[1] Univ Calif Los Angeles, David Geffen Sch Med, Med Ctr, Div Neurosurg, Los Angeles, CA 90095 USA
[2] Univ Calif Los Angeles, David Geffen Sch Med, Dept Neurol, Los Angeles, CA 90095 USA
[3] Georgetown Univ, Dept Neurol, Washington, DC 20057 USA
[4] Washington Hosp Ctr, Washington, DC 20010 USA
[5] Univ Calif Los Angeles, David Geffen Sch Med, Dept Emergency Med, Los Angeles, CA 90095 USA
[6] Univ Calif Los Angeles, David Geffen Sch Med, Dept Biomath, Los Angeles, CA 90095 USA