1. Departments of Critical Care Medicine and Clinical Neurosciences, Hotchkiss Brain Institute, Foothills Medical Center, University of Calgary, Calgary, Alberta, Canada
2. Department of Neurology, University of Virginia, Charlottesville, Virginia
3. Department of Surgery, Division of Neurosurgery, University of Alberta, Calgary, Alberta, Canada
4. Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia
5. Rush Medical College, Rush University Medical Center, Chicago, Illinois
6. Departments of Neurology and Internal Medicine, University of Virginia, Charlottesville, Virginia