[1] Ajou Univ, Ajou Univ Hosp, Dept Neurosurg, Sch Med, Suwon, South Korea
[2] Yonsei Univ, Severance Hosp, Dept Neurosurg, Coll Med, 50 Yonsei Ro, Seoul 03722, South Korea
[3] Yonsei Univ, Gangnam Severance Hosp, Dept Neurosurg, Coll Med, Seoul, South Korea
[4] Yonsei Univ, Severance Hosp, Dept Pathol, Coll Med, Seoul, South Korea