Abstract Details

Title Immune-mediated Rippling Muscles with and without Myasthenia Gravis

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) Neuromuscular and Clinical Neurophysiology (EMG) Posters (7:00 AM-5:00 PM)

Poster/Presentation
Number 102

Objective

To review the first reported case of immune-mediated rippling muscle disease (iRMD) with myasthenia gravis and the subsequently reported cases of iRMD over the last 25 years.

Background The first case of rippling muscles with myasthenia gravis was described 25 years ago (Arch Neurol 1996; 53:197-199). Since then, multiple cases of iRMD both with and without myasthenia gravis have been reported. The rippling muscles in iRMD are identical to those in inherited rippling muscle disease (hRMD). The hallmark of both iRMD and hRMD are stretch and percussion-activated muscle contractions that travel across skeletal muscle in an organized wave-like pattern. Rippling muscles are described as electrically-silent with no evidence of myotonia, neuromyotonia, or myokymia. The genetic defects in hRMD localizes to the gene encoding caveolin-3.

Design/Methods The original case of iRMD with myasthenia gravis and subsequently reported cases of iRMD both with and without myasthenia gravis were reviewed. The findings will be summarized and reviewed in the context of the potential roles of caveolin-3 and caveolae in striated muscle and neuromuscular disorders.

Results Case reports of iRMD with myasthenia gravis and additional cases of iRMD without myasthenia gravis were reviewed. Muscle biopsies on these patients showed mild myopathic and inflammatory changes and a mosaic pattern of caveolin-3 staining on immunohistochemistry with normal or somewhat decreased caveolin-3 levels. Patients with hRMD have more severe myopathic or dystrophic changes on muscle biopsies, homogeneously decreased or absent caveolin staining, and markedly decreased or absent caveolin-3 levels.

Conclusions iRMD both with and without myasthenia gravis are characterized by mild myopathic and inflammatory changes and a mosaic- pattern of caveolin-3 staining on muscle biopsies. The caveolin-3 staining in hRMD is homogeneously and much more markedly decreased, with dystrophic changes reported on muscle biopsies. These analogous findings suggest that iRMD and hRMD may share common pathophysiological characteristics.

Authors/Disclosures
Carl F. Ansevin, MD, FAAN (Ohio Neurologic Institute and Sleep Center) PRESENTER	Dr. Ansevin has nothing to disclose.

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