Effect of sacral nerve stimulation on autonomic nerve function

Transcutaneous Neuromodulation for Constipation and Fecal Incontinence in Children: A Systematic Review and Meta-Analysis

INTRODUCTION

Constipation is a disorder with a multifactorial origin. Constipation has a varied clinical presentation, including infrequent defecation of bulky stools and episodes of retentive fecal incontinence. Neuromodulation has been used to treat many health problems, with promising results.

OBJECTIVE

To conduct a systematic review of randomized clinical trials based on the effects of transcutaneous neuromodulation in treating constipation and retentive fecal incontinence in children and adolescents.

METHODS

A systematic review of randomized clinical trials was performed. Medline (PubMed), PEDro, SciELO, Cochrane (CENTRAL), Embase, and Scopus databases were searched from March 2000 to August 2022. We included clinical trials evaluating transcutaneous neuromodulation in children with constipation and fecal incontinence compared or associated with other types of treatment. Two reviewers independently selected relevant studies, assessed the methodological quality, and extracted the data.

RESULTS

Three studies with 164 participants were included in this review. Two meta-analyses were generated based on these studies. These analyses revealed that transcutaneous neuromodulation is an effective adjuvant treatment modality that improves children's constipation and retentive fecal incontinence. The methodological quality of the included studies was classified as high based on the assessment of the quality of evidence, with a high degree of confidence based on the GRADE system.

CONCLUSIONS

Transcutaneous neuromodulation is an effective adjuvant treatment modality for children with constipation and retentive fecal incontinence.

Modulation of the autonomic nervous system by one session of spinal low-level laser therapy in patients with chronic colonic motility dysfunction

Patients with a defecation disorder may not evoke a normal defecation reflex, or the reflex may be excessive, as a dysfunction of the spinal autonomic nervous system. Treatment with various forms of lumbar and sacral neuromodulation have shown symptom improvement, but potential changes in autonomic functioning are rarely studied. Here we evaluate the effects on autonomic function of a single session of low-level laser therapy (LLLT) on the lumbar and sacral spine in 41 patients with chronic gastrointestinal motor dysfunction. The LLLT protocol used red LED light at a wavelength of 660 nm for 10 min and infrared LED light at a wavelength of 840 nm for 10 min, followed by infrared laser light at a wavelength of 825 nm for 10 min. Effects on the autonomic nervous system were assessed by measuring heart rate variability (HRV) changes. Respiratory Sinus Arrhythmia (RSA) and Root Mean Square of Successive Differences (RMSSD) were used to quantify parasympathetic reactivity; the Baevsky’s Stress Index (SI) reflected sympathetic activity while the ratios SI/RSA and SI/RMSSD were used to show shifts in autonomic dominance. The results indicate that lumbar and sacral neuromodulation using light arrays reduced, whereas stimulation by the laser probes significantly increased parasympathetic activity. The light arrays increased whereas the laser probes significantly decreased sympathetic activity (SI). The entire protocol shifted the autonomic balance toward parasympathetic activity. The comparison of actual vs. sham neuromodulation proved that the change in HRV parameters was due to actual light stimulation and not due to the arrays and probe touching the skin. In conclusion, a single session of LLLT markedly affects autonomic nervous system activity reflected in changes in HRV which is only possible by generating activity in the spinal autonomic nerves. These results warrant a study into the effects of LLLT on restoring autonomic dysfunction in chronic refractory colonic motility disorders.

Effects of neuromodulation on treatment of recurrent anal fissure: A systematic review

BACKGROUND

Anal fissure is a linear tear in the distal anoderm most frequently occurring in the posterior midline. Lateral internal sphincterotomy is considered the gold standard for the treatment of this condition. To this date, several pharmacological and neuromodulatory therapies have been tried out as alternative non-invasive treatments for anal fissures, however, the efficacy of some of these methods remains to be understood.

OBJECTIVE

the primary aim of this study was to review available literature on neuromodulatory treatments for recurrent anal fissure as a potentially effective cure for this condition.

DATA SOURCES

A search was conducted among five main online databases Embase, PubMed, Web of Science, Scopus, and Scholar.

STUDY SELECTION

All published human studies in English literature addressing neuromodulation for the treatment of recurrent anal fissure were selected.

INTERVENTION

neuromodulation for the treatment of anal fissure. We chose to include all articles in which the authors stated that the procedure they performed was via neuromodulation technique, or that the described technique used in their study resembled the technique.

RESULT

Among a total of 3487 evaluated studies, seven represented the effects of neuro modulation on treatment of recurrent anal fissure, among which two were randomized controlled trials and the rest were prospective studies. A total of 186 patient were evaluated in these studies. The mean age of the participants was 46.97 ± 8.2. The average VAS score before intervention was 7.77 ± 2.13, which decreased to 0.31 ± 1.13 after intervention.

LIMITATIONS

limitations of this study include the lack of related articles, and data regarding this subject.

CONCLUSION

Posterior tibial nerve stimulation (PTNS) provides rapid pain relief and fissure healing especially in short-to mid-terms with little to no complications, however, using this treatment, symptoms of anal fissure do not improve as well as LIS, especially in the long-term.

The role of percutaneous tibial nerve stimulation (PTNS) in the treatment of chronic anal fissure: a systematic review

PURPOSE

This study was designed to summarize the current evidence regarding the role of percutaneous tibial nerve stimulation (PTNS) in the treatment of chronic anal fissure (CAF).

METHODS

The present systematic review of the literature was conducted on the basis of the PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. The primary endpoint of our study was the CAF recurrence rate. Quality assessment was based on the RoB 2 tool and the Case Series Quality Checklist.

RESULTS

Overall, 5 studies and 102 patients were included. A considerably heterogeneity in the neuromodulation technique and setting was identified. The pooled recurrence rate was estimated at the level of 19% (16/84). Post-interventional pain and Wexner scores were considerably reduced. The 2-month healing rate was 72% (18/25), whereas 73.6% of patients were symptom-free at 6 months.

CONCLUSIONS

PTNS is an effective alternative for the non-operative management of CAF. Due to several limitations further larger and higher quality studies are required.

Functional segregation within the pelvic nerve of male rats: a meso- and microscopic analysis

The pelvic splanchnic nerves are essential for pelvic organ function and have been proposed as targets for neuromodulation. We have focused on the rodent homologue of these nerves, the pelvic nerves. Our goal was to define within the pelvic nerve the projections of organ-specific sensory axons labelled by microinjection of neural tracer (cholera toxin, subunit B) into the bladder, urethra or rectum. We also examined the location of peptidergic sensory axons within the pelvic nerves to determine whether they aggregated separately from sacral preganglionic and paravertebral sympathetic postganglionic axons travelling in the same nerve. To address these aims, microscopy was performed on the major pelvic ganglion (MPG) with attached pelvic nerves, microdissected from young adult male Sprague-Dawley rats (6-8 weeks old) and processed as whole mounts for fluorescence immunohistochemistry. The pelvic nerves were typically composed of five discrete fascicles. Each fascicle contained peptidergic sensory, cholinergic preganglionic and noradrenergic postganglionic axons. Sensory axons innervating the lower urinary tract (LUT) consistently projected in specific fascicles within the pelvic nerves, whereas sensory axons innervating the rectum projected in a complementary group of fascicles. These discrete aggregations of organ-specific sensory projections could be followed along the full length of the pelvic nerves. From the junction of the pelvic nerve with the MPG, sensory axons immunoreactive for calcitonin gene-related peptide (CGRP) showed several distinct patterns of projection: some projected directly to the cavernous nerve, others projected directly across the surface of the MPG to the accessory nerves and a third class entered the MPG, encircling specific cholinergic neurons projecting to the LUT. A subpopulation of preganglionic inputs to noradrenergic MPG neurons also showed CGRP immunoreactivity. Together, these studies reveal new molecular and structural features of the pelvic nerves and suggest functional targets of sensory nerves in the MPG. These anatomical data will facilitate the design of experimental bioengineering strategies to specifically modulate each axon class.

