Site of Origin of Fasciculations in Voluntary Muscle

Involuntary contractions of groups of muscle fibers apparent through the intact skin, and known as fasciculations, have long been considered as evidence of disease of the anterior horn cells. This opinion has resulted from their appearance in cases of disease involving the anterior horn cells. The increase of fasciculations produced by prostigmine and some of the observations reported on the effect of nerve root and peripheral nerve block cast doubt on the central origin of these involuntary movements. These investigations were undertaken to determine the site of origin of fasciculations. METHOD Four patients were studied, 3 of whom had amyotrophic lateral sclerosis. The remaining patient had pronounced fasciculations, weakness and atrophy as residuals of acute infectious polyneuritis. Restless and poorly cooperative patients were not included in these studies, for by their automatic and voluntary movements the incidence of fasciculations would have been increased and inclusions of data for periods in