1. No. 1 Department of Neurology, Qingdao Central Hospital, Shandong 266000, P.R. China
2. Department of Neurosurgery, People's Hospital of Rizhao, Shandong 276800, P.R. China
3. No. 2 Department of Neurology, Qingdao Central Hospital, Shandong 266000, P.R. China