[1] Univ Calif San Francisco, Dept Neurol Surg, Neurooncol Serv, San Francisco, CA 94143 USA
[2] Univ Massachusetts, Sch Med, Ctr Outcome Res, Dept Surg, Worcester, MA USA
[3] Carolina Neurosurg & Spine Associates, Charlotte, NC USA
[4] Univ Toronto, Div Neurosurg, Toronto, ON, Canada
[5] Univ Colorado, Dept Neurol Surg, Denver, CO 80202 USA
[6] Johns Hopkins Univ, Dept Neurol Surg & Oncol, Baltimore, MD USA
[7] Univ Virginia, Dept Neurol Surg, Charlottesville, VA USA