[1] Seoul Natl Univ Hosp, Dept Neurosurg, Seoul 110744, South Korea
[2] Seoul Natl Univ Hosp, Dept Radiol, Seoul 110744, South Korea
[3] Seoul Natl Univ, Coll Med, Div Pediat Neurosurg, Childrens Hosp, 101 Daehak Ro, Seoul 03080, South Korea
[4] Seoul Natl Univ, Coll Med, Dept Anat, Seoul 03080, South Korea