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

Habit training versus habit training with direct visual biofeedback in adults with chronic constipation: study protocol for a randomised controlled trial

Background

Constipation affects up to 20% of adults. Chronic constipation (CC) affects 1–2% of adults. Patient dissatisfaction is high; nearly 80% feel that laxative therapy is unsatisfactory and symptoms have significant impact on quality of life. There is uncertainty about the value of specialist investigations and whether equipment-intensive therapies using biofeedback confer additional benefit when compared with specialist conservative advice.

Methods/design

A three-arm, parallel-group, multicentre randomised controlled trial.

Objectives: to determine whether standardised specialist-led habit training plus pelvic floor retraining using computerised biofeedback is more clinically effective than standardised specialist-led habit training alone; to determine whether outcomes are improved by stratification based on prior investigation of anorectal and colonic pathophysiology. Primary outcome measure is response to treatment, defined as a 0.4-point (10% of scale) or greater reduction in Patient Assessment of Constipation–Quality of Life (PAC-QOL) score 6 months after the end of treatment. Other outcomes up to 12 months include symptoms, quality of life, health economics, psychological health and qualitative experience.

Hypotheses: (1) habit training (HT) with computer-assisted direct visual biofeedback (HTBF) results in an average reduction in PAC-QOL score of 0.4 points at 6 months compared to HT alone in unselected adults with CC, (2) stratification to either HT or HTBF informed by pathophysiological investigation (INVEST) results in an average 0.4-point reduction in PAC-QOL score at 6 months compared with treatment not directed by investigations (No-INVEST).

Inclusion: chronic constipation in adults (aged 18–70 years) defined by self-reported symptom duration of more than 6 months; failure of previous laxatives or prokinetics and diet and lifestyle modifications. Consenting participants (n = 394) will be randomised to one of three arms in an allocation ratio of 3:3:2: [1] habit training, [2] habit training and biofeedback or [3] investigation-led allocation to one of these arms. Analysis will be on an intention-to-treat basis.

Discussion

This trial has the potential to answer some of the major outstanding questions in the management of chronic constipation, including whether costly invasive tests are warranted and whether computer-assisted direct visual biofeedback confers additional benefit to well-managed specialist advice alone.

Trial registration

International Standard Randomised Controlled Trial Number: ISRCTN11791740. Registered on 16 July 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1880-0) contains supplementary material, which is available to authorized users.

Bilateral Posterior Tibial Nerve Stimulation in the Treatment of Rectal Evacuation Disorder: A Preliminary Report

BACKGROUND

Posterior tibial nerve stimulation influences both motor and sensory pathways, as well as the central nervous system. Stimulation of posterior tibial nerve roots (L4 to S3) could improve stool evacuation through S3 and/or S2 stimulation.

OBJECTIVE

This study aimed to assess the efficiency of bilateral posterior tibial nerve stimulation in the treatment of rectal evacuation disorder without anatomic obstruction.

DESIGN

This was a prospective case series studying the treatment of patients with obstructed defecation by posterior tibial nerve stimulation.

SETTING

The study was conducted at a tertiary referral academic medical center.

PATIENTS

Patients with rectal evacuation disorder without anatomic obstruction who were failing maximal conservative treatments were included.

INTERVENTION

Thirty minutes of bilateral transcutaneous posterior tibial nerve stimulation was applied 3 times weekly for each patient for 6 consecutive weeks.

MAIN OUTCOME MEASURES

The primary end point was the change in the modified obstructed defecation score. Secondary end points were changes in rectal sensitivity volumes (urge to defecate volume and maximal tolerable volume) and quality of life using the Patient Assessment of Constipation-Quality of Life questionnaire.

