Walking With Overground Robotic Exoskeleton Device to Increase Behavioral Responsiveness in Patients With Disorders of Consciousness (WALK DOC)

The goal of this observational study is to learn whether walking with an overground robotic exoskeleton (ORE) can improve responsiveness and brain activity in adults with disorders of consciousness (DoC) during inpatient rehabilitation after a severe brain injury. Participants include adults ages 18-70 who are in a coma, unresponsive wakefulness syndrome, or minimally conscious state and are receiving rehabilitation care at Spaulding Rehabilitation Hospital. The main questions it aims to answer are: * Does using an ORE improve behavioral responsiveness compared with lying down, sitting, or standing? * Does using an ORE increase brain activity, and are changes in brain activity related to changes in responsiveness? * Is ORE therapy safe, tolerable, and feasible for people with DoC during inpatient rehabilitation? Researchers will compare participants' responses during sessions involving lying down, sitting, standing, and walking with the robotic exoskeleton to see if the exoskeleton leads to greater improvements in responsiveness and brain activity. Participants will: * Complete an initial screening session to determine whether they can safely use the robotic exoskeleton. * Participate in six study sessions over about two weeks during their rehabilitation stay. During these sessions, participants will complete activities that may include lying down, sitting, standing, and walking with a robotic exoskeleton. The order of activities will be assigned at random. * Have their level of responsiveness measured before and after each session using a standardized assessment called the Coma Recovery Scale-Revised (CRS-R). * Wear a wireless EEG cap before, during, and after sessions so researchers can measure brain activity. * Have their heart rate and safety monitored throughout the study sessions.