1. Department of Neurology, Dalian Municipal Central Hospital, Dalian, Liaoning 116033, P.R. China
2. Department of Neurology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China
3. Department of Neurology, Nanjing Gaochun People's Hospital, Nanjing, Jiangsu 211300, P.R. China
4. Department of Neurology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China