Efficacy and safety of sacral nerve modulation for faecal incontinence after pelvic radiotherapy

OBJECTIVE

To assess the efficacy and safety of sacral nerve modulation (SNM) in patients with faecal incontinence (FI) after pelvic radiotherapy in comparison with results of SNM for FI related to other conditions.

METHODS

Prospectively collected data from patients who underwent SNM therapy between January 2010 and December 2015 at 7 tertiary colorectal units were reviewed retrospectively. Patients with FI following pelvic radiotherapy were identified and matched (1:2) for age and sex with 38 patients implanted over the same period for FI without previous radiotherapy. The treatment was considered favourable if the patient reported any therapeutic benefit from SNM, had no further complaints or interventions and did not consider stopping the treatment. Long-term results, surgical revision and definitive explantation rates were compared.

RESULTS

Among 352 patients who received a permanent SNM implant, 19 (5.4%) had FI following pelvic radiotherapy. After a mean follow-up of 3.5 ± 1.9 years, the cumulative successful treatment rates were similar between the groups (p = 0.60). For patients with FI following pelvic radiotherapy, the cumulative success rates were 99.4% [85.4-99.8], 96.7% [78.1-99.6], 91.7% [70.4-98.1] and 74.6% [48.4-94.8] at 1, 2, 3 and 5 years respectively. The revision and definitive explantation rates for infection did not differ significantly.

CONCLUSION

The long-term success rate of SNM for FI after pelvic radiotherapy is similar to that of SNM for FI related to other more frequent conditions. Our study suggests that FI after pelvic radiotherapy could be improved with SNM without an increased risk of complication.

Sacral nerve stimulation with appropriate parameters improves constipation in rats by enhancing colon motility mediated via the autonomic-cholinergic mechanisms

Although sacral nerve stimulation (SNS) has been applied for treating constipation, its parameters were adopted from SNS for fecal incontinence, its effects are limited, and mechanisms are largely unknown. We investigated the effects and mechanism of SNS with appropriate parameters on constipation in rats treated with loperamide. First, using rectal compliance as an outcome measure, an experiment was performed to derive effective SNS parameters. Then, a 7-day SNS was performed in rats with constipation induced by loperamide. Autonomic functions were assessed by spectral analysis of heart rate variability (HRV) derived from an electrocardiogram. Serum levels of pancreatic polypeptide (PP), norepinephrine (NE), and acetylcholine (ACh) in colon were assessed. 1) Acute SNS at 5 Hz, 100 µs was found effective in enhancing rectal compliance and accelerating distal colon transit (P < 0.05 vs. sham SNS). 2) The 7-day SNS normalized loperamide-induced constipation, assessed by the number, weight, and water content of fecal pellets, and accelerated the distal colon transit (29.4 ± 3.7 min with sham SNS vs. 16.4 ± 5.3 min with SNS but not gastric emptying or intestinal transit. 3) SNS significantly increased vagal activity (P = 0.035) and decreased sympathetic activity (P = 0.012), assessed by spectral analysis of HRV as well as by the serum PP. 4) SNS increased ACh in the colon tissue; atropine blocked the accelerative effect of SNS on distal colon transit. We concluded that SNS with appropriate parameters improves constipation induced by loperamide by accelerating distal colon motility, mediated via the autonomic-cholinergic function.NEW & NOTEWORTHY Although sacral nerve stimulation (SNS) has been applied for treating constipation, its parameters were adopted from SNS for fecal incontinence, effects are limited, and mechanisms are largely unknown. This paper shows that SNS with appropriate parameters improves constipation induced by loperamide by accelerating distal colon motility mediated via the autonomic-cholinergic function.

Transcutaneous sacral nerve stimulation for intraoperative verification of internal anal sphincter innervation

BACKGROUND

The current standard for pelvic intraoperative neuromonitoring (pIONM) is based on intermittent direct nerve stimulation. This study investigated the potential use of transcutaneous sacral nerve stimulation for non-invasive verification of pelvic autonomic nerves.

METHODS

A consecutive series of six pigs underwent low anterior rectal resection. For transcutaneous sacral nerve stimulation, an array of ten electrodes (cathodes) was placed over the sacral foramina (S2 to S4). Anodes were applied on the back, right and left thigh, lower abdomen, and intra-anally. Stimulation using the novel method and current standard were performed at different phases of the experiments under electromyography of the autonomic innervated internal anal sphincter (IAS).

KEY RESULTS

Transcutaneous stimulation induced increase of IAS activity could be observed in each animal under specific cathode-anode configurations. Out of 300 tested configurations, 18 exhibited a change in the IAS activity correlated with intentional autonomic nerve damage. The damage resulted in a significant decrease of the relative area under the curve of the IAS frequency spectrum (P<.001). Comparison of the IAS spectra under transcutaneous and direct stimulation revealed no significant difference (after rectal resection: median 5.99 μV•Hz vs 7.78 μV•Hz, P=.12; after intentional nerve damage: median -0.27 μV•Hz vs 3.35 μV•Hz, P=.29).

CONCLUSIONS AND INFERENCES

Non-invasive selective transcutaneous sacral nerve stimulation could be used for verification of IAS innervation.

Parasacral transcutaneous electrical nerve stimulation for overactive bladder in constipated children: The role of constipation

BACKGROUND

Parasacral transcutaneous electrical nerve stimulation (TENS) is an effective method for the treatment of overactive bladder (OAB), and, additionally, it accelerates bowel transit time. Therefore, not only does parasacral transcutaneous electrical nerve stimulation (TENS) improve lower urinary tract symptoms (LUTS), but it also resolves the problem of constipation in a significant number of children. Since TENS has a positive effect on LUTS and on the symptoms of fecal retention, it is possible that its action regarding OAB could be directly associated with the improvement in constipation. In other words, the positive effect of parasacral TENS in OAB would be because constipation was resolved. The objective of this study was to test that hypothesis.

OBJECTIVE

To test the hypothesis that the positive effect of parasacral TENS in OAB would be because constipation had improved with this method.

STUDY DESIGN

In this prospective study, children with OAB alone were submitted to parasacral TENS. The inclusion criteria consisted of children with idiopathic OAB alone The Rome III criteria for children of 4-18 years of age were used to diagnose constipation. All the children were treated with 20 sessions of parasacral TENS applied for 20 min, three times weekly on alternating days (Figure). No instructions were given to the participants with respect to diet, laxatives, or pharmaceutical treatment for constipation throughout the study period. None of the patients used anticholinergics. Standard urotherapy was prescribed.

RESULTS

Parasacral TENS improves OAB and constipation. The presence of constipation before treatment was not associated with a poorer prognosis insofar as the resolution of the symptoms of OAB was concerned. Likewise, there was no association between the resolution of constipation with parasacral TENS and the resolution of OAB.

