Effect of taVNS on Abdominal Pain and Other Symptoms in Constipation-predominant Irritable Bowel Syndrome

The Efficacy and Mechanisms of Transcutaneous Auricular Vagus Nerve Stimulation on Abdominal Pain and Other Symptoms in Patients With Constipation-predominant Irritable Bowel Syndrome

This study aims to investigate the effects and possible mechanisms of transcutaneous auricular vagal nerve stimulation (taVNS) on abdominal pain and other symptoms in patients with IBS-C.

This study is designed as an early-feasibility, single-center, single-blinded, randomized controlled trial (RCT), in which subjects are consented, undergo a baseline assessment, and receive taVNS or sham-taVNS treatment twice a day (8 a.m. and 8 p.m.) for 30 minutes each time for a period of 4 weeks. The taVNS and sham-taVNS treatment was applied using the commercially-available Transcutaneous Electrical Applicator device (Model SNM-FDC01, Ningbo MedKinetic Medical Device Co., Ltd.) with the skin electrodes placed bilaterally on auricular concha. The patients are requested to score the abdominal pain (using VAS) and complete BSFS, IBS-SSS, IBS-QOL, SAS, and SDS forms every week and fill out the bowel diary during taVNS or sham-taVNS. Emergency medications (Macrogol 4000 and pinaverium) are permitted for use when the patient cannot tolerate symptoms of constipation and abdominal pain.

Inclusion Criteria:

1. willing to sign a written informed consent form
2. met the Rome IV diagnostic criteria for IBS-C

Exclusion Criteria:

1. history of previous abdominal surgery (other than appendectomy)
2. presence of carcinoma
3. any organic diseases causing constipation or neurologic diseases such as multiple sclerosis, rachischisis, Parkinson's disease, or spinal cord injury
4. taking antidepressant agents including tricyclic antidepressants and selective serotonin reuptake inhibitors
5. serious concomitant disease of the heart, liver, kidney, or diabetes
6. pregnancy or lactation
7. participating in another trial or enrolled in a trial during the past month
8. allergic reaction to surface electrodes