Excellent Response to Therapeutic Plasma Exchange in Myasthenia Gravis Patients with or Without Autoantibodies

A 96 percent response rate to treatment with therapeutic plasma exchange (PLEX) was seen in a series of 58 consecutive myasthenia gravis (MG) patients, with no significant difference in response between those with or without autoantibodies, according to a study by investigators at the University of Texas Southwestern Medical Center. Eighty-eight percent(51 of 58) of patients were autoantibody-positive, 44 had antibodies to acetylcholine receptor(AChR) and seven had antibodies against muscle-specific kinase (MuSK).

A complete response with resolution of symptoms was seen in 26 patients, 24 of whom were antibody-positive. Eighteen of these 24 complete responders (16 antibody-positive) required only an acute course of PLEX. Twenty-four other patients remain on maintenance PLEX, and two patients had no or minimal response (both of whom were AChR antibody positive). All seronegative patients, who comprised 12 percent of patients in this study, responded to PLEX, although the majority of them required maintenance therapy.

While AChR antibodies, MuSK antibodies, early-onset MG, thymoma and thymectomy were not significantly associated with outcome, patient sex did show significant association with outcome,with males more likely to experience complete response and females more likely to require maintenance PLEX therapy. Late-onset MG was also significantly associated with higher likelihood of complete response to PLEX therapy (P = 0.03).