Teaching Video NeuroImages: Vestibulo-ocular reflex defect in cerebellar stroke.

Abstract

A 69-year-old man presented with acute vertigo, nausea, and vomiting. The patient had left-beating nystagmus and an abnormal vestibulo-ocular reflex with corrective saccades on right head impulse (video 1). He had impaired pursuits to the left but no other cerebellar/neurologic findings (skew/hearing loss). MRI showed an acute stroke affecting the left cerebellar flocculonodular region (figure). Prior research has shown that an abnormal head impulse test (HIT) strongly predicts a peripheral process, and is inversely associated with posterior fossa stroke.1 Our case illustrates the limited specificity of this clinical test. Nine percent of patients with a positive HIT have cerebellar strokes.2