Anal acoustic reflectometry predicts the outcome of percutaneous nerve evaluation for faecal incontinence.

BACKGROUND: Sacral nerve stimulation (SNS) is effective for some patients with faecal incontinence. Before insertion of a costly implant, percutaneous nerve evaluation (PNE) is undertaken to identify patients likely to report success from SNS. The aim of this study was to determine whether variables of anal sphincter function measured by anal acoustic reflectometry (AAR) could predict the outcome of PNE for faecal incontinence. METHODS: Women with faecal incontinence undergoing PNE were recruited. AAR, followed by anal manometry, was performed on the day of surgery, immediately before PNE. The outcome of PNE was determined by bowel diary results and incontinence severity score. Patients with a successful PNE outcome were compared with those with an unsuccessful outcome; logistic regression analysis was used to identify any independent predictors of success. RESULTS: Fifty-two patients were recruited, of whom 32 (62 per cent) had a successful PNE outcome and 20 (38 per cent) an unsuccessful outcome. The AAR variable opening pressure was significantly greater in patients who subsequently had a successful PNE result compared with the pressure in patients who did not (28 versus 17 cmH2 O; P = 0·008). No difference was seen in the manometric equivalent, maximum resting pressure. Opening pressure was an independent predictor of success with an odds ratio of 1·08 (95 per cent confidence interval 1·01 to 1·16; P = 0·018). CONCLUSION: AAR is a sensitive test of sphincter function and can identify differences between patients who respond to PNE and those who do not. Opening pressure is an independent predictor of success in PNE, and may be of value in the selection of patients for this expensive treatment option.

Insertion under local anaesthetic of temporary electrodes for sacral nerve stimulation testing is reliable and cost effective.

AIM: The aim of this study was to determine whether temporary electrode implantation under local anaesthesia (LA), with reliance on sensory response rather than motor response, gives as good a result as implantation under general anaesthesia (GA). METHOD: A retrospective review of a prospectively maintained database of patients with faecal incontinence treated with sacral nerve stimulation (SNS) was performed. RESULTS: A total of 111 consecutive patients underwent a 2-week trial of SNS. Forty-seven (42%) had the temporary electrode implanted under LA and 64 (58%) under GA. There was no significant difference between the two groups in relation to the improvement in Vaizey score (P = 0.15), incontinent episodes per day (P = 0.73) and incontinent episodes per week (P = 0.93). There was no significant difference (P = 0.14) in the percentage of successful trials between the LA group (64%) and the GA group (77%); however, only 62% of the GA group were discharged home on the same day when compared with 89% of the LA group (P < 0.0001). CONCLUSION: Similar success rates for temporary trial with SNS can be achieved with LA and GA. Insertion under LA is associated with reduced cost, shorter hospital stay and quicker recovery, and it avoids the risk of general anaesthesia.

Programming InterStim for faecal incontinence.

OBJECTIVE: Sacral nerve stimulation (SNS) for faecal incontinence (FI) is achieved by implanting a pulse generator attached to a tined lead with individually programmable electrodes. Our aim was to establish whether the 'ideal' programme for the treatment of FI has been used most commonly. We also wished to determine whether re-programming changed the symptom severity scores. METHOD: The following data were extracted from our SNS patient database: the frequency with which each programme was used, the length of time it was effective for, the number of months from implantation that the programme was started and the symptom severity scores prior to a change or no change in programme. RESULTS: Thirty-eight patients have had implanted pulse generators inserted since 2004. One hundred and two programme changes were documented in the database. The 'ideal' programme was not most commonly programmed. The common programmes were effective for longest. The electrode furthest from the tip was used in the initial programme only once and the median duration from implantation to the start of a programme including it is 13 months. Symptom severity scores were significantly higher in patients who required re-programming than in those whose programme remained unchanged. CONCLUSIONS: In our patients the 'ideal' programme was not the programme used most frequently, nor for the longest duration. The theoretical migration of the tined lead inwards with time is upheld by our results. Patients who feel the sensation of SNS perianally have lower symptom scores than those who do not and who require re-programming.

Sacral nerve stimulation reduces corticoanal excitability in patients with faecal incontinence.

BACKGROUND: Sacral nerve stimulation (SNS) can produce symptomatic relief in patients with faecal incontinence. Moreover, peripheral nerve stimulation has been shown to affect brain function. The aim of this study was to determine whether SNS might produce important changes in cortical activity linked to improved continence. METHODS: In an experimental study, ten women with intractable faecal incontinence (mean age 51.3 years) were serially mapped with transcranial magnetic stimulation before and immediately after 14 days of temporary SNS (15 Hz, pulse width 210 micros), and then 2 weeks later. Anal sphincter electromyographic responses were recorded to cortical stimulation of multiple points over a scalp grid covering the bilateral medial cortex. Continence scores, anorectal manometry and rectal sensitivity data were also collected. RESULTS: SNS improved global symptom scores in the majority of patients; mean(s.e.m.) continence scores fell from 16.9(1.6) to 10.6(1.8) (P = 0.042). Cortical mapping showed a consistent decrease in corticoanal representation and overall excitability immediately after SNS compared with baseline (mean(s.e.m.) 38,083(13,669) versus 42,507(13,297) microV s; P = 0.017), which was reversed 2 weeks after SNS wire removal. CONCLUSION: SNS produces symptom benefit in patients with faecal incontinence that is associated with a reversible reduction in corticoanal excitability. SNS therefore drives dynamic brain changes that may play a functional role in influencing anal continence.