Multiple system atrophy with neuronal intranuclear hyaline inclusions. Report of a new case with light and electron microscopic studies.

An 18-year-old girl died following a slowly progressive neurodegenerative disease of nine years duration. At 9 years of age, she developed intellectual deterioration associated with speech difficulty, pseudobulbar palsy and ataxia. The progression included spastic quadriplegia, anarthria, severe dysphagia, ophthalmoplegia, and pes cavus. There was no family history. The brain was uniformly small and the substantia nigra was not pigmented. Neuronal loss and gliosis involving globus pallidus, subthalamic nucleus, thalamic nuclei, brain stem, cerebellum, and spinal cord gave the picture of multisystem atrophy. Intranuclear hyaline inclusions were observed in numerous neurons of the central and peripheral nervous system. These were auto-fluorescent and were made up of intermingled straight filaments (8-9 nm in diameter). Only two previously reported cases showing these same inclusions are known. They are reviewed, compared, and discussed in relation to primary neuronal degenerations.