Akshay Thaper1,2,3, Matthew E Miller1,2. 1. Department of Physical Medicine and Rehabilitation, Walter Reed National Military Medical Center, Bethesda, Maryland, USA. 2. Center for Rehabilitation Sciences Research, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA. 3. Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, USA.