[1] Childrens Hosp Philadelphia, Div Neurosurg, Philadelphia, PA USA
[2] Univ Penn, Perelman Sch Med, Dept Neurosurg, Philadelphia, PA USA
[3] Rowan Univ, Sch Osteopath Med, Stratford, NJ USA
[4] Univ Penn, Childrens Hosp Philadelphia, Perelman Sch Med, Dept Anesthesiol & Crit Care Med, Philadelphia, PA USA
[5] Childrens Hosp Philadelphia, Philadelphia, PA 19104 USA