Defecatory malfunction caused by motility disorder of the neorectum after anterior resection for rectal cancer

Ondansetron for Low Anterior Resection Syndrome (LARS): A Double-Blind, Placebo-Controlled, Cross-Over, Randomized Study

OBJECTIVE

The aim of the study was to examine the efficacity and safety of ondansetron, a serotonin receptor antagonist, to treat patients with low anterior resection syndrome (LARS).

BACKGROUND

LARS after rectal resection is common and debilitating. Current management strategies include behavioral and dietary modifications, physiotherapy, antidiarrheal drugs, enemas, and neuromodulation, but the results are not always satisfactory.

METHODS

This is a randomized, multicentric, double-blinded, placebo-controlled, and cross-over study. Patients with LARS (LARS score >20) no longer than 2 years after rectal resection were randomized to receive either 4 weeks of ondansetron followed by 4 weeks of placebo (O-P group) or 4 weeks of placebo followed by 4 weeks of ondansetron (P-O group). The primary endpoint was LARS severity measured using the LARS score; secondary endpoints were incontinence (Vaizey score) and irritable bowel syndrome quality of life (IBS-QoL questionnaire). Patients' scores and questionnaires were completed at baseline and after each 4-week treatment period.

RESULTS

Of 46 randomized patients, 38 were included in the analysis. From baseline to the end of the first period, in the O-P group, the mean (SD) LARS score decreased by 25% [from 36.6 (5.6) to 27.3 (11.5)] and the proportion of patients with major LARS (score >30) went from 15/17 (88%) to 7/17 (41%), ( P =0.001). In the P-O group, the mean (SD) LARS score decreased by 12% [from 37 (4.8) to 32.6 (9.1)], and the proportion of major LARS went from 19/21 (90%) to 16/21 (76%). After crossover, LARS scores deteriorated again in the O-P group receiving placebo, but further improved in the P-O group receiving ondansetron. Mean Vaizey scores and IBS QoL scores followed a similar pattern.

CONCLUSIONS

Ondansetron is a safe and simple treatment that appears to improve both symptoms and QoL in LARS patients.

Low anterior resection syndrome

Low anterior resection syndrome (LARS) is the distressful defecatory functional problem after sphincter-saving surgery for rectal cancer. Although the symptoms of fecal urgency, frequency, and incontinence may develop in most of the patients after surgery, there is no definitive treatments for LARS. Multifactorial etiologies and various risk factors have been identified, but the reduction of storage capacity in the rectum is one of the main reasons for LARS. Anal sphincter muscle or nerve damage during rectoanal resection or anastomosis construction, and intersphincteric resection for low-lying tumors or hand-sewing anastomosis, are the absolute risk factors for LARS. Preoperative radiotherapy, postoperative complications, such as anastomosis leakage, or longer duration of stoma, are also risk factors. The severity of LARS can be confirmed using the LARS score questionnaire. The questionnaire has been translated to numerous language versions including Korean and have been validated. Diverse empirical treatments, such as loperamide, fiber, probiotics, or enema, have been tried, but the safety and efficacy have not been verified yet. The 5-Hydroxytryptamine (5-HT) receptor antagonist, ramosetron, used for diarrhea-dominant irritable bowel syndrome, is one potential drug for relieving the symptoms of major LARS. A randomized-controlled trial suggested the use of ramosetron could be safe and efficacious for patients who have major LARS after sphincter-saving rectal cancer surgery. Novel techniques or drugs for relieving the symptoms of LARS should be developed more and further studies are necessary.

Mesorectal reconstruction with pedicled greater omental transplantation to relieve low anterior resection syndrome following total intersphincteric resection in patients with ultra-low rectal cancer

BACKGROUND

Total intersphincteric resection (ISR) is the ultimate anus-preserving surgery for patients with ultra-low rectal cancer (ULRC), which can result in various degrees of anorectal dysfunction. Known as low anterior resection syndrome (LARS), it seriously affects the postoperative quality of life of patients. The aim of this study was to discuss the value of mesorectal reconstruction with pedicled greater omental transplantation (PGOT) to relieve LARS following total ISR in patients with ULRC, hoping to provide new ideas and strategies for the prevention and improvement of LARS.

METHODS

We retrospectively analyzed hospitalization data and postoperative anorectal function of 26 ULRC patients, who were met inclusion and exclusion criteria in our center from January 2015 to February 2022. And combined with the results of anorectal manometry and rectal magnetic resonance imaging (MRI) defecography of some patients, we assessed comprehensively anorectal physiological and morphological changes of the patients after surgery, and their correlation with LARS.

RESULTS

In this study, 26 patients with ULRC were enrolled and divided into observation group (n = 15) and control group (n = 11) according to whether PGOT was performed. There were no significant differences in surgical results such as operative time, intraoperative blood loss and postoperative complications between the two groups (P > 0.05). Postoperative follow-up showed that patients in both groups showed severe LARS within 3 months after surgery, but from the 3rd month after surgery, LARS in both groups gradually began to decrease, especially in the observation group, which showed faster recovery and better recovery, with statistically significant difference (P < 0.001). Through anorectal manometry, the mean rectal resting pressure in the observation group was significantly lower than that in the control group (P = 0.010). In addition, the postoperative thickness of the posterior rectal mesenterium in the observation group was significantly higher than that in the control group (P = 0.001), and also higher than the preoperative level (P = 0.018). Moreover, rectal MRI defecography showed that the neo-rectum had good compliance under the matting of greater omentum, and its intestinal peristalsis was coordinated.

CONCLUSIONS

ULRC patients, with the help of greater omentum, coordinated their neo-rectum peristalsis after total ISR and recovery of LARS was faster and better. PGOT is expected to be an effective strategy for LARS prevention and treatment of ULRC patients after surgery and is worthy of clinical promotion.

Should anorectal manometry be routine before stoma reversal in patients after an intersphincteric resection?

INTRODUCTION

Anorectal manometry (ARM) is sometimes performed before ostomy reversal in patients with an intersphincteric resection (ISR) to predict bowel function. However, no clinical predictive data exist regarding its utility.

METHODS

The single-centre, retrospective data of ISR patients who had an ARM prior to ostomy reversal, and bowel functional assessment with the low anterior resection syndrome (LARS) and Wexner incontinence scores at least 6 months after reversal, were considered. Correlation statistics were performed with each of the manometric parameters and functional outcome categories.

