1. The Third Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi 710068, P.R. China
2. The Department of West Yard Ward 2 (Geriatrics), Shaanxi Provincial People's Hospital, Xi'an, Shaanxi�710068, P.R. China
3. Department of Radiotherapy, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi�710068, P.R. China
4. Department of Internal Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi�710061, P.R.�China