termination of his employment.

         13. Inventions; Developments. Employee agrees to notify the Companies
of any discovery, invention, innovation, or improvement which is related to the
Business or to the business of any customer or supplier (collectively called
"Developments") conceived or developed by Employee during the term of the
Employee's employment. Developments shall include, without limitation,
developments in computer software, logical systems, algorithms, and any or all
other intellectual properties related to the Business. All Developments,
including but not limited to 
<PAGE>   8
all written documents pertaining thereto, shall be the exclusive property of ANS
or the Parent, as the case may be, and shall be considered Confidential
Information subject to the terms of this Agreement. Employee agrees that when
appropriate, and upon written request of ANS or the Parent, the Employee will
acknowledge that Developments are "works for hire" and will file for patents or
copyrights with regard to any or all Developments and will sign documentation
necessary to evidence ownership of Developments in ANS or the Parent.

         14. Exit Interview. To insure a clear understanding of this Agreement,
including but not limited to the protection of the Companies' business
interests, Employee agrees, at no additional expense to the Companies, to engage
in an exit interview with the Companies prior to Employee's departure from the
Companies at a time and place designated by the Companies. In the event that the
exit interview takes place in a location outside of the Dallas/Fort Worth
metropolitan area, the Companies agree to reimburse Employee for reasonable
expenses associated with his travel to and from said exit interview.

         15. Right of Setoff. The Companies shall be entitled, at their option
and not in lieu of any other remedies to which they may be entitled, to set off
any amounts due Employee or any affiliate of Employee against any amount due and
payable by Employee or any affiliate of Employee to the Companies ("Set-Offs")
pursuant to this Agreement or otherwise, provided that the Set-Offs are set
forth in detail in writing with supporting evidence to substantiate each
Set-Off.

         16. Notice Provision. Any notice, demand or request required or
permitted to be given or made under this Agreement shall be in writing and shall
be deemed given or made when delivered in person, when sent by United States
registered or certified mail, or postage prepaid, or when telecopied to a party
at its address or telecopy number specified below:

             If to ANS:

             Advanced Neuromodulation Systems, Inc.
             201 Allentown Parkway
             Allen, Texas 75002

             Telecopy number:  (972) 390-9687

             If to the Parent:

             Quest Medical, Inc.
             201 Allentown Parkway
             Allen, Texas 75002

             Telecopy number:  (972) 390-9687
<PAGE>   9
             If to Employee:

             Christopher G. Chavez
             2903 Forestwood Drive
             Arlington, TX   76006

             Telecopy number:
                             ------------------

             The parties to this Agreement may change their addresses for notice
in the manner provided above.

         17. Headings Non-binding. All section titles and captions in this
Agreement are for convenience only, shall not be deemed part of this Agreement,
and in no way shall define, limit, extend or describe the scope or intent of any
provisions hereof.

         18. Words to have Contextual Meaning. Whenever the context may require,
any pronoun used in this Agreement shall include the corresponding masculine,
feminine or neuter forms, and the singular form of nouns, pronouns and verbs
shall include the plural and vice versa. Additionally, the words "and" and "or"
shall be given their contextual meaning and not be interpreted blindly as being
solely conjunctive or disjunctive, as the case may be.

         19. Execution of Agreement. The parties shall execute all documents,
provide all information and take or refrain from taking all actions as may be
reasonably necessary or appropriate to achieve the purposes of this Agreement.

         20. Partial Assignment Clause. This Agreement shall be binding upon and
inure to the benefit of the parties hereto, their representatives and permitted
successors and assigns. Employee's duties hereunder are personal services and
are not assignable. Except for the provisions of Sections 11, 12 and 13 of this
Agreement, which are intended to benefit ANS' and the Parent's affiliates as
third party beneficiaries, or as otherwise expressly provided in this Agreement,
nothing in this Agreement, express or implied, is intended to confer upon any
person other than the parties to this Agreement, their respective
representatives and permitted successors and assigns, any rights, remedies or
obligations under or by reason of this Agreement. In the event of a merger of
Quest and ANS, the rights conferred upon Employee hereunder shall survive, and
all attendant obligations of Quest and/or ANS hereunder shall be assumed by the
surviving entity.

         21. Limitation of Benefits Clause. None of the provisions of this
Agreement shall be for the benefit of or enforceable by any creditors of the
parties, except as otherwise expressly provided herein.

