[1] Northwestern Univ, Dept Neurol Surg, Feinberg Sch Med, Chicago, IL USA
[2] Ann & Robert H Lurie Childrens Hosp, Div Pediat Neurosurg, Chicago, IL USA
[3] Rush Univ, Dept Neurol Surg, Chicago, IL USA
[4] Indiana Univ Sch Med, Riley Hosp Children, Dept Neurol Surg, Sect Pediat Neurosurg, Indianapolis, IN USA
[5] Indiana Univ Sch Med, Riley Hosp Children, Dept Pediat, Div Pediat Crit Care Med, Indianapolis, IN USA
[6] Indiana Univ Hlth, Charles Warren Fairbanks Ctr Med Eth, Indianapolis, IN USA
[7] Northwestern Univ, Ann & Robert H Lurie Childrens Hosp, Dept Neurosurg, Div Pediat Neurosurg,Feinberg Sch Med, 225 E Chicago Ave,Box 28, Chicago, IL 60611 USA