The incidence of hemorrhagic stroke in Japan is twice compared with western countries: the Akita stroke registry.

The purpose of this study is to find out new knowledge about stroke among huge Japanese stroke registry involving complete brain images. The first stroke events from 1995 to 2004 in the Akita stroke registry (28,781 cases) were included in this study. According to brain images, we classified them into three types; cerebral infarction (CI 18,018 cases, 62.6 %), cerebral hemorrhage (CH 7,423 cases, 25.8 %), and subarachnoid hemorrhage (SAH 3,340, 11.6 %). CI and CH were classified according to the lesional areas, respectively. SAH was divided into three types according to arterial sites of ruptured aneurysm. The proportion of hemorrhagic stroke in Japan (37.4 %) was two times higher than in Western countries. Among CI group; lacunar infarction, cortical infarction, and infratentorial infarction occupied 5,437 (30.2 %), 6,121 (34.0 %), and 2,703 (15.0 %) cases, respectively. Among CH group; putamen, thalamus, and subcortex occupied 1,379 (18.6 %), 2,251 (30.3 %), and 1,204 (16.2 %) cases, respectively. According to ruptured cerebral aneurysm site, they were obviously different between men and women, proportion of internal carotid artery was the most (40.8 %) in women and that of anterior communicating artery was the most (46.8 %) in men on the contrary. The incidence of hemorrhagic stroke in Japan is twice as much as in the western countries.