Optimization of Transcutaneous Electrical Acustimulation (TEA) Modalities for Treatment of IBS-C

This study aims to determine the most effective treatment with Transcutaneous Electrical Acustimulation (TEA) for Irritable Bowel Syndrome with Constipation (IBS-C) by comparing efficacy between 5 separate sessions. The rectum pressure as measured by a device called a barostat will be compared between visits. Each session will be testing a different combination of frequency and body position of the electrodes. Electrodes placed at either the wrist or knee will be stimulated at either 25 Hz or 100 Hz.

This study aims to discern whether acute, single-session Transcutaneous Electrical Acustimulation (TEA) at acupuncture points ST36 or PC6 will relieve abdominal pain induced by rectal distension in patients with IBS-C. Each study participant will have 5 research visits at the Michigan Medicine GI physiology lab. During these visits, participants will undergo a procedure similar to Anal Rectal Manometry (ARM) performed by the GI physiology lab staff. TEA is similar to this procedure as it uses the barostat device and is performed by the GI physiology lab staff. This device has a rubber catheter that will be inserted 5-15 cm into the rectum of the study participant. Then the GI physiology staff will inflate the catheter. Study participants will then be asked when they can sense the catheter. Then the GI physiology staff will continue to inflate the catheter and the study participants feel discomfort (described as the 'urge to defecate'). Then the study participant will be asked to pass the balloon (like they would pass a bowel movement).

The difference between ARM procedure and the study procedure is that there will be stimulation of acupuncture point ST36 which is below the knee cap or stimulation of acupuncture point PC6 which is just above the wrist. For this study, this mild electrical stimulation will occur simultaneously with the barostat procedure.

At each visit there will be stimulation of only one of the points at either 100Hz or 25Hz. These are the potential combinations: ST36 100Hz, ST36-25Hz, PC6-100Hz, PC6-25Hz, Sham-TEA.

The frequency and position combination (or sham visit) is randomly assigned. The randomization determines the order in which the study participant moves through the study. Every study participant will, in the end, complete one visit at each frequency and a sham visit. The study participant will also complete surveys at the appointment.

The TEA device is classified by the FDA as a non-significant risk device.

Eligibility Criteria:
Inclusion Criteria:

* Willing to comply with all study procedures and be available for the duration of the study
* Diagnosed with IBS-C satisfying Rome IV criteria
* Have symptoms present for at least the last 3 months
* Have abdominal pain that is not adequately relieved at the time of screening and the time of randomization
* Has a Visual Analog Scale (VAS) pain score of \>3 (on 0-10 score)

Exclusion Criteria:

* Have an unrelated active disorder which may involve abdominal pain, such as inflammatory bowel disease, diabetes, unstable thyroid disease
* Have history of abdominal surgery (other than cholecystectomy or appendectomy)
* Are taking anticoagulants or antispasmodic, antidiarrheal, or opioids or other pain relief medications and cannot stop these medications for three consecutive days before each study visit
* Are pregnant or lactating; women of child bearing potential complete a pregnancy test at each visit
* Have known allergic reactions to components of the ECG electrodes
* Received treatment with an investigational drug or other intervention within 6 months of the date of consent
* Anything that, in the opinion of the investigator, would place the study participant at increased risk or preclude the study participant's full compliance with or completion of the study
* Are unable to provide informed consent