1999). Objective medical evidence is necessary to establish the existence and extent of an injury but not essential to establish the casual relationship between the injury and work-related accident. Wal-Mart Stores, Inc. v. VanWagner, 337 Ark. 443, 990 S.W.2d 522 (1999) . In the present case, Dr. Thrash reported that appellee was " x-rayed and examined," and he diagnosed her with lumbar subluxation.