Deficits of smooth-pursuit eye movements in two patients with a lesion in the (para-)floccular or dorsolateral pontine region

Abstract

Visually and vestibularly guided slow eye movements are described in two patients with small unilateral lesions in the region of the (para-)flocculus and of the dorsolateral pontine nucleus, respectively. Deficits in smooth eye movement performance are comparable to those observed in monkeys with similarly located lesions: the velocity of visually induced smooth-tracking movements is severely reduced, and the vestibulo-ocular reflex is not suppressed by visual fixation. Deficits occurred for bilateral stimulation in the patient with the dorsolateral pontine lesion and mainly for stimulation to the lesion side in the patient with the (para-)floccular lesion. Velocity and accuracy of saccadic eye movements made in response to stationary targets were normal.

Key Words:

• visual-vestibular interaction
• smooth pursuit
• optokinetic nystagmus
• flocculus
• dorsolateral pontine nucleus
• cerebellum