Single-fiber electromyography shows terminal axon dysfunction in Miller Fisher syndrome: a case report.

We studied a patient with ophthalmoparesis and pupillary areflexia 2 weeks after a viral syndrome. Miller Fisher syndrome was suspected but GQ1b antibodies were not detected. To define neuromuscular involvement we performed electrodiagnostic studies. Single-fiber electromyography (SFEMG) in the extensor digitorum communis (EDC) showed abnormal jitter and axonal blocking, suggesting terminal axon dysfunction. Subsequent GQ1b antibody titers were elevated to borderline levels. Clinical symptoms gradually resolved. SFEMG may help characterize neuropathies associated with antibodies to neuronal ganglioside and identify involvement of the terminal axon and neuromuscular junction.