Presynaptic parkinsonism in olivopontocerebellar atrophy: clinical, pathological, and neurochemical evidence.

The substrate for olivopontocerebellar atrophy parkinsonism is obscure due to the lack of clinical and pathological reports and the absence of studies on dopamine receptors in this entity. We describe a patient with olivopontocerebellar atrophy whose clinical presentation was levodopa-responsive parkinsonism in whom pathological examination disclosed pronounced nigral cell loss with no striatal damage. Autoradiographic labeling with 3H-spiperone showed normal densities of D2 dopamine striatal receptors. These data show that indistinguishable nigral, presynaptic parkinsonism occurs in patients with idiopathic Parkinson's disease and in patients with olivopontocerebellar atrophy, and also how a favorable response to levodopa is neither synonymous with idiopathic Parkinson's disease, nor does it exclude multiple-system, atrophy-related parkinsonism.