The somatosensory cortex in multiple system atrophy.

In multiple system atrophy (MSA), it has been accepted that the motor-related cortical area may degenerate. However, there have been few investigations of the postcentral cortex of the somatosensory area. For this reason, we investigated the effects of MSA on both the precentral and the postcentral cortex and were able to demonstrate degenerative changes in each. Furthermore, our study showed that degeneration of the postcentral cortex preceded that of the precentral cortex. In addition, we showed that the Betz cells were not selectively lost, but merely depleted like other neurons of the deep cortical layers. Therefore, the effects of MSA are apparently related to selective loss of the small-sized myelinated fibers in the corticospinal tract.