Author information: (1)Stroke Center, Osaka University Hospital, Suita, Osaka, Japan. ktodo@neurol.med.osaka-u.ac.jp. (2)Department of Neurosurgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan. (3)Department of Stroke Neurology, National Hospital Organization Osaka National Hospital, Osaka, Japan. (4)Department of Cerebrovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan. (5)Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan. (6)Stroke Center, Osaka University Hospital, Suita, Osaka, Japan. (7)Department of Neurosurgery, National Hospital Organization Sendai Medical Center, Sendai, Miyagi, Japan. (8)Cerebrovascular Center, National Hospital Organization Kyushu Medical Center, Fukuoka, Japan. (9)Department of Neurology, Tokyo Women's Medical University, Tokyo, Japan. (10)Department of Neurological Science, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan. (11)Institute for Biomedical Sciences, Iwate Medical University, Morioka, Iwate, Japan. (12)Department of Neurology, Saitama Medical University International Medical Center, Hidaka, Saitama, Japan. (13)Department of Stroke Neurology, Saiseikai Toyama Hospital, Toyama, Japan. (14)Division for Stroke Prevention and Treatment, Department of Neurosurgery, University of Tsukuba, Tsukuba, Ibaraki, Japan. (15)Department of Clinical Epidemiology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan.