1. Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan, China.
2. Department of Gastroenterology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
3. Department of National Clinical Medical Research Center for Geriatric Diseases, Xiangya Hospital, Central South University, Changsha, Hunan, China.