Anal Sphincter Asymmetry in Anal Incontinence After Restorative Proctectomy for Rectal Cancer

Resting vector volume measured before ileostomy reversal may be a predictor of major fecal incontinence in patients with mid or low rectal cancer: a longitudinal cohort study using a prospective clinical database

PURPOSE

Despite a high incidence of fecal incontinence following sphincter-preservation surgery (SPS), there are no definitive factors measured before ileostomy reversal that predict fecal incontinence. We investigated whether vector volume anorectal manometry before ileostomy reversal predicts major fecal incontinence following SPS in patients with mid or low rectal cancer.

METHODS

This longitudinal prospective cohort study comprised 173 patients who underwent vector volume anorectal manometry before ileostomy reversal. The Fecal Incontinence Severity Index was measured 1 year after the primary SPS and classified as major incontinence (FISI score ≥ 25) or continent/minor incontinence (FISI score < 25). Multivariable logistic regression analysis was used to identify predictors of major incontinence.

RESULTS

Ninety-two patients (53.1%) had major incontinence. Although tumor stage, location, and neoadjuvant chemoradiotherapy were comparable, the major incontinence group had lower resting pressure (28.4 vs. 34.3 mmHg, P = 0.027), greater asymmetry at rest (39.1% vs. 34.1%, P = 0.002) and squeezing (34.2% vs. 31.4%, P = 0.046), shorter sphincter length (3.3 vs. 3.7 cm, P = 0.034), and lower resting vector volume (143,601 vs. 278,922 mmHg² mm, P < 0.001) compared with the continent/minor incontinence group. Resting vector volume was the only independent predictor of major incontinence (odds ratio = 0.675 per 100,000 mmHg² mm, 95% confidence interval, 0.532-0.823; P = 0.006).

CONCLUSIONS

This study revealed that resting vector volume before ileostomy reversal may predict major fecal incontinence. We suggest that the physiology of the anorectum should be discussed with patients before ileostomy reversal in patients at high risk of fecal incontinence.

3D high-definition manometry in evaluation of children after surgery for Hirschsprung's disease: A pilot study

PURPOSE

Anorectal 3-dimensional high definition manometry (3D HRM) could be the best tool for postoperative assessment of restorative surgical procedures for Hirschsprung's disease. The aim of our study was to evaluate patients after surgery for Hirschsprung's disease using 3D HRM.

MATERIALS AND METHODS

Anorectal function was evaluated using solid state 3D HRM. We measured the length of the anal canal, mean resting squeeze pressures, the presence of rectoanal inhibitory reflex, cough reflex, ano-anal reflex and the bear down manoeuvre.

RESULTS

We studied 14 children operated on for Hirschsprung's disease. The mean values of pressure asymmetry were higher in patients after the Duhamel procedure than after the TEPT procedure (29.58% vs. 22.26% during resting and 26.1% vs. 14.01% during squeeze, respectively). No difference between the groups was observed in the measurement of all the manometric parameters except the presence of rectoanal inhibitory reflex (87.5% after TEPT vs. 33% after Duhamel).

CONCLUSIONS

Anorectal 3D HRM evaluation of patients with Hirschsprung's disease demonstrated that the asymmetry of the anal canal occurred in a similar percentage after both procedures.

Risk factors for bowel dysfunction after sphincter-preserving rectal cancer surgery: a prospective study using the Memorial Sloan Kettering Cancer Center bowel function instrument

BACKGROUND

Until recently, no studies have prospectively evaluated bowel function after sphincter-preserving surgery for rectal cancer with the use of a validated bowel function scoring system.

OBJECTIVE

The aim of this study was to investigate possible risk factors for altered bowel function after sphincter-preserving surgery.

DESIGN

This was a prospective study.

SETTINGS

The study was conducted between January 2006 and May 2012 at the authors' institution.

PATIENTS

Patients who underwent sphincter-preserving rectal cancer surgery were recruited.

