Sacral nerve stimulation (SNS) has become a well-established treatment for patients with fecal incontinence since 1995. The mechanism of action of SNS is still not fully understood but recent studies have shown changes in both colonic motility and rectal sensibility. We have previously shown IBS patients to benefit from sacral nerves stimulation. With the present study, we aim to evaluate if subsensory sacral nerve stimulation is as effective as suprasensory sacral nerve stimulation.

Twenty four patients with IBS-D or IBS-M according to the ROME III criteria, will be enrolled in the study.

Having meet inclusion criteria, the patients are randomised to receive either OFF-subsensory or subsensory-OFF stimulation in a 2+2-week period followed by 2 weeks of suprasensory stimulation. Hereby rendering a percutaneous nerve evaluation (PNE) test of a total of 6 weeks.

During the PNE test the effect of the stimulation is evaluated by specific IBS symptom and quality of life questionnaires (GSRS-IBS and IBS-IS) and bowel habit diaries.

Inclusion Criteria:

• Patients aged over 18
• Patients who are psychologically stable and suitable for intervention and able to provide informed consent.
• Patients who are diagnosed with IBS-D or IBS-M according to the Rome III criteria
• Minimum average of 40 points in the symptom quistionnaire evaluated at baseline

Exclusion Criteria:

• Overt bowel diseases including inflammatory bowel disease
• Pregnant or breast feeding
• Patients who are considered unable to follow the planned programme of the study, including mentally illness or physiological instability
• Patients who are on medication with known influence on gastrointestinal motility including those for thyroid disease, diabetes mellitus, celiac disease and neurological disease