[An autopsy case of hereditary ataxia (hereditary spastic ataxia)].

An autopsy case of hereditary spastic ataxia is reported. There are four family members with similar symptomatology through three generations. A 36-year-old man developed atactic gait at the age of 22 years, with following dysarthria, scanning speech, pyramidal signs, dysmetria, dysdiadochokinesia, nystagmus and mild sensory disturbance. The clinical course was steadily progressive and terminated about 14 years after the onset. The gross examination showed smallness of the brain stem and spinal cord with marked symmetrical atrophy of the anterior and lateral columns, especially at thoracic level. Histologically, pronounced degeneration was found in the anterior and posterior spino-cerebellar tracts, spino-thalamic tracts, and spinal ganglia. The olivary nuclei, pons and cerebellum were spared. The dentate nuclei showed considerable loss of neurons with degeneration, however there were no clinical signs related to this pathology. This case is considered to fall in the group of hereditary spastic ataxia according to Greenfield's classification, however, there was no report on degeneration of the dentate nucleus in this disease for the present. Hereditary spastic ataxia is very rare disease and only four cases have well been documented in our country to the best of our knowledge. The presence of nystagmus and superficial sensory disturbance, and sparing of the posterior column of the spinal cord seems to be common clinico-pathology in Japanese cases, differing from those of foreign cases. The fact that reactive astrogliosis was immunohistochemistry demonstrated in the degenerative regions of the spinal cord and where is no discrepancy between degenerative and reparative processes as reported before is stressed.(ABSTRACT TRUNCATED AT 250 WORDS)