District of Philadelphia v. Workers' Compensation Board (Lanier) 727 A.2d 1171 (Pa. Cmwlth. 1999), held that medical evidence was necessary to prove disability was casually related to the work injury, Wileater Lanier's (Lanier) physician testified that he was "intentionally being nebulous" because he did not know whether Lanier could function at work. Id. at 1173. Because the medical expert had not testified that Lanier's work injury prohibited her from returning to work, this Court held the medical evidence introduced was insufficient and equivocal. Id. at 1174.