[1] Seoul Natl Univ, Coll Med, Seoul Natl Univ Hosp, Dept Neurosurg, Seoul 110744, South Korea
[2] Seoul Natl Univ, Childrens Hosp, Dept Neurosurg, Div Pediat Neurosurg, Seoul 110744, South Korea
[3] Seoul Natl Univ, Coll Med, Dept Pathol, Seoul Natl Univ Hosp, Seoul 110744, South Korea