[1] Stanford Univ, Sch Med, Div Pediat Neurosurg, Stanford, CA 94305 USA
[2] Stanford Univ, Sch Med, Dept Radiol, Div Pediat Neuroradiol, Stanford, CA 94305 USA
[3] Lucile Packard Childrens Hosp, Stanford, CA USA
[4] Univ Childrens Hosp Basel, Dept Neurosurg, Div Pediat Neurosurg, Basel, Switzerland