[1] Sungkyunkwan Univ, Dept Neurol, Seoul 135710, South Korea
[2] Hallym Univ, Kang Nam Sacred Heart Hosp, Dept Radiol, Seoul, South Korea
[3] Ajou Univ, Dept Neurol, Suwon 441749, South Korea
[4] Yonsei Univ, Dept Neurol, Seoul 120749, South Korea
[5] Univ Calif Los Angeles, Med Ctr, Dept Neurol, Los Angeles, CA 90024 USA