The influence of sacral nerve stimulation on anorectal dysfunction

Sacral nerve modulation for irritable bowel syndrome: A randomized, double-blinded, placebo-controlled crossover study

BACKGROUND

Irritable bowel syndrome (IBS) is among the most common gastrointestinal disorders, and a substantial proportion of patients have an insufficient response to treatment. In a single-blinded study, sacral nerve modulation (SNM) significantly reduced symptoms of IBS. The aim of the present double-blinded, randomized, placebo-controlled study was to evaluate the effect of SNM for IBS.

METHODS

We included patients with diarrhea-predominant or mixed IBS and a minimum baseline IBS-specific symptom score of 40 points (Gastrointestinal Symptom Rating Scale-IBS version). Patients underwent a 6-week period of SNM. In the first 4 weeks, the patients were randomized 1:1 to have the neurostimulator set subsensory or OFF for 2 weeks and then the opposite for another 2 weeks. Patients and investigators were blinded to settings. In the remaining 2 weeks, the stimulation was set suprasensory. IBS-specific symptoms and quality of life were assessed with validated questionnaires and bowel diaries.

KEY RESULTS

Twenty-one patients were randomized and eligible for analysis. The IBS-specific symptom score was reduced with borderline significance during stimulation (subsensory-OFF median change -1 (-26, 9), OFF-subsensory median change 8 (-11, 36); P = 0.0572). Pain was significantly reduced during stimulation (subsensory-OFF median change -1.5 (-4, 1), OFF-subsensory median change 1 (-4, 3); P = 0.0188), along with the number of daily bowel movements (subsensory-OFF median change 0 (-1.8, 0.2), OFF-subsensory median change 0.2 (-0.5, 1.1); P = 0.0373). The median placebo effect was 14% (0, 55).

CONCLUSION AND INFERENCES

Sacral nerve modulation for IBS seems promising but should be considered experimental until larger multicenter studies have been performed.

Percutaneous tibial nerve stimulation (PTNS): an alternative treatment option for chronic therapy resistant anal fissure

Background

The aim of the present study was to evaluate percutaneous tibial nerve stimulation (PTNS) for treatment resistant chronic anal fissure.

Methods

Consecutive patients with chronic anal fissure were treated with neuromodulation via the posterior tibial nerve between October 2013 and January 2014. Patients had PTNS for 30 min on 10 consecutive days. All patients had failed conventional medical treatment. The visual analogue scale (VAS) score, St. Marks score, Wexner’s constipation score, Brief Pain Inventory (BPI-SF), bleeding and mucosal healing were evaluated before treatment, at termination, after 3 months, and then yearly for 3 years.

Results

Ten patients (4 males and 6 females; mean age 49.8 years) were identified but only 9 were evaluated as one patient’s fissure healed before PTNS was started. At 3-year follow-up, fissures had remained completely healed in 5 out of 9 patients. All patients stopped bleeding and were almost completely pain-free at 3 years (VAS p = 0.010) and pain relief improved from 50% at completion to 90% at 3 years. The patients’ Wexner constipation scores improved significantly (p = 0.007).

Conclusions

In this small series, PTNS enhanced healing of chronic anal fissure and reduced pain and bleeding with an associated improvement in bowel function.

Outcomes of Implementation of Sacral Nerve Stimulation in Incontinent Patients in Shiraz

BACKGROUND

Fecal incontinence is a common disorder in old age; however, it may not threaten life, but it can cause morbidity and many problems. Sacral nerve stimulation (SNS) is a minimally invasive surgical procedure performed by chronic electrical stimulation of the nerves in the sacral plexus through a lead implanted at the S3 foramen. This study aimed to evaluate the outcomes of SNS in Shiraz.

MATERIALS AND METHODS

Data from patients who underwent implantation of an SNS device from 2012 to 2018 were reviewed in Shiraz. Thirty patients who had incontinence were evaluated by a committee. Pre- and postoperative assessments of the severity of incontinence were performed using Wexner Incontinence Score. Statistical analysis was performed using paired t-test.

RESULTS

Twenty-seven patients proceeded to insertion in the temporary SNS, and of these, 16 were elected to have a permanent SNS. Finally, seven patients were satisfied with their treatment. There was a significant reduction in the pre- and post-SNS Wexner Incontinence Scores from a median of 15-10, respectively (P < 0.05).

