[Provisional diagnostic criteria of corticobasal degeneration (CBD) and the survey of patients with CBD in Japan].

We conducted the survey of patients with CBD in 2001 for 29 neurological institutions in Japan which joined Research Group on Neurodenerative Diseases supported by Ministry of Health and Welfare. Provisional diagnostic criteria of CBD were as follows: "probable CBD" means a clinical category including (1) classical form, consisting of progressive limb-kinetic apraxia and akinetic rigidity, predominant on one side, associated with late dementia, (2) quasi-classical form, revealing other corticobasal signs, predominant on one side, associated with late dementia, and (3) non-classical from, showing early aphasia, dementia, behavior disorder, etc., followed by lateralized limb-kinetic apraxia and akinetic rigidity. "Possible CBD" was not made. "Definite CBD" is pathologically confirmed CBD. There were 151 patients with "probable CBD", comprising 121 patients with classical form, 17 with quasi-classical form and 13 with non-classical from, while patients with "definite CBD" were 13. The number of patients with progressive supranuclear palsy (PSP) was also examined. The ratio of the number of patients CBD/PSP was 1/2.6 in clinical cases and 1/2.5 in autopsy cases. Nakashima et al. performed population survey of PSP patients in Yonago city in 1999, demonstrating prevalence of PSP 4.36/100,000. Considering this rate, the prevalence of CBD is assumed as 1.7 and the presumed number of PSP and CBD patients in 1999 in Japan could be 5,500 and 2,100, respectively.