Progressive supranuclear palsy: electomyographic examinations of eye muscles.

Electromyographic examination of vertical and lateral extraocular muscles was carried out in five patients suffering from progressive supranuclear palsy, and incapable of performing voluntary vertical eye movements. No evidence of a lower motor neurone lesion or paradoxical innervation of eye muscles was noted. Reciprocal inhibiton of antagonist vertical muscles though present in oculocephalic (doll's head) stimulation, was incomplete on attempted voluntary movement. This factor is held to be the probable immediate cause of the vertical gaze palsy.