MAIN OUTCOME MEASURES

Bowel function was assessed 1 day before (baseline) and at 1 year after sphincter-preserving surgery or temporary ileostomy takedown with the use of the Memorial Sloan Kettering Cancer Center questionnaire. Multivariable analysis was performed to identify the factors associated with altered bowel function after surgery.

RESULTS

Overall, 266 patients were eligible for the analysis. The tumor was located in the upper, middle, and lower rectum in 68 (25.5%), 113 (42.5%), and 85 (32.0%) patients. Intersphincteric resection and temporary ileostomy were performed in 18 (6.8%) and 129 (48.5%) patients. The mean Memorial Sloan Kettering Cancer Center score was 64.5 ± 7.6 at 1 year after sphincter-preserving surgery or temporary ileostomy takedown. The Memorial Sloan Kettering Cancer Center score decreased in 163/266 patients (61.3%) between baseline and 1 year after surgery. Tumor location (p = 0.01), operative method (p = 0.03), anastomotic type (p = 0.01), and temporary ileostomy (p = 0.01) were associated with altered bowel function after sphincter-preserving surgery in univariate analyses. In multivariable analysis, only tumor location was independently associated with impaired bowel function after sphincter-preserving rectal cancer surgery.

LIMITATIONS

This study was limited by its nonrandomized design and the lack of measurement before preoperative chemoradiotherapy.

CONCLUSION

We suggest that preoperative counseling should be implemented to inform patients of the risk of bowel dysfunction, especially in patients with lower rectal cancer, although this study cannot exclude the effect of chemoradiotherapy owing to the limitation of study.

Low anterior resection syndrome (LARS): cause and effect and reconstructive considerations

Between 25 and 80% of patients undergoing a low or very low anterior resection will suffer postoperatively, from a constellation of symptoms including fecal urgency, frequent bowel movements, bowel fragmentation and incontinence, collectively referred to as the low anterior resection syndrome (LARS). The etiology of LARS is multifactorial with the potential of sphincter injury during anastomosis construction, alterations in anorectal physiology, the development of a pudendal neuropathy, and a lumbar plexopathy with exacerbation of symptoms if there is associated anastomotic sepsis or the use of adjuvant and neoadjuavnt therapies. The symptoms of LARS may be obviated in part by the construction of a neorectal reservoir which may take the form of a colonic J-pouch, a transverse coloplasty, or a side-to-end anastomosis. This review outlines the factors contributing to LARS symptomatology along with the short- and medium-term functional results of comparative trials with the different types of neorectal reconstructions.

Study on reconstruction of rectal sensation based on wavelet packet analysis and SVM strategy

To control anal incontinence, we have developed an artificial anal sphincter system with sensor feedback. The artificial anal sphincter system is a novel hydraulic-electric muscle which mainly comprises an artificial anal sphincter, a wireless power supply subsystem, and a rectal sensation reconstruction subsystem. To investigate the features of the patients' rectal sensation, we have developed an in vitro experimental platform of artificial anal sphincter. In vitro experiments have been performed, and demonstrate that the traditional threshold method is not suitable for predicting the time for defecation. The traditional threshold method only uses single-dimensional pressure time series which may contain a few interdependent components simultaneously. A wavelet packet analysis algorithm is employed to extract the feature vector of the rectal pressure signal, then the rectal sensation prediction model is constructed based on a support vector machine for defecation pattern recognition. The results show that the proposed method is an effective approach for the reconstruction of patients' rectal sensation.

Anal canal vector volume manometry

BACKGROUND

Anal manometry is routinely used in the assessment of the anal sphincters in patients with fecal incontinence or suspected sphincter injury. Such physiological information is complementary to the anatomical assessment provided by anal endosonography. The evolution of 3-dimensional anal endosonography provides more diagnostically useful information in complex cases. Vector volume manometry has been developed to give a 3-dimensional view of the anal sphincters.

