[Extrapyramidal manifestations in hereditary olivopontocerebellar atrophy--clinical study of 10 cases in three affected pedigrees].
We studied 3 pedigrees affected with autosomal dominant olivopontocerebellar atrophy (OPCA), and clinical features of 10 patients were reported. Clinically, 6 cases were dominated with cerebellar ataxia, one with Parkinsonism, and three with choreiform movements. Furthermore, they were characterized by slow eye movement and progressive loss of tendon reflexes. Generally, extrapyramidal manifestations, such as Parkinsonism or choreiform movements, are occasionally observed in dominant OPCA. However, the pathogeneses are different from each other. The choreiform movements are unique in dominant OPCA, and generally not observed in sporadic OPCA. In the distribution of degenerated foci, dominant OPCA is often associated with degeneration of not only substantia nigra, but also with other structures such as dentate nucleus, red nucleus, external segment of globus pallidus (GPe), and subthalamic nucleus. This dentatorubral and pallido-Luysian system degeneration are parts of neuropathological findings in hereditary DRPLA (Naito-Oyanagi form). In both disorders, choreiform movements is observed. Current theory indicates that hyperactivity of neostriatal dopamine neurons and degeneration of GPe play roles in the pathogenesis of chorea. Clinically, choreiform movements are common in hereditary DRPLA, but not in dominant OPCA. This difference could be explained by the nigral degeneration in dominant OPCA, which suppress the generation of choreiform movements.