The Application of Electrical Stimulation in Postoperative Pain Management of Thyroid Surgery

Transcutaneous Electrical Nerve Stimulation Based on Wrist-Ankle Acupuncture Theory for Postoperative Pain After Thyroid Surgery: A Multicenter Randomized Clinical Trial

Post-thyroidectomy pain is a prevalent early postoperative complication. While pharmacological agents remain the mainstay of analgesia, their clinical application is constrained by adverse effects including nausea, respiratory depression, and gastrointestinal disturbances. Transcutaneous electrical nerve stimulation based on wrist-ankle acupuncture theory (TENS-WAA) is a non-invasive analgesic modality that has demonstrated preliminary benefits in multiple pain scenarios. Nevertheless, robust evidence for its efficacy in post-thyroidectomy pain management is still lacking, limited by single-center designs and small sample sizes in existing studies.

This trial aims to evaluate the efficacy and safety of TENS-WAA for pain control after thyroidectomy. The findings are expected to support a standardized non-pharmacological analgesic option as an adjunct to multimodal postoperative pain regimens, aligning with Enhanced Recovery After Surgery (ERAS) principles.

Background Post-thyroidectomy pain is a prevalent early complication stemming from incision trauma, tissue retraction and cervical muscle spasm, which impairs early functional recovery and reduces patient satisfaction. Opioids and non-steroidal anti-inflammatory drugs remain the mainstay of postoperative analgesia, but their clinical value is limited by suboptimal pain control, well-recognized adverse effects (nausea, respiratory depression, constipation, bleeding and renal risks), and marked inter-individual variability in therapeutic response. Aligned with Enhanced Recovery After Surgery (ERAS) principles, multimodal analgesia integrating pharmacological and non-pharmacological strategies is increasingly recommended. However, no standardized non-pharmacological analgesic protocol exists for post-thyroidectomy pain. Transcutaneous electrical nerve stimulation based on wrist-ankle acupuncture theory (TENS-WAA) is a non-invasive, self-administrable analgesic approach. Preliminary evidence supports its efficacy across multiple pain conditions, potentially via modulating pain-related brain regions and promoting endogenous opioid release. Current evidence in thyroidectomy populations is limited by single-center designs, small samples and protocol heterogeneity, requiring high-quality multicenter randomized controlled trials for validation.

Study Objectives To evaluate the efficacy of TENS-WAA in reducing post-thyroidectomy pain intensity compared with sham stimulation.

Study Design This is a prospective, multicentre, randomised, open-label, assessor-blinded, parallel-group superiority controlled trial, conducted across three tertiary hospitals in China. A total of 668 patients scheduled for elective conventional thyroidectomy will be enrolled. Eligible participants will be stratified by surgery type (unilateral thyroidectomy vs. bilateral thyroidectomy), and randomised in a 1:1 ratio to either the active TENS-WAA group or the sham stimulation group via stratified block randomisation. Random allocation will be implemented through a central web-based randomisation system to ensure allocation concealment. Given the perceptible nature of electrical stimulation, participants and intervention administrators will not be blinded to group assignment. However, outcome assessors responsible for pain scoring, data collection and biosample processing, as well as the study statistician, will remain blinded to group allocation throughout the trial. All primary efficacy analyses will follow the intention-to-treat (ITT) principle. The recruitment period is scheduled from May 2025 to December 2026.

Intervention Description All participants will receive standard postoperative care in accordance with each institution's routine clinical protocols. The study intervention will be delivered at three postoperative time points: immediately upon returning to the ward, and 2 hours and 4 hours after returning to the ward, with each stimulation session lasting 30 minutes.

Primary Outcome Pain intensity measured by the 10-cm Visual Analogue Scale (VAS), where 0 represents "no pain" and 10 represents "the worst pain imaginable". VAS assessments will be conducted at multiple time points: upon awakening from anaesthesia, immediately after each stimulation session, and at 3, 9, 15, and 24 hours after surgery. Longitudinal VAS data will be analysed using generalized estimating equations, adjusted for baseline VAS score, age, sex and surgery type.

1. Inclusion Criteria:

   • Be over 18 years of age;
   • The operation time is less than 4 hours;
   • Postoperative VAS pain score ≥3 points ;
   • Clear consciousness, able to answer questions accurately, free speech, no hearing impairment;
   • Informed consent

2. Exclusion Criteria:

   • Neck or thyroid surgery within the past ten years;
   • Menstruating, pregnant and lactating females;Those who are not satisfied with blood glucose control;
   • Skin injury or allergy; skin ulceration;
   • Past history of psychiatric disorder that met the diagnostic criteria of Diagnostic and Manual of Mental Disorders, DSM-IV;
   • Upper respiratory tract infection within 2 weeks before surgery;
   • History of implantation of pace or defibrillator;
   • Allergic to gel or intolerant to electrical stimulation;
   • History of chronic pain, pain VAS score 1 at the examination;
   • Use of sedative analgesic drugs for a long time or within 24 hours;
   • Particip in other clinical trials in the past 4 weeks.