Sacral Nerve Stimulation for Faecal Incontinence - Placebo or Clinical Effective (SNS)

Sacral Nerve Stimulation for Faecal Incontinence - Placebo or Clinical Effective: A Randomized Blinded Study

Sacral nerve stimulation (SNS) has over the last 20 years been recognised as an efficient treatment option for faecal incontinence (FI). In a selected patient group we have evidence that 90% of patients will have a successful test period (≥50% reduction in incontinence episodes). If preoperative there is motor response on at least 3 out of 4 poles on the lead, at a threshold ≤1.5 mAMP. Hypotheses In a selected patient group suffering from faecal incontinence a one-stage permanent implant will be possible. The functional results will be improved as more time can be spent finding the optimal pacemaker settings as the risk of infection is reduced compared to the stage implant. One-Stage implantation gives the opportunity to test the amount of placebo effect with SNS. During the first 3 months postoperative patients will be randomized to either stimulation amplitude set at 90% of sensory threshold (control group) or 3 periods of stimulation at 0.05v (placebo), 50% and 90% of sensory threshold. Patients are randomized in a 1 to 2 pattern. After the initial 3 months the stimulation amplitude is increased to sensory threshold. After six months the project ends and the number of patients achieving the 50% improvement in incontinence episodes are evaluated.

Sacral nerve stimulation (SNS) has over the last 20 years been recognised as an efficient treatment option for faecal incontinence (FI). The therapy is recommended by the International Continence Society (ICS) if conservative treatments such as; regulation of diet and fibre supplements, medication, biofeedback therapy, glycerol suppositories, mini enema or transanal irrigation have been insufficient to improve continence to a satisfactory level. The SNS therapy has traditionally been applied as a two step procedure. Firstly, a 3-4 week test-period, often with a permanent electrode with tines, followed by permanent implantation if at least a 50% symptom reduction has been obtained during the test stimulation. In a selected patient group(idiopathic faecal incontinence or incontinence as a result of an external anal sphincter tear (<160 degrees)) we have evidence that 90% of patients will have a successful test period (≥50% reduction in incontinence episodes). If preoperative there is motor response on at least 3 out of 4 poles on the lead, at a threshold ≤1.5 mAMP(unpublished data, submitted for publication) . Thus, only 10% of the patients have the lead explanted after 3 to 4 weeks. In 90% of the patients a pacemaker is implanted after the test period, these patients will have an additional operation that could have been avoided if they had the permanent pacemaker implanted at the first stage. Hypotheses In a selected patient group suffering from faecal incontinence a one-stage permanent implant will be possible. The functional results will be improved as more time can be spent finding the optimal pacemaker settings as the risk of infection is reduced compared to the stage implant. One-Stage implantation gives the opportunity to test the amount of placebo effect with SNS. During the first 3 months postoperative patients will be randomized to either stimulation amplitude set at 90% of sensory threshold (control group) or 3 periods of stimulation at 0.05v (placebo), 50% and 90% of sensory threshold. Patients are randomized in a 1 to 2 pattern. After the initial 3 months the stimulation amplitude is increased to sensory threshold. After six months the project ends and the number of patients achieving the 50% improvement in incontinence episodes are evaluated.

Patients will be randomized to either control group (Stimulation amplitude at 90% of sensory threshold) or intervention arm (different stimulation amplitude - 0.05 V, 50 and 90% of sensory threshold)

Alle patients are stimulated sub-sensory in (3x4 weeks) and will be blinded. The investigators will not participate in the randomization, and setting of the stimulation amplitude.

Alternation of stimulation amplitude Period - Stimulation amplitude 0.05 Volts (lowest possible) Period - Stimulation amplitude - 50% of sensory threshold. Period - Stimulation amplitude - 90% of sensory threshold.

Change in number of incontinence episodes(Bowel Habit diary - ≥50% reduction in fecal incontinence episodes), compared to baseline.

Change in number of incontinence episodes(Bowel Habit diary - ≥50% reduction in fecal incontinence episodes), compared to baseline.

Change in number of incontinence episodes(Bowel Habit diary - ≥50% reduction in fecal incontinence episodes), compared to baseline.

VAS-score (0-100) for patients satisfaction with overall: Social function Bowel function Quality of life Baseline value used as reference

Functional Lumen Imaging Probe (endoFLIP) and anal sensibility. The endoFLIP allows dynamic examination of the geometry and segmental distensibility properties of the anal canal by simultaneous measurement of anal pressure(PSI) and luminal cross sectional areas (CSAs) at 16 points along the length of the anal canal

Inclusion Criteria: ≥18 years Informed consent Idiopathic faecal incontinence or incontinence following external sphincter tear ≤ 160 degrees. ≥ one faecal incontinence episode after optimized conservative treatment. Ability to use the patient programmer. Exclusion Criteria: Pregnancy Diabetes Neurological diseases, including spinal cord injuries Pelvic irradiation Rectal resections

All participants in the study group have access to the data and if agreed in the study group sub-analysis can be made after the trial has ended.