RESULTS

Thirty-six patients (25 women) completed the trial. The mean age of patients was 57.2 years (SD = 14.4 y). No adverse events were reported. Symptomatic successful outcome was reported in 17 patients (47%) and modified obstructed defecation score decreased over 6 weeks (mean decrease = 10 points (95% CI, 8.7-11.3 points); p < 0.0001). Patients with successful outcome (responders) had relatively lower preoperative modified obstructed defecation score compared with patients with unsuccessful outcome (nonresponders). In the successful group, there were significant improvement after 6 weeks in both Patient Assessment of Constipation-Quality of Life score (mean improvement = 43.0 points (95% CI, 35.2-50.7 points); p < 0.0001) and rectal sensitivity (significant reductions in urge to defecate volume (from 258.1 ± 21.2 to 239.6 ± 15.3; p < 0.0001) and maximal tolerable volume (from 304.5 ± 24.8 to 286.8 ± 19.7; p < 0.0001)). No significant change in Patient Assessment of Constipation-Quality of Life or rectal sensitivity was observed in the nonresponders.

LIMITATIONS

The study was designed just to proof the concept, but small sample size is a limitation. Another limitation is the short duration of study of only 6 weeks.

CONCLUSIONS

Current data showed that bilateral transcutaneous posterior tibial nerve stimulation can improve symptoms in a considerable percentage of patients with obstructed defecation without anatomic obstruction. The procedure is more effective in patients with a less-modified obstructed defecation score. Additional studies are needed to discover the predictive factors for success.

Randomized clinical trial of sacral nerve stimulation for refractory constipation

Background

Open studies have reported favourable results for sacral nerve stimulation in the treatment of refractory constipation. Here, its efficacy was assessed in a double-blind crossover RCT.

Methods

Patients with at least two of the following criteria were included: fewer than three bowel movements per week; straining to evacuate on more than 25 per cent of attempts; or sensation of incomplete evacuation on more than 25 per cent of occasions. Response to therapy was defined as at least three bowel movements per week and/or more than 50 per cent improvement in symptoms. Responders to an initial 3-week peripheral nerve evaluation were offered permanent implantation of a pulse generator and were assigned randomly in a crossover design to two 8-week intervals of active or sham stimulation. At the end of the two trial periods, the patients received active stimulation until the final evaluation at 1 year.

Results

Thirty-six patients (34 women; mean(s.d.) age 45(14) years) underwent peripheral nerve evaluation. Twenty responded and received a permanent stimulator. A positive response was observed in 12 of 20 and 11 of 20 patients after active and sham stimulation periods respectively (P = 0·746). Pain related to the device occurred in five patients and wound infection or haematoma in three, leading to definitive removal of the pulse generator in two patients. At 1 year, 11 of the 20 patients with an implanted device continued to respond. Stimulation had no significant effect on colonic transit time.

Conclusion

These results do not support the recommendation of permanent implantation of a pulse generator in patients with refractory constipation who initially responded to temporary nerve stimulation. Registration number: NCT01629303 (http://www.clinicaltrials.gov).

Pathophysiology of fecal incontinence differs between men and women: a case-matched study in 200 patients

BACKGROUND

Fecal incontinence (FI) is a common and socially disabling condition with obstetric trauma considered the principal etiological factor. This study aimed to systematically evaluate symptom presentation and anorectal function in both females and males with FI.

METHODS

One hundred males (M) and 100 age-matched females (F) with FI presenting between 2012 and 2014 were identified from a prospectively collected database. Comparison of clinical (history, symptom profile, and severity using validated questionnaires) and anorectal physiological (manometry, rectal sensory testing, endoanal ultrasonography, and evacuation proctography) data between M and F was performed.

KEY RESULTS

Incidence of prior anal surgery (M: 28% vs F: 18%, p = 0.13) and abdominal surgery (M: 25% vs F: 26%, p = 0.90) was similar between sexes, but females had a higher incidence of previous pelvic surgery (M: 4% vs F: 47%, p < 0.001). Eighty-five females were parous and 75% reported history of traumatic vaginal delivery. There was a trend toward higher St Mark's incontinence scores in females (mean ± SD; M: 13 ± 4 vs F: 14 ± 5, p = 0.06). In men, structural sphincter abnormalities were uncommon (M: 37% vs F: 77%, p < 0.001), while impaired rectal sensation (M: 24% vs F: 7%, p = 0.001) and functional disturbances of evacuation (M: 36% vs F: 13%, p = 0.001) were more common than in women. No abnormality on all tests performed was observed in twice as many males (M: 18% vs F: 9%, p = 0.10).

