1. Department of Neurosurgery, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
2. Department of Cerebrovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
3. Department of Cerebrovascular Disease, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
4. Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan