1. Department of Preventive Medicine and Epidemiology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
2. Department of Neurology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
3. Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
4. National Cerebral and Cardiovascular Center Hospital, Suita, Japan