[1] Univ Toronto, Dept Med, Toronto, ON M5S 1A1, Canada
[2] Univ Toronto, Dept Surg, Div Neurosurg, Toronto, ON M5S 1A1, Canada
[3] McMaster Univ, Div Neurosurg, Hamilton, ON, Canada
[4] McMaster Univ, Div Crit Care Med, Hamilton, ON, Canada
[5] Univ Toronto, Dept Med, Div Emergency Med, Fac Med, Toronto, ON, Canada
[6] Ornge Transport Med, Mississauga, ON, Canada