RESULTS

Eighty-nine patients were included. The median basal and squeeze pressures were 41 and 100 mmHg, respectively. Any LARS (score ≥20) and major incontinence (score ≥11) was observed in 51.7% and 16.9%, respectively. None of the manometric parameters (median basal or maximum squeeze pressure, anal canal length, volume at urge and the ability to expel) correlated with LARS or incontinence.

CONCLUSIONS

Anorectal manometry (ARM) before ostomy reversal to predict bowel function at 6 months or beyond was not helpful in patients with an ISR and diverting stoma. No manometric parameter correlated with the LARS or Wexner incontinence scores.

Advances in diagnosis and treatment of low anterior resection syndrome

Rectal cancer is one of the most common cancers. As much as 90% of patients with low rectal cancer complain of increased frequency of defecation, fecal incontinence, and evacuation problems after surgery, which is termed as low anterior resection syndrome (LARS). LARS detrimentally affects the quality of life for patients with rectal cancer. In this paper, we review the pathogenesis, risk factors, assessment tools, and treatment strategies for LARS.

Management of Low Anterior Resection Syndrome (LARS) Following Resection for Rectal Cancer

INTRODUCTION

A total of 60-80% of patients undergoing rectal resection (mostly as a treatment for rectal cancer) suffer from a variety of partly severe functional problems despite preservation of the anal sphincter. These patients are summarized under the term low anterior resection syndrome (LARS). Preoperative radiotherapy, vascular dissection and surgical excision of the low rectum and mesorectum lead, alone or all together, to a significant impairment of colonic and (neo-) rectal motility. This results in a variety of symptoms (multiple defecation episodes, recurrent episodes of urge, clustering, incontinence, etc.) which are associated with severe impairment of quality of life (QOL).

METHODS

This narrative review summarizes the present state of knowledge regarding the pathophysiology of LARS as well as the evidence for the available treatment options to control the symptoms resulting from this condition.

RESULTS

A review of the literature (Medline, Pubmed) reveals a variety of treatment options available to control symptoms of LARS. Medical therapy, with or without dietary modification, shows only a modest effect. Pelvic floor rehabilitation consisting of muscle exercise techniques as well as biofeedback training has been associated with improvement in LARS scores and incontinence, albeit with limited scientific evidence. Transanal irrigation (TAI) has gained interest as a treatment modality for patients with LARS due to an increasing number of promising data from recently published studies. Despite this promising observation, open questions about still-unclear issues of TAI remain under debate. Neuromodulation has been applied in LARS only in a few studies with small numbers of patients and partly conflicting results.

CONCLUSION

LARS is a frequent problem after sphincter-preserving rectal surgery and leads to a marked impairment of QOL. Due to the large number of patients suffering from this condition, mandatory identification, as well as treatment of affected patients, must be considered during surgical as well as oncological follow-up. The use of a standardized treatment algorithm will lead to sufficient control of symptoms and a high probability of a marked improvement in QOL.

Exploring the pathophysiology of LARS after low anterior resection for rectal cancer with high-resolution colon manometry

BACKGROUND

A total mesorectal excision for rectal cancer-although nerve- and sphincter-sparing-can give rise to significant bowel symptoms, commonly referred to as low anterior resection syndrome (LARS). The exact pathophysiology of this syndrome still remains largely unknown, and the impact of radical surgery on colonic motility has only been scarcely investigated.

METHODS

High-resolution colon manometry was performed in patients, 12-24 months after restoration of transit. Patients were divided into two groups: patients with major LARS and no/minor LARS, according to the LARS-score. Colonic motor patterns were compared, and the relationship of these patterns with the LARS-scores was investigated.

KEY RESULTS

Data were analyzed in 18 patients (9 no/minor LARS, 9 major LARS). Cyclic short antegrade motor patterns did occur more in patients with major LARS (total: p = 0.022; post-bisacodyl: p = 0.004) and were strongly correlated to LARS-scores after administering bisacodyl (p &lt; 0.001). High amplitude propagating contractions (HAPC's) that started in the proximal colon and ended in the mid-section of the colon occurred significantly less in patients with major LARS compared with patients with no/minor LARS (p = 0.015).

CONCLUSIONS AND INFERENCES

The occurrence of more cyclic short antegrade motor patterns and less HAPC's (from the proximal to the mid-colon) is more prevalent in patients with major LARS. These findings help to understand the differences in pathophysiology in patients developing major versus no/minor bowel complaints after TME for rectal cancer.

The role of colonic motility in low anterior resection syndrome

Low anterior resection syndrome (LARS) describes the symptoms and experiences of bowel dysfunction experienced by patients after rectal cancer surgery. LARS is a complex and multifactorial syndrome exacerbated by factors such as low anastomotic height, defunctioning of the colon and neorectum, and radiotherapy. There has recently been growing awareness and understanding regarding the role of colonic motility as a contributing mechanism for LARS. It is well established that rectosigmoid motility serves an important role in coordinating rectal filling and maintaining continence. Resection of the rectosigmoid may therefore contribute to LARS through altered distal colonic and neorectal motility. This review evaluates the role of colonic motility within the broader pathophysiology of LARS and outlines future directions of research needed to enable targeted therapy for specific LARS phenotypes.

Risk factors for Low Anterior Resection Syndrome (LARS) in patients undergoing laparoscopic surgery for rectal cancer

Background

Total mesorectal excision (TME) represents the “gold standard” of rectal cancer surgery. In locally advanced lesions neoadjuvant treatments (e.g. radiotherapy-nRT, radio chemotherapy-cnRT) have been shown to improve TME oncological results, reducing local recurrences rate. Nevertheless, these treatments have significant functional consequences impacting patients’ quality of life (QoL). The resulting syndrome is known as Low Anterior Resection Syndrome (LARS). The purpose of this work was to evaluate the association between risk factors and the development of LARS in a prospective series of laparoscopic sphincter-saving TME.

Methods

The study was conducted as a retrospective observational epidemiological study of a prospective database, including all patients undergoing laparoscopic anterior resection surgery for rectal cancer at our Unit from 1st January 2013 to 31st May 2018. The diagnosis of LARS was performed using the LARS Score. We classified risk factors in patient-related, pre-, intra- and post-operative factors.