CONCLUSION

In our study, 16 patients underwent SNS protocol, and 43.7% of them showed a good response and recovered. It is recommended as a method for the treatment of fecal incontinence. Permanent SNS is effective, showing a significant improvement in fecal incontinence scores.

Human studies of anorectal sensory function

This review addresses three main questions: (1) Why is anorectal sensory function important in humans? (2) What is the evidence for anorectal sensory dysfunction in disease? (3) Can anorectal sensory function be modified for therapeutic benefit?

Increased yield pressure in the anal canal during sacral nerve stimulation: a pilot study with the functional lumen imaging probe

BACKGROUND

Sacral nerve stimulation (SNS) is a well-established treatment for fecal incontinence but its mode of action remains obscure. Anal sphincter function is usually evaluated with manometry but resistance to distension may be a more appropriate parameter than luminal pressure. The functional lumen imaging probe allows detailed description of distension properties of the anal canal. Our objective in this study was to characterize the impact of SNS on distension properties of the anal canal in patients with idiopathic fecal incontinence.

METHODS

We studied 10 women (median age 64 [44-79] years) with idiopathic fecal incontinence at baseline and during SNS. The luminal geometry of the anal canal was examined with the FLIP at rest and during squeeze and the distensibility of the anal canal was investigated during filling of the bag.

KEY RESULTS

All patients were successfully treated with SNS and the mean Wexner Incontinence Score was reduced from 14.9 ± 4 to 7.1 ± 4.8 (P<.001). The pressure required to open the narrowest point of the anal canal during distension (yield pressure) increased from 14.5 ± 12.2 mmHg at baseline to 20.5 ± 13.3 mmHg during SNS (P<.01). The pressure-strain elastic modulus increased non-significantly from 2.2 ± 0.5 to 2.9 ± 1.6 kPa, indicating increased stiffness of the anal canal.

CONCLUSION AND INFERENCES

The yield pressure and the resistance to distension increased in response to SNS for idiopathic fecal incontinence. This will inevitably increase the resistance to flow through the anal canal, which may contribute to the benefits of sacral nerve stimulation.

Home Transcutaneous Electrical Stimulation Therapy to Treat Children With Anorectal Retention: A Pilot Study

AIM

As transcutaneous electrical stimulation (TES) increased defecation in children and adults with Slow-Transit Constipation (STC), we performed a pilot study to test if TES can improve symptoms (defecation and soiling) in children with chronic constipation without STC and transit delay in the anorectum.

METHODS

Children with treatment-resistant constipation presenting to a tertiary hospital had gastrointestinal nuclear transit study (NTS) showing normal proximal colonic transit and anorectal holdup of tracer. TES was administered at home (1 hour/day for 3 months) using a battery-powered interferential stimulator, with four adhesive electrodes (4 × 4 cm) connected so currents cross within the lower abdomen at the level of S2-S4. Stimulation was added to existing laxatives. Daily continence diary, and quality-of-life questionnaires (PedsQL4.0) were compared before and after TES.

RESULTS

Ten children (4 females: 5-10 years, mean 8 years) had holdup in the anorectum by NTS. Nine had <3 bowel motions (BM)/week. After three months TES, defecation frequency increased in 9/10 (mean 0.9-4.1 BM/week, p = 0.004), with 6/9 improved to ≥3 BM/week. Soiling reduced in 9/10 from 5.9 to 1.9 days/week with soiling, p = 0.004. Ten were on laxatives, and nine reduced/stopped laxative use. Quality-of-life improved to within the normal range.

CONCLUSION

TES improved symptoms of constipation in >50% of children with treatment-resistant constipation with isolated holdup in the anorectum. Further studies (RCTs) are warranted in these children.

Acute lumbosacral nerve stimulation does not affect anorectal motor function in a rodent model

BACKGROUND

Sacral nerve stimulation has become a first line treatment for fecal incontinence, however, its effect on the motor function of the anorectum is uncertain. The aim of this study was to apply acute lumbosacral nerve stimulation in an animal model and to determine its effect on the external and internal anal sphincter forces, the rectoanal inhibitory and excitatory reflexes, and the slow wave frequency of the internal anal sphincter.

METHODS

Lumbosacral nerve stimulation was applied to 16 nulliparous female rats. A novel in vivo preparation was designed to allow simultaneous monitoring of external and internal anal sphincter forces. The effect of rectal distension on the two anal sphincters was also studied.

