DECREASE IN NEURONAL DENSITY IN THE CEREBRAL-CORTEX IN MULTIPLE SYSTEM ATROPHY

The presence of argyrophilic oligodendroglial cytoplasmic inclusions ( GCIs) is a pathognomonic feature of multiple system atrophy (MSA), whi ch has established MSA as a nosological entity, and serves as a diagno stic criterion. As a neurodegenerative disease, MSA exhibits neuronal degeneration and loss from several regions of the central nervous syst em. Recent mapping studies of the distribution of GCIs have shown thei r presence in regions of the brain previously thought not to be affect ed in MSA, for example the cerebral cortex. This study has used stereo logical techniques to establish whether neuronal loss is related to th e presence of GCIs in three regions of the cerebral cortex. In the pre frontal cortex, in which GCIs are sparse, there is no significant diff erence in either neuronal or glial cell numerical density in MSA cases compared to controls. However in two cortical regions which are both GCI rich, the anterior central gyrus and the supplementary motor corte x, there is a marked reduction in neuronal density of 18.7% and 21.4% respectively, which is statistically significant only in the supplemen tary motor cortex. In both of these regions there is a concomitant inc rease in glial cell numerical density which results in a significant c hange in the ratio of neurons to glial cells. These results indicate t hat there is a regional reduction in the neuronal density in the corte x in multiple system atrophy which is associated with the presence of GCIs.