Infantile onset spinocerebellar ataxia with sensory neuropathy (IOSCA): neuropathological features

Infantile onset spinocerebellar ataxia (IOSCA, MIM 271245) is a recessively inherited, progressive neurological disease, which we have described in 19 Finnish patients. The clinical symptoms of IOSCA include ataxia, athetosis , hypotonia, hearing deficit, ophthalmoplegia, sensory neuropathy, female h ypogonadism, and epilepsy as a late manifestation. We have mapped the IOSCA locus to 10q24. In our two autopsy cases of IOSCA, the neuropathological f indings were almost uniform. The cerebral hemispheres were quite well prese rved, but the brain stem and the cerebellum were moderately atrophic. The m ost severe atrophic changes were seen in the spinal cord: in the dorsal roo ts, the posterior columns and the posterior spinocerebellar tracts. There w as a severe neuronal loss in the dorsal nucleus (Clarke's column) of both c ases and slight atrophy of the intermediolateral column in one case. The ce rebellar peduncles, the inferior olives, the accessory cuneate nuclei and e specially the dentate nuclei were atrophic and gliotic. The eighth cranial nerve and nucleus were atrophic. The ventral pontine nuclei and transverse fibers were slightly affected. Tegmental nuclei and tracts, especially sens ory structures, were more severely affected. In mesencephalon, there was at rophy of the oculomotor nuclear complex and periaqueductal gray matter. The cerebellar cortex showed patchy atrophy. Degenerative changes were seen in dorsal root ganglia, and there was a severe axonal loss in the sural nerve . The neuropathological picture of IOSCA thus seems close to that reported in Friedreich's ataxia, another recessively inherited usually childhood-ons et ataxia. (C) 1998 Elsevier Science BSI. All rights reserved.