SLOW VERTICAL SACCADES IN MOTOR-NEURON DISEASE - CORRELATION OF STRUCTURE AND FUNCTION

We studied eye movements and brainstem pathology in 2 patients with sl ow vertical saccades and autopsy-proven amyotrophic lateral sclerosis (ALS). In both patients, the main ocular motor finding was supranuclea r vertical gaze impairment with slow vertical saccades. The second pat ient had difficulty opening his eyes on command, with preserved sponta neous eyelid opening. Postmortem examination in both patients demonstr ated cell loss in the rostral interstitial nucleus of the medial longi tudinal fasciculus (riMLF) and substantia nigra, along with histopatho logical findings consistent with ALS. The extent of the pathological c hanges in the riMLF correlated well with the degree of functional impa irment as reflected in the slow vertical saccades. We suggest that mot or neuron disease with early involvement of vertical saccades represen ts a distinct clinicopathological entity.