Results

The sample included 153 consecutive patients. Forty-one were affected by “low” rectal cancer, 74 by “middle” rectal cancer, 38 by “high” rectal cancer. The prevalence of overall LARS (major LARS + minor LARS) in our series was 35.9% (55/153 cases). Association between nRT and overall/major LARS was significant (respectively p = 0.03 and 0.02). Distal localization of tumor was also significantly associated with LARS [overall LARS (p = 0.03), major LARS (p = 0.014)].

Conclusions

In our study, neoadjuvant radiotherapy and tumor localization resulted independent risk factors for LARS after laparoscopic sphincter-saving TME. Tumor localization in the “middle” and “high” rectum resulted a protective factor compared to the localization in “low” rectum.

Analysis of presacral tissue structure in LARS and the prevention of LARS by reconstruction of presacral mesorectum with pedicled greater omentum flap graft

BACKGROUND

The greater omentum has played a unique biological role in regenerative surgery. The aim of our study was to alter the anterior sacral structure by filling the anterior sacral space with the greater omentum and evaluate its effect on the low anterior resection syndrome (LARS) after total mesorectal excision (TME) surgery for low rectal cancer.

METHODS

We retrospectively collected clinical data of patients with primary low rectal cancer who underwent TME and ileostomy closure in our hospital from March 2018 to March 2020. Spearman correlation analysis was conducted to analyze the correlation between postoperative mesorectal fascia (MRF) thickness and LARS score. Subsequently, we prospectively used a tipped greater omental flap graft to reconstruct the anterior rectal sacral structures (MRF reconstruction) in 17 patients and compared LARS scores and rectal compliance (RC) at week 12 after closure of the ileostomy in both groups.

RESULTS

There were 47 patients with No-MRF reconstruction (31 males, mean age 60.68 ± 9.21 years) and 17 with MRF reconstruction (10 males, mean age 49.82 ± 14.74 years). Correlation analysis indicated that MRF thickness and RC were negatively correlated with LARS severity (p < 0.05). The LARS score of patients with MRF reconstruction at 12 weeks was significantly better than that of those with No-MRF reconstruction (32.97 ± 2.65 vs. 26.94 ± 1.52, p = 0.001), and the RC of MRF reconstruction were lower (2.80 ± 0.55 vs. 3.67 ± 0.38, p = 0.001). In addition, MRF reconstruction and No-MRF reconstruction have the similar incidence of postoperative complications (p = 0.156). No hemorrhage or necrosis of the greater omentum flap was observed in any of the patients.

CONCLUSIONS

Greater omentum flap transplantation can significantly improve the symptoms of LARS at 12 weeks after ileostomy closure and we expect it to become a new surgical procedure for the treatment of low rectal cancer.

A study on the clinical application of greater omental pedicle flap transplantation to correct anterior resection syndrome in patients with low rectal cancer

Introduction

Low anterior resection syndrome (LARS) is the most common complication after total mesorectal excision (TME) in patients with low rectal cancer and has been a challenge in colorectal surgery that severely impacts the quality of life of patients. This study aimed to introduce a revised surgical procedure which could effectively maintain rectal compliance and significantly improve LARS after the operation.

Methods

We performed mesorectal reconstruction after routine Dixon TME using greater omental pedicle flap transplantation in 11 patients with low rectal cancer (5 cases of preoperative neoadjuvant chemoradiotherapy, 5 cases of preoperative neoadjuvant chemotherapy, and 1 case of postoperative adjuvant chemotherapy), thereby simulating the initial anatomical structure of the mesorectum and significantly reducing the postoperative anterior resection syndrome. The lars precision syndrome assessment scale (LARSS) was used to access the LARS.

Results

At 12 weeks after the 11 patients recovered from the anal defecation function, the average score on the LARS questionnaire was 25.5 ± 1.5 (minor). The average time at which anal function began to recover was 6.2 ± 2.6 weeks after surgery. The recovery was rapid, as the rectal and anal function of all patients generally returned to normal levels within 12 weeks, and the quality of life was close to that before surgery.

Conclusion

Greater omental flap transplantation can significantly improve LARS after Dixon TME in patients with low rectal cancer.

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Omental pedicle flap transplantation is a revised and promising surgical procedure.

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The procedure reconstructing the mesorectum could maintain rectal compliance.

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The procedure can significantly improve low anterior resection syndrome.

Chronic constipation in adults: Contemporary perspectives and clinical challenges. 1: Epidemiology, diagnosis, clinical associations, pathophysiology and investigation

BACKGROUND

Chronic constipation is a prevalent disorder that affects patients' quality of life and consumes resources in healthcare systems worldwide. In clinical practice, it is still considered a challenge as clinicians frequently are unsure as to which treatments to use and when. Over a decade ago, a Neurogastroenterology & Motility journal supplement devoted to the investigation and management of constipation was published (2009; 21 (Suppl.2)). This included seven articles, disseminating all themes covered during a preceding 2-day meeting held in London, entitled "Current perspectives in chronic constipation: a scientific and clinical symposium." In October 2018, the 3rd London Masterclass, entitled "Contemporary management of constipation" was held, again over 2 days. All faculty members were invited to author two new review articles, which represent a collective synthesis of talks presented and discussions held during this meeting.

PURPOSE

This article represents the first of these reviews, addressing epidemiology, diagnosis, clinical associations, pathophysiology, and investigation. Clearly, not all aspects of the condition can be covered in adequate detail; hence, there is a focus on particular "hot topics" and themes that are of contemporary interest. The second review addresses management of chronic constipation, covering behavioral, conservative, medical, and surgical therapies.

Multicenter investigation of bowel evacuation function after transanal total mesorectal excision for mid-low rectal cancer

PURPOSE

To determine the effect of transanal total mesorectal excision (taTME) procedure on the postoperative bowel evacuation function of patients with low rectal cancer.

METHODS

Bowel evacuation function was investigated in 316 patients with rectal cancer after taTME in 18 hospitals in China. Low anterior resection syndrome (LARS) score, Wexner score, and EORTC QLQ-C30 were used for functional evaluation. The association between perioperative risk factors and LARS score was determined by univariate and multivariate analyses.

