VESTIBULAR COMPENSATION IN A PATIENT WITH A CEREBELLAR INFARCTION

We report the case of a 67-year-old man who suffered a traumatic unila teral peripheral vestibular injury subsequent to an unrelated prior ce rebellar infarction that occurred at least 2 years earlier. The patien t's clinical course was marked by poor compensation for his peripheral vestibular loss. Four months after his vestibular injury, his symptom s of dizziness had not resolved. He had a spontaneous vestibular nysta gmus, and laboratory testing indicated an asymmetric semicircular cana l-ocular reflex. The otolith-ocular reflex, tested using off-vertical axis rotation, also was asymmetric but had a preserved modulation comp onent. Visual-vestibular interaction and semicircular canal-otolith in teraction were normal. An MRI indicated preservation of the flocculo-n odular lobe but infarction of the pyramis and uvula. Taken together, t he findings in this case suggest that despite structural and functiona l preservation of the flocculo-nodular lobe, an anatomic region often labeled the ''vestibulo-cerebellum,'' a lesion of the cerebellum that can impair CNS compensation for a unilateral peripheral lesion in huma ns.