CONCLUSION

There was no statistically significant difference in urinary symptoms between the constipated and nonconstipated children. There was an improvement in urgency, urge incontinency and in holding maneuvers in both the constipated and non-constipated children; however, there was no significant improvement in enuresis. The resolution of OAB was not associated with the resolution of constipation and vice versa.

Parasacral transcutaneous electrical stimulation for overactive bladder in children: An assessment per session

OBJECTIVE

Neuromodulation has emerged as an effective therapeutic option for treatment of OAB in children. However, to our knowledge, no study has yet evaluated the results of neuromodulation on a session-by-session basis. The aim of this study was to evaluate the rate of complete response of overactive bladder (OAB) symptoms for each session of transcutaneous electrical stimulation (TENS), in a protocol of 20 sessions of therapy.

METHOD

This is a prospective study of the improvement of LUTS in children with isolated OAB. Included in this study were children over the age of 4 years who complained of urinary urgency, had bell-or tower-shaped uroflowmetry patterns, and post-void residual <10% of expected capacity for their age and/or less than 20 mL. No patient was treated with an anticholinergic. Children were excluded with lower urinary tract symptoms (LUTS) secondary to urinary tract abnormalities. All patients underwent parasacral transcutaneous neurostimulation (TENS). The development of symptoms was observed right before each session using a visual analog scale (VAS) in which 0 means the absence of improvement and 10 represents maximum improvement of symptoms.

RESULTS

We noted a complete resolution of symptoms (urgency, urge incontinence, frequency, and holding maneuvers) in some patients starting after the third session. In the 10th and 20th (last) sessions, 12 (17.4%) and 38 (55.1%) patients reported a complete resolution of symptoms. After complete resolution, 12 (17.4%) patients reported that their symptoms worsened to a minimum level of 40% improvement, but this was temporary and all returned to 100% improvement. Children who showed an improvement level greater than 50% in the fifth treatment session were 4.18 (p = 0.007) times more likely to have success in the last treatment session.

CONCLUSION

We found that a patient can experience complete symptom resolution as quickly as following the third session of TENS. The complete response rate progressively increases with the number of sessions, slowly until the 12th session and more rapidly after that. When symptom improvement of at least 50% is reported in the fifth session, there is a higher chance that the patient will have full resolution of symptoms at the end of treatment.

Advances in the Surgical Treatment of Fecal Incontinence

Although surgery for fecal incontinence has been shown to be effective, it is still very challenging and sometimes frustrating. Overlapping sphincteroplasty, by far the most common procedure, is effective in patients with sphincter defects; however, recent data suggest that success rates tend to deteriorate over time. A thorough preoperative evaluation incorporates numerous factors, including patient characteristics, severity of incontinence, type and size of the sphincter defect as assessed by physical examination, anal ultrasound, and anorectal physiology studies including anal manometry, electromyography, and pudendal nerve terminal motor latency assessment. The use of these evaluation methods has allowed better patient assignment for a variety of new alternative treatment options. Innovations in the surgical treatment of fecal incontinence range from simple, office-based sphincter augmentation techniques to surgical implantation of mechanical devices. This article reviews 5 alternative surgical treatment options for fecal incontinence: injection of carbon-coated beads in the submucosa of the anal canal, radiofrequency energy delivery, stimulated graciloplasty, artificial bowel sphincter, and sacral nerve stimulation.

Diagnosis and treatment of faecal incontinence: Consensus statement of the Italian Society of Colorectal Surgery and the Italian Association of Hospital Gastroenterologists

Faecal incontinence is a common and disturbing condition, which leads to impaired quality of life and huge social and economic costs. Although recent studies have identified novel diagnostic modalities and therapeutic options, the best diagnostic and therapeutic approach is not yet completely known and shared among experts in this field. The Italian Society of Colorectal Surgery and the Italian Association of Hospital Gastroenterologists selected a pool of experts to constitute a joint committee on the basis of their experience in treating pelvic floor disorders. The aim was to develop a position paper on the diagnostic and therapeutic aspects of faecal incontinence, to provide practical recommendations for a cost-effective diagnostic work-up and a tailored treatment strategy. The recommendations were defined and graded on the basis of levels of evidence in accordance with the criteria of the Oxford Centre for Evidence-Based Medicine, and were based on currently published scientific evidence. Each statement was drafted through constant communication and evaluation conducted both online and during face-to-face working meetings. A brief recommendation at the end of each paragraph allows clinicians to find concise responses to each diagnostic and therapeutic issue.

A prospective trial of temporary sacral nerve stimulation for constipation associated with neurological disease

AIM

This study assessed the effectiveness of temporary sacral nerve stimulation (SNS) in patients with constipation associated with neurological disease using an off-on-off design, and evaluated the long-term response in patients undergoing permanent SNS.

METHOD

Patients with chronic constipation associated with neurological disease receiving specialist clinic care at the University Hospital North Durham over a 2-year period were recruited to a trial of SNS. Recordings of bowel function were made for 6 weeks (baseline) and a temporary electrode was then inserted and recordings were made for the next 3 weeks (stimulation). The electrodes were then removed and assessment was continued for a further 3 weeks (posttreatment). Patient-completed questionnaires were used to determine the severity of constipation (Global Assessment of Symptoms, Constipation, GA Constipation), symptoms (Patient Assessment of Constipation Symptoms score, PAC-SYM) and quality-of-life (Patient Assessment of Constipation-Quality Of Life score, PAC-QOL; European Quality of Life-Five-Domain score; European Quality of Life-Visual Analogue Score). Information was obtained on bowel function and medication. Physiological data were also available for transit and laser Doppler flow cytometry to measure mucosal blood flow.

RESULTS

Twenty-two patients were recruited, of whom 18 completed the trial. GA Constipation reduced significantly during temporary SNS: -1.09 (95% CI -1.59 to -0.59; P = 0.0003). PAC-SYM and PAC-QOL scores showed similar improvements. There was also a significant fall in the time spent in the toilet (P = 0.04) and a decrease in laxative use (P = 0.03). Twelve (67%) patients responded to temporary SNS and received a permanent implant with long-term success in 50%.

CONCLUSION

Sacral nerve stimulation can be effective in treating some patients with refractory severe neuroconstipation. A response to temporary SNS may predict long-term benefit in only half the patients undergoing permanent SNS.

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.

Percutaneous nerve evaluation based on electrode placement under control of autonomic innervation

BACKGROUND

Foramen needle electrode placement for percutaneous nerve evaluation (PNE) is currently carried out while observing the somatic motor response. This study investigated electrode placement while observing the autonomic as well as the somatic response.

METHODS

A consecutive series of ten patients (seven women) with a median age of 51.9 (range 30-75) years undergoing PNE for faecal incontinence (n = 6) and obstipation (n = 4) were investigated prospectively. Electrode placement was carried out under simultaneous electromyography (EMG) of the external anal sphincter (EAS) and internal anal sphincter (IAS) and cystomanometry.

RESULTS

PNE under control of somatic and autonomic nerve responses was carried out in all patients. In three out of ten patients, initial needle electrode placement showed single evoked EMG signals from the EAS. Final electrode placement resulted in adequate somatic motor and autonomic responses in all patients. Comparison of the increases in IAS EMG amplitude on the right and left stimulation sites for sacral nerves S3 and S4 demonstrated significant differences [S3 right: median 15.3 (interquartile range (IQR) 10.4; 20.1) µV vs. S3 left: median 11.6 (IQR 8.6; 16.0) µV, p = 0.034 and S4 right: median 24.1 (IQR 20.1; 37.2) µV vs. S4 left: median 12.0 (IQR 10.7; 13.7) µV, p = 0.012]. Stimulation-induced bladder activation was achieved in all seven patients with concomitant urinary dysfunction.