         22. Non-waiver Provision. No failure by any party to insist upon the
strict performance of any covenant, duty, agreement or condition of this
Agreement or to exercise any right or remedy consequent upon a breach thereof
shall constitute waiver of any such breach or any other covenant, duty,
agreement or condition.
<PAGE>   10

         23. Multiple Originals. This Agreement may be executed in counterparts,
all of which together shall constitute one agreement binding on all the parties
hereto, notwithstanding that all such parties are not signatories to the
original or the same counterpart.

         24. CHOICE OF LAWS. THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE
WITH AND GOVERNED BY THE LAWS OF THE STATE OF TEXAS, WITHOUT REGARD TO THE
PRINCIPLES OF CONFLICTS OF LAW.

         25. Subject Claims; Initiation of Binding Arbitration. The matters,
claims, rights, and obligations subject to these arbitration provisions include
all rights, claims and obligations arising out of or relating to this Agreement
or to the employee's employment and/or its termination, including, without
limitation, any and all claims, rights or causes of action which may ever arise
or be asserted under any federal, state, local or foreign statutory, regulatory
or common law, and including, without limitation, claims of discrimination,
wrongful discharge or termination, breach of contract, tort (such as intentional
infliction of emotional distress, libel, slander, wrongful invasion of privacy
or personal injury), workers compensation or unemployment compensation. All of
the foregoing types of matters, claims, rights and obligations subject to these
arbitration provisions are herein called "Subject Claims". In the event of a
dispute relating to any Subject Claim, then, upon notice by any party to the
other parties (an "Arbitration Notice") and to American Arbitration Association
("AAA"), Dallas, the controversy or dispute shall be submitted to a sole
arbitrator who is independent and impartial, for binding arbitration in Dallas,
Texas, in accordance with AAA's National Rules for the Resolution of Employment
Disputes (the "Rules") as modified or supplemented hereby. The parties agree
that they will faithfully observe this agreement and the Rules and that they
will abide by and perform any award rendered by the arbitrator. The arbitration
shall be governed by the Federal Arbitration Act, 9 U.S.C. Section 116 (or by
the same principles enunciated by such Act in the event it may not be
technically applicable). The award or judgment of the arbitrator shall be final
and binding on all parties and judgment upon the award or judgment of the
arbitrator may be entered and enforced by any court having jurisdiction. If any
party becomes the subject of a bankruptcy, receivership or other similar
proceeding under the laws of the United States of America, any state or
commonwealth or any other nation or political subdivision thereof, then, to the
extent permitted or not prohibited by applicable law, any factual or substantive
legal issues arising in or during the pendency of any such proceeding shall be
subject to all of the foregoing mandatory mediation and arbitration provisions
and shall be resolved in accordance therewith. The agreements contained herein
have been given for valuable consideration, are coupled with an interest and are
not intended to be executory contracts. The fees and expenses of the arbitrator
will be shared equitably (as determined by the arbitrator) by all parties
engaged in the dispute or controversy.
<PAGE>   11

             Selection of Arbitrator. Promptly after the Arbitration Notice is
given, AAA will select five possible arbitrators, to whom AAA will give the
identities of the parties and the general nature of the controversy. If any of
those arbitrators disqualifies himself or declines to serve, AAA shall continue
to designate potential arbitrators until the parties have five to select from.
After the panel of five potential arbitrators has been completed, a two page
summary of the background of each of the potential arbitrators will be given to
each of the parties, and the parties will have a period of 10 days after
receiving the summaries in which to attempt to agree upon the arbitrator to
conduct the arbitration. If the parties are unable to agree upon an arbitrator,
then one of the parties shall notify AAA and the other party, and AAA will
notify each party that it has five days from the AAA notice to strike two names
from the list and advise AAA of the two names stricken. After expiration of the
strike period, if all but one candidate has been stricken, the remaining one
will be the arbitrator, but, if two or more have not been stricken, AAA shall
select the arbitrator from one of those not stricken. The decision of AAA with
respect to the selection of the arbitrator will be final and binding in such
case.

             No Litigation; Damages Limitation. Unless and only to the extent
mandatory arbitration is validly prohibited or limited by applicable statute or
regulation, no litigation or other proceeding may ever be instituted at any time
in any court or before any administrative agency or body for the purpose of
adjudicating, interpreting or enforcing any of the rights, duties, liabilities
or obligations of the parties hereto or any rights, duties, liabilities or
obligations relating to any Subject Claim, whether or not covered by the express
terms of this Agreement, or for the purpose of adjudicating a breach or
determination of the validity of this Agreement, or for the purpose of appealing
any decision of an arbitrator, except a proceeding instituted (i) for the
purpose of having the award or judgment of an arbitrator entered and enforced or
(ii) to seek an injunction or restraining order (but not damages in connection
therewith) in circumstances where such relief is available. Unless and only to
the extent a limitation of damages is validly prohibited or limited by
applicable statute or regulation, no punitive, exemplary or consequential
damages may ever be awarded by the arbitrator or anyone else, and each of the
parties hereby waives any and all rights to make, claim or recover any such
damages.

