EFFECTS OF EDROPHONIUM ON SACCADIC VELOCITY IN NORMAL SUBJECTS AND MYASTHENIC AND NONMYASTHENIC OCULAR PALSIES

We measured saccadic peak velocities in 8 patients with myasthenia gra vis, 8 patients with proven nonmyasthenic ocular palsies, and 3 contro ls. Patients followed a target moving td and from primary position at 1-second intervals for 8 minutes. We measured the amplitudes and veloc ities of centrifugal saccades at the Start of the task, after 3 minute s of the task (fatigue) and 1 minute after receiving IV edrophonium. T he effects of fatigue, though prominent in some myasthenic patients, d id not distinguish between the groups. However, edrophonium increased saccadic peak velocities in myasthenic patients but decreased them in both controls and nonmyasthenic patients. Analysis of saccades by ampl itude bins showed that these changes in peak velocity reflected shifts in the velocity-amplitude relationship.