CONCLUSIONS & INFERENCES

Pathophysiological mechanisms of FI differ between sexes. Anal sphincter dysfunction was an uncommon finding in males, with impaired rectal sensation and functional disturbances of evacuation much more prominent than in the female cohort. These findings are likely to impact options for symptom management.

Sacral Nerve Stimulation Fails to Offer Long-term Benefit in Patients With Slow-Transit Constipation

BACKGROUND

Sacral nerve stimulation is proposed as a treatment for slow-transit constipation. However, in our randomized controlled trial we found no therapeutic benefit over sham stimulation. These patients have now been followed-up over a long-term period.

OBJECTIVE

The purpose of this study was to assess the long-term efficacy of sacral nerve stimulation in patients with scintigraphically confirmed slow-transit constipation.

DESIGN

This study was designed for long-term follow-up of patients after completion of a randomized controlled trial.

SETTINGS

It was conducted at an academic tertiary public hospital in Sydney.

PATIENTS

Adults with slow-transit constipation were included.

MAIN OUTCOME MEASURES

At the 1- and 2-year postrandomized controlled trial, the primary treatment outcome measure was the proportion of patients who reported a feeling of complete evacuation on >2 days per week for ≥2 of 3 weeks during stool diary assessment. Secondary outcome was demonstration of improved colonic transit at 1 year.

RESULTS

Fifty-three patients entered long-term follow-up, and 1 patient died. Patient dissatisfaction or serious adverse events resulted in 44 patients withdrawing from the study because of treatment failure by the end of the second year. At 1 and 2 years, 10 (OR = 18.8% (95% CI, 8.3% to 29.3%)) and 3 patients (OR = 5.7% (95% CI, -0.5% to 11.9%)) met the primary outcome measure. Colonic isotope retention at 72 hours did not differ between baseline (OR = 75.6% (95% CI, 65.7%-85.6%)) and 1-year follow-up (OR = 61.7% (95% CI, 47.8%-75.6%)).

LIMITATIONS

This study only assessed patients with slow-transit constipation.

CONCLUSIONS

In these patients with slow-transit constipation, sacral nerve stimulation was not an effective treatment.

Sacral neuromodulation in children and adolescents with chronic constipation refractory to conservative treatment

PURPOSE

Functional constipation in children and adolescents is a common and invalidating condition. In a minority of patients, symptoms persist despite optimal conservative therapy. The aim of this study was to evaluate whether the short-term effects of sacral neuromodulation (SNM) in children and adolescents with constipation are sustained over prolonged period of time.

METHODS

Patients aged 10-20 years, with refractory constipation, fulfilling the Rome III criteria, were included in our study. If SNM test treatment showed >50 % improvement in defecation frequency, a permanent stimulator was implanted. Primary outcome measure was defecation frequency during 3 weeks. Secondary endpoints were abdominal pain and Wexner score. To assess sustainability of treatment effect, a survival analysis was performed. Cross-sectional quality of life was assessed using the EQ-5D VAS score.

RESULTS

Thirty girls, mean age 16 (range 10-20), were included. The mean defecation frequency increased from 5.9 (SD 6.5) in 21 days at baseline to 17.4 (SD 11.6) after 3 weeks of test treatment (p < 0.001). During test treatment, abdominal pain and Wexner score decreased from 3.6 to 1.5 and 18.6 to 8.5 (p < 0.001), respectively. Improvement of symptoms sustained during a median follow-up of 22.1 months (12.2-36.8) in 42.9 % of patients. On a scale from 0 to 100, quality of life was 7 points lower than the norm score (mean 70 vs. 77).

CONCLUSION

SNM is a therapeutic option for children with chronic constipation not responding to intensive oral and/or laxative therapy, providing benefits that appear to be sustained over prolonged period of time.

