1. Rick Hansen Institute, Vancouver, British Columbia, Canada.
2. Service de Neurochirurgie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
3. Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada.
4. Dalhousie University, Halifax, Nova Scotia; Horizon Health Network, Division of Neurosurgery, Saint John Regional Hospital, Saint John, New Brunswick, Canada.