CONCLUSIONS

Control of not just the somatic motor response but also the autonomic nerve response during foramen needle electrode placement may objectify PNE.

What is the best option for failed sphincter repair?

AIM

This study aimed to evaluate the outcome of various procedures for patients with fecal incontinence following failed sphincteroplasty.

METHOD

Patients who underwent surgery for failed sphincteroplasty from January 2000 to June 2011 [corrected] were identified. They were assessed using the Fecal Incontinence Quality of Life (FIQoL) scale and the Cleveland Clinic Florida-Wexner Fecal Incontinence Score (CCFFIS).

RESULTS

Fifty-nine patients [97% females; median age 52 (25-81) years] were identified. They underwent either repeat sphincteroplasty (RS; n = 33), artificial bowel sphincter (ABS; n = 11) or sacral nerve stimulation (SNS; n = 15). The median follow-up was 31 (3-138) months. The RS group had a significantly wider external sphincter defect and had undergone fewer previous sphincteroplasties. The most common complication was infection. The incidence of complications was significantly higher after ABS (73%) compared with RS (24%) and SNS (33%) (P = 0.01). Seventeen (29%) patients required re-operation for complications or failure, with a lower rate in the RS group (P = 0.004). There was no difference in the rates of device removal after ABS or SNS. Ten (17%) patients underwent further surgery or re-implantation of the device with no difference between the groups. At follow-up, five (45%) ABS and 10 (67%) SNS patients retained a functioning device (P = 0.4). The mean postoperative CCFFIS decreased from 17.5 to 11.5 in the RS group, from 18.7 to 8.6 in the ABS group, and from 17.6 to 9.1 in the SNS group (P ≤ 0.02 for all). There were no differences in the improvement of CCFFIS or FIQoL scores among groups.

CONCLUSION

RS, ABS and SNS are associated with similar improvements in continence after failed sphincteroplasty. Due to increased complications and re-operation with ABS and SNS, RS may be the first step in managing these patients.

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.

Turning off sacral nerve stimulation does not affect gastric and small intestinal motility in patients treated for faecal incontinence

AIM

Sacral nerve stimulation (SNS) reduces symptoms in up to 80% of patients with faecal incontinence (FI). Its effects are not limited to the distal colon and the pelvic floor. Accordingly, spinal or supraspinal neuromodulation have been suggested as part of the mode of action. The effect of SNS on gastric and small-intestinal motility was studied.

METHOD

Using the magnet tracking system, MTS-1, a small magnetic pill was tracked twice through the upper gastrointestinal tract of eight patients with FI successfully treated with SNS. Following a randomized double-blind crossover design, the stimulator was either left active or was turned off for 1 week before investigations with MTS-1.

RESULTS

The median (range) frequency of gastric con-tractions was 3.05 (2.83-3.40) per min during SNS and 3.04 (2.79?-3.76) per min without (P=NS). The median (range) frequency of contractions in the small intestine during the first 2h after pyloric passage was 10.005 (9.68-10.70) per min during SNS and 10.09 (9.79-10.29) per min without SNS (P=NS). The median (range) velocity of the magnetic pill during the first 2h in the small intestine was 1.6 (1.2-2.8) cm/min during SNS and 1.7 (0.8-3.7) cm/min without SNS (P=NS). Small-intestinal propagation mainly occurred during very fast movements (>15cm/min), accounting for 51% (42-60%) of the distance 3% (2-4%) of the time during SNS and for 53% (18-73%) of the distance 3% (1-8%) of the time without SNS (P=NS).

CONCLUSION

Turning off SNS for 1week did not affect gastric or small-intestinal motility patterns.

Sacral nerve stimulation enhances epithelial barrier of the rectum: results from a porcine model

BACKGROUND

The mechanism of action of sacral nerve stimulation (SNS) remains largely elusive. The aims of this study were to develop a clinically relevant animal model for percutaneous SNS and to describe its effect on the epithelial barrier of the rectum.

METHODS

Under general anesthesia and after percutaneous electrode placement for S3 nerve root stimulation, six pigs underwent unilateral stimulation and six bilateral stimulation. Animals were stimulated for 3 h using an external pulse generator (1-2.5 V; 14 Hz; 210 μs). Six animals underwent electrode implantation without stimulation and served as controls. Full-thickness rectal biopsies were performed prior to and after stimulation. Paracellular permeability was evaluated by measuring sulfonic acid flux across the rectal mucosa in Ussing chambers. Histological assessment of mucosal thickness, epithelial desquamation, and mucus expression were performed.

KEY RESULTS

Percutaneous stimulation resulted in successful anal contractions whose amplitude and uniformity was enhanced following bilateral compared with unilateral stimulation. In controls, paracellular permeability significantly increased during the stimulation period whereas it remained unchanged following unilateral stimulation. In contrast, permeability was significantly reduced by bilateral stimulation. This effect was associated with a concomitant reduction in mucosal thickness and a trend toward increased amount of mucus on surface epithelium compared with controls.

CONCLUSIONS & INFERENCES

The development of a porcine model of percutaneous SNS revealed the ability of neuromodulation to reinforce rectal epithelial barrier. Furthermore, our results suggest that SNS could be used for treatment of gastrointestinal pathologies with reduced rectal mucosal barrier functions.

Temporary sacral nerve stimulation alters rectal sensory function: a physiological study

BACKGROUND

The indications for sacral nerve stimulation are increasing, but the mechanism remains poorly understood.

OBJECTIVE

This study aimed to examine the effect of sacral nerve stimulation on rectal compliance and rectal sensory function.

DESIGN

This was a prospective study.

SETTINGS

This study took place at a university teaching hospital.

PATIENTS

Twenty-three consecutive consenting patients (22 female; median age, 49 y) undergoing temporary sacral nerve stimulation for fecal incontinence were prospectively studied. Clinical response was assessed by the use of bowel diaries and Wexner scores.

MAIN OUTCOME MEASURES

Anal manometry, rectal compliance, volume and pressure thresholds to rectal distension (barostat), and rectal Doppler mucosal blood flow were measured before and at the end of stimulation.

RESULTS

Sixteen patients (70%) had a favorable clinical response. Median anal squeeze pressures increased with stimulation from 40 (range, 6-156) cmH2O to 64 (range, 16-243) cmH2O. Median rectal compliance did not significantly change with stimulation (prestimulation: 11.5 (range, 7.9-21.8) mL/mmHg, poststimulation: 12.4 (range, 6.2-22) mL/mmHg, P = .941). Rectal wall pressures associated with urge (baseline: 15.4 (range, 11-26.7) mmHg, poststimulation: 19 (range, 11.1-42.7) mmHg, P = .054) and maximal tolerated thresholds (baseline: 21.6 (8.5-31.9) mmHg, poststimulation: 27.1 (14.3-43.3) mmHg, P = .023) significantly increased after stimulation. Rectal Doppler mucosal blood flow did not significantly change with stimulation (baseline: 125.8 (69.9-346.8), poststimulation: 112.4 (50.2-404.1), P = .735). Changes in anal resting pressure and rectal wall pressures with stimulation were evident only in responders; however, changes in anal squeeze pressures were evident in both responders and nonresponders.

