1. From the Department of Neurosurgery (K.U., S.Y.), Hyogo College of Medicine, Nishinomiya, Japan
2. Department of Clinical Epidemiology (K.U., T.M.), Hyogo College of Medicine, Nishinomiya, Japan
3. Department of Neurosurgery, Kobe City Medical Center General Hospital, Japan (N.S.)
4. Division of Stroke Care Unit, National Cerebral and Cardiovascular Center, Suita, Japan (H.Y.).