RESULTS

The prevalence rate of no LARS, minor LARS, and major LARS in patients after taTME was 39.9%, 28.2%, and 31.9%, respectively. The two most frequently reported symptoms of LARS after taTME were bowel clustering (72.8%) and fecal urgency (63.3%). Patients with major LARS had significantly higher Wexner score and worse global health status and financial difficulties according to the EORTC QLQ-C30 questionnaire than those without major LARS. Preoperative chemoradiotherapy was an independent risk factor of major LARS occurrence after taTME (OR: 3.503, P = 0.044); existing preoperative constipation (OR: 0.082, P = 0.040) and manual anastomosis (OR: 4.536, P = 0.021) were favorable factors affecting bowel evacuatory function within 12 months after taTME, but for patients whose follow-up time was longer than 12 months, postoperative chemoradiotherapy (OR: 8.790, P = 0.001) and defunctioning stoma (OR: 3.962, P = 0.010) were independent risk factors.

CONCLUSIONS

The bowel evacuation function after taTME is acceptable. Perioperative chemoradiotherapy, anastomotic method, and preoperative constipation are factors associated with bowel dysfunction after taTME.

Functional results after treatment for rectal cancer

Introduction With improving survival of rectal cancer, functional outcome has become increasingly important. Following sphincter-preserving resection many patients suffer from severe bowel dysfunction with an impact on quality of life (QoL) – referred to as low anterior resection syndrome (LARS).

Study objective To provide an overview of the current knowledge of LARS regarding symptomatology, occurrence, risk factors, pathophysiology, evaluation instruments and treatment options.

Results LARS is characterized by urgency, frequent bowel movements, emptying difficulties and incontinence, and occurs in up to 50-75% of patients on a long-term basis. Known risk factors are low anastomosis, use of radiotherapy, direct nerve injury and straight anastomosis. The pathophysiology seems to be multifactorial, with elements of anatomical, sensory and motility dysfunction. Use of validated instruments for evaluation of LARS is essential. Currently, there is a lack of evidence for treatment of LARS. Yet, transanal irrigation and sacral nerve stimulation are promising.

Conclusion LARS is a common problem following sphincter-preserving resection. All patients should be informed about the risk of LARS before surgery, and routinely be screened for LARS postoperatively. Patients with severe LARS should be offered treatment in order to improve QoL. Future focus should be on the possibilities of non-resectional treatment in order to prevent LARS.

Low Anterior Resection Syndrome

PURPOSE OF REVIEW

Low anterior resection syndrome is a highly prevalent condition that can develop after anal sphincter-sparing surgery for rectal cancer and impair quality of life. In this review, we summarize the major features and pathophysiology of this syndrome and discuss treatment approaches.

RECENT FINDINGS

Quality of life correlates significantly with severity of low anterior resection syndrome. Prompt assessment and initiation of therapy are essential to rehabilitating damaged mechanical and neural structures. Anorectal manometry demonstrates a global decrease in sphincteric function postoperatively, though in many patients, function does recover. Transanal irrigation, pelvic floor rehabilitation, and biofeedback are the mainstays of the treatment of major LARS. Definitive stoma can be considered in therapy refractory LARS > 2 years. The development of low anterior resection syndrome likely involves an interplay between mechanical and neural pathways. Clinically, patients present at varying levels of severity, and scoring systems are available to help assess patient symptoms and guide therapy. Treatment approaches range from conservative therapies to biofeedback and sacral nerve stimulation. Future randomized controlled trials aimed at risk stratification of patients and development of severity-based treatment algorithms are warranted.

Rapid transit in the left-sided colon is related to poor defecatory function at early period after stoma closure

Sphincter-saving surgery (SSS) is the gold standard for rectal cancer surgery but results in a wide spectrum of bowel dysfunction. This study investigated the impact of colonic dysmotility on the incontinent form of bowel dysfunction. Bowel function of patients who received SSS with loop ileostomy for treating rectal cancer was reviewed retrospectively from June 2013 two August 2015 at a single hospital. Immediately after closure of a diverting stoma, patients were tested for the colonic transit time (CTT) using radiopaque markers. Bowel dysfunction at 6 and 12 months after SSS was measured as the severity of fecal incontinence according to the Cleveland Clinic Incontinence Score (CCIS) and the use of an anti-diarrheal drug. A short CTT for the left colonic segment was significantly associated with the high CCIS and use of an antidiarrheal agent at 6 months after sphincter preservation. However, the CTT didn't correlate with the CCIS at 12 months after SSS. Rather, age and surgical method demonstrated a significant association. Colonic dysmotility after SSS appears to intensify fecal incontinence for a relatively short period. Its impact abates within a year.

Etiology and management of low anterior resection syndrome based on the normal defecation mechanism

Low anterior resection syndrome (LARS) commonly develops after an anal sphincter-preserving operation (SPO). The etiology of LARS is not well understood, as the anatomical components and physiological function of normal defecation, which may be damaged during the SPO, are not well established. SPOs may damage components of the anal canal (such as the internal anal sphincter, longitudinal conjoint muscle, or hiatal ligament), either mechanically or via injury to the nerves that supply these organs. The function of the rectum is substantially impaired by resection of the rectum, division of the rectococcygeus muscle, and/or injury of the nervous supply. When the remnant rectum is small and does not function properly, an important functional role may be played by the neorectum, which is usually constructed from the left side of the colon. Hypermotility of the remnant colon may affect the manifestation of urge fecal incontinence. To develop an SPO that minimizes the risk of LARS, the anatomy and physiology of the structures involved in normal defecation need to be understood better. LARS is managed similarly to fecal incontinence. In particular, management should focus on reducing colonic motility when urge fecal incontinence is the dominant symptom.

The "rectosigmoid brake": Review of an emerging neuromodulation target for colorectal functional disorders

The regulation of gastrointestinal motility encompasses several overlapping mechanisms including highly regulated and coordinated neurohormonal circuits. Various feedback mechanisms or "brakes" have been proposed. While duodenal, jejunal, and ileal brakes are well described, a putative distal colonic brake is less well defined. Despite the high prevalence of colonic motility disorders, there is little knowledge of colonic motility owing to difficulties with organ access and technical difficulties in recording detailed motor patterns along its entire length. The motility of the colon is not under voluntary control. A wide range of motor patterns is seen, with long intervals of intestinal quiescence between them. In addition, the use of traditional manometric catheters to record contractile activity of the colon has been limited by the low number of widely spaced sensors, which has resulted in the misinterpretation of colonic motor patterns. The recent advent of high-resolution (HR) manometry is revolutionising the understanding of gastrointestinal motor patterns. It has now been observed that the most common motor patterns in the colon are repetitive two to six cycles per minute (cpm) propagating events in the distal colon. These motor patterns are prominent soon after a meal, originate most frequently in the rectosigmoid region, and travel in the retrograde direction. The distal prominence and the origin of these motor patterns raise the possibility of them serving as a braking mechanism, or the "rectosigmoid brake," to limit rectal filling. This review aims to describe what is known about the "rectosigmoid brake," including its physiological and clinical significance and potential therapeutic applications.