             Arbitration Hearing. Within 20 days after the selection of the
arbitrator, the parties and their counsel will appear before the arbitrator at a
place and time designated by the arbitrator for the purpose of each party making
a one hour or less presentation and summary of the case. Thereafter, the
arbitrator will set dates and times for additional hearings in accordance with
the Rules until the proceeding is concluded. The desire and goal of the parties
is, and the arbitrator will be advised that his goal should be, to conduct and
conclude the arbitration proceeding as expeditiously as possible. If any party
or his counsel fails to appear at any hearing, the arbitrator shall be entitled
to reach a decision based on the evidence which has been presented to him by the
parties who did appear.

         26. Severability and Reformation. If any provision of this Agreement is
declared or found to be illegal, unenforceable, or void, in whole or in part,
then the parties shall be relieved of all obligations arising under such
provision, but only to the extent that it is illegal, unenforceable or void, it
being the intent and agreement of the parties that this Agreement shall be
deemed amended by modifying such provision to the extent necessary to make it
legal and enforceable 
<PAGE>   12
while preserving its intent or, if that is not possible, by substituting
therefor another provision that is legal and enforceable and achieves the same
objectives.

         27. Written Amendments Provision. No supplement, modification or
amendment of this agreement or waiver of any provision of this Agreement shall
be binding unless executed in writing by all parties to this Agreement. No
waiver of any of the provisions of this Agreement shall be deemed or shall
constitute a waiver of any other provision of this Agreement (regardless of
whether similar), nor shall any such waiver constitute a continuing wavier
unless otherwise expressly provided.

         28. Actions to Enforce Non-Compete, Confidentiality or Inventions.
Employee acknowledges and agrees that ANS and the Parent would be irreparably
harmed by any violation of Employee's obligations under Sections 11, 12 and 13
hereof and that, in addition to all other rights or remedies available at law or
in equity, ANS and the Parent will be entitled to injunctive and other equitable
relief to prevent or enjoin any such violation. Additionally, both parties agree
that irrespective of their agreement to arbitrate, either party may seek to have
its rights under Sections 11, 12 or 13 of this agreement enforced by legal or
equitable action in a Court of Competent jurisdiction. The provisions of
Sections 11, 12 and 13 hereof will survive any termination of this Agreement, in
accordance with their terms.

         29. Written Consent for Assignment. No party may assign this Agreement
or any rights or benefits thereunder without the written consent of the other
parties to this Agreement.

         30. Choice of Forum. Any action initiated pursuant to paragraph 28 must
proceed in a Texas District Court in Collin County, Texas. If such an action can
not proceed in District Court due to jurisdictional limitations, then it shall
proceed in any State or County court of competent jurisdiction in Collin County,
Texas.


             EXECUTED as of the date first above written.

                              QUEST MEDICAL, INC. AND ITS SUBSIDIARY,
                              ADVANCED NEUROMODULATION SYSTEMS, INC.



                              By: /s/ Hugh Morrison
                                  ------------------------------------
                                      Hugh Morrison
                                      Chairman of the Board


                                  /s/ Christopher G. Chavez
                                  ------------------------------------
                                      Christopher G. Chavez




<PAGE>   13
                                   EXHIBIT A


Annual Bonus

In addition to the base salary described in Section 4 of this Agreement,
Employee shall be eligible for an annual performance-based cash bonus.
Employee's standard bonus percentage would be 50% of his annual base salary, to
be earned by meeting certain strategic milestones and objective measurements of
profitability and shareholder value, such milestones and objectives to be
determined by mutual agreement of Employee and the Board of Directors, such that
Employee will receive the full 50% bonus amount if all such objectives are fully
met. In the event that Employee's performance exceeds the objectives established
by Employee and the Board of Directors, Employee shall be eligible for a bonus
in an amount larger than the standard bonus percentage stated above. In the
event that Employee's performance falls short of the objectives established by
Employee and the Board of Directors, Employee may receive less than the full
bonus percentage.