Olivopontocerebellar atrophy studied by positron emission tomography and magnetic resonance imaging.

We examined 9 patients with olivopontocerebellar atrophy (OPCA) using positron emission tomography and magnetic resonance imaging (MRI). Regional cerebral blood flow and oxygen metabolism were compared with the findings in 10 normal age-matched volunteers. The volumes of the basis pontis and the cerebellar hemispheres were quantitated by MRI to assess the relationship between morphological changes of the pons or cerebellum and the cerebellar circulation and metabolism. In the patients with OPCA, cerebellar hemispheric blood flow and oxygen metabolism were significantly lower than in the normal volunteers. Pontine volume showed a significant correlation with the cerebellar blood flow and the metabolic rate of oxygen. In contrast, the cerebellar hemispheric volume showed no correlation with either of these parameters. Our results suggest that the disruption of pontocerebellar pathway may contribute to the reduction of both blood flow and oxygen metabolism in the cerebellum of OPCA and that detection of cerebellar circulatory impairment without marked cerebellar atrophy by neuroimaging may be suggestive of OPCA.