Functional outcome of low rectal resection evaluated by anorectal manometry

BACKGROUND

Low anterior resection syndrome (LARS) covers disordered bowel function after rectal resection, leading to deterioration in patients' quality of life. The aim of this study was to evaluate anorectal function after laparoscopic low anterior resection (LAR) by means of standardized instruments.

METHODS

This was a prospective clinical cohort study conducted in a single institution to assess functional outcome of patients 1 year after laparoscopic LAR by means of LARS score and high-resolution anorectal manometry.

RESULTS

In total, 65 patients were enrolled in the study. Mean tumour height was 9.4 ± 1.8 cm; total mesorectal excision during laparoscopic LAR with low end-to-end colorectal anastomosis was performed in all patients. One year after the surgery, minor LARS was detected in 33.9% of patients, major LARS in 36.9% of patients. Anorectal manometry revealed decreased resting pressure and normal squeeze pressure of the anal sphincters in the majority of our patients. Rectal compliance and rectal volume tolerability (first sensation, urge to defaecate and discomfort volume) were significantly reduced. The statistical testing of the correlation between LARS and manometry parameters showed that with increasing seriousness of LARS, values of some parameters (resting pressure, first sensation, urge to defaecate, discomfort volume and rectal compliance) were reduced.

CONCLUSION

This study indicates that the majority of patients after laparoscopic LAR experience symptoms of minor or major LARS. These patients have decreased resting anal sphincter pressures, decreased rectal volume tolerability and decreased rectal compliance.

Defining low anterior resection syndrome: a systematic review of the literature

AIM

There is increasing awareness of the poor functional outcome suffered by many patients after sphincter-preserving rectal resection, termed 'low anterior resection syndrome' (LARS). There is no consensus definition of LARS and varying instruments have been employed to measure functional outcome, complicating research into prevalence, contributing factors and potential therapies. We therefore aimed to describe the instruments and outcome measures used in studies of bowel dysfunction after low anterior resection and identify major themes used in the assessment of LARS.

METHOD

A systematic review of the literature was performed for studies published between 1986 and 2016. The instruments and outcome measures used to report bowel function after low anterior resection were extracted and their frequency of use calculated.

RESULTS

The search revealed 128 eligible studies. These employed 18 instruments, over 30 symptoms, and follow-up time periods from 4 weeks to 14.6 years. The most frequent follow-up period was 12 months (48%). The most frequently reported outcomes were incontinence (97%), stool frequency (80%), urgency (67%), evacuatory dysfunction (47%), gas-stool discrimination (34%) and a measure of quality of life (80%). Faecal incontinence scoring systems were used frequently. The LARS score and the Bowel Function Instrument (BFI) were used in only nine studies.

CONCLUSION

LARS is common, but there is substantial variation in the reporting of functional outcomes after low anterior resection. Most studies have focused on incontinence, omitting other symptoms that correlate with patients' quality of life. To improve and standardize research into LARS, a consensus definition should be developed, and these findings should inform this goal.

Manometric evaluation of anorectal function in patients treated with neoadjuvant chemoradiotherapy and total mesorectal excision for rectal cancer

BACKGROUND

An altered anorectal function is reported after chemoradiotherapy (CRT) and surgery for rectal cancer.

AIM

The aim of this study was to clarify the relative contribution of neoadjuvant chemoradiation and surgical resection on the impairment of anorectal function as evaluated by anorectal manometry.

METHODS

Thirty-nine patients with rectal cancer, who underwent neoadjuvant CRT and laparoscopic rectal resection, were evaluated with the Pescatori Faecal Incontinence score, and with anorectal manometry: before neoadjuvant therapy (T0), after neoadjuvant therapy and before surgery (T1), 12 months after stoma closure (T2).

RESULTS

Resting and/or maximum squeeze pressure and/or volume thresholds for urgency were below the normal values in 12 (30%) patients at baseline. After CRT the mean resting pressure significantly decreased (p=0.007). Surgery determined a significantly decrease of the resting pressure (p=0.001), of the maximum squeeze pressure (p=0.001) and of the volume threshold for urgency (p=0.001). Impairment of continence was reported by 5, 11 and 18 patients at T0, T1 and T2, with a mean incontinence score of 3, 3.8 and 3.9 respectively.

CONCLUSIONS

CRT is detrimental to the function of the internal anal sphincter. Rectal resection significantly affects both internal and external anal sphincter function and the maximum tolerated volume of the neo-rectum, particularly in patients with low rectal cancer, significantly impairing anal continence.

Clinical pharmacology of daikenchuto assessed by transit analysis using radiopaque markers in patients with colon cancer undergoing open surgery: a multicenter double-blind randomized placebo-controlled study (JFMC39-0902 additional study)

BACKGROUND

This exploratory trial was conducted to investigate whether daikenchuto accelerates the recovery of gastrointestinal function in patients undergoing open surgery for sigmoid or rectosigmoid cancer.

METHODS

Eighty-eight patients who underwent colectomy at one of the 11 clinical trial sites in Japan from January 2009 to June 2011 were registered in the study. Patients received either placebo or daikenchuto (15.0 g/day, 5 g three times a day) from postoperative day 2 to postoperative day 8. The study end points included the gastrointestinal tract transit time evaluated with radiopaque markers and the time to first flatus. The safety profile of daikenchuto was also evaluated until postoperative day 8.

RESULTS

Seventy-one patients (daikenchuto, n = 38; placebo, n = 33) were statistically analyzed. Although the number of radiopaque markers in the anal side of the small intestine at 6 h was significantly greater in the daikenchuto group than in the placebo group (15.19 vs 10.06, p = 0.008), the total transit analysis results and the mean time to first flatus did not differ significantly between the two groups.

CONCLUSIONS

Daikenchuto has a positive effect on the resolution of delayed gastric emptying, but has a limited effect on the resolution of postoperative paralytic ileus after open surgery in patients with sigmoid or rectosigmoid cancer. Daikenchuto may contribute to early oral intake in the postoperative course.

Randomized clinical trial of defaecatory function after anterior resection for rectal cancer with high versus low ligation of the inferior mesenteric artery

Background

Defaecatory function is often poor after anterior resection. Denervation of the neorectum following high ligation of the inferior mesenteric artery (IMA) is a possible cause of impaired defaecatory function. The purpose of this randomized clinical trial was to clarify whether the level of ligation of the IMA in patients with rectal cancer affects defaecatory function.

Methods

Between 2008 and 2011, patients who underwent anterior resection for rectal cancer were randomized to receive either high or low ligation of the IMA. The primary endpoint was to demonstrate the superiority of low ligation in terms of defaecatory function.

Results

One hundred patients were enrolled in the study; 51 were randomized to high ligation of the IMA and 49 to low ligation. There were no differences between the groups in terms of clinical data, except tumour stage, which was more advanced in the high-ligation group (P = 0·046). Nor were there any differences in defaecatory function, self-assessment of defaecation, Faecal Incontinence Quality of Life scale or continence score between groups at 3 months and 1 year. The number of harvested lymph nodes was similar. The rate of symptomatic anastomotic leakage was 16 per cent in the high-ligation group and 10 per cent in the low-ligation group (P = 0·415).

Conclusion

The level of ligation of the IMA in patients with rectal cancer did not affect defaecatory function or the incidence of postoperative complications. Registration number: NCT00701012 (http://www.clinicaltrials.gov).

A hyperactive postprandial response in the neorectum--the clue to low anterior resection syndrome after total mesorectal excision surgery?

AIM

To investigate neorectal properties regarding biomechanical, sensory and postprandial response in patients after total mesorectal excision without neoadjuvant radiotherapy in groups of no low anterior resection syndrome (LARS) patients and major LARS patients.

METHOD

Patients without LARS (n = 9) and patients with major LARS (n = 23) were investigated by multimodal rectal stimulation and standard anorectal physiological tests, and results were compared.

RESULTS

Patients with major LARS had an increased postprandial response with a significant increase in pressure in the neorectum after a meal compared with patients without LARS (P = 0.017). No biomechanical differences could be detected.

CONCLUSION

Low anterior resection syndrome seems to be caused by physiological changes due to neural damage more than structural changes in the ano-neorectum.

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.

Serotonin (5-HT3) receptor antagonists for the reduction of symptoms of low anterior resection syndrome

Purpose

Serotonin (5-hydroxytryptamine [5-HT])₃ receptor antagonists are effective for the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D), in which exaggerated intestinal/colonic hypermotility is often observed. Recent studies have suggested that the motility disorder, especially spastic hypermotility, seen in the neorectum following sphincter-preserving operations for rectal cancer may be the basis of the postoperative defecatory malfunction seen in these patients. We investigated the efficacy of 5-HT₃ receptor antagonists in patients suffering from severe low anterior resection syndrome.

Patients and methods

A total of 25 male patients with complaints of uncontrollable urgency or fecal incontinence following sphincter-preserving operations were enrolled in this study. Defecatory status, assessed on the basis of incontinence score (0–20), urgency grade (0–3), and number of toilet visits per day, was evaluated using a questionnaire before and 1 month after the administration of the 5-HT₃ antagonist ramosetron.

Results

All the parameters assessed improved significantly after taking ramosetron for 1 month. The effect was more prominent in cases whose anastomotic line was lower, ie, inside the anal canal. Defecatory function was better in patients who commenced ramosetron therapy within 6 months postoperatively, as compared to those who were not prescribed ramosetron for more than 7 months postoperatively.

Conclusion

These results suggest that 5-HT₃ antagonists are effective for the treatment of low anterior resection syndrome, as in diarrhea-predominant irritable bowel syndrome. The improvement in symptoms is not merely time dependent, but it is related to treatment with 5-HT₃ antagonists.

Anterior resection syndrome

Up to 80% of patients with rectal cancer undergo sphincter-preserving surgery. It is widely accepted that up to 90% of such patients will subsequently have a change in bowel habit, ranging from increased bowel frequency to faecal incontinence or evacuatory dysfunction. This wide spectrum of symptoms after resection and reconstruction of the rectum has been termed anterior resection syndrome. Currently, no precise definition or causal mechanisms have been established. This disordered bowel function has a substantial negative effect on quality of life. Previous reviews have mainly focused on different colonic reconstructive configurations and their comparative effects on daily function and quality of life. The present Review explores the potential mechanisms underlying disturbed functions, as well as current, novel, and future treatment options.

Recovery of upper gastrointestinal bowel movement after rectosigmoid cancer surgery: a pilot transit analysis

Postoperative gastrointestinal bowel transit right after colorectal resection has not yet been clarified. Thirty patients with rectosigmoid cancer were treated in this pilot study. The nasogastric tube was removed on the first postoperative day. One Sitzmarks capsule was given to each patient on the second postoperative day. Abdominal X-rays were taken at 3, 6, 8, 24, 48, and 72 hours after capsule intake. Distribution of the remaining Sitzmarks capsules were counted on X-ray films to clarify postoperative gastrointestinal movement after bowel resection. All Sitzmarks capsules were observed in the stomach at 3 and 6 hours after capsule intake. At 8 hours (second postoperative day), the Sitzmarks capsules were distributed from the stomach to the small intestine. Sitzmarks capsules were distributed in the right side colon at 24 hours (third postoperative day) after intake. Although the main distribution was still in the right side colon, several patients had evacuations accompanied by the disappearance of the Sitzmarks capsules. In 50% of the patients, it took approximately 72 hours (fifth postoperative day) for the first defecation after intake of the capsules. However, the Sitzmarks capsules remained mainly in the right side colon. Eight hours after intake, the majority of the Sitzmarks capsules shifted to the small intestine. Therefore, medication or feeding should be safely possible starting on the second postoperative day. There was no particular impact of bowel resection on upper gastrointestinal transit in patients with rectosigmoid cancer.

