[An MRI study of hereditary spinocerebellar degenerations].

We evaluated magnetic resonance image (MRI) in 21 cases of hereditary spinocerebellar degenerations (SCD) of autosomal dominant trait. By the discriminant formula based on size of the cerebellar vermis and ventral pons, which was reported in our previous study, the patients were classified into three types. Group 1 included the cases with atrophies in the vermis and pons; OPCA type. Group 2 showed vermian atrophy and less significant atrophy in pons; LCCA type. And Group 3 was no significant atrophies both in vermis and pons. Cases in Group 1 were furthermore divided into two groups according to width of the midbrain tegmentum. Group 1A, with normal midbrain tegmentum, was consisted of five cases. Four cases were diagnosed as Menzel type OPCA. Another case showed various clinical symptoms and relatively mild atrophies for his duration of illness. His family members were classified to Group 3. Seven cases in Group 1B showed reduced midbrain tegmentum. Four cases showed ataxia, spasticity, ocular symptoms, bladder dysfunction and amyotrophy with or without fasciculation, and they seemed to be a special type of SCD mimicking Joseph disease. One case showed bulging eyes, ocular movement palsy and dystonia. However, his sister manifested only ataxia with very mild ocular movement disorder. Their MRI demonstrated severe atrophies in the cerebellum, pons and afferent cerebellar peduncli, and this pedigree was thought to be Menzel type OPCA with various associated disorders. Another case was clinically diagnosed as dentate-rubro-pallido-luysian atrophy. Group 2 was consisted of 6 cases who were clinically diagnosed as Holmes type LCCA. MRI demonstrated medial dominant cerebellar atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)