1 Case Western Reserve University, MetroHealth Rehabilitation Institute, 4229 Pearl Road, Cleveland, OH 44109, USA. Electronic address: jchae@metrohealth.org.
2 Departments of Physical Medicine and Rehabilitation, Neurology and Neuroscience, Johns Hopkins Hospital, Johns Hopkins University, 600 North Wolfe Street, Baltimore, MD 21287, USA. Electronic address: pcelnik@jhmi.edu.