1. Department of Anesthesiology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
2. Department of Neurology, The Ninth People's Hospital of Shenyang, Shenyang, Liaoning 110024, P.R. China
3. Department of Gerontology and Geriatrics, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China