1. Traumatic Brain Injury Program, McGill University Health Centre (Montreal General Hospital), Montreal, QC, Canada H3G 1A4
2. Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada H3A 0G4
3. Social and Preventive Medicine Department, University of Montreal, Montreal, QC, Canada H3C 3J7
4. Department of Neurosurgery, University at Buffalo, The State University of New York, Buffalo, NY 14260-1660, USA