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 gravis, 9 patients with proven nonmyasthenic ocular palsies, and 3 controls. Patients followed a target moving to and from primary position at 1-second intervals for 8 minutes. We measured the amplitudes and velocities of centrifugal saccades at the start of the task, after 3 minutes of the task (fatigue) and 1 minute after receiving IV edrophonium. The effects of fatigue, though prominent in some myasthenic patients, did 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 amplitude bins showed that these changes in peak velocity reflected shifts in the velocity-amplitude relationship.

Muscarinic antagonists in the treatment of acquired pendular and downbeat nystagmus: a double-blind, randomized trial of three intravenous drugs.

We performed a double-blind, randomized trial of intravenous scopolamine, benztropine, and glycopyrrolate in 7 patients with acquired nystagmus and oscillopsia. Five patients had pendular nystagmus and 2, downbeat nystagmus. We recorded eye movements with a magnetic search coil technique and tested visual acuity and motion perception before and after administration of each drug. Scopolamine reduced nystagmus in all patients. Benztropine was moderately effective and glycopyrrolate had a negligible impact. Visual acuity improved only with scopolamine; motion discrimination and oscillopsia improved significantly with scopolamine and benztropine. Pendular and downbeat nystagmus respond to intravenous antagonists of central muscarinic receptors.

Vertical saccades in senescence.

PURPOSE: To determine the metrics of vertical saccades in elderly subjects for comparison in neurologic disease. METHODS: Sixteen elderly subjects, ten middle-aged subjects, and thirteen young subjects were examined using a magnetic search coil technique. Saccades were measured to predictable vertical target steps and maximal saccadic excursion was measured from primary position. RESULTS: Maximal upward voluntary excursion was reduced in the elderly (mean 32.9 degrees) compared to young subjects (mean 43.1 degrees). Maximal downward voluntary excursion was also reduced in the elderly (mean 32.8 degrees), compared to young subjects (mean 46.8 degrees). The limited ocular motor range of the elderly was not increased by oculocephalic maneuvers. Individual young subjects had significantly larger downward than upward excursions, but elderly subjects generally had symmetrical upward and downward excursions. Asymptotic peak velocities were not significantly slower in the elderly. Individual young subjects made faster upward than downward saccades. Vertical saccade latencies were significantly prolonged and saccadic accuracy was reduced in the elderly compared to the young subjects. CONCLUSIONS: The range and accuracy of upward and downward saccades decrease, and their latency increases in senescence. This quantitative study provides norms for the detection of brain or orbital disease in young, middle-aged, and elderly subjects.