1. School of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia 750001, P.R. China
2. Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, Ningxia 750001, P.R. China
3. Neurology Center, General Hospital of Ningxia Medical University, Yinchuan, Ningxia 750004, P.R. China
4. Department of Neurology, Shenmu Hospital, Yulin, Shanxi 719000, P.R. China
5. Department of Neurology, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia 750004, P.R. China