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Sacral nerve stimulation for faecal incontinence in adults

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effects of sacral nerve stimulation using implanted eletrodes for the treatment of faecal incontinence in adults.

Background

Faecal incontinence is a socially embarrassing and physically disabling condition. It may be defined as the uncontrolled loss of faeces (liquid or solid) from the bowel. It may occur passively (without the person affected being aware of passing faeces) or be preceded by urgency ‐ a sense of an urgent need to defaecate. Faecal incontinence may result from damage to the anal sphincter mechanism (either from direct trauma or damage to its nerve supply), idiopathic degeneration of the sphincter, spinal injury or other neurological causes.

Those affected usually resort to containment using absorbent pads or anal plugs but these are often unsatisfactory. Clinical treatment is conservative in the first instance, including dietary advice, antidiarrhoeal medication and physical and behavioural therapy, for example pelvic floor muscle training and biofeedback (Cheetham 2001; Norton 2000; Norton 2003). A proportion of patients will remain resistant to these forms of treatment. With up to 10% of the adult population being affected by some degree of faecal incontinence a considerable number of people potentially require further treatment (Drossman 1993; Giebel 1998; Nelson 1998).

Surgical intervention has been the next step in the management of these patients. For external anal sphincter defects, overlapping sphincter repair may be undertaken. Early results show good symptomatic relief, but tend to deteriorate with time (Malouf 2000). Dynamic graciloplasty and artificial bowel sphincter implants may be attempted to improve continence, but require major surgery and have high morbidity and failure rates (Baeten 2000; Lehur 1998). Permanent stoma (colostomy or ileostomy) is another surgical option.

For people who do not respond to conservative treatments, sacral nerve stimulation (SNS) is a minimally invasive technique that should avoid the risks and morbidity associated with other types of surgery but might carry other risks. It allows modulation of the nerves and muscles of the pelvic floor and hindgut with potential beneficial effects, although the mechanism of its action is unclear.

SNS involves applying a low amplitude electrical current to a sacral nerve via an electrode placed through its corresponding sacral foramen. SNS has the advantage that it is possible to test each patient, over a two to three week period, with a percutaneous electrode attached to an external stimulator. If a significant benefit is achieved, implantation of the definitive implanted pulse generator (IPG) can then be carried out. Furthermore, the device can be removed if necessary, for example if complications occur. SNS using low amplitude electrical current for the treatment of faecal incontinence is a recent, innovative technique and a systematic review is needed to summarise the available evidence on its effects.

Objectives

To assess the effects of sacral nerve stimulation using implanted eletrodes for the treatment of faecal incontinence in adults.

Methods

Criteria for considering studies for this review

Types of studies

Randomised or quasi randomised trials.

Types of participants

Adults with faecal incontinence.

If the evidence allows, we will undertake sub‐group analysis on the following categories of patients.
(1) Patients with faecal urgency.
(2) Patients with structural defects of the anal sphincter.
(3) Patients with partial spinal cord injury.
(4) Patients with central neurological disease.

Types of interventions

One arm of the study must use a surgically implanted device to provide sacral nerve stimulation.

Comparators will include mock, sham or placebo treatment and any alternative intervention considered appropriate by the trialists, such as dynamic graciloplasty, artificial bowel sphincter implants, colostomy, absorbent pads, anal plugs and physical or behavioural therapies.

Magnetic and transcutaneous stimulation will not be considered.

Types of outcome measures

The primary outcomes for the review are (a) cure or improvement of incontinence and (b) quality of life. Outcomes will be considered in the following six categories.
(1) Faecal incontinence (number cured or improved, episodes of faecal incontinence, urgency, ability to defer defaecation, use of pads, use of anal plugs, incontinence score, and need for further treatment such as medication or surgery).
(2) Quality of life (generic and condition‐specific).
(3) Surrogate measures, such as anorectal manometry (resting pressure, maximum squeeze pressure, rectal sensory threshold to balloon distention, sensation of urgency to balloon distention and maximum tolerated rectal volume to balloon distention).
(4) Adverse effects (infection and/or pain at the implantation site, displacement of the electrodes, technical failure requiring removal and/or change in urinary function).
(5) Health economics (costs, resource implications and cost‐effectiveness or cost utility evaluation).
(6) Other outcomes (other outcome measures quoted by authors and judged to be important by the reviewers).

Search methods for identification of studies

This review will draw on the search strategy developed for the Incontinence Group as a whole. Relevant trials will be primarily identified from the Cochrane Incontinence Group trials register. The methods used to derive this, including the search strategy, are described under the Group's details in The Cochrane Library. The register contains trials identified from MEDLINE, CINAHL and the Cochrane Central Register of Controlled Trials (CENTRAL) and hand searching of journals and conference proceedings. Additionally all reference lists of identified trials will be searched. No language or other limitations will be imposed.

Data collection and analysis

Two reviewers will independently evaluate reports of all potentially eligible studies for inclusion, and independently assess the methodological quality of the included studies using the Cochrane Incontinence Group's assessment criteria. Studies will not be excluded from the review on the basis of methodological quality.

Two reviewers will independently undertake data extraction. We will seek clarification from the trialists where data are collected but not reported, or reported in a form unsuitable for the review. Included data will be processed as described in the Cochrane Reviewers' Handbook (http://www.cochrane.org/cochrane/hbook.htm). When data are combined, fixed effects methods will be applied, with relative risk or weighted mean differences used where appropriate.

If visual inspection or the chi squared test for heterogeneity suggest heterogeneity at the 10% level then we will seek an explanation for this. If the level of heterogeneity is serious enough to affect the validity of the results then consideration will be given to using a random effects method. Alternatively, data from the included studies will not be combined and we will instead present a qualitative synthesis of the results of the primary studies. Sensitivity analysis will be considered to test the effects of including studies of poor methodological quality, if appropriate.

Any disagreements will be resolved by discussion or arbitration by a third person.