Ocular tilt reaction due to unilateral cerebellar lesion

We report two patients with an ocular tilt reaction (OTR) due to unilateral caudal cerebellar lesion. One patient had a caudal cerebellar hemorrhage, the other a posterior inferior cerebellar artery territory infarct. There w as head tilt in both patients which had not been reported previously. These findings support the previous proposal that the mechanism of a tonic contr aversive OTR with unilateral cerebellar lesion is an increased tonic restin g activity in the ipsilesional vestibular nucleus due to a loss of inhibiti on from the lesioned nodulus.