Vagus Nerve Stimulation in Patients in Comatose State

This prospective, single-center, open-label, single-arm pilot study enrolls a subcohort of comatose TBI patients from the parent SeeMe study (NCT07560631) whose legally authorized representative consents to a stimulation addendum. Dual-site transcutaneous auricular nerve stimulation is delivered to the left ear: the vagal site (cymba conchae) targets the auricular branch of the vagus nerve, and the trigeminal site (outer ear) targets the auriculotemporal branch - each with distinct, optimized parameters. Mechanistically, vagal afferents project to the nucleus tractus solitarius and the ascending reticular activating system to promote arousal, while trigeminal afferents project via the spinal trigeminal nucleus to thalamus and cortex to enhance thalamocortical connectivity; the dual-site paradigm aims to drive the cortico-striatal-thalamic-cortical loop from two convergent directions. Baseline assessment captures CRS-R, GCS, vital signs, NCS-R, heart-rate variability, and EEG. Daily one-hour sessions include pre/post vitals, NCS-R-guided titration, continuous telemetry, ear-site inspection, and daily CRS-R. In parallel, the SeeMe computer-vision platform quantifies stimulus-evoked facial and hand movements. The course runs 7 consecutive days, extendable to 28 days. Findings will inform a future sham-controlled randomized trial and closed-loop integration with SeeMe.

Inclusion criteria

• Age ≥ 18 years
• Coma, vegetative state/unresponsive wakefulness syndrome (VS/UWS), or minimally conscious state (MCS) as determined by baseline CRS-R
• Acute traumatic brain injury with documented intracranial pathology on neuroimaging
• Admission to the Neurology or Neurosurgical ICU
• Legally authorized representative (LAR) available and willing to consent, including the Stimulation Addendum Consent Form

Exclusion criteria

• Implanted cardiac pacemaker, vagus nerve stimulator, or other active implanted device
• Known cardiac arrhythmia (e.g., 2nd-/3rd-degree AV block, atrial fibrillation with uncontrolled rate)
• Active seizures not controlled by current antiepileptic regimen
• Skin breakdown, infection, or anatomical abnormality of the left ear precluding electrode placement
• Pregnancy
• Hemodynamic instability requiring vasopressor escalation at the time of enrollment