KEY RESULTS

Lumbosacral nerve stimulation delivered at either S1 or L6 in rodents did not affect sphincter forces, rectoanal reflexes or slow wave frequency of anal canal smooth muscle.

CONCLUSIONS & INFERENCES

The absence of effect on the motor pathways of continence suggests that the mechanism of action is predominantly on sensory feedback mechanisms from the anorectum, thereby increasing cortical awareness of the pelvic floor.

Sacral nerve stimulation for faecal incontinence and constipation in adults

BACKGROUND

Faecal incontinence (FI) and constipation are both socially-embarrassing and physically-disabling conditions that impair quality of life. For both, surgery may be required in a minority of people when more conservative measures fail. However, the invasiveness and irreversible nature of direct surgery on bowel and sphincter muscles, poor long-term outcomes and well-established compIications makes such procedures unappealing for these benign conditions. A less-invasive surgical option to treat faecal incontinence and constipation is direct, low-voltage stimulation of the sacral nerve roots, termed sacral nerve stimulation (SNS). SNS has become the first line surgical treatment for FI in people failing conservative therapies. Its value in the treatment of constipation is less clear.

OBJECTIVES

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

SEARCH METHODS

We searched the Cochrane Incontinence Group Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, ClinicalTrials.gov, the World Health Organization (WHO) ICTRP and handsearched journals and conference proceedings (searched 5 February 2015), EMBASE (1 January 1947 to 2015 Week 5), and the reference lists of retrieved relevant articles.

SELECTION CRITERIA

All randomised or quasi-randomised trials assessing the effects of SNS for faecal incontinence or constipation in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, assessed the methodological quality of the included trials, and undertook data extraction.

MAIN RESULTS

Six crossover trials and two parallel group trials were included.Six trials assessed the effects of SNS for FI. In the parallel group trial conducted by Tjandra, 53 participants with severe FI in the SNS group experienced fewer episodes of faecal incontinence compared to the control group who received optimal medical therapy (mean difference (MD) -5.20, 95% confidence interval (CI) -9.15 to -1.25 at 3 months; MD -6.30, 95% CI -10.34 to -2.26 at 12 months). Adverse events were reported in a proportion of participants: pain at implant site (6%), seroma (2%) and excessive tingling in the vaginal region (9%).In the parallel group trial carried out by Thin, 15 participants with FI in the SNS group experienced fewer episodes of FI compared with the percutaneous tibial nerve stimulation (PTNS) group (MD -3.00, 95% CI -6.61 to 0.61 at 3 months; MD -3.20, 95% CI -7.14 to 0.74 at 12 months). Adverse events were reported in three participants: mild ipsilateral leg pain during temporary testing (n = 1); and stimulator-site pain following insertion of neurostimulator (n = 2).In the crossover trial by Leroi 7 of 34 recruited participants were excluded from the crossover due mainly to complications or immediate device failure. Twenty-four of the remaining 27 participants while still blinded chose the period of stimulation they had preferred. Outcomes were reported separately for 19 participants who preferred the 'on' and five who preferred the 'off' period. For the group of 19, the median (range) episodes of faecal incontinence per week fell from 1.7 (0 to 9) during the 'off' period to 0.7 (0 to 5) during the 'on' period; for the group of five, however, the median (range) rose from 1.7 (0 to 11) during the 'off' period compared with 3.7 (0 to 11) during the 'on' period. Four of 27 participants experienced an adverse event resulting in removal of the stimulator.In the crossover trial by Sørensen and colleagues, participants did not experience any FI episodes in either the one-week 'on' or 'off' periods.In the crossover trial by Vaizey, participants reported an average of six, and one, episodes of faecal incontinence per week during the 'off' and 'on' periods respectively in two participants with FI. Neither study reported adverse events.In the crossover trial by Kahlke, 14 participants with FI experienced significantly lower episodes of FI per week during the stimulator 'on' (1 (SD, 1.7)) compared with the 'off' period (8.4 (SD, 8.7)). Adverse events reported include: haematoma formation (n = 3); misplacement of tined lead (1); and pain at stimulator site (n = 1).Two trials assessed SNS for constipation. In the Kenefick trial, the two participants experienced an average of two bowel movements per week during the 'off' crossover period, compared with five during the 'on' period. Abdominal pain and bloating occurred 79% of the time during the 'off' period compared with 33% during the 'on' period. No adverse events occurred. In contrast, in the trial by Dinning with 59 participants, SNS did not improve frequency of bowel movements and 73 adverse events were reported, which included pain at site of the implanted pulse generator (32), wound infection (12), and urological (17) events.

