1. Department of Anesthesiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin, People's Republic of China.
2. Department of Neurosurgery, Jilin Province Hospital, Changchun, Jilin, People's Republic of China.
3. Department of Neurosurgery, West China Hospital of Sichuan University, Chengdu, Sichuan, People's Republic of China.
4. Department of Neurology, China-Japan Union Hospital of Jilin University, Changchun, Jilin, People's Republic of China.