Hereditary cerebellar degeneration with downbeat nystagmus. A case and it's treatment.

We present a female patient of 48 years with downbeat nystagmus (DBN), moderate impairment of coordination testing and a family history of cerebellar ataxia. We report that a single 2 mg dose of clonazepam (following Currie & Matsuo) resulted in a virtual disappearance of nystagmus and of the patient's symptom of oscillopsia. This result is interpreted in terms of current models of DBN.