Rectal prolapse traumatizes rectal neuromuscular microstructure explaining persistent rectal dysfunction

PURPOSE

Internal rectal prolapse is common and correlates with age. It causes a plug-like physical obstruction and is a major cause of defecation disorder. The progressive distortion of the prolapsing rectum likely causes secondary defects in the rectal wall, which may exacerbate rectal dysfunction. We undertook a prospective observational study to detect and quantify the neurologic and histopathologic changes in the rectal wall.

METHODS

We examined dorsal and ventral rectal wall specimens from consecutive patients with internal rectal prolapse undergoing stapled transanal rectal resection (STARR). We subjected specimens to histopathologic and neuropathologic assessment, including immunohistochemistry. We also recorded patients' clinical and demographic characteristics and sought correlations between these and the pathologic findings.

RESULTS

We examined 100 specimens. The severity of rectal prolapse and the extent of descent of the perineum correlated significantly with age. Concomitant hemorrhoidal prolapse was noted in all male patients and in 79 % of female patients. Muscular and neuronal defects were detected in 94 and 90 % of the specimens, respectively. Only four specimens (4 %) were free of significant structural defects.

CONCLUSION

Rectal prolapse traumatizes the rectum causing neuromuscular defects. The tissue trauma is due to shearing forces and ischemia caused by the intussusception. This initiates a self-reinforcing vicious circle of physical and functional obstruction, further impairing rectal evacuation and causing constipation and incontinence. The correlation between extent of prolapse and age suggests that internal rectal prolapse can be considered a degenerative disorder. Neural and motor defects in the wall of the rectum caused by rectal prolapse are likely irreversible.

A review of sacral nerve stimulation for faecal incontinence following rectal surgery and radiotherapy

AIM

Faecal incontinence may occur following rectal surgery and/or radiotherapy for rectal cancer. The aim of this paper was to review the evidence to support the use of sacral nerve stimulation (SNS) for patients with incontinence who had undergone rectal surgery or received rectal radiotherapy.

METHOD

A search was performed of PubMed, Medline and Embase. All studies which reported the outcome of SNS in patients who had undergone a rectal resection or radiotherapy were reviewed.

RESULTS

The first report of SNS following rectal surgery was in 2002. Since then seven further studies have described its effect in patients who have undergone anterior resection or pelvic radiotherapy. The total number of patients was 57. All studies were single group series, which ranged in size from one to 15 patients. The follow-up ranged from 1 to 36 months. The success of peripheral nerve evaluation ranged from 47% to 100%. Permanent SNS improved the symptoms and in some studies this was reflected in improved quality of life. The wide variation of patient factors, operations performed, the dose of radiotherapy given and time from operation makes interpretation of the results difficult.

CONCLUSION

Larger studies with better patient selection are needed to investigate the effect of SNS on incontinence following radiotherapy or rectal surgery.

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.

Acute sacral nerve stimulation reduces visceral mechanosensitivity in Rat through spinal opioid pathway

BACKGROUND

Sacral nerve stimulation (SNS) is an alternative surgical treatment of refractory urge incontinence and/or fecal incontinence. Despite its clinical efficacy, the mechanisms of action of SNS remain poorly understood. The aim of this experimental study was to evaluate the effect of SNS on visceral mechanosensitivity in rats.

METHODS

Anesthetized Sprague-Dawley rats were treated with SNS or sham stimulation. SNS was performed by implanting an electrode close to the sacral nerve root S1. Rats were administered either a non-selective opioid receptor antagonist (naloxone) or a nitric oxide synthase inhibitor (L-NAME). Colonic mechanosensitivity was evaluated using the variation of arterial blood pressure as a spino-bulbar reflex in response to graded isobaric colorectal distension (CRD). C-fos immunoreactive neurons were quantified in spinal and supraspinal sites. μ-opioid receptor (MOR) internalization was counted in the sacral spinal cord with sham or effective SNS in response to CRD.

KEY RESULTS

SNS reduced visceral mechanosensitivity in response to CRD. This effect was reversed by intrathecal and intraveinous naloxone administration. In both models, CRD induced increased c-fos immunoreactivity in the dorsal horn neurons of the sacral spinal cord and supraspinal areas. This increase was prevented by SNS. MOR internalization was significantly higher in stimulated group.

