[1] Univ Calgary, Dept Neurosurg, 12th Floor Foothills Med Ctr,1403 29 St NW, Calgary, AB T2N 2T9, Canada
[2] Dalhousie Univ, Halifax Infirm, Dept Surg, Div Neurosurg, 3rd Floor, Halifax, NS, Canada
[3] McMaster Univ, Hamilton Gen Hosp, Hamilton, ON, Canada
[4] Univ Saskatchewan, Royal Univ Hosp, Saskatoon, SK, Canada
[5] Univ Manitoba, Dept Surg, Sect Neurosurg, GB1-820 Sherbrook St, Winnipeg, MB, Canada
[6] McGill Univ, Montreal Neurol Inst & Hosp, Dept Neurol & Neurosurg, 3801 Univ Ave,Suite 109, Montreal, PQ, Canada
[7] King Abdulaziz Univ, Dept Surg, Div Neurosurg, Jeddah, Saudi Arabia
[8] Univ Sherbrooke, Dept Surg, Div Neurosurg, Sherbrooke, PQ, Canada
[9] McGill Univ, McGill Univ Hlth Ctr, Div Neurol & Neurosurg, Montreal, PQ, Canada
[10] Univ British Columbia, Dept Surg, Div Neurosurg, Vancouver, BC, Canada
[11] McGill Univ, Montreal Neurol Inst & Hosp, Neurol Intens Care Unit, Montreal, PQ, Canada