Transcutaneous Auricular Vagus Nerve Stimulation Added to Rehabilitation for Complex Regional Pain Syndrome Type I

Complex regional pain syndrome type I is a disabling condition that may develop aftertrauma, fracture, surgery, or immobilization. It is characterized by pain that isdisproportionate to the initial injury and may be accompanied by sensory, autonomic,motor, edema, and trophic abnormalities. Despite multidisciplinary rehabilitation andpharmacological treatment, some patients continue to experience persistent pain andfunctional impairment.Transcutaneous auricular vagus nerve stimulation is a non‐invasive neuromodulation methodthat stimulates auricular regions innervated by the vagus nerve. It may affect painprocessing, autonomic nervous system regulation, central sensitization, andneuroinflammatory mechanisms that may contribute to CRPS‐I. Evidence regarding theclinical effectiveness of taVNS in this patient population remains limited.The primary objective of this study is to determine whether active taVNS added tostandard rehabilitation provides greater pain reduction than sham taVNS added to the samerehabilitation program. Secondary objectives are to compare the effects of theinterventions on CRPS clinical severity, edema‐related hand and wrist circumferencemeasurements, hand function, activities of daily living, health‐related quality of life,anxiety and depression symptoms, and perceived stress.Participants will be randomly allocated in a 1:1 ratio to standard rehabilitation plusactive taVNS or standard rehabilitation plus sham taVNS. Both groups will receive anidentical 4‐week rehabilitation program. Active and sham stimulation will be deliveredwith the same session duration and frequency. Participants and the outcomes assessor willbe blinded to group allocation. The physiotherapist administering the stimulation will beaware of the allocation and will not participate in outcome assessments. Treatmenteffects and their persistence will be evaluated at weeks 4, 8, and 12.