Transcutaneous vagus nerve stimulation for postoperative pain reduction in patients with childhood trauma: A randomized controlled pilot study

BACKGROUND: Transcutaneous auricular vagus nerve stimulation (taVNS) is a promising non-pharmacological approach for postoperative pain management, but its interaction with childhood trauma (CT) remains unclear. This three-armed randomized controlled trial examined the analgesic efficacy of taVNS after surgery and whether CT influences pain severity, illness perceptions, and well-being. METHODS: 74 patients undergoing orthopedic or gynecological/obstetric surgery were allocated to active taVNS (VNS), sham stimulation (SHAM), or treatment as usual (TAU). Pain (SF-MPQ), well-being (WHO-5), illness perceptions (IPQ-R), and daily pain ratings were assessed at baseline (T0), discharge (T1), and three-month follow-up (T2). CT was measured using the short-form Childhood Trauma Questionnaire (CTQ-SF). ANCOVA and multilevel modeling evaluated treatment effects; correlational analyses examined associations between CT and outcomes. RESULTS: TaVNS was associated with short-term pain reductions after stimulation; however, these effects did not differ from sham stimulation. CT did not moderate analgesic effects but was strongly correlated with pain severity at T2 (ρ = 0.72) and moderately related with negative emotional illness representations. Emotional neglect correlated moderately with lower well-being at T2. Daily diary data showed reduced pain severity after stimulation across groups. No serious adverse events occurred. CONCLUSION: TaVNS showed immediate within-session pain reductions, which were not superior to sham stimulation. CT was strongly correlated with long-term pain severity and reduced well-being but did not alter responsiveness to taVNS. Future studies should investigate short-term effects and clarify clinical relevance compared to SHAM and TAU in larger samples, emphasizing standardized protocols and CT. TRIAL REGISTRATION NUMBER: DRKS00034812.