Preservation of the inferior mesenteric artery via laparoscopic sigmoid colectomy performed for diverticular disease: real benefit or technical challenge: a randomized controlled clinical trial

BACKGROUND

Defecatory disorders are very common complications after left hemicolectomy and anterior rectal resection. These disorders seem related primarily to colonic denervation after the resection. To evaluate the real benefits of inferior mesenteric artery (IMA) preservation via laparoscopic left hemicolectomy performed for diverticular disease in terms of reduced colonic denervation and improved postoperative intestinal functions, a randomized, single-blinded (patients) controlled clinical trial was conducted.

METHODS

From January 2004 to January 2010, patients with symptomatic diverticular disease and a surgical indication were enrolled in the study and randomly assigned to two treatment groups. The first group underwent laparoscopic left hemicolectomy, which preserved the IMA by sectioning the sigmoid arteries one by one near the colonic wall, In the second group, the IMA was sectioned immediately below the origin of left colic artery. Defecation disorders were assessed by anorectal manometry and by three questionnaires to evaluate constipation, incontinence, and quality of life 6 months after the intervention.

RESULTS

A total of 107 patients were included in the study. The 54 patients with preserved IMA showed a statistically lower incidence of defecation disorders such as fragmented evacuations, alternating bowel function, constipation, and minor incontinence, as well as less lifestyle alteration than the 53 patients with the IMA sectioned just below the left colic artery.

CONCLUSIONS

This study confirmed that preservation of the IMA should be recommended to reduce the incidence of defecatory disorders after left hemicolectomy for benign disease.

J-pouch vs side-to-end coloanal anastomosis after preoperative radiotherapy and total mesorectal excision for rectal cancer: a multicentre randomized trial

AIM

Comparison of functional and surgical outcome of the J-pouch with the side-to-end coloanal anastomosis after preoperative radiotherapy and total mesorectal excision in rectal cancer patients.

METHOD

In a multicentre study, patients with a carcinoma of the lower two-thirds of the rectum were randomized to either a J-pouch or a side-to-end reconstruction. Primary outcome was function of the neorectum 1 year after surgery. A functional outcome [COloREctal Functional Outcome (COREFO)] questionnaire, and two quality of life questionnaires (EORTC-QLQ-CR38 and SF-36) were to be completed by all participants preoperatively, and 4 and 12 months postoperatively. Independent data managers recorded surgical outcome. A group size of 30 patients in each group was calculated based on a 15-point difference of the COREFO scale.

RESULTS

In total, 107 patients were randomized, 55 in the J-pouch group and 52 in the side-to-end anastomosis group. The COREFO incontinence scale at 4 months and the total functional outcome at 4 and 12 months showed better results for the J-pouch group in comparison with the side-to-end anastomosis group. The remaining COREFO scales (frequency, social impact, stool-related aspects and bowel medication), surgical outcome (complications, reoperations, length of hospital stay, readmissions and mortality) and quality of life did not show significant differences between treatment groups.

CONCLUSION

The overall results of a coloanal J-pouch and a side-to-end anastomosis are comparable, although functional results are slightly better with a J-pouch. The side-to-end anastomosis is technically less demanding and therefore a justified alternative in sphincter-saving surgery.

Using the greater omental flap to cover the cut surface of the liver for prevention of delayed gastric emptying after left-sided hepatobiliary resection: a prospective randomized controlled trial

OBJECTIVE

The aim of this randomized controlled trial is to evaluate the effect on delayed gastric emptying (DGE) of using the greater omental flap to cover the cut surface of the liver after left-sided hepatobiliary resection.

METHODS

From June 2007 to December 2008, all eligible patients were randomly assigned to either the greater omental flap group (OF group) or the control group (non-OF group).

RESULTS

A total of 40 patients remained for final analysis. The incidence of DGE after left-sided hepatobiliary resection was 25%. The incidence of DGE showed no statistically significant differences between the OF group (10%) and the non-OF group (40%) (p = 0.065). The assessment of DGE using radiopaque rings revealed that changes over time in the gastric emptying ratio (GER, percentage of rings excreted from stomach) did not differ in a significant manner between the two groups. There were significant differences in changes over time in GER (p = 0.044) between the patients with and without DGE. The patients with DGE also showed higher GER at 5 h (p = 0.042) and at 6 h (p = 0.034) than those without DGE.

CONCLUSIONS

Using the greater omental flap to cover the cut surface of the liver may reduce the incidence of DGE after left-sided hepatobiliary resection. Assessment using radiopaque markers may be useful to evaluate DGE.

Effects of autonomic nerve stimulation on colorectal motility in rats

BACKGROUND

Several disease processes of the colon and rectum, including constipation and incontinence, have been associated with abnormalities of the autonomic nervous system. However, the autonomic innervation to the colon and rectum are not fully understood. The aims of this study were to investigate the effect of stimulation of vagus nerves, pelvic nerves (PN) and hypogastric nerves (HGN) on colorectal motility in rats.

METHODS

Four strain gauge transducers were implanted on the proximal colon, mid colon, distal colon and rectum to record circular muscle contractions in rats. Electrical stimulation was administered to the efferent distal ends of the cervical vagus nerve, PN and HGN. Motility index (MI) was evaluated before and during stimulation.

KEY RESULTS

Electrical stimulation (5-20 Hz) of the cervical vagus elicited significant contractions in the mid colon and distal colon, whereas less pronounced contractions were observed in the proximal colon. Pelvic nerves stimulation elicited significant contractions in the rectum as well as the mid colon and distal colon. Atropine treatment almost completely abolished the contractions induced by vagus nerve and PN stimulation. Hypogastric nerves stimulation caused relaxations in the rectum, mid colon and distal colon. The relaxations in response to HGN stimulation were abolished by propranolol.

CONCLUSIONS & INFERENCES

Vagal innervation extends to the distal colon, while the PN has projections in the distribution of the rectum through the mid colon. This suggests a pattern of dual parasympathetic innervation in the left colon. Parasympathetic fibers regulate colorectal contractions via muscarinic receptors. The HGN mainly regulates colorectal relaxations via beta-adrenoceptors.

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.

Characteristic findings on defecography according to reconstruction method and defecatory disorder following sphincter-saving surgery for rectal cancer

BACKGROUND AND AIMS

This study used postoperative defecography to characterize morphological features of defecatory disorders in patients following rectal resection. We also evaluated differences in dynamic defecatory condition depending on reconstruction methods for sphincter-saving surgery.

