<PAGE>   1
                                                                     EXHIBIT 2.2




                  FIRST AMENDMENT TO STOCK PURCHASE AGREEMENT


         FIRST AMENDMENT (the "First Amendment") dated as of August 25, 1998 by
and among Lamar Advertising Company, a Delaware corporation ("Buyer"), Outdoor
Communications, Inc., a Delaware corporation (the "Company"), and each of the
stockholders of the Company (the "Stockholders").

         WHEREAS Buyer, the Company and each of the Stockholders are parties to
that certain Stock Purchase Agreement dated as of August 10, 1998 (the
"Agreement") pursuant to which each of the Stockholders has agreed to sell to
Buyer, and Buyer has agreed to purchase, all of the Company Securities held by
such Stockholder; and

         WHEREAS Buyer, the Company and the Stockholders desire to amend
Exhibit A to the Agreement in accordance with the provisions of Section 11.7 of
the Agreement to provide the correct the number of shares of Series A Preferred
Stock of the Company held by certain Stockholders listed on such Exhibit A.

         NOW, THEREFORE, for good and valuable consideration, the undersigned
hereby agree as follows:

     1.          Capitalized terms not otherwise defined herein shall have the
meanings ascribed to such terms in the Agreement.

     2.          The Agreement is hereby amended, as of the effective date of
this First Amendment, by deleting Exhibit A thereto in its entirety and
substituting therefor Exhibit A attached hereto.

     3.          Section 3.3(iii) of the Agreement is hereby amended, as of the
effective date of this First Amendment by deleting the number "186,130.52"
therefrom and substituting therefor "186,220.93".

     4.          The effective date of this Amendment shall be the date first
set forth above.

     5.          As amended by this First Amendment, the Agreement is in all
respects ratified and confirmed, and as so amended by this First Amendment, the
Agreement shall be read, taken and construed as one and the same instrument.

     6.          This Amendment may be executed in any number of counterparts
and by the parties hereto in separate counterparts, each of which so executed
shall be deemed to be an original, but all of such counterparts shall together
constitute but one and the same instrument.

     7.          This Amendment shall be governed in accordance with the laws
of the State of Delaware without regard to principles of conflicts of law.
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         IN WITNESS WHEREOF the parties hereto have caused this First Amendment
to be executed as of the date set forth above by their duly authorized
representatives.


                                       BUYER:
                                       
                                       LAMAR ADVERTISING COMPANY
                                       
                                       
                                       
                                       By:     /s/ Keith A. Istre 
                                            -----------------------------------
                                            Title:  Chief Financial Officer
                                       
                                       
                                       
                                       COMPANY:
                                       
                                       OUTDOOR COMMUNICATIONS, INC.
                                       
                                       
                                       By:     /s/ John C Stanley IV 
                                            -----------------------------------
                                            John C Stanley IV, Chairman
                                       
                                       
                                       
                                       
                                       STOCKHOLDERS:
                                       
                                       
                                       By:     /s/ John C Stanley IV
                                            -----------------------------------
                                            John C Stanley IV, on behalf of 
                                            each of the Stockholders, in his 
                                            capacity as a Stockholders' 
                                            Representative
                                       
                                       
                                       By:     /s/ Stephen F. Gormley 
                                            -----------------------------------
                                            Stephen F. Gormley, on behalf of 
                                            each of the Stockholders, in his 
                                            capacity as a Stockholders' 
                                            Representative



                                       2
<PAGE>   3
                                    EXHIBIT A


<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                             Shares of    Shares of     Shares of
    Name and Address of       Class A      Class B      Series A        Preferred      Option     Pro Rata     Indemnification Cap 
        Stockholder           Common       Common       Preferred     LLC Interests    Shares      Share             Amount
                              Stock5       Stock          Stock
-----------------------------------------------------------------------------------------------------------------------------------
<S>                          <C>           <C>         <C>            <C>              <C>      <C>            <C>
Media/Communications II      3,227.67      2,017.29    104,990.98            ,           ,       41.2080452%    $ 4,120,804.52
Limited Partnership
c/o Media/Communications
Partners
75 State Street
Boston, MA  02109
-----------------------------------------------------------------------------------------------------------------------------------
Chase Venture Capital        2,048.57      1,587.94     72,793.75            ,           ,       28.5709459%    $ 2,857,094.59
Associates, L.P.
c/o Chase Capital Partners
380 Madison Avenue
12th Floor
New York, NY  10017
-----------------------------------------------------------------------------------------------------------------------------------
John C Stanley IV             1092.16         ,             ,           2,388,127.71    212      10.2463859%    $ 1,024,638.59
4305 Shiloh Road
Corinth, MS 38834
-----------------------------------------------------------------------------------------------------------------------------------
A.B. Isbell                     938           ,             ,           2,082,385.76    120       8.3123821%     $ 831,238.21
6400 Shiloh Road
Corinth, MS  38834
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>