AUTHORS' CONCLUSIONS

The limited evidence from the included trials suggests that SNS can improve continence in a proportion of patients with faecal incontinence. However, SNS did not improve symptoms in patients with constipation. In addition, adverse events occurred in some patients where these were reported. Rigorous high quality randomised trials are needed to allow the effects of SNS for these conditions to be assessed with more certainty.

Systematic review of the impact of sacral neuromodulation on clinical symptoms and gastrointestinal physiology

Background

Sacral neuromodulation (SNM) has emerged as a treatment option for faecal incontinence (FI). However, its objective effect on symptoms and anorectal function is inconsistently described. This study aimed to systematically review the impact of SNM on clinical symptoms and gastrointestinal physiology in patients with FI, including factors that may predict treatment outcome.

Methods

An electronic search of MEDLINE (1946–2014)/EMBASE database was performed in accordance with PRISMA guidelines. Articles that reported the relevant outcome measures following SNM were included. Clinical outcomes evaluated included: frequency of FI episodes, FI severity score and success rates. Its impact on anorectal and gastrointestinal physiology was also evaluated.

Results

Of 554 citations identified, data were extracted from 81 eligible studies. Meta‐analysis of the data was precluded due to lack of a comparison group in most studies. After permanent SNM, ‘perfect’ continence was noted in 13–88% of patients. Most studies reported a reduction in weekly FI episodes (median difference of the mean −7.0 (range: −24.8 to −2.7)) and Wexner scores (median difference of the mean −9 (−14.9 to −6)). A trend towards improved resting and squeeze anal pressures and a reduction in rectal sensory volumes were noted. Studies failed to identify any consistent impact on other physiological parameters or clinicophysiological factors associated with success.

Conclusion

SNM improves clinical symptoms and reduces number of incontinence episodes and severity scores in patients with FI, in part by improving anorectal physiological function. However, intervention studies with standardized outcome measures and physiological techniques are required to robustly assess the physiological impact of SNM.

Is sacral neuromodulation here to stay? Clinical outcomes of a new treatment for fecal incontinence

INTRODUCTION

Sacral neuromodulation (SNM) was approved by the FDA for the treatment of fecal incontinence (FI) in 2011, and previous industry-sponsored trials have shown excellent clinical outcomes. The purpose of this study is to examine clinical outcomes of patients treated during our initial experience with SNM.

METHODS

A prospective database of patients treated with SNM for FI by one of three colorectal surgeons at two separate institutions was maintained starting in 2011. Patients showing ≥50% improvement of weekly incontinent episodes during test stimulation were offered permanent implantation of the SNM device. Disease severity was tracked using the Wexner score.

RESULTS

A total of 145 patients received a full system implantation (of 152 who received test stimulation). The median preoperative Wexner score of 14 decreased to 3, 3 months after implantation and persisted to 12 months. At 12 months, 95.2% of patients achieved >50% improvement in Wexner Score and 67.6% achieved >75% improvement. The most common adverse event was infection (3.4%). Three patients (2.1%) required lead revision.

CONCLUSIONS

SNM is a safe and effective therapy for the treatment of FI. Postoperative patient surveillance is important, as many patients require programming changes, and some will require a lead revision over time.

Sacral nerve stimulation changes rectal sensitivity and biomechanical properties in patients with irritable bowel syndrome

BACKGROUND

Sacral nerve stimulation (SNS) has been demonstrated to alleviate symptoms and improve quality of life in selected patients with irritable bowel syndrome (IBS). The mechanisms of action, however, remain unknown. The aim of the study was to evaluate the effects of SNS on rectal sensitivity and biomechanical properties in patients with IBS.

METHODS

Twenty patients with diarrhea-predominant (n = 11) or mixed (n = 9) IBS were treated with SNS in a controlled, randomized crossover trial. They were randomized to either 1 month of SNS (ON) or placebo (OFF) with the opposite setting for the next month. Sensory and biomechanical parameters were assessed by multimodal rectal stimulation at the end of each period. IBS-specific symptoms were evaluated at baseline and at the end of each treatment period.