MATERIALS AND METHODS

Subjects comprised 62 patients (male/female, 41/21; mean age, 61 years) who underwent defecography after sphincter-saving surgery for rectal cancer. Semisolid barium (100 ml) was introduced into the rectum, and images were taken in a sitting position. Characteristic dynamic findings in defecography were evaluated according to operative methods and were compared with symptoms of defecatory disorders.

RESULTS

Defecographic findings closely associated with postoperative defecatory disorder were as follows: (1) low volume of neorectum in patients with worse incontinence grade (p < 0.05), (2) low evacuation fraction in patients with significantly impaired function such as soiling, urgency, and worsened incontinence score (p < 0.05), (3) minor alteration of anorectal angle at evacuation in patients with major soiling and worsened incontinence score (p < 0.05), and (4) barium shadow in the anal canal at rest in patients with urgency (p < 0.05). By reconstruction method, the J-pouch displayed a larger volume than straight anastomosis but a significantly wider anorectal angle than high anterior resection (HAR). Side-to-end anastomosis offered a moderate volume and a sharp anorectal angle as in HAR.

CONCLUSIONS

Defecography is useful for visualizing and characterizing defecatory disorders following rectal resection. Based on defecography, J-pouch reconstruction offers advantageous volume, while side-to-end anastomosis provides a more acute anorectal angle for patients who have received rectal resection with low anastomosis. A new reconstruction method offering both advantages was discussed.

Anorectal function problems after left hemicolectomy

BACKGROUND

The aim of this study was to evaluate the subjective anorectal function in patients with left hemicolectomy and to clarify the clinical factors influencing postoperative anorectal function problems.

MATERIALS AND METHODS

One hundred and twenty one patients who underwent left hemicolectomy from April 2002 to December 2003 were enrolled in this study and sent questionnaires concerning anorectal function. Left hemicolectomy in patients with cancer was performed by high ligation of the inferior mesenteric artery; in patients with diverticulitis or polyposis, the inferior mesenteric artery was cut just below the branch of the left colonic artery. One hundred patients replied to the questionnaire: 52 men and 48 women, aged 37 to 85, with a mean age of 66.6 years. Differences were analyzed for statistical significance by the Chi square test and by logistic regression.

RESULTS

Anorectal function problems was present in 33% of patients: female gender (P = 0.02), laparoscopic surgery (P = 0.04), and postoperative diarrhea (P = 0.04) had significant independent effects on anorectal function problems. Transient early fecal incontinence was observed in 16% of patients and laparoscopic surgery had significant independent effects on this problem (P = 0.04). Inability to discriminate between gas and stool, tenesmus, or urgency were present in 21%, 18%, and 17% of cases, respectively, and were independently associated respectively with laparoscopic surgery (P = 0.005) and postoperative diarrhea (P = 0.019) (P = 0.015).

CONCLUSION

In our study the following two issues were clarified: anorectal function problems are frequent after left hemicolectomy, and the laparoscopic technique is linked to poor postoperative anorectal function. The technical methods of high ligation of the inferior mesenteric artery could explain this result.

Pudendal Nerve Terminal Motor Latency in Patients With or Without Soiling 5 Years or more after Low Anterior Resection for Lower Rectal Cancer

BACKGROUND

To clarify the neurological function with respect to external anal sphincter (EAS) muscles in patients with or without soiling after low anterior resection (LAR) for lower rectal cancer, we examined the terminal motor latency in the pudendal motor nerves (PNTML).

MATERIALS AND METHODS

Thirty-eight patients after LAR for lower rectal cancer were studied electrophysiologically and compared with 30 healthy volunteers as controls (19 men and 11 women, aged 44 to 76 years of age, with a mean age of 65.5 years). Patients after LAR were divided into two groups [18 patients with soiling (12 men and 6 women, aged 51 to 77 years with a mean age of 64.8 years), 20 patients without soiling (13 men and 7 women, aged 47 to 75 years with a mean age of 62.1 years)]. The mean follow-up time from LAR was 67.2 months (range 60-84 months). Bilateral (left-sided and right-sided) PNTML tests were performed on all patients in order to measure the latency of the response in the bilateral EAS muscle following digitally directed transrectal pudendal nerve stimulation.

RESULTS

The distance from the anal verge to the level of anastomosis in patients with soiling (mean, 2.2 cm) was significantly shorter than that in patients without soiling (mean, 4.1 cm) (P < 0.05). Conduction delay of the bilateral PNTML in patients with soiling was longer than that in patients without soiling and normal subjects, significantly (P < 0.01, respectively). There was no significant difference between the right-sided and left-sided PNTML.

CONCLUSIONS

These findings support the hypothesis that soiling after LAR may be partially caused by damage to the bilateral pudendal motor nerves.

Induction and recovery of colonic motility/defecatory disorders after extrinsic denervation of the colon and rectum in rats

BACKGROUND

Anterior resection for rectal disease is associated with extrinsic autonomic denervation of the neorectum, which may influence the myenteric plexus, and subsequently the motility/defecatory status after operation.

METHODS

A rat model with denervated neorectum was constructed. Colonic contractile activity in vivo, the amount of generic neuron marker (PGP 9.5) and nitric oxide synthase (NOS) were measured periodically. The responses of the muscle strip in each period to electrical field stimulation were evaluated using various neurotransmitters.

RESULTS

In rats with denervated neorectum, giant migrating contractions (GMCs) of the distal colon, the number of fecal lumps per day and their small size, significantly increased in the early phase postoperatively, although both recovered in the late-phase period. The contractile response of the muscle strip of the denervated colon to acetylcholine was reduced throughout the period; however, contraction of the denervated colon under the addition of NO inhibitor (l-NAME) was enhanced significantly in the late-phase period, and recovered to the control level by atropine. Neuronal NOS, but not PGP 9.5 concentration, in the myenteric plexus at the distal denervated colon, significantly increased in the late-phase period. None of the above items differed from the control at other colonic portions throughout the period.

CONCLUSIONS

Extrinsic autonomic denervation causes abnormal hyper-motility in the neorectum, which may be associated with multiple evacuations in the early phase postoperatively. Increased acetylcholine and the subsequent increase of neuronal NOS in the myenteric plexus may be an adaptive mechanism to compensate for such abnormal colonic motility after extrinsic denervation.