Anatomical differences between CBS-corticobasal degeneration and CBS-Alzheimer's disease

We compare patterns of gray matter loss on MRI in subjects presenting as corticobasal syndrome (CBS) with Alzheimer disease pathology (CBS-AD) to those presenting as CBS with corticobasal degeneration pathology (CBS-CBD). Voxel-based morphometry was used to compare patterns of gray matter loss in pathologically confirmed CBS-AD subjects (n = 5) and CBS-CBD subjects (n = 6) to a group of healthy controls (n = 20), and to each other. Atlas based parcellation using the automated anatomic labeling atlas was also utilized in a region-of-interest analysis to account for laterality. The CBS-AD subjects were younger at the time of scan when compared with CBS-CBD subjects (median: 60 years vs. 69; P = 0.04). After adjusting for age at time of MRI scan, the CBS-AD subjects showed loss in posterior frontal, temporal, and superior and inferior parietal lobes, while CBS-CBD showed more focal loss predominantly in the posterior frontal lobes when compared with controls. In both CBS-AD and CBS-CBD groups, there was basal ganglia volume loss, yet relative sparing of hippocampi. On direct comparisons between the two subject groups, CBS-AD showed greater loss in both temporal and inferior parietal cortices than CBS-CBD. No regions showed greater loss in the CBS-CBD group compared to the CBS-AD group. These findings persisted when laterality was taken into account. In subjects presenting with CBS, prominent temporoparietal, especially posterior temporal and inferior parietal, atrophy may be a clue to the presence of underlying AD pathology.