KEY RESULTS

Cold stimuli were better tolerated in the ON period (19.9 °C[± 0.6]) compared to the OFF period (21.8 °C[± 0.6]; p = 0.03). Significantly lower cross-sectional areas were needed to elicit sensory responses in the ON period (1545 mm(2) [± 95]) compared to the OFF period (1869 mm(2) [± 92]; p = 0.015). The association between reduced sensory threshold and improvement of constipation was of borderline significance (p = 0.05). Wall stiffness was significantly lower in the ON period (192 mmHg[± 10]) compared to the OFF period (234 mmHg[± 10]; p = 0.004). Reduced wall stiffness was significantly associated with improved overall GSRS-IBS symptom score (p = 0.01). Reduced sensory threshold to stretch (p = 0.02) and reduced wall stiffness (p < 0.001) were predictors of the GSRS-IBS symptom score.

CONCLUSIONS & INFERENCES

SNS for diarrhea-predominant and mixed IBS relaxes the rectal wall, while making it more sensitive to stretch and less sensitive to cold. Reduced wall stiffness and increased sensitivity to stretch are associated with improved GSRS-IBS symptom score.

A systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation

BACKGROUND

Sacral nerve stimulation (SNS) is now well established as a treatment for fecal incontinence (FI) resistant to conservative measures and may also have utility in the management of chronic constipation; however, mechanism of action is not fully understood. End organ effects of SNS have been studied in both clinical and experimental settings, but interpretation is difficult due to the multitude of techniques used and heterogeneity of reported findings. The aim of this study was to systematically review available evidence on the mechanisms of SNS in the treatment of FI and constipation.

METHODS

Two systematic reviews of the literature (performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses framework) were performed to identify manuscripts pertaining to (a) clinical and (b) physiological effects of SNS during the management of hindgut dysfunction.

KEY RESULTS

The clinical literature search revealed 161 articles, of which 53 were deemed suitable for analysis. The experimental literature search revealed 43 articles, of which nine were deemed suitable for analysis. These studies reported results of investigative techniques examining changes in cortical, gastrointestinal, colonic, rectal, and anal function.

CONCLUSIONS & INFERENCES

The initial hypothesis that the mechanism of SNS was primarily peripheral motor neurostimulation is not supported by the majority of recent studies. Due to the large body of evidence demonstrating effects outside of the anorectum, it appears likely that the influence of SNS on anorectal function occurs at a pelvic afferent or central level.

A randomized, controlled, crossover study of sacral nerve stimulation for irritable bowel syndrome

OBJECTIVE

To investigate whether sacral nerve stimulation reduces irritable bowel syndrome (IBS)-specific symptoms by a randomized, controlled, crossover study.

BACKGROUND

IBS affects 3% to 22% of the population worldwide, but most patients continue to have symptoms despite treatment.

METHODS

Patients included from our tertiary center had diarrhea-predominant or mixed IBS, with a minimum baseline IBS symptom score (Gastrointestinal Syndrome Rating Scale-IBS questionnaire) of 40 points reduced by a minimum of 30% during the percutaneous nerve evaluation before permanent implantation. Patients were randomized (1:1) to have the stimulator ON or OFF for 1 month and then the opposite for another month. Investigators and patients were not informed of the setting. IBS-specific symptoms and quality of life were assessed through bowel diaries and validated questionnaires. Primary endpoint was the IBS-specific symptom score.

RESULTS

Twenty-one patients were randomized. Ten were eligible for analysis in each group. IBS-specific symptom scores were significantly reduced during stimulation: the median difference in the ON-OFF group was 12 (range, -22 to 44) and in the OFF-ON group -17.5 (range, -48 to -1) (P = 0.0009). IBS-specific quality-of-life scores improved significantly during stimulation: the median difference in the ON-OFF group was 16 (range, -24 to 69) and in the OFF-ON group -42.5 (range, -77 to 0) (P = 0.0003). At 1-year follow-up, the median IBS-specific symptom score (25; range, 13-65) was significantly lower than that at baseline (62; range, 45-80) (P = 0.0001).

CONCLUSIONS

Sacral nerve stimulation significantly reduces symptoms and improves quality of life of highly selected patients with IBS.

Effects of stimulation frequency and intensity in sacral neuromodulation on anorectal inputs to the somatosensory cortex in an experimental model

Introduction

Although sacral neuromodulation (SNM) is an established treatment for faecal incontinence, stimulation parameters have been derived empirically and only one frequency (14 Hz) is employed clinically. The aim of this study was to test a range of stimulation frequencies to establish an optimal frequency of SNM for maximum augmentation of anal canal cortical evoked potentials (EPs) in an animal model.

