[1] Univ Laval, Dept Rehabil, Fac Med, Quebec City, PQ G1V 2M2, Canada
[2] Carleton Univ, Sport Med Ctr, Ottawa, ON K1S 5B6, Canada
[3] Toronto Western Hosp, Div Neurosurg, Toronto, ON M5T 2S8, Canada
[4] Univ Toronto, Toronto, ON, Canada
[5] Toronto Western Hosp, Canadian Sports Concuss Project, Toronto, ON M5T 2S8, Canada
[6] Canadian Med Assoc, Dept Publ Hlth, Ottawa, ON, Canada
[7] Univ Western Ontario, Dept Family Med, Schulich Sch Med & Dent, London, ON, Canada