Alternating myasthenia and myastheniform syndrome in the same subject.

A man of 23 years was affected by myasthenia with amyotrophic patterns. From the neurophysiological viewpoint, there were typical electrophysiological aspects of myasthenia gravis and the Eaton-Lambert syndrome simultaneously. In some instances the various electrophysiological tests were preceeded by the administration of Tensilon, calcium gluconate and sodium benzoate caffeine. It is hypothesized that there are two types of endplates present, or there is a functional variability by which at different moments a block results from a defect in the formation or liberation of acetylcholine.