Methods

In female Wistar rats, anal canal EPs were recorded over the primary somatosensory cortex using a flexible multielectrode array, and the effect of SNM was studied. SNM was applied at 0·1–100 Hz and a frequency response curve plotted. The data were fitted to a quadratic equation.

Results

The magnitude of potentiation of anal canal EPs caused by SNM depended significantly on stimulation frequency (P &lt; 0·001). The frequency–potentiation relationship was parabolic in form, with a clear optimum at 2 Hz. The SNM must be applied for at least 3 min. The theoretical maximal potentiation predicted by the model was not found to be statistically different to actual data recorded (P = 0·514–0·814). The response depended on stimulation amplitude in an ‘all-or-nothing’ fashion. EPs were augmented when the SNM intensity was 0·5 times the motor threshold to tail twitch or greater, but values below this intensity failed to affect the EPs.

Conclusion

The effect of SNM in this animal model is governed principally by frequency, with an optimum of 2 Hz. If animal data can be translated to humans, optimization of SNM frequency may offer a clinically relevant improvement in the efficacy of SNM.

Effects of transcutaneous tibial nerve stimulation on anorectal physiology in fecal incontinence: a double-blind placebo-controlled cross-over evaluation

BACKGROUND

Transcutaneous electrical tibial nerve stimulation (TENS) is of growing interest for the treatment of fecal incontinence (FI), but its mechanism of action remains uninvestigated. We aimed to further assess the anorectal response to TENS in a dynamic model.

METHODS

We performed a placebo-controlled, randomized, double-blinded crossover study in 19 patients suffering from FI to assess the effects of TENS on anorectal function. Anorectal physiology and perception were recorded through two sequences of rectal isobaric distension using an electronic barostat device to measure anal and rectal pressures, rectal volumes, and perception scores.

KEY RESULTS

Maximal rectal pressure and volume variation were affected by TENS, with higher mean maximal rectal pressure (5.33 and 4.06 mmHg in the active and sham TENS respectively, p < 0.0001) and lower volume variation (11.45 and 14.7 mL in the active and sham stimulation respectively, p < 0.05). Rectal compliance was not modified by active TENS. Pressure of the upper anal canal was significantly lower with raised isobaric distension in sequences assigned to active TENS.

CONCLUSIONS & INFERENCES

Acute TENS modified anorectal physiology by strengthening the myogenic response to distension rather than increasing muscle relaxation and related rectal compliance in patients with FI.

High resolution colonic manometry--what have we learnt?--A review of the literature 2012

Despite its size and physiological importance, the human colon is one of the least understood organs of the body. Many disorders arise from suspected abnormalities in colonic contractions, yet, due largely to technical constraints, investigation of human colonic motor function still remains relatively primitive. Most measures of colonic motility focus upon the transit speed (radiology, scintigraphy and, more recently, "smart pills"); however, only colonic manometry can measure pressure/force from multiple regions within the colon in real time (Dinning and Scott (Curr Opin Pharmacol 11:624-629, 2011)). Based upon data from colonic manometry studies, a number of different colonic motor patterns have been distinguished: (1) antegrade high amplitude propagating sequences (contractions), (2) low amplitude propagating sequences, (3) non-propagating contractions, and (4) and rarely episodes of retrograde (oral) propagating pressure waves (Dining and Di Lorenzo (Best Pract Res Clin Gastrolenterol 25(1): 89-101, 2011)). Abnormalities in the characteristics of these motor patterns should help to characterize dysmotility in a patient populations, and in both adults and children colonic motor abnormalities have been identified with manometry studies (Rao et al. Am J Gastroenterol 99(12):2405-2416, (2004), Di Lorenzo et al. Gut. 34(1): 803-807, (1993)). Yet, despite more than two decades of such studies, the clinical utility of colonic manometry remains marginal with no specific manometric biomarkers of colonic dysfunction being established ([Camilleri et al. Neurogastroenterol Motil. 20(12): 1269-1282, 2008). This has been highlighted recently in a colonic manometry study by Singh et al. (2013), in which 41 % of 80 patients, with confirmed slow transit constipation, were reported to have normal motility. While this may suggest that no motor abnormalities exist in a proportion of such patients, the finding may also reflect technical constraints in our ability to detail colonic motility patterns.

