Perioperative transcutaneous auricular vagus nerve stimulation and EEG biomarkers of sleep improvement after gynecologic laparoscopy: protocol for a randomized controlled trial.

Background: Postoperative sleep disturbance (POSD) affects up to 62% of patients undergoing gynecologic laparoscopy and is associated with prolonged recovery, chronic pain, and cardiovascular complications. Transcutaneous auricular vagus nerve stimulation (taVNS) modulates thalamocortical oscillations through afferent vagal pathways, offering a potential non-pharmacological mechanism to prevent acute sleep disruption during critical perioperative neuroplastic windows. This study aims to evaluate whether perioperative dual-session taVNS reduces the incidence of clinically significant POSD compared with sham stimulation. Methods: This single-center, randomized, double-blind, sham-controlled trial is planned to enroll 116 patients aged 18-65 years scheduled for elective gynecologic laparoscopy. Participants will be allocated 1:1 to active taVNS or sham stimulation using permuted block randomization with concealed allocation. Blinding is maintained for participants, anesthesia providers, surgeons, postoperative ward staff, outcome assessors, and data analysts. Active taVNS will be applied to the left cymba conchae (20 Hz, 250 μs) in two sessions: 30 min before anesthesia induction and 5 min after extubation. The sham stimulation current amplitude will be incrementally increased until the participant perceives a tingling sensation; the current will then be immediately discontinued. Each session will last 30 min with continuous frontal electroencephalography (EEG) monitoring (0.5-45 Hz) at six timepoints. The primary endpoint is the incidence of POSD on postoperative day 1 (AIS score ≥ 6). Secondary endpoints include sleep quality trajectory (AIS, actigraphy), anxiety and depression (HADS), recovery quality (QoR-15), and exploratory EEG spectral analyses. Discussion: This trial is the first to introduce a perioperative dual-session taVNS protocol integrated with continuous EEG monitoring, investigating its preventive effects on acute POSD in gynecologic laparoscopic patients through a comprehensive set of mechanistic and clinical endpoints. Comprehensive multidimensional assessment combines subjective, objective, and mechanistic (EEG spectral analysis) measures. If proven effective, taVNS could offer a safe and cost-effective non-pharmacological adjunctive therapy for managing POSD in the perioperative setting. Furthermore, the findings have the potential to elucidate how perioperative cortical oscillatory dynamics regulate postoperative sleep quality, offering mechanistic insights for future neuromodulation interventions. Clinical trial registration: http://www.chictr.org.cn, identifier ChiCTR2600120222.