Pathologic heterogeneity in clinically diagnosed corticobasal degeneration

Background: Early reports suggested that corticobasal degeneration (CBD) is a distinct clinicopathologic entity. Because patients have had a fairly co nsistent constellation of clinical and laboratory findings, many have propo sed that the pathologic diagnosis can be surmised with confidence during li fe. Objective: To analyze the pathologic findings in a large series of case s with clinically diagnosed CBD. Methods: Using the medical research linkag e system of the Mayo Clinic for the period January 1990 to December 1997, w e identified cases diagnosed during life with CBD who subsequently underwen t autopsy. All patients had progressive asymmetric rigidity and apraxia (ex cept one with rigidity but no apraxia) with other findings, suggesting addi tional cortical and basal ganglionic dysfunction. All cases underwent stand ardized neuropathologic examination with the distribution and severity of t he pathologic changes determined for each case and the pathologic diagnoses based on currently accepted criteria. Results: Thirteen cases were identif ied. The pathologic diagnoses were CBD in seven, AD in two, and one each fo r progressive supranuclear palsy, Pick's disease, nonspecific degenerative changes, and Creutzfeldt-Jakob disease. Two cases had negligible basal gang lia and nigral degeneration despite previously having obvious extrapyramida l signs. However, all patients had focal or asymmetric cortical atrophy wit h coexisting neuronal loss and gliosis with or without status spongiosis, w hich was maximal in the parietal and frontal cortical regions. Conclusions: The constellation of clinical features considered characteristic of CBD is associated with heterogeneous pathologies. Furthermore, this syndrome can occur in the absence of basal ganglia and nigral degeneration. The one inva riable pathologic abnormality in patients with this syndrome, however, is a symmetric parietofrontal cortical degeneration. At present, accurate diagno sis of CBD requires tissue examination.