A review of posterior tibial nerve stimulation for faecal incontinence

AIM

This review aimed to assess the published results of posterior tibial nerve stimulation (PTNS) for faecal incontinence.

METHOD

A search was performed of PubMed, MEDLINE and Embase to identify studies describing the clinical outcome of PTNS for faecal incontinence.

RESULTS

Thirteen studies were identified. These described the outcome of PTNS for faecal incontinence in 273 patients. Four described transcutaneous PTNS, eight percutaneous PTNS and one compared both methods of PTNS with a sham transcutaneous group. One investigated patients with faecal incontinence and spinal cord injury and another with inflammatory bowel disease. There was marked heterogeneity of the treatment regimens and of the end points used. All reported that PTNS improved faecal incontinence. A > 50% improvement was reported in episodes of faecal incontinence in 63-82% of patients. An improvement was seen in urgency (1-5 min). Improvement was also described in the Cleveland Clinic faecal incontinence score in eight studies. Patients with urge and mixed incontinence appear to benefit more than those with passive incontinence. Treatment regimens ranged in duration from 1-3 months. A residual therapeutic effect is seen after completion of treatment. Follow-up ranged from 1-30 months.

CONCLUSION

PTNS is effective for faecal incontinence. However, many of the published studies are of poor quality. Comparison between studies is difficult owing to differences in the outcome measures used, technique of PTNS and the timing and duration of treatment.

The effect of sacral nerve stimulation on distal colonic motility in patients with faecal incontinence

BACKGROUND

Sacral nerve stimulation (SNS) is an effective treatment for neurogenic faecal incontinence (FI). However, the clinical improvement that patients experience cannot be explained adequately by changes in anorectal function. The aim of this study was to examine the effect of SNS on colonic propagating sequences (PSs) in patients with FI in whom urgency and incontinence was the predominant symptom.

METHODS

In patients with FI a high-resolution fibre-optic manometry catheter, containing 90 sensors spaced at 1-cm intervals, was positioned colonoscopically and clipped to the caecum. A unipolar or quadripolar tined electrode was implanted into the S3 sacral nerve foramen. Colonic manometry was evaluated in a double-blind randomized crossover trial, using true suprasensory stimulation or sham stimulation. Each stimulation period, lasting 2 h, was preceded by a 2-h basal manometric recording.

RESULTS

All 11 patients studied showed a colonic response to SNS. In ten patients there was a significant increase in the frequency of retrograde PSs throughout the colon during true stimulation compared with sham stimulation (P = 0·014). In one outlier, with baseline retrograde PS frequency nine times that of the nearest patient, a reduction in retrograde PS frequency was recorded. Compared with sham stimulation, SNS had no effect on the frequency of antegrade PSs or high-amplitude PSs.

CONCLUSION

SNS modulates colonic motility in patients with faecal urge incontinence. These data suggest that SNS may improve continence and urgency through alteration of colonic motility, particularly by increasing retrograde PSs in the left colon.

Sacral nerve stimulation for constipation

BACKGROUND

For over 10 years sacral nerve stimulation (SNS) has been used for patients with constipation resistant to conservative treatment. A review of the literature is presented.

METHODS

PubMed, MEDLINE and Embase databases were searched for studies demonstrating the use of SNS for the treatment of constipation.

RESULTS

Thirteen studies have been published describing the results of SNS for chronic constipation. Of these, three were in children and ten in adults. Test stimulation was successful in 42-100 per cent of patients. In those who proceeded to permanent SNS, up to 87 per cent showed an improvement in symptoms at a median follow-up of 28 months. The success of stimulation varied depending on the outcome measure being used. Symptom improvement correlated with improvement in quality of life and patient satisfaction scores.

CONCLUSION

SNS appears to be an effective treatment for constipation, but this needs to be confirmed in larger prospective studies with longer follow-up. Improved outcome measures need to be adopted given the multiple symptoms that constipation may be associated with. Comparison with other established surgical therapies also needs consideration.

