1. Department of ENT, Qingdao Municipal Hospital, Qingdao, Shandong 266011, P.R. China
2. Department of Nephrology, Qingdao Municipal Hospital, Qingdao, Shandong 266011, P.R. China
3. The Affiliated Central Hospital of Qingdao University, Qingdao, Shandong 266042, P.R. China
4. Department of Neurology, East Hospital of Qingdao Municipal Hospital, Qingdao, Shandong 266071, P.R. China