The vestibulo-ocular reflex and dysequilibrium after hemispheric stroke

Patients with hemispheric lesions frequently suffer from equilibrium impairment that may be prolonged and may interfere with rehabilitation. In an effort to clarify whether this phenomenon is related to vestibular dysfunction, we examined the relationship of the horizontal vestibulo-ocular reflex (VOR) with stability in 15 patients with unilateral hemispheric stroke. The study included electro-oculographic recording of the VOR while the patients were rotated in a vestibular chair. Stability was scored in accordance with the patients' ability to maintain equilibrium in six graded positions. The findings demonstrated relationship between VOR gain (eye/head displacement) and equilibrium. It is suggested that the "loss of balance" after stroke may be related to an impairment of the corticovestibular modulation of the vestibular function.