Abnormal head impulse test in a unilateral cerebellar lesion

Abstract

Background The findings of head impulse tests (HIT) are usually normal in cerebella lesions. Case Report A 46-year-old male presented with progressive dizziness and imbalance of 3 weeks duration. The patient exhibited catch-up saccades during bedside horizontal HIT to either side, which was more evident during the rightward HIT. However, results of bithermal caloric tests and rotator chair test were normal. MRI revealed a lesion in the inferior cerebellum near the floccules. Conclusions Ties case provides additional evidence that damage to the floccules or its connections may impair the vestibule-ocular refax only during high-speed stimuli, especially when the stimuli are applied to the contralesional side. By observing accompanying cerebella signs, the abnormal HIT findings caused by a cerebella disorder can be distinguished from those produced by peripheral vestibular disorders.