[1] Cedars Sinai Med Ctr, Dept Neurosurg, Maxine Dunitz Neurosurg Inst, Ctr Neurosurg Outcomes Res, Adv Hlth Sci Pavil, Los Angeles, CA 90048 USA
[2] Univ Arizona, Coll Med, Dept Surg, Tucson, AZ 85721 USA
[3] Univ N Carolina, Dept Neurosurg, Chapel Hill, NC USA
[4] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[5] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90095 USA
[6] Univ Southern Calif, Childrens Hosp Los Angeles, Dept Neurosurg, Los Angeles, CA USA