CONCLUSIONS & INFERENCES

SNS impacts on visceral mechanosensitivity by decreasing the spino-bulbar reflex in response to CRD. Spinal opioid receptors are likely involved in this effect.

Results after sacral nerve stimulation for chronic constipation

BACKGROUND

Sacral nerve stimulation is an established treatment for fecal incontinence and initial reports describe successful results also in subjects with chronic constipation.

METHODS

Consecutive patients with slow transit or outlet obstruction type constipation were offered external stimulation through a test electrode inserted in a sacral foramen during a 3-week period. The symptomatic evaluation was based on the number of bowel movements and a validated obstructed defecation score (ODS). A permanent implant was performed provided an overall 50% decrease in symptoms was observed.

KEY RESULTS

In total, 44 patients with chronic constipation were treated with a 3-week test stimulation. Fifteen experienced a 50% reduction of symptoms and received a permanent implant. Four of the 15 with permanent implants were explanted during the course of the study. Five subjects (11% of original group) reported sustained symptom relief at final follow-up after a mean of 24 months (range 4-81). Mean ODS score did not change during the treatment. Patients with predominantly slow transit constipation or outlet obstruction did not differ concerning success rate.

CONCLUSIONS & INFERENCES

Sacral nerve stimulation has limited efficacy in unselected patients with chronic constipation and cannot be recommended for treatment on routine basis.

Treatment efficacy of sacral nerve stimulation in slow transit constipation: a two-phase, double-blind randomized controlled crossover study

OBJECTIVES

Sacral nerve stimulation (SNS) is a potential treatment for constipation refractory to standard therapies. However, there have been no randomized controlled studies examining its efficacy. In patients with slow transit constipation, we evaluated the efficacy of suprasensory and subsensory SNS compared with sham, in a prospective, 18-week randomized, double-blind, placebo-controlled, two-phase crossover study. The primary outcome measure was the proportion of patients who, on more than 2 days/week for at least 2 of 3 weeks, reported a bowel movement associated with a feeling of complete evacuation.

METHODS

After 3 weeks of temporary peripheral nerve evaluation (PNE), all patients had permanent implantation and were randomized to subsensory/sham (3 weeks each) and then re-randomized to suprasensory/sham (3 weeks each) with a 2-week washout period between each arm. Daily stool dairies were kept, and quality of life (QoL; SF36) was measured at the end of each arm.

RESULTS

Between November 2006 and March 2012, 234 constipated patients were assessed, of whom 59 were willing and deemed eligible to participate (4 male; median age 42 years). Of the 59 patients, 16 (28%) responded to PNE. Fifty-five patients went on to permanent SNS implantation. The proportion of patients satisfying the primary outcome measure did not differ between suprasensory (30%) and sham (21%) stimulations, nor between subsensory (25%) and sham (25%) stimulations. There were no significant changes in QoL scores.

CONCLUSIONS

In patients with refractory slow transit constipation, SNS did not improve the frequency of complete bowel movements over the 3-week active period.

Colonic motor abnormalities in slow transit constipation defined by high resolution, fibre-optic manometry

BACKGROUND

Slow transit constipation (STC) is associated with colonic motor abnormalities. The underlying cause(s) of the abnormalities remain poorly defined. In health, utilizing high resolution fiber-optic manometry, we have described a distal colonic propagating motor pattern with a slow wave frequency of 2-6 cycles per minute (cpm). A high calorie meal caused a rapid and significant increase in this activity, suggesting the intrinsic slow wave activity could be mediated by extrinsic neural input. Utilizing the same protocol our aim was to characterize colonic meal response STC patients.

METHODS

A fiber-optic manometry catheter (72 sensors at 1 cm intervals) was colonoscopically placed with the tip clipped at the ascending or transverse colon, in 14 patients with scintigraphically confirmed STC. Manometric recordings were taken, for 2 h pre and post a 700 kCal meal. Data were compared to 12 healthy adults.

