Paired Vagus Nerve Stimulation in Mobilization of Patients With Prolonged Disorders of Consciousness

T1: At baseline prior to initiating Phase 1, participants will be assessed using Coma Recovery Scale-Revised (CRS-R), Glasgow Coma Scale (GCS), and Glasgow Outcomes Scale- Extended (GOSE). Following this baseline assessment, participants will continue with 4 weeks of their current standard of care. During Phase 1, no study interventions will be implemented. At completion of T1, the CRS-R, GCS, and GOSE will be reassessed. Following Phase 1,

T2a: will be initiated immediately thereby and will entail a 4-week mobilization only phase. Participants will complete 8 sessions of physical therapy over 4 weeks, receiving progressive verticalization and mobilization using a robotic tilt table with robotic stepping (Erigo; Hocoma).

T2b: Immediately after 4 week mobilization only period, participants will complete 8 sessions of physical therapy over 4 weeks, receiving the paired taVNS + RTTM intervention. Upon completion of phase 2b, participants will be reassessed with CRS-R, GCS, and GOSE.

T3: Following the intervention period, participants will complete three additional study visits for assessment at 3-, 6-, and 12-months post intervention using the CRS-R, GOSE, and GCS. Across all study phases, secondary healthcare utilization, including re-admission rates, number of physicians follow up visits and emergency room visits, will be captured from the patient electronic medical record (EMR) and reported.

Inclusion criteria

• Patients with a diagnosis of pDOC (includes coma, VS/UWS, MCS, MCS +, MCS-) as defined as disorder of consciousness (DOC) greater than 6 weeks post onset
• Patients deemed medically safe to participate in physical therapy (PT) as evaluated by the study physicians.

Exclusion criteria

• Patients who have emerged from MCS (CRS-R score 6 on Motor Function scale and/or 2 on Communication Scale).
• Patients medically unsafe for participation in PT as indicated by one of the study physicians (including but not limited to those receiving intravenous sedation, those with integumentary breakdown or known pressure injuries, those with cardiovascular or cerebrovascular conditions precluding initiation of physical therapy [ie uncontrolled intracranial pressure, severe symptomatic orthostatic hypotension, etc.).
• Patients with DOC less than 6 weeks post onset will also be excluded.
• Patients who do not meet technical requirements of the RTTM device will be excluded

• weighing greater than 135 kg
• length of legs below 75 cm or above 100 cm,
• fixed contractures of lower extremity including hip, knee, ankle, or foot).
• Does not have an identified care partner or legally authorized representative to consent to participation