Trans Auricular Vagal Nerve Stimulation in Patients With IBS-C

June 17, 2026 updated by: Zain Sobani, West Virginia University

Randomized Controlled Trial Evaluating Trans Auricular Vagal Nerve Stimulation in Patients With Irritable Bowel Syndrome Constipation Subtype

This study evaluates the efficacy and safety of transcutaneous auricular vagus nerve stimulation (ta-VNS) in adults with constipation-predominant irritable bowel syndrome (IBS-C). Participants will be randomized to receive either active or sham stimulation using a non-invasive auricular device over a 60-day period.

The primary objectives are to assess changes in symptom severity and quality of life using validated instruments, including the IBS Symptom Severity Scale (IBS-SSS) and the IBS Quality of Life questionnaire (IBS-QOL). Secondary assessments include safety and participant compliance.

This study aims to determine whether ta-VNS is an effective non-invasive therapeutic modality for improving symptoms and quality of life in patients with IBS-C.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

80

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • West Virginia
      • Morgantown, West Virginia, United States, 26506
        • West Virginia University- Gastroenterology and Hepatology
        • Contact:
        • Principal Investigator:
          • Zain Sobani, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Referred to the WVU Department of Gastroenterology and Hepatology
  • Diagnosis of IBS-C

Exclusion Criteria:

  • Failure of second-line therapy with secretagogues (linaclotide, lubiprostone, plecanatide, or tenapanor)
  • Failure of third-line therapy with tegaserod
  • Known debilitating psychiatric illness
  • Cognitive impairment
  • Pregnancy
  • Prisoners
  • Active substance use disorder
  • Concurrent opioid use
  • History of major gastrointestinal surgery resulting in luminal alteration
  • History of vagotomy
  • Secondary causes of constipation (e.g., opioid use, uncontrolled hypothyroidism, celiac disease)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Transcutaneous Auricular Vagus Nerve Stimulation (ta-VNS)
Participants will receive active transcutaneous auricular vagus nerve stimulation (ta-VNS) using the Parasym device (Parasym Health, Inc., London, UK). The device delivers electrical stimulation to the auricular branch of the vagus nerve via an ear clip. Stimulation will be administered once daily for 30 minutes over 60 days at a consistent time chosen by the participant. Stimulation parameters are set at 25 Hz and 250 microseconds, with intensity adjusted to just below the participant's discomfort threshold (0-36 mA).
Device: Transcutaneous Auricular Vagus Nerve Stimulation (ta-VNS)
Delivery of non-invasive electrical stimulation to the auricular branch of the vagus nerve using the Parasym device. Stimulation is applied via an ear clip at 25 Hz and 250 microseconds, with intensity titrated to just below discomfort (0-36 mA). Administered for 30 minutes daily over 60 days.
Sham Comparator: Sham Transcutaneous Auricular Vagus Nerve Stimulation
Participants will receive sham stimulation using an identical-appearing Parasym device. The device delivers a brief, low-level electrical output at the start of each session, which ramps down to zero and provides no stimulation for the remainder of the session. Sessions will last 30 minutes daily for 60 days at a consistent time of the participant's choosing. The device will look, feel, and sound identical to the active device to maintain blinding.
Device: Sham Transcutaneous Auricular Vagus Nerve Stimulation
Use of a sham Parasym device that mimics active stimulation but delivers only a brief, low-level output at session onset before ramping down to zero for the remainder of the 30-minute session. Administered daily for 60 days to maintain participant blinding.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change From Baseline in IBS Symptom Severity Scale (IBS-SSS) Score at Day 60
Time Frame: Baseline to Day 60
Evaluate the effect of transcutaneous auricular vagus nerve stimulation (ta-VNS) on symptom severity in patients with IBS-C using the IBS Symptom Severity Scale (IBS-SSS). The IBS-SSS assesses abdominal pain severity and frequency, abdominal distension, bowel habit satisfaction, and interference with quality of life. Scores range from 0 to 500, with higher scores indicating more severe symptoms (≤75 remission, 75-174 mild, 175-299 moderate, 300-500 severe). The outcome measure is defined as the change in IBS-SSS score from baseline to Day 60.
Baseline to Day 60
Change From Baseline in IBS Quality of Life (IBS-QOL) Total Score at Day 60
Time Frame: Baseline to Day 60
Evaluate the impact of ta-VNS on quality of life in patients with IBS-C using the IBS Quality of Life (IBS-QOL) questionnaire. The IBS-QOL is a 34-item validated instrument scored on a 5-point Likert scale and converted into a total score ranging from 0 to 100, with higher scores indicating better quality of life. The outcome measure is defined as the change in IBS-QOL total score from baseline to Day 60.
Baseline to Day 60

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of Adverse Events
Time Frame: Baseline through Day 60
Evaluate the safety of ta-VNS in patients with IBS-C by assessing the incidence of adverse events during the 60-day intervention period.
Baseline through Day 60
Participant Compliance With ta-VNS Intervention
Time Frame: Baseline to Day 60
Assess participant compliance with the ta-VNS intervention by measuring the number of days the device was used according to the study protocol over the 60-day intervention period.
Baseline to Day 60
Change From Baseline in IBS Quality of Life (IBS-QOL) Domain Scores at Day 60
Time Frame: Baseline to Day 60
Evaluate the impact of transcutaneous auricular vagus nerve stimulation (ta-VNS) in patients with IBS-C using the IBS Quality of Life (IBS-QOL) questionnaire domain scores. The IBS-QOL is a validated instrument that includes the following domains: dysphoria, interference with activity, body image, health worry, food avoidance, social reaction, and relationships. Each domain score is transformed to a 0 to 100 scale, with higher scores indicating better quality of life. The outcome measure is defined as the change in each domain score from baseline to Day 60.
Baseline to Day 60

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

West Virginia University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2026

Primary Completion (Estimated)

May 1, 2027

Study Completion (Estimated)

July 1, 2027

Study Registration Dates

First Submitted

June 17, 2026

First Submitted That Met QC Criteria

June 17, 2026

First Posted (Actual)

June 23, 2026

Study Record Updates

Last Update Posted (Actual)

June 23, 2026

Last Update Submitted That Met QC Criteria

June 17, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STUDY00000105

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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