OBJECTIVE

We reviewed the published literature on this technique, with the intention of deriving a system of standardization based on the published literature and to summarize the derivation and physiological meaning of the parameters measurable by vector volume studies, as well.

DATA SOURCES

We undertook a MEDLINE search using the terms "vector volume" or "vector manometry" and "anal canal." We also reviewed further publications found from references cited in the original articles identified from the above search.

STUDY SELECTION

Only English language articles of studies performed on humans were reviewed.

INTERVENTION

Anal canal vector volume manometry was the intervention.

RESULTS

With the development of automated puller systems and associated software, parameters such as total vector volume, maximum pressure, mean pressure, anal canal symmetry, anal canal length, and the length of the high-pressure zone can be readily calculated.

LIMITATIONS

There are conflicting studies related to the clinical value of both anal manometry and vector volume manometry, in part, because of the lack of standardization of equipment and technique.

CONCLUSIONS

The vector volume parameters have been shown to correlate with both imaging results and incontinence scores with automated puller systems. The clinical utility of vector volume manometry would be improved further by the standardization of equipment and technique. The main clinical utility may lie in the treatment selection and preoperative assessment of patients awaiting surgery for anal pathology that has yet to be evaluated.

Research on a novel artificial anal sphincter for human incontinence

This paper discusses a novel artificial anal sphincter with sensor feedback for controlling anal incontinence. The artificial anal sphincter system is a novel hydraulic-electric muscle which mainly comprises an artificial anal sphincter, a wireless power supply subsystem, and a communication subsystem. High integration of all functional components and no wire linking to the outer device make surgical implantation easier and lower risk. The wireless power supply subsystem employs a Class-E power amplifier based on adaptive control technique, and the electromagnetic compatibility in biological tissue is analysed. With the goal of designing a reliable and safe instrument, the models of human colonic blood flow and rectum motion are developed, the biomechanical material properties of human rectum and tissue ischaemia are analysed. The results show that the deformation of the artificial anal sphincter can be controlled by the press of reservoir below the upper limit of human tissue ischaemia. In vitro experiments demonstrate the artificial anal sphincter system is a good cure for human anal incontinence problems.

The short-term effect of neoadjuvant chemoradiation on anorectal function in low and midrectal cancer: analysis using preoperative manometric data

PURPOSE

The purpose of this study was to evaluate the short-term preoperative effects of neoadjuvant chemoradiation on anorectal function, excluding the bias of postoperative impairment.

METHODS

We analyzed 80 patients on whom preoperative anorectal manometry data were available for both prechemoradiation and postchemoradiation. Patients were divided into 2 groups according to the tumor location; lower rectum (n = 52) and mid rectum (n = 28). The paired t test was used to compare prechemoradiation and postchemoradiation parameters including the mean resting pressure, maximum squeeze pressure, percentage asymmetry of the resting and squeeze sphincter, length of the high-pressure zone, rectal sensory threshold, and rectal compliance.

RESULTS

In patients with a lower rectal cancer, there were significant differences in the percentage asymmetry of the squeeze sphincter (27.81 +/- 6.46 vs 25.38 +/- 5.93%, P < .01), length of the high-pressure zone (2.14 +/- 0.74 vs 2.33 +/- 0.72 cm, P = .05), and rectal compliance (1.14 +/- 0.41 vs 1.02 +/- 0.40 mL/mmHg, P = .04). In patients with midrectal cancer, only the mean resting pressure increased significantly (45.08 +/- 18.57 vs 52.83 +/- 17.87 mmHg, P < .01). Clinical symptom evaluation demonstrated a significant decrease in the number of defecations and the frequency of tenesmus.

CONCLUSION

Neoadjuvant chemoradiation did not impair overall short-term sphincter function significantly, regardless of the location of the primary tumor. Although there was a decrease in rectal compliance, it seemed that the tumor-downsizing effect compensated the expected worsening of anorectal function in the early postchemoradiation period.