[Corticobasal degeneration and atypical progressive supranuclear palsy: their symptomatology, laboratory examination and differential diagnosis].

Corticobasal degeneration (CBD) and atypical progressive supranuclear palsy (PSP) were reviewed with special reference to their symptomatology, laboratory examination and differential diagnosis. In our survey of the autopsy cases of CBD in Japan, only about 60% of the pathologically confirmed CBD cases were correctly diagnosed clinically, meaning that atypical (non-classical) clinical forms are common in CBD. Concerning the autopsy cases of PSP in Japan, 75% of the PSP cases had correct clinical diagnosis. In literatures, the clinically atypical CBD includes (1) frontotemporal dementia, also with primary progressive aphasia and frontal lobe dementia as subforms, (2) PSP-like form, and (3) others. The clinically atypical PSP comprises (1) pure akinesia, (2) pure easy falling syndrome (Yuasa), (3) no postural instability, (4) no gaze palsy, (5) asymmetric parkinsonism, (6) no or severe dementia, etc.. PSP with cortical manifestations such as primary progressive aphasia and CBD-like features were also reported. The atypical CBD and PSP probably reflect the distribution of tau pathology different from that in typical forms. Except for the report that phosphorylated tau is increased in CSF in CBD, but not in PSP (Urakami et al), no reliable laboratory data have been available on clinical differentiation between atypical CBD and PSP.