Influence of Caloric Nystagmus on Smooth Pursuit Eye Movements

Abstract

In patients with peripheral vestibular disorders, spontaneous nystagmus is sometimes superimposed on smooth pursuit eye movements and reveals unilateral saccadic pursuit. To determine whether caloric nystagmus has an influence on smooth pursuit, we recorded horizontal eye tracking with cold water caloric stimulation in 12 normal subjects. We found that brisk caloric nystagmus was superimposed on smooth pursuit eye movements, and we measured slow phase velocity and fast phase velocity of the superimposed nystagmus. The influence was great when tracking was in the same direction as caloric nystagmus. We suggest that saccadic pursuit indicates not only central disorders but also peripheral vestibular lesions.