S.C. Code Ann. § 42-11-130

The medical board employed to determine controverted medical questions shall consist of three members appointed by the commission or hearing commissioner and selected from the medical advisory panel as follows: one to be named by the claimant and one to be named by the employer or his insurer as the case may be, and the third to be chosen by the commission or hearing commissioner. But if within ten days after the hearing in which a controverted medical question is raised one or more of the parties have failed to nominate a member, the commission or commissioner hearing the case shall nominate a member or members to complete the board to three members.