Rectal hyposensitivity

Impaired or blunted rectal sensation, termed rectal hyposensitivity (RH), which is defined clinically as elevated sensory thresholds to rectal balloon distension, is associated with disorders of hindgut function, characterised primarily by symptoms of constipation and fecal incontinence. However, its role in symptom generation and the pathogenetic mechanisms underlying the sensory dysfunction remain incompletely understood, although there is evidence that RH may be due to 'primary' disruption of the afferent pathway, 'secondary' to abnormal rectal biomechanics, or to both. Nevertheless, correction of RH by various interventions (behavioural, neuromodulation, surgical) is associated with, and may be responsible for, symptomatic improvement. This review provides a contemporary overview of RH, focusing on diagnosis, clinical associations, pathophysiology, and treatment paradigms.

Prospective randomized double-blind study of temporary sacral nerve stimulation in patients with rectal evacuatory dysfunction and rectal hyposensitivity

OBJECTIVE

Prospective randomized double-blind placebo-controlled crossover trial of 14 female patients (median age 52 [30-69] years) with proctographically defined evacuatory dysfunction (ED) and demonstrable rectal hyposensitivity (elevated thresholds to balloon distension in comparison with age- and sex-matched controls).

BACKGROUND

Sacral nerve stimulation (SNS) is an evolving treatment for constipation. However, variable outcomes might be improved by better patient selection. Evidence that the effect of SNS may be mediated by modulation of afferent signaling promotes a role in patients with ED associated with rectal hyposensation.

METHODS

SNS was performed by the standard 2-stage technique (temporary then permanent implantation). During a 4-week period of temporary stimulation, patients were randomized ON-OFF/OFF-ON for two 2-week periods. Before insertion (PRE), and during each crossover period, primary (rectal sensory thresholds) and secondary (bowel diaries, constipation, and GIQoL [gastrointestinal quality of life] scores) outcome variables were blindly assessed.

RESULTS

Thirteen patients completed the trial. Following stimulation, defecatory desire volumes to rectal balloon distension were normalized in 10 of 13 patients (PRE: mean 277 mL [234-320] vs ON: 163 mL [133-193] vs OFF: 220 mL [183-257 mL]; P = 0.006) and maximum tolerable volume in 9 of 13 (PRE: mean 350 mL [323-377] vs ON: 262 mL [219-305] vs OFF: 298 mL [256-340 mL]; P = 0.012). There was a significant increase in the percentage of successful bowel movements (PRE: median 43% [0-100] vs ON: 89% [11-100] vs OFF: 83% [11-100]; P = 0.007) and Wexner constipation scores improved (PRE: median 19 [9-26] vs ON: 10 [6-27] vs OFF: 13 [5-29]; P = 0.01). There were no significant changes in disease-specific or generic quality of life measures. Eleven patients progressed to permanent stimulation (9/11 success at 19 months).

CONCLUSIONS

Most patients with chronic constipation secondary to ED with rectal hyposensitivity responded to temporary SNS. The physiological results presented support a mechanistic role for rectal afferent modulation.

Pancolonic motor response to subsensory and suprasensory sacral nerve stimulation in patients with slow-transit constipation

BACKGROUND

Sacral nerve stimulation (SNS) is emerging as a potential treatment for patients with constipation. Although SNS can elicit an increase in colonic propagating sequences (PSs), the optimal stimulus parameters for this response remain unknown. This study evaluated the colonic motor response to subsensory and suprasensory SNS in patients with slow-transit constipation.

METHODS

Patients with confirmed slow-transit constipation were studied. Either a water-perfused manometry catheter or a high-resolution fibre-optic manometry catheter was positioned colonoscopically to the caecum. A temporary electrode was implanted transcutaneously in the S3 sacral nerve foramen. In the fasted state, three conditions were evaluated in a double-blind randomized fashion: sham, subsensory and suprasensory stimulation. Each 2-h treatment period was preceded by a 2-h basal period. The delta (Δ) value was calculated as the frequency of the event during stimulation minus that during the basal period.

RESULTS

Nine patients had readings taken with a water-perfused catheter and six with a fibre-optic catheter. Compared with sham stimulation, suprasensory stimulation caused a significant increase in the frequency of PSs (mean(s.d.) Δ value - 1·1(7·2) versus 6·1(4·0) PSs per 2 h; P = 0·004). No motor response was recorded in response to subsensory stimulation compared with sham stimulation. Compared with subsensory stimulation, stimulation at suprasensory levels caused a significant increase in the frequency of PSs (P = 0·006).

CONCLUSION

In patients with slow-transit constipation, suprasensory SNS increased the frequency of colonic PSs, whereas subsensory SNS stimulation did not. This has implications for the design of therapeutic trials and the clinical application of the device.