LIMITATIONS

The study reports results following short-term stimulation in a small but homogenous group of patients. A larger long-term study will follow.

CONCLUSION

Temporary sacral nerve stimulation does not change rectal compliance, but is associated with significant changes to the pressure thresholds of rectal distension. This, together with the observation that outcome is not related to sphincter integrity, supports the hypothesis of an afferent-mediated mechanism of action.

How sacral nerve stimulation works in patients with faecal incontinence

AIM

Sacral nerve stimulation (SNS) reduces incontinence episodes and improves the quality of life of patients treated for faecal incontinence. However, the exact mechanism of action of this technique remains unclear. The present article reviews the pertinent neuroanatomy and neurophysiology related to SNS and provides explanations for potential mechanisms of action.

METHOD

A systematic review of the literature was performed for studies of the potential mechanisms of action of SNS, using MEDLINE, PubMed, Embase and the Cochrane Library. Articles dealing with the technique, adverse events and economic evaluations of SNS, as well as literature reviews, were excluded, except for reviews dealing with the mechanisms of action of SNS. The following inclusion criteria were used to select articles: (i) articles in English, (ii) randomized, double-blinded, sham-controlled studies, and (iii) cohort studies. Case-control studies or retrospective studies were cited only when randomized or cohort studies could not be found.

RESULTS

We propose three hypotheses to explain the mechanism of action of SNS: (i) a somato-visceral reflex, (ii) a modulation of the perception of afferent information, and (iii) an increase in external anal sphincter activity.

CONCLUSION

The mechanism of action of SNS in patients with faecal incontinence almost certainly depends on the modulation of spinal and/or supraspinal afferent inputs. Further research on humans and animals will be required to gain a better understanding of the mechanisms of action of SNS.

The influence of sacral nerve stimulation on anorectal dysfunction

AIM

Sacral nerve stimulation (SNS) has become an established option in the management of defaecatory disorders. There are many data on the end-organ effects of SNS, but limited consensus on its mechanism of action. The objective of this review was to determine the effect of sacral nerve stimulation (SNS) on anorectal function.

METHOD

Systematic literature review of the effect of sacral nerve stimulation (SNS) on anorectal function.

RESULTS

There was significant heterogeneity of data pertaining to the effects of SNS on anorectal function, with no consistent change in physiological measures identified. Most data supported a mixed mechanism of action on anal motor and rectal sensory functioning.

CONCLUSION

To date, conflicting data exist on the mechanism of action of SNS as determined by end-organ changes in anorectal physiology. Nevertheless, the data as they stand best support a mixed mechanism of action on anal motor and rectal sensory functions.

Neuromodulation for constipation: sacral and transcutaneous stimulation

Constipation is a frequently occurring digestive ailment that is usually treated conservatively. Neuromodulation is altering function of an organ by altering neural activity. This paper reviews methods of neuromodulation used to treat constipation. This includes direct stimulation of sacral nerves and stimulation across the skin. Direct stimulation of sacral nerves is the most well developed method and is presented in detail. It is generally accepted that the mechanism of action is modulation rather than stimulation so it is called sacral neuromodulation (SNM). SNM involves percutaneous placement of an electrode in the third sacral foramen and implanting a stimulating device under the skin in the buttocks. SNM is founded on the physiological principle that activity in one neural pathway modulates pre-existing activity in another through synaptic interaction. The mechanism of action in constipation may be neuromodulation of the extrinsic neural control of the large bowel or modulation of reflexes inhibiting large bowel function. Limited evidence is available to assess the outcome of SNM in constipation. Results in the medium term seem promising for selected patients with idiopathic slow and normal transit constipation not responding to optimal conservative treatment. Adverse events include electrode migration and infection. The availability of a testing phase provides a predictor of treatment outcome. In addition, transcutaneous stimulation using sticky pad electrodes over the lumbosacral region or acupuncture points has been reported to improve constipation symptoms. In general, the level of evidence is low and further studies are needed.

Sacral nerve stimulation for the treatment of fecal incontinence

The use of sacral nerve stimulation as a treatment for fecal incontinence for intact but functionally deficient sphincter and pelvic floor musculature, as well as for some sphincter injuries, is an attractive concept that is currently undergoing clinical trials in the United States. Electrical stimulation of the peripheral nerve supply to the striated anal sphincter muscles at the level of the sacral spinal nerves exploits the accessibility of the most distal common location of the dual peripheral nerve supply to these muscles. While the mechanism of sacral nerve stimulation's salutary effect remains conjectural at present and is likely multifactorial, current experimental data point toward both an enhancement in striated muscular activity as well as neuromodulation of sacral reflexes that regulate rectal sensitivity and contractility.

Sacral nerve neuromodulation is effective treatment for fecal incontinence in the presence of a sphincter defect, pudendal neuropathy, or previous sphincter repair

PURPOSE

To assess the effectiveness of sacral nerve neurostimulation in the setting of sphincter defects, previous sphincter repair, or pudendal neuropathy.

METHODS

A total of 55 patients underwent insertion of a sacral nerve neurostimulator for fecal incontinence. There were 52 female and 3 male patients, with a mean age of 51 (range, 25-65) years and a median follow-up of 37 (range, 15-41) months.

RESULTS

There was a significant improvement in the median Cleveland Clinic continence score for all of the patients, from a median of 15 (13-18) before insertion of the neurostimulator, to a median of between 4 and 7 during the follow-up period of up to 48 months. (P < .001-.008). Patients with a sphincter defect on endoanal ultrasound, a pudendal neuropathy, or a previous sphincter repair did not show any significant differences in continence scores during the follow-up period (P = .46, .25, and .81, respectively). The Fecal Incontinence Quality of Life score also showed a significant improvement on all 4 scales, Lifestyle (median 2.00 baseline to 3.00-3.70 P = .001-.008), Coping/Behavior (median 1.56 baseline to 2.89-3.22 P = .001-.007), Depression/Self-Perception (median 2.29 baseline to 2.93-3.71 P = .001-.005), and Embarrassment (median 1.50 baseline to 2.17-3.00 P = .001-.013) after insertion at all time intervals up to 36 months. The Fecal Incontinence Quality of Life score was higher than the baseline at 48 months but only statistically significant for Lifestyle (median 3.10, P = .04) and Coping/Behavior (median 2.63, P = .03) scores. There were 6 device-related complications.

CONCLUSIONS

Sacral nerve neuromodulation results in a significant improvement in fecal incontinence and Fecal Incontinence Quality of Life scores after medium-term follow-up, even when there is a sphincter defect or pudendal neuropathy.

Sympathetic and parasympathetic regulation of rectal motility in rats

INTRODUCTION

The colon and rectum are regulated by the autonomic nervous system (ANS). Abnormalities of the ANS are associated with diseases of the colon and rectum while its modulation is a putative mechanism for sacral nerve stimulation. The purpose of this study is to establish a rat model elucidating the role of the efferent ANS on rectal motility.

MATERIALS AND METHODS

Rectal motility following transection or stimulation of parasympathetic pelvic nerves (PN) or sympathetic hypogastric nerves (HGN) was measured with rectal strain gauge transducers and quantified as a motility index (MI). Colonic transit was measured 24 hours after transection by calculating the geometric center (GC) of distribution of (51)Cr

RESULTS AND DISCUSSION

Transection of PN and HGN decreased MI to 518 +/- 185 g*s (p < 0.05) and increased MI to 5,029 +/- 1,954 g*s (p < 0.05), respectively, compared to sham (975 +/- 243 g*s). Sectioning of PN and HGN decreased transit with GC = 4.9 +/- 0.2 (p < 0.05) and increased transit with GC = 8.1 +/- 0.7 (p < 0.02), respectively, compared to sham (GC = 5.8 +/- 0.3). Stimulation of PN and HGN increased MI to 831 +/- 157% (p < 0.01) and decreased MI to 251 +/- 24% (p < 0.05), respectively.

