Improving the Efficacy of Sacral Nerve Stimulation for Fecal Incontinence by Alteration of Stimulation Parameters

• Number of incontinence episodes [ Time Frame: Will be assessed every four weeks durring a twenty-week period ] [ Designated as safety issue: No ]
  Assess number of incontinence episodes, by means of bowel habit diary. Four week bowel habit diary will be evaluated five times during the twenty-week protocol perioed.
• Days with faecal soiling [ Time Frame: Will be assessed every four weeks during a twenty-week period ] [ Designated as safety issue: No ]
  By means of a four week bowel habit diary
• Days with faecal urgency. [ Time Frame: Will be assessed every four weeks during a twelve-week period ] [ Designated as safety issue: No ]
  By means of a four week bowel habit diary
• Wexner incontinence score [ Time Frame: Will be assessed every four weeks during a twenty-week period ] [ Designated as safety issue: No ]
• St. Marks Incontinence score [ Time Frame: Will be assessed every four weeks during a twenty-week period ] [ Designated as safety issue: No ]
• Assess changes in anorectal volume and pressure with different pacemaker settings [ Time Frame: Will be assessed every four weeks during a twenty-week period ] [ Designated as safety issue: No ]
  Resting, maximal anal sphincter pressure and rectal filling(first sensation, urge to defacate and maximal tolerabel volume(Air))pressure will be measured with different pacemaker settings. In total five evaluations will be made in the twenty week protocol perioed.

Faecal incontinence is a devastating condition affecting 2,2 to 5 % of the adult population. The magnitude of the problem is probably underestimated. Sacral nerve stimulation (SNS), has over the last decade given hope to patient failing conservative treatment. Some patient do not have optimal continence after SNS-therapy. This study aims to identify optimal stimulation parameters - that will improve the functional outcome of SNS-therapy thru a double blinded randomized cross-over study.

Faecal incontinence is a devastating condition affecting daily living and has major influences on quality of life. Faecal incontinence affects 2,2 to 5 % of the adult population. The magnitude of the problem is probably underestimated, because most patients don't discuss this affliction with their general practitioner. A new treatment, SNS has over the last decade given new hope to these patients. But a group of these patients has minor effect of the treatment - despite a satisfactory test-stimulation period. This study aims to identify optimal stimulation parameters that will improve patient continence and quality of life. Four different stimulation parameters will be tested through a double blind, randomized crossover study - standard stimulation parameters (frequency: 14 Hz, pulse width 210 microsec.) will serve as control stimulation.

The study includes five arms that will be tested in a randomized order. Each arm will be tested for four weeks in which the patient fill in bowel habit diaries and standardized questionnaires. The first week in each period will not be evaluated - is serves as a wash-out period.

Before any pacemaker changes anorectal manometry and rectal filling tests will be performed.

• Active Comparator: Standard settings
  Amplitude: Sensory threshold Frequency:14 Hz Pulse width 210 μsec
  Intervention: Device: Medtronic InterStim / InterStim II
• Experimental: Experimental Setting 1
  Amplitude: Sensory threshold Frequency:6.9 Hz Pulse width 210 μsec
  Intervention: Device: Medtronic InterStim / InterStim II
• Experimental: Experimental setting 2
  Amplitude: Sensory threshold Frequency:31 Hz Pulse width 210 μsec
  Intervention: Device: Medtronic InterStim / InterStim II
• Experimental: Experimental setting 3
  Amplitude: Sensory threshold Frequency:14 Hz Pulse width 330 μsec
  Intervention: Device: Medtronic InterStim / InterStim II
• Experimental: Experimental setting 4
  Amplitude: Sensory threshold Frequency:14 Hz Pulse width 90 μsec
  Intervention: Device: Medtronic InterStim / InterStim II

Inclusion Criteria:

• Informed Consent
• Diagnosed with idiopathic faecal incontinence,incontinence with minor (≤60 degrees) sphincteric defects or incontinence following sphincter repair.
• Medtronic Interstim IPG(pacemaker)implanted for more than 6 months
• minimum one incontinence episodes pr. week during ongoing SNS-therapy

Exclusion Criteria:

• Colorectal surgery after IPG-implantation
• Pregnancy or breastfeeding
• Anal/perianal pain or discomfort
• Patients who are not deemed able to follow the planned testing program, including mental illness or mentally unstable patients
• Medication with known effects on gastrointestinal motility, thyroid disease, diabetes, coeliac, neurological disorders.
• Spinal cord injury
• Irritable Bowel Syndrome