Electromyography of extraocular muscles in Duane's syndrome

Abstract

The horizontal rectus muscles of twenty eyes with Duane's syndrome were examined by EMG. The lateral rectus in nineteen instances showed gross anomalies of firing pattern, varying from paradoxical innervation to innervation in the correct sense but with incomplete inhibition in adduction and recruitment in abduction. The amplitude of the signal from the lateral rectus was often reduced. Signal analysis of the EMG in eight cases showed the lateral rectus to have longer than normal spike durations.