Olivopontocerebellar atrophy presenting with hemiparkinsonian ocular motor signs

A patient with olivopontocerebellar atrophy presented with an asymmetric parkinsonian syndrome consisting of right limb rigidity, bradykinesia, masked facies, and a hypophonic, monotonous voice. Right limb clumsiness suggested corticospinal tract involvement. Gait was slightly wide based, but no other cerebellar or brainstem signs were present. Eye movements were characteristic of parkinsonism with low-gain pursuit and hypometric rightward saccades. Saccadic velocity and the vestibular ocular reflex were within normal limits. There was no pathologic nystagmus or saccadic dysmetria. Magnetic resonance imaging showed cerebellar and lower brainstem atrophy virtually diagnostic of olivopontocerebellar atrophy. Olivopontocerebellar atrophy may present uncommonly with asymmetric parkinsonian features, including parkinsonian eye movement abnormalities.