1. Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
2. Harvard Medical School, Massachusetts General Hospital, Spaulding Rehabilitation Hospital, and Boston VA Healthcare System
3. Department of Physical Medicine and Rehabilitation, Neuromuscular Section, University of California, Davis Medical School, Sacramento, CA, USA
4. Department of Physical Medicine and Rehabilitation St Luke’s Rehabilitation Institute, Spokane, WA, USA
5. Duke University School of Medicine, and Durham Veterans Affairs Medical Center, Durham, NC, USA