                                        3
<PAGE>   4

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                             Shares of    Shares of     Shares of
    Name and Address of       Class A      Class B      Series A        Preferred      Option     Pro Rata     Indemnification Cap 
        Stockholder           Common       Common       Preferred     LLC Interests    Shares      Share             Amount
                              Stock5       Stock          Stock
-----------------------------------------------------------------------------------------------------------------------------------
<S>                          <C>           <C>         <C>            <C>              <C>      <C>            <C>
Media/Communications          134.49        84.05       4,374.63             ,           ,        1.7170019%     $ 171,700.19
Investors Limited
Partnership
c/o Media/Communications
Partners
75 State Street
Boston, MA  02109
-----------------------------------------------------------------------------------------------------------------------------------
The JCS Trust                  98.19          ,             ,            194,737.40      ,        0.7714488%      $ 77,144.88
c/o John C Stanley IV,
Trustee
4305 Shiloh Road
Corinth, MS 38834
-----------------------------------------------------------------------------------------------------------------------------------
JCS Trust No. 2                 56            ,             ,                ,           ,        0.4399749%      $ 43,997.49
c/o Lenoir W. Stanley,
Trustee
4305 Shiloh Road
Corinth, MS 38834
or
c/o Priscilla S. Denton,
Trustee
112 Pidgeon Road
Memphis, TN  38117
-----------------------------------------------------------------------------------------------------------------------------------
The LWS Trust                  98.19          ,             ,            194,737.40      ,        0.7714488%      $ 77,144.88
c/o Lenoir W. Stanley,
Trustee
 4305 Shiloh Road
Corinth, MS 38834
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>




                                        4
<PAGE>   5

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                             Shares of    Shares of     Shares of
    Name and Address of       Class A      Class B      Series A        Preferred      Option     Pro Rata     Indemnification Cap 
        Stockholder           Common       Common       Preferred     LLC Interests    Shares      Share             Amount
                              Stock5       Stock          Stock
-----------------------------------------------------------------------------------------------------------------------------------
<S>                          <C>           <C>         <C>            <C>              <C>      <C>            <C>
LWS Trust No. 2                 56            ,             ,                ,           ,        0.4399749%      $ 43,997.49
c/o John C Stanley IV,
Trustee
4305 Shiloh Road
Corinth, MS 38834
or
c/o Priscilla S. Denton,
Trustee
112 Pidgeon Road
Memphis, TN  38117
-----------------------------------------------------------------------------------------------------------------------------------
Priscilla S. Denton            87.50          ,             ,            173,532.17      ,        0.6874607%      $ 68,746.07
112 Pidgeon Road
Memphis, TN 38117
-----------------------------------------------------------------------------------------------------------------------------------
William Hull Davis             87.50          ,             ,            173,532.17      ,        0.6874607%      $ 68,746.07
3008 Lake Terrace Drive
Corinth, MA 38834
-----------------------------------------------------------------------------------------------------------------------------------
Douglas W. Ferris, Jr.         87.50          ,             ,            173,532.17      ,        0.6874607%      $ 68,746.07
40 South Rose Road
Memphis, TN 38117
-----------------------------------------------------------------------------------------------------------------------------------
G. Robert Joiner               68.50          ,         1,018.24             ,           40       0.8524513%      $ 85,245.13
1005 Peachtree Street
Corinth, MS 38834
-----------------------------------------------------------------------------------------------------------------------------------
Gerald P. Scott                52.50          ,         1,018.24             ,           40       0.7267442%      $ 72,674.42
3505 Shiloh Ridge Road
Corinth, MS 38834
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>



                                        5
<PAGE>   6

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------------
                             Shares of    Shares of     Shares of
    Name and Address of       Class A      Class B      Series A        Preferred      Option     Pro Rata     Indemnification Cap 
        Stockholder           Common       Common       Preferred     LLC Interests    Shares      Share             Amount
                              Stock5       Stock          Stock

-----------------------------------------------------------------------------------------------------------------------------------
<S>                          <C>           <C>         <C>            <C>              <C>      <C>            <C>
Norman Isbell                  79.95          ,         1,030.31         103,031.12      ,        0.6281427%      $ 62,814.27
119 W. Linden Street
Corinth, MS 38834
-----------------------------------------------------------------------------------------------------------------------------------
Mark K. Sherwood               35.00          ,          665.48              ,           40       0.5892520%      $ 58,925.20
8508 Cedarcrest
Traverse City, MI 49684
-----------------------------------------------------------------------------------------------------------------------------------
John Andrews                   35.00          ,          665.48              ,           40       0.5892520%      $ 58,925.20
201 N. 37th Street
Birmingham, AL 35222
-----------------------------------------------------------------------------------------------------------------------------------
Ricky W. Thomas                16.00          ,             ,                ,           89       0.8249529%      $ 82,495.29
3205 Melinda Lane
Corinth, MS 38824
-----------------------------------------------------------------------------------------------------------------------------------
Richard Ebersole               35.00          ,          694.13              ,           40       0.5892520%      $ 58,925.20
1135 Picadilly
Traverse City, MI  49684
-----------------------------------------------------------------------------------------------------------------------------------
Steven B. Isbell                28            ,             ,                ,           ,        0.2199874%      $ 21,998.74
2333 Timothy Drive
Cookeville, IN 38506
-----------------------------------------------------------------------------------------------------------------------------------
Brad Isbell                     28            ,             ,                ,           ,        0.2199874%      $ 21,998.74
2410 Wilford Drive
Nashville, TN 37214
-----------------------------------------------------------------------------------------------------------------------------------
Lydia A. Bethay                 28            ,             ,                ,           ,        0.2199874%      $ 21,998.74
P.O. Box 442
Booneville, MS 38829
-----------------------------------------------------------------------------------------------------------------------------------
</TABLE>



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