CONCLUSION

Rectal motility is significantly altered by sectioning or stimulating either HGN or PN. This model may be useful in studying how sacral nerve stimulation exerts its effects and provide insight into the maladies of colonic motility.

Function and dysfunction of the colon and anorectum in adults: working team report of the Swedish Motility Group (SMoG)

Symptoms of fecal incontinence and constipation are common in the general population. These can, however, be unreliably reported and are poorly discriminatory for underlying pathophysiology. Furthermore, both symptoms may coexist. In the elderly, fecal impaction always must be excluded. For patients with constipation, colon transit studies, anorectal manometry and defecography may help to identify patients with slow-transit constipation and/or pelvic floor dysfunction. The best documented medical treatments for constipation are the macrogols, lactulose and isphagula. Evolving drugs include lubiprostone, which enhances colonic secretion by activating chloride channels. Surgery is restricted for a highly selected group of patients with severe slow-transit constipation and for those with large rectoceles that demonstrably cause rectal evacuatory impairment. For patients with fecal incontinence that does not resolve on antidiarrheal treatment, functional and structural evaluation with anorectal manometry and endoanal ultrasound or magnetic resonance (MR) of the anal canal may help to guide management. Sacral nerve stimulation is a rapidly evolving alternative when other treatments such as biofeedback and direct sphincter repair have failed. Advances in understanding the pathophysiology as a guide to treatment of patients with constipation and fecal incontinence is a continuing important goal for translational research. The content of this article is a summary of presentations given by the authors at the Fourth Meeting of the Swedish Motility Group, held in Gothenburg in April 2007.

Neurogenic bowel dysfunction: pathophysiology, clinical manifestations and treatment

Bowel dysfunction (e.g., fecal incontinence, infrequent or difficult defecation) are both frequent and severely troubling problems for patients with spinal cord injury, multiple sclerosis and Parkinson's disease. The etiology of these symptoms is complex; there may be autonomic and pelvic nerve dysfunction (with attenuation of voluntary motor function and impaired anorectal sensation and anorectal reflexes), or generalized systemic factors (e.g., altered diet and behavior, impaired mobility, psychological disturbances or drug adverse effects). The mainstay of current treatment is adapting a conservative approach towards reversing the systemic effects and optimizing the mechanics of defecation through the use of laxatives and irrigation approaches. When successful, this approach improves both evacuation and incontinence symptoms, with associated improvements in quality of life and independence. Future therapies may be directed at modulating pelvic innervation through electrical stimulation. Stoma formation remains an option for patients refractory to other approaches.

Reduced somatosensory cortical activation in experimental models of neuropathic fecal incontinence

PURPOSE

Alteration in cortical awareness may be the underlying abnormality in patients with neuropathic fecal incontinence. The cortical effects of inferior rectal nerve injury were determined using somatosensory evoked cortical potential recordings in an experimental model of neuropathic fecal incontinence.

METHODS

Eighteen female virgin Wistar rats were assigned equally to one of three groups: an unoperated control group, a nerve crush group (positive control), and a nerve balloon compression group. Four weeks following the injury, all animals underwent somatosensory evoked cortical potential recordings. Following this, the inferior rectal nerve was harvested, resin-embedded, sectioned (1 microm thickness), and axonal counts and axonal cross-sectional areas were analyzed using Scion Image software.

RESULTS

Somatosensory evoked cortical potentials were reduced in the nerve crush and balloon compression groups compared with controls (P = 0.024, P = 0.03, respectively). The inferior rectal nerve was harvested in 14 of the 18 animals (4 control, 5 nerve crush, 5 balloon compression). There were no differences in median inferior rectal nerve total axonal counts (P = 0.69) or in the frequency distribution of axonal cross-sectional area between groups (control vs. nerve crush and control vs. balloon compression: P = 0.92, P = 0.17, respectively).

CONCLUSIONS

Somatosensory evoked cortical potential amplitude is reduced following crush or compression injury to the inferior rectal nerve. In neuropathic fecal incontinence, alteration in cortical awareness may be the result of processing modification at a central and not peripheral level.

Neuromodulation for functional bowel disorders

In patients with functional bowel disorders not responding to maximal medical treatment, bowel lavage or biofeedback therapy, can nowadays be treated by sacral nerve neuromodulation (SNM). SNM therapy has evolved as a treatment for faecal incontinence and constipation. The exact working mechanism remains unknown. It is known that SNM therapy causes direct stimulation of the anal sphincter and causes changes in rectal sensation and several central nervous system areas. The advantage of SNM therapy is the ability to do a minimally invasive temporary screening phase to assess permanent stimulation outcome. Ideal candidates for SNM therapy are not known. Several studies have described positive and negative predictive factors, but the temporary screening remains the instrument of choice. Clinical results are good and as the technique is developing, fewer complications occur. New indications for SNM include constipation and anorectal or pelvic pain.

Improving the efficacy of sacral nerve stimulation for faecal incontinence by alteration of stimulation parameters

Background

Sacral nerve stimulation (SNS) is an effective treatment for faecal incontinence, but only standard stimulation parameters have been used. This study assessed the clinical impact of altering the parameters.

Methods

Twelve patients with partially improved faecal incontinence following SNS underwent acute testing to select optimal stimulation parameters; rectal compliance was used as a surrogate marker. Parameters tested were: stimulation off; frequency 14 (standard), 31 or 6·9 Hz; and pulse duration 210 (standard), 450 or 90 µs. Patients completed a 2-week bowel diary, St Mark's continence score (SMCS) and Rockwood faecal incontinence quality-of-life (FIQL) score before testing using standard settings, and after testing using optimized settings.

Results

Optimal settings, determined by greatest increase in rectal compliance, were shorter pulse width in five patients and higher frequency in seven. Optimized stimulation resulted in a decrease in mean episodes of incontinence from 2·3 to 1·2 per week (P = 0·031), soiling from 3·3 to 1·7 days per week (P = 0·016), faecal urgency from 31 to 18 per cent of all evacuations (P = 0·055) and SMCS from 12·3 to 8·7 (P = 0·008); the FIQL coping/behaviour score improved (P = 0·008).

Conclusion

With a shorter pulse width and higher frequency, clinical efficacy in patients undergoing SNS for faecal incontinence can be improved.

