Edrophonium test in Eaton-Lambert syndrome: quantitative oculography.

Accurate ocular motility recordings were made of the saccadic responses of five patients with Eaton-Lambert syndrome (ELS). It was found that, contrary to common belief, the ocular motor system is affected. The saccades of ELS patients mimicked those of patients with myasthenia gravis (MG). Both groups exhibited hypometria and multiple, closely spaced saccades. Two patients demonstrated both saccadic facilitation and positive edrophonium tests. The ELS patients had slow or normal saccadic velocities, not the "super-fast" velocities found in patients with ocular MG.