Muscle-Specific Kinase Antibody–Positive Myasthenia Gravis

A review of U.S. cases confirms the strong female predominance, poor response to acetylcholinesterase inhibitor therapy, and improvement after various immunomodulatory therapies.

Few data are available on U.S. patients with myasthenia gravis (MG) and antibodies to muscle-specific kinase (MuSK). In this study, researchers retrospectively reviewed clinical findings in patients with MuSK MG (MMG) seen at nine U.S. academic centers.

Of 53 MMG patients identified, 85% were female, and most were Caucasian. Facial, bulbar, and neck symptoms were nearly universal (>90%); ocular (72%) and respiratory symptoms (60%) were less common. Three patients had tongue or facial atrophy, and only one presented with neck weakness and dyspnea. Repetitive nerve stimulation was most often abnormal in facial muscles. Single-fiber electromyography results were positive in 19 of 21 patients tested, primarily in the extensor digitorum communis …

Reviewing Authors

Jeffrey Guptill, MD

Donald B. Sanders, MD, FAAN