Neuropathological study on the nucleus basalis of Meynert in Pick's disease

The pathological changes in the nucleus basalis of Meynert (nbM) in 10 autopsied cases with Pick's disease were studied in comparison with 15 age-matched controls. Both the number and density of nerve cells and the degree of fibrillary gliosis were examined at the anterior, intermediate, and posterior divisions of the nbM. In only 2 of the 10 Pick cases was the number of neurons significantly reduced, with moderate fibrillary gliosis at the anterior division (case 5: reduced by 64%, case 8: reduced by 46%). This neuronal loss in the anterior nbM division may not be a retrograde degeneration secondary to the cortical lesions, since there were some cases without neuronal loss in the nbM despite the presence of much more severe cortical lesions than in these two cases. In all Pick cases except case 1, mild to moderate fibrillary gliosis was found without an apparent neuronal loss at the posterior division of the nbM. This change in the posterior nbM division may be due to secondary retrograde degeneration, since there was a parallel relationship between the degree of fibrillary gliosis in the posterior nbM division and the severity of cortical lesions in the temporal tip and the superior temporal gyrus, to which the cholinergic fibers are known to project from the posterior division of the nbM. The present study suggests that the mild degeneration of the nbM in most cases with Pick's disease may be secondary, but that there are also some cases of Pick's disease with a primary degeneration in the nbM.