MSA is a sporadic degenerative disease that occurs in striatonigral degeneration (SND), SDS and most cases of sporadic OPCA. Oligodendroglial inclusion is a hallmark of MSA. Recently there have been a small number of reports of neuronal argyrophilic inclusions. To clarify the distribution and dynamic process of neuronal cytoplasmic inclusions (NCI), 31 cases of MSA were studied using histology, immunohistochemistry, and electron microscopy. The inclusions were exclusively found in the pontine nucleus and there was a correlation between the incidence of NCI and the severity of OPCA, but not of SND. NCI were increased to some extent in the cases with moderate OPCA and decreased in number in proportion to devastation of the pontine nuclei. Immunohistochemical and ultrastructural features of NCI were virtually identical to those of glial cytoplasmic inclusions (GCI), which gives some clues to the pathogenesis of MSA. It is tempting to interpret this as NCI playing a significant role in the degenerative changes of the neurons at least in the pons. Further systematic studies on NCI in the other brain regions are necessary to elucidate the pathogenesis of neuronal degeneration in MSA.

We report autopsy cases of two siblings who developed muscular atrophy and dementia, clinically considered to be familial motor neuron disease (MND). They presented with motor neuron signs predominantly in the distal limbs without sensory impairment. At autopsy, severe neuronal loss in the anterior horn consistent with MND was found, but histopathological hallmarks like Bunina bodies and skein-like inclusions were absent. Surprisingly, numerous huge axonal swellings (about 30 microm in diameter) and onion-bulb-like structures were found in the spinal ventral roots. These changes were not observed in spinal dorsal roots or peripheral nerves. However, obvious segmental demyelination of the ventral root was not found. In addition, neurofibrillary tangles (NFTs) and neuritic plaques were present in the frontal cortex, temporal cortex and hippocampus, and to a lesser degree, in the amygdala, substantia nigra and thalamus. Our two cases are a hitherto unreported type of MND, which shows focal giant axonopathy and prominent formation of onion-bulb-like structures due to Schwann cell proliferation restricted to the spinal ventral roots.

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