1. Department of Neurology, The Affiliated Hospital of Southwest Jiaotong University and The Third People's Hospital of Chengdu, Chengdu, Sichuan 610010, P.R. China
2. Department of Ultrasonography, The Affiliated Hospital of Southwest Jiaotong University and The Third People's Hospital of Chengdu, Chengdu, Sichuan 610010, P.R. China
3. Department of Neurology, The Affiliated Hospital of Southwest Jiaotong University and The Third People's Hospital of Chengdu, Chengdu, Sichuan 610010, P.R. China