KEY RESULTS

Prior to and/or after the meal the cyclic propagating motor pattern was identified in 13 of 14 patients. However, the meal, did not increase the cyclic motor pattern (preprandial 7.4 ± 7.6 vs postprandial 8.3 ± 4.5 per/2 h), this is in contrast to the dramatic increase observed in health (8.3 ± 13.3 vs 59.1 ± 89.0 per/2 h; p < 0.001).

CONCLUSIONS & INFERENCES

In patients with STC a meal fails to induce the normal increase in the distal colonic cyclic propagating motor patterns. We propose that these data may indicate that the normal extrinsic parasympathetic inputs to the colon are attenuated in these patients.

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.

Management of pelvic floor disorders: biofeedback and more

OPINION STATEMENT

Defecatory disorders (DD) and fecal incontinence (FI) are common conditions. DD are primarily attributable to impaired rectoanal function during defecation or structural defects. FI is caused by one or more disturbances of anorectal continence mechanisms. Altered stool consistency may be the primary cause or may unmask anorectal deficits in both conditions. Diagnosis and management requires a systematic approach beginning with a thorough clinical assessment. Symptoms do not reliably differentiate a DD from other causes of constipation such as slow or normal transit constipation. Therefore, all constipated patients who do not adequately respond to medical therapy should be considered for anorectal testing to identify a DD. Preferably, two tests indicating impaired defecation are required to diagnose a DD. Patients with DD, or those for whom testing is not available and the clinical suspicion is high, should be referred for biofeedback-based pelvic floor physical therapy. Patients with FI should be managed with lifestyle modifications, pharmacotherapy for bowel disturbances, and management of local anorectal problems (e.g., hemorrhoids). When these measures are not beneficial, anorectal testing and pelvic floor retraining with biofeedback therapy should be considered. Sacral nerve stimulation or perianal bulking could be considered in patients who have persistent symptoms despite optimal management of bowel disturbances and pelvic floor retraining.

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.

An update on anorectal disorders for gastroenterologists

Gastroenterologists frequently encounter pelvic floor disorders, which affect 10% to 15% of the population. The anorectum is a complex organ that collaborates with the pelvic floor muscles to preserve fecal continence and enable defecation. A careful clinical assessment is critical for the diagnosis and management of defecatory disorders and fecal incontinence. Newer diagnostic tools (eg, high-resolution manometry and magnetic resonance defecography) provide a refined understanding of anorectal dysfunctions and identify phenotypes in defecatory disorders and fecal incontinence. Conservative approaches, including biofeedback therapy, are the mainstay for managing these disorders; new minimally invasive approaches may benefit a subset of patients with fecal incontinence, but more controlled studies are needed. This mini-review highlights advances, current concepts, and controversies in the area.

Assessment of rectal afferent neuronal function and brain activity in patients with constipation and rectal hyposensitivity

BACKGROUND

Blunted rectal sensation (rectal hyposensitivity: RH) is present in almost one-quarter of patients with chronic constipation. The mechanisms of its development are not fully understood, but in a proportion, afferent dysfunction is likely. To determine if, in patients with RH, alteration of rectal sensory pathways exists, rectal evoked potentials (EPs) and inverse modeling of cortical dipoles were examined.

METHODS

Rectal EPs (64 channels) were recorded in 13 patients with constipation and RH (elevated thresholds to balloon distension) and 11 healthy controls, in response to electrical stimulation of the rectum at 10 cm from the anal verge using a bipolar stimulating electrode. Stimuli were delivered at pain threshold. Evoked potential peak latencies and amplitudes were analyzed, and inverse modeling was performed on traces obtained to determine the location of cortical generators.

KEY RESULTS

Pain threshold was higher in patients than controls [median 59 (range 23-80) mA vs 24 (10-55) mA; P = 0.007]. Median latency to the first negative peak was 142 (±24) ms in subjects compared with 116 (±15) ms in controls (P = 0.004). There was no difference in topographic analysis of EPs or location of cortical activity demonstrated by inverse modeling between groups.

CONCLUSIONS & INFERENCES

This study is the first showing objective evidence of alteration in the rectal afferent pathway of individuals with RH and constipation. Prolonged latencies suggest a primary defect in sensory neuronal function, while cerebral processing of visceral sensory information appears normal.

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.