Dentatorubro Pallidoluysial Atrophy

Dentatorubro-pallidoluysial atrophy (DRPLA) occurs from infancy to adult life. It is relatively common among the Japanese. It is inherited as an autosomal dominant trait and is associated with an expanded CAG repeat in the DRPLA gene on chromosome 12. The CAG repeats expand to 54 to 79; the normal number of repeats is from 6 to 35. Progressive cerebellar ataxia is associated with combinations of choreoathetosis, myoclonus, seizures, and mental retardation in children, and with dementia in adults. On radiograph, a thick skull is noted. On MRI T2-weighted images, cerebellar and brainstem atrophy and hyperintense lesions in the hemispheric white matter, pallidum, and thalamus are characteristic.

Grossly, the brainstem and the cerebellum are atro-phic, and the globus pallidus has a brown-tan discoloration. Histology:, the disease is confined to the cerebellum and its efferent connection —, the red nucleus, and to the globus pallidus and its efferent connection, the sub-thalamic nucleus. A loss of neurons occurs in the dentate nucleus, and myelin pallor and gliosis is noted in the dentate hilus and the superior cerebellar brachia. The remaining dentate neurons display grumose degeneration with eosinophilic and argyrophilic granular materials around the perikaryon and dendrites. They derive from axonal terminals of the Purkinje cells. The red nuclei show gliosis and some neuronal losses. The globus pallidus and the subthalamic nucleus show neuronal losses and gliosis, and a loss of myelin occurs in the pallidosubthalamic tracts. Variable neuronal losses occur in the cerebral cortex, and myelin losses and gliosis are present in the hemispheric white matter.

The presence of neuronal inclusions is characteristic. The dentate neurons display round, eosinophilic, nuclear and filamentous cytoplasmic inclusions. Both immunoreact for ubiquitin and expanded polyglutamine tracts. Neurons with intranuclear inclusions, which represent aggregates of expanded polyglutamine tracts, are widely distributed.

0 0

Post a comment