[1] Univ Maryland, Dept Neurol, Program Trauma, Sch Med, 22 S Greene St,G7k19, Baltimore, MD 21201 USA
[2] Univ Maryland, Dept Med, Sch Med, Baltimore, MD 21201 USA
[3] Univ Texas Houston, Dept Neurosurg, Houston, TX USA
[4] Kingston Gen Hosp, Clin Evaluat Res Unit, Kingston, ON, Canada
[5] Queens Univ, Dept Crit Care Med, Kingston, ON, Canada