Surgery and sacral nerve stimulation for constipation and fecal incontinence

Fecal continence is a complex bodily function, which requires the interplay of sensation, rectal capacity, and anal neuromuscular function. Fecal incontinence affects approximately 2% of the population and has a prevalence of 15% in elderly patients. Constipation is one of the most common gastrointestinal disorders. The variety of symptoms and risk factors suggest a multifactorial origin. Before any invasive intervention, the surgeon should have a thorough understanding of the etiology of these conditions. Appropriate medical management can improve symptoms in the majority of patients. Surgery is indicated when all medical possibilities are exhausted. This review discusses the most used surgical procedures emphasizing the latest experiences. Sacral nerve stimulation (SNS) is a promising option for patients with fecal incontinence and constipation. The procedure affords patients improved continence and quality of life. The mechanism of action is still poorly understood. This treatment has been used before in other more invasive surgical procedures or even after their failure to improve patients' symptoms and avoid a definitive stoma. Before any invasive intervention, the surgeon should have a thorough understanding of the etiology of these conditions. Appropriate medical management can improve symptoms in the majority of patients. Surgery is indicated when all medical possibilities are exhausted. This review discusses the most used surgical procedures emphasizing the latest experiences. Sacral nerve stimulation (SNS) is a promising option for patients with fecal incontinence and constipation. The procedure affords patients improved continence and quality of life. The mechanism of action is still poorly understood. This treatment has been used before in other more invasive surgical procedures or even after their failure to improve patients' symptoms and avoid a definitive stoma.

Sacral nerve stimulation and rectal function: results of a prospective study in faecal incontinence

The mechanisms of action of sacral nerve stimulation (SNS) to treat faecal incontinence remain poorly understood.

THE AIMS OF OUR STUDY WERE

(i) to measure the effect of SNS on rectal function and (ii) to evaluate rectal function as a predictive factor of clinical response to SNS. Rectal function was studied before and 3 months after permanent SNS in 18 patients (17 women, mean age 58.5 years) with faecal incontinence, using an electronic barostat. Rectal sensitivity and volume variations were recorded during isobaric distensions. Three months after SNS, 14 patients had a significant improvement of faecal incontience symptoms and four had not. Baseline 'maximal tolerated volume' was significantly lower in the positive response group (210 +/- 56 vs 286 +/- 30 mL, P = 0.02). Baseline rectal compliance was lower in patients with a positive response than those without, although this difference did not reach significance (6.2 +/- 3.2 vs 9.2 +/- 2.9 mL mmHg(-1),P = 0.10). Rectal compliance was not significantly modified by SNS. Our results suggest that an increased rectal capacity as measured by the maximal tolerated volume may be a predictive factor of poor response to SNS in faecal incontinence. SNS does not significantly modify rectal function.

Sacral nerve stimulation for faecal incontinence

BACKGROUND

Faecal incontinence resulting from obstetric injury is a socially disabling condition with a significant impact on quality of life. Sacral nerve stimulation (SNS) is a relatively new treatment modality, which offers patients a potential for improved continence.

METHODS

We reviewed our initial experience of SNS in 14 patients (mean age 54 years, range 30-72) with faecal incontinence from January 2006 to June 2007. Background demographics, past medical and obstetric history, anal manometry, endoanal ultrasound and pudendal nerve studies were recorded on all patients. All patients who had permanent SNS implants inserted had pre and post operative questionnaires consisting of the Wexner Continence Score and the Rockwood and SF-36 Quality of Life Indices.

RESULTS

Out of 14 patients, 13 had incontinence related to obstetric injuries while one was related to a cauda equina syndrome. All patients had a test procedure consisting of placement of temporary electrodes and a 2-week trial of external SNS. Ten patients noted a significant improvement in their continence and these 10 patients subsequently had a permanent SNS device implanted with an overall significant improvement in continence (P < 0.001) and quality of life (P < 0.01). There were no immediate postoperative complications and one late failure consisting of a lead fracture, which was replaced successfully. Four (29%) patients did not have a significant benefit from temporary SNS and two of these patients subsequently had a colostomy.

CONCLUSIONS

SNS offers improvement in continence and quality of life in patients with faecal incontinence whose only other option might otherwise be a permanent colostomy.

Evolving therapy for fecal incontinence

BACKGROUND

Fecal incontinence is common and can be socially debilitating. Nonoperative management of fecal incontinence includes dietary modification, antidiarrheal medication, and biofeedback. The traditional surgical approach is sphincteroplasty if there is a defect of the external sphincter. Innovative treatment modalities have included sacral nerve stimulation, injectable implants, dynamic graciloplasty, and artificial bowel sphincter.

DISCUSSION

This review was designed to assess the various surgical options available for fecal incontinence and critically evaluate the evidence behind these procedures. The algorithm in the surgical treatment of fecal incontinence is shifting. Injectable therapy and sacral nerve stimulation are likely to be the mainstay in future treatment of moderate and severe fecal incontinence, respectively. Sphincteroplasty is limited to a small group of patients with isolated defect of the external sphincter. A stoma, although effective, can be avoided in most cases.

Permanent sacral nerve stimulation for treatment of functional anorectal pain: report of a case

PURPOSE

Patients with functional anorectal pain in the absence of an organic cause often have symptoms that are resistant to conventional medical and behavioral therapy. This study assessed the use of sacral nerve stimulation in the treatment of this condition.

METHODS

A 56-year-old, female subject with an 18-month history of intermittent severe anorectal pain, in the absence of any evacuatory disorder or gross pathology, underwent temporary then subsequent permanent sacral nerve stimulation. Treatment efficacy was measured by verbal pain scores obtained at baseline, during screening, after screening, and subsequent follow-up.

RESULTS

Temporary sacral nerve stimulation of the left S3 root (3-5 V; 14 Hz; 210 microsec) resulted in total alleviation of the patient's symptoms. A verbal pain score of 10/10 preoperatively was reduced to 0/10 with no adverse effects from stimulation. On completing the trial evaluation, the symptoms of pain returned with a verbal pain score of 10/10. A permanent pulse generator was implanted with a Medtronic 3093 quadripolar electrode lead, placed in the left S3 foramen. Results of chronic stimulation showed that pain symptoms were again abolished with no recurrence of symptoms seen at one-year follow-up (1.3 V; 14 Hz; 210 microsec).

CONCLUSIONS

Sacral nerve stimulation may be of benefit in the treatment of functional anorectal pain resistant to conventional treatments. The mechanism of action is not known. Further prospective evaluation of a series of patients is required using pain scoring, quality of life, and psychologic assessment to aid selection.

Sacral nerve stimulation for fecal disorders: evolution, current status, and future directions

Sacral nerve stimulation (SNS) aims to recruit residual function of the anorectal continence organ by electrostimulation of its peripheral nerve supply. Since its first application for the treatment of fecal incontinence in 1994, its acceptance has been broadened and it is today considered a valuable addition to the therapeutic armentarium. Initially, its use was based on conceptual considerations, but changed to a pragmatic trial and error approach. Thus, the patients selection evolved: patients suffering from fecal incontinence due to a wide variety of causes are today selected for permanent SNS after a phase of temporary test stimulation. This test is highly predictive. If it is of clinical benefit, a neurostimulation device is implanted for chronic stimulation. Permanent stimulation not only improves or restores continence, but also has a substantial impact on quality of life. This has been uniformaly proven in multiple single and multicentre trials in a wide variety of aetiologies causing fecal incontinence. Despite the growing experience with the clinical use of SNS and its therapeutic effectiveness, the knowledge of its mechanism of action remains limited. Current research aims to improve our understanding of its action, to expand the spectrum of clinical applications and to implement recent technical developments.

Novel approaches in the treatment of fecal incontinence

The availability of novel techniques to treat end-stage FI gives hope for a better quality of life in patients who were traditionally treated by a permanent stoma. The diversity of causes of FI and the different modes of action of the various treatment modalities mandate a tailored, individualized approach in each case. A meticulous preoperative evaluation process is imperative in the course of the decision-making of which procedure to perform, with full awareness that a stoma still may be the best option for some patients who have end-stage FI.

