1. Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada; Spinal Program, Krembil Neuroscience Center, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
2. Department of Surgery, Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada. 2Spinal Program, Krembil Neuroscience Center, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada