1 Department of Anesthesia and Pain Management and Institute of Health Policy Management and Evaluation, University of Toronto, University Health Network-Toronto Western Hospital, Toronto, Ontario, Canada, [email protected] Departments of Anesthesiology and Critical Care Medicine, Neurology, and Physical Medicine and Rehabilitation, Johns Hopkins School of Medicine, Baltimore, Maryland Departments of Anesthesiology and Physical Medicine and Rehabilitation, Walter Reed National Military Medical Center, Bethesda, Maryland.