Sacral nerve stimulation can be successful in patients with ultrasound evidence of external anal sphincter disruption

PURPOSE

This study was designed to determine whether patients with fecal incontinence and endoanal ultrasound evidence of anal sphincter disruption may be successfully treated by sacral nerve stimulation.

METHODS

Five consecutive females with incontinence to solids and endoanal ultrasound evidence of anal sphincter disruption were treated by a two-week trial of sacral nerve stimulation. If successful, patients then proceeded to permanent sacral nerve stimulation implantation.

RESULTS

Five patients, aged 34 to 56 years, were treated by temporary sacral nerve stimulation. Four had symptoms starting after childbirth. Two had previously had an anterior sphincter repair. After a two-week trial, three females reported full continence and an improvement in all aspects of their Rockwood fecal incontinence quality of life scores. These three females underwent permanent sacral nerve stimulation implantation. The remaining two patients reported no improvement and underwent dynamic graciloplasty or end colostomy respectively.

CONCLUSIONS

Sacral nerve stimulation may successfully restore bowel continence in some patients with endoanal ultrasound evidence of a defect in their external anal sphincter.

Sacral nerve stimulation for faecal incontinence in patients with previous partial spinal injury including disc prolapse

BACKGROUND

This study examined the use of sacral nerve stimulation (SNS) to treat faecal incontinence in patients with partial spinal injury.

METHODS

Patients selected for SNS had experienced more than one episode of faecal incontinence per week to liquid or solid stool for more than 1 year and had failed maximal conservative treatment. All patients had an intact external anal sphincter.

RESULTS

Temporary SNS was performed in 13 patients (median age 58.5 (range 39-73) years). The spinal insults were disc prolapse (six), trauma (four), spinal stenosis (one) or occurred during neurosurgery (two). Twelve patients (eight women and four men) had successful temporary stimulation and proceeded to permanent implantation. The median follow-up time was 12 (range 6-24) months. The mean(s.d.) number of episodes of incontinence decreased from 9.33(7.64) per week at baseline to 2.39(3.69) at last follow-up (P = 0.012). The number of days per week with incontinence and staining decreased significantly (both P < 0.001). Ability to defer defaecation improved from a median of not being able to defer (range 0-1 min) to being able to defer for 5-15 (range 0 to over 15) min (P = 0.022).

CONCLUSION

SNS can benefit patients with faecal incontinence following partial spinal injury.

Neuromodulation for constipation and fecal incontinence

The evidence is consistent with permanent SNM substantially improving continence in patients with severe fecal incontinence resistant to medical treatment. This treatment has been used in patients in whom a major surgical intervention would normally have been the next stage in treatment and the option of a minimally invasive treatment, with the added advantage of testing before definitive implantation, has the potential to have a major impact on this patient group. The results of the early case series examining the use of SNM for constipation are encouraging. Patients who have failed maximal medical treatment for constipation pose considerable clinical difficulties, with current surgical treatments requiring a bowel resection or stoma formation. If SNM proves to be of benefit to a proportion of these patients, this will be of considerable importance in terms of their future treatment options. Fecal incontinence and idiopathic constipation are both conditions in which conservative treatment is the mainstay of treatment in most cases,but for a small proportion surgical intervention is warranted. The surgical procedures available,however, have a considerable invasive component with often little guarantee of symptom resolution. SNM is becoming more widely used for patients with fecal incontinence as series sizes get larger and follow-up longer. Its potential benefit in constipation has been shown in pilot studies but larger trials are still required.

Sacral nerve stimulation: an emerging treatment for faecal incontinence

Faecal incontinence is common, distressing to the patient and socially incapacitating. The treatment options depend on the severity and aetiology of incontinence. For mild cases of faecal incontinence, medical management and pelvic floor physiotherapy may be adequate. For more severe cases, surgery is often required. Patients who have a distinct sphincter defect are amenable to surgical repair. In many cases, there is a combination of diffuse structural damage of the anal sphincters with pudendal neuropathy. Conventional surgical repairs have a modest degree of success and the results tend to deteriorate with time. Neosphincter procedures such as artificial bowel sphincter and dynamic graciloplasty are potentially morbid and technically complex. Sacral nerve stimulation is innovative and has had a medium-term success with improvement of quality of life in over 80% of patients treated for faecal incontinence. These results are superior to other techniques in treating patients with severe refractory faecal incontinence, where current maximal therapy has failed. The technique is unique because there is a screening phase, which has a high predictive value. It is also associated with minimal complications that are usually minor. However, most published reports of sacral nerve stimulation for treatment of faecal incontinence were case studies and methods of assessing outcome were variable. Criteria for patient selection are evolving and are yet to be defined. The present paper critically reviews the publications to date on sacral nerve stimulation for treatment of faecal incontinence. This will form the basis for future evaluation of this emerging treatment of severe, intractable faecal incontinence. Randomized clinical trials like that of the Melbourne trial will further clarify the role and indications of sacral nerve stimulation for faecal incontinence.

Systematic review of sacral nerve stimulation for faecal incontinence and constipation

BACKGROUND AND METHOD

This systematic review assesses the efficacy and safety of sacral nerve stimulation (SNS) for faecal incontinence and constipation. Electronic databases and selected websites were searched for studies evaluating SNS in the treatment of faecal incontinence or constipation. Primary outcome measures included episodes of faecal incontinence per week (faecal incontinence studies) and number of evacuations per week (constipation studies).

RESULTS

From 106 potentially relevant reports, six patient series and one crossover study of SNS for faecal incontinence, and four patient series and one crossover study of SNS for constipation, were included. After implantation, 41-75 per cent of patients achieved complete faecal continence and 75-100 per cent experienced improvement in episodes of incontinence. There were 19 adverse events among 149 patients. The small crossover study reported increased episodes of faecal incontinence when the implanted pulse generator was switched off. Case series of SNS for constipation reported an increased frequency of evacuation. There were four adverse events among the 20 patients with a permanent implant. The small crossover study reported a reduced number of evacuations when the pulse generator was switched off.

CONCLUSION

SNS results in significant improvement in faecal incontinence in patients resistant to conservative treatment. Early data also suggest benefit in the treatment of constipation.

Innovations in fecal incontinence: sacral nerve stimulation

OBJECTIVE

The aim of this study was to present an overview of sacral nerve stimulation in the treatment of fecal incontinence. We describe the evolution in technique, patient selection, and indications, and review results and complications.

METHODS

All articles on sacral nerve stimulation for fecal incontinence that were recovered on MEDLINE search were reviewed. With multiple articles from an institution, the most recent reports with the longest follow-up and largest cohort of patients were selected, unless information from earlier reports was relevant.

RESULTS

The technique of sacral stimulation is well established, carries little risk, and continues to be refined (e.g., a less invasive approach has been proposed). Patient selection is based on a two-stage diagnostic test stimulation (acute and subchronic), for which the predictive value is high. On this basis, permanent sacral nerve stimulation has proved effective in both single-center and multicenter trials in patients with a functional deficit but limited morphologic lesions or no morphologic lesions. The clinical benefit derives from multiple symptomatic improvements contributing to better bowel control and from substantially improved quality of life. The underlying mechanism of action remains undefined, but both somatic and autonomic function appears affected.

CONCLUSION

Sacral nerve stimulation offers a safe treatment mode in a patient population in whom conservative treatment has failed and traditional surgical approaches would have limited success. The high predictive value of the diagnostic approach offers a unique therapeutic advantage.