Corticobasal ganglionic degeneration and/or frontotemporal dementia? A report of two overlap cases and review of literature

Objective-According to the existing viewpoint, Corticobasal degeneration (C BD) is thought of as a predominantly extrapyramidal motor disorder that is distinct and unrelated to frontotemporal dementia (FTD), the most common fo rm of non-Alzheimer dementias. A lack of understanding of the aetiopathogen esis, and poor correlation between the pathology and the clinical syndromes , has resulted in a disparity in the classification of cases of non-Alzheim er dementias. This report intends to highlight the overlap between FTD and CBD in the Light of the evolution of these terms, and to discuss the implic ations of these findings on the nosology of CBD and the classification of n on-Alzheimer dementias. Methods and results-Two cases who presented with cognitive dysfunction, whi ch, on comprehensive neuropsychological testing warranted an antemortem dia gnosis of FTD are reported. A detailed necropsy study of their brains, howe ver, favoured a pathological diagnosis of CBD. The literature on the overla p between CBD and FTD is also reviewed. Conclusions-Firstly, evidence is emerging to suggest that the clear distinc tion drawn between FTD and CBD by the existing viewpoint, needs revision. S econdly, until such time that a comprehensive classification of non-Alzheim er dementias is evolved, it may be better to distinguish between the clinic al and pathological levels of description and to classify cases, in vivo, o n the basis of the clinical phenotype.