Corticobasal degeneration with primary progressive aphasia and accentuated cortical lesion in superior temporal gyrus: case report and review

Abstract

A 57-year-old woman showed progressive sensory aphasia as an initial symptom, and then developed total aphasia within 6 years and, finally, severe dementia. Neuropathologically, the cerebral cortex was most severely affected in the superior and transverse temporal gyri, and subsequently in the inferior frontal gyrus, especially in the pars opercularis. The degeneration in the subcortical grey matter was most severe in the substantia nigra, and it was moderate to mild in the ventral part of thalamus, globus pallidus and striatum. Cytopathologically, in addition to achromatic ballooned neurons, massive tau-positive types of cytosekeletal abnormalities were observed both in neurons and glia, mainly in the degenerating region. This cytoskeletal pathology coincided with that reported in corticobasal degeneration (CBD). On Bodian staining, only a few neurofibrillary tangles were found in the entorhinal pre-alpha layer and substantia nigra. Pick’s bodies and senile plaques could not be found. This case is thought to represent a type of CBD, but with its cortical lesion focus located in the speech area instead of the frontoparietal region. A survey of 28 pathologically evaluated cases of CBD revealed two similar cases, both of which began with progressive aphasia and presented cortical degeneration in the superior temporal gyrus. An overview of CBD cases clarified the features in another group of cases, in which the cerebral accentuated focus was shifted forward from the central region, clinically resembling Pick’s disease. The clinical manifestations in CBD seem to be the expression of these diverse cortical lesions. Primary progressive aphasia may include cases of CBD with involvement of the language center.