Altered colonic motility is associated with low anterior resection syndrome

And after surgery, what's new for the rectal cancer survivor?

Low anterior resection syndrome is a common but underestimated complication after rectal cancer surgery that significantly impacts the quality of life of the surviving patient. It is characterised by symptoms such as faecal incontinence and voiding dysfunction and affects up to 90% of patients undergoing low anterior rectal resection. The aetiology of the syndrome is multifactorial with no clear determining factor. It includes the use of preoperative radiotherapy, the indication for a protective ileostomy, sphincteric lesions, nerve damage to the rectal autonomic plexuses, and changes in left colon motor function. Although various therapeutic modalities have been shown to be effective in the management of the symptoms of the syndrome, there is still no standard treatment or patient selection pattern. In this article, a critical review of the therapeutic possibilities for patients who have survived rectal surgery will be made.

Truly Inevitable-Our Perspective on the Complications After Surgery for Rectal Cancer

Rectal cancer is one of the most common malignancies in the GI tract. Although recent technology and treatments are available today, complications are still there. The focus of this study is to draw attention towards the important complications and their management options in rectal cancer surgeries. Retrospective study of 57 patients diagnosed and operated with rectal cancer between 2012 and 2022 using questionnaire data. 21.05% developed complications following surgery for rectal cancer including SSI, LARS, anastomosis leak, and stomal stenosis. LARS was seen in 26.31% out of the 19 patients involved in the study (LAR + ULAR) of which 80% had minor LARS scores and 20% had major LARS scores. In LARS, 80% had received long-term chemoradiotherapy in a neoadjuvant setting. The study revealed a rising trend of rectal cancer in young individuals (35.08%). Complications are an inevitable part of rectal cancer surgery even with recent technology. Use of long-course radiotherapy in neoadjuvant settings and LAR and ULAR may improve sphincter preservation with the risk of increasing incidence of low anterior resection syndrome, and anastomosis leak should be used cautiously with proper patient selection.

An expert's guide to classical manometric patterns seen in high-resolution colonic manometry

INTRODUCTION

High-resolution colonic manometry is a research and diagnostic tool used to evaluate colonic motility. Used in health it helps us understand normal colonic motility and the colonic response to physiological stimuli such as meal, as well as chemical (laxatives) and mechanical (distension) stimuli. In pediatric and adult patients with suspected colonic disorders, it can help to understand the abnormal colonic motility associated with the condition.

AREA COVERED

High-resolution manometric catheters contain multiple closely spaced sensors that detect intraluminal pressure changes and contractile force, which can be interpreted as contractile activity. This activity forms several distinctive motor patterns that help in understanding normal colonic physiology and provide insights into the potential pathophysiology underlying colonic disorders such as constipation. After a PubMed search of colonic high-resolution manometry studies, this review provides an overview of the characterized motor patterns, when they occur, how they are initiated, their clinical relevance, and their role, if any, in guiding therapeutic interventions.

EXPERT OPINION

High-resolution colonic manometry has identified motor patterns that were missed or mislabeled by low-resolution recordings. How best to use this information to guide treatment remains to be determined.

From the organ bath to the whole person: a review of human colonic motility

Motor function of the colon is essential for health. Our current understanding of the mechanisms that underlie colonic motility are based upon a range of experimental techniques, including molecular biology, single cell studies, recordings from muscle strips, analysis of part or whole organ ex vivo through to in vivo human recordings. For the surgeon involved in the clinical management of colonic conditions this amounts to a formidable volume of material. Here, we synthesize the key findings from these various experimental approaches so that surgeons can be better armed to deal with the complexities of the colon.

Validation of body surface colonic mapping (BSCM) against high resolution colonic manometry for evaluation of colonic motility

Abnormal cyclic motor pattern (CMP) activity is implicated in colonic dysfunction, but the only tool to evaluate CMP activity, high-resolution colonic manometry (HRCM), remains expensive and not widely accessible. This study aimed to validate body surface colonic mapping (BSCM) through direct correlation with HRCM. Synchronous meal-test recordings were performed in asymptomatic participants with intact colons. A signal processing method for BSCM was developed to detect CMPs. Quantitative temporal analysis was performed comparing the meal responses and motility indices (MI). Spatial heat maps were also compared. Post-study questionnaires evaluated participants' preference and comfort/distress experienced from either test. 11 participants were recruited and 7 had successful synchronous recordings (5 females/2 males; median age: 50 years [range 38-63]). The best-correlating MI temporal analyses achieved a high degree of agreement (median Pearson correlation coefficient (Rp) value: 0.69; range 0.47-0.77). HRCM and BSCM meal response start and end times (Rp = 0.998 and 0.83; both p < 0.05) and durations (Rp = 0.85; p = 0.03) were similar. Heat maps demonstrated good spatial agreement. BSCM is the first non-invasive method to be validated by demonstrating a direct spatio-temporal correlation to manometry in evaluating colonic motility.

To explore the pathogenesis of anterior resection syndrome by magnetic resonance imaging rectal defecography

BACKGROUND

Over 90% of rectal cancer patients develop low anterior resection syndrome (LARS) after sphincter-preserving resection. The current globally recognized evaluation method has many drawbacks and its subjectivity is too strong, which hinders the research and treatment of LARS.

AIM

To evaluate the anorectal function after colorectal cancer surgery by quantifying the index of magnetic resonance imaging (MRI) defecography, and pathogenesis of LARS.

METHODS

We evaluated 34 patients using the standard LARS score, and a new LARS evaluation index was established using the dynamic images of MRI defecography to verify the LARS score.

RESULTS

In the LARS score model, there were 10 (29.41%) mild and 24 (70.58%) severe cases of LARS. The comparison of defecation rate between the two groups was 29.36 ± 14.17% versus 46.83 ± 18.62% (P = 0.004); and MRI-rectal compliance (MRI-RC) score was 3.63 ± 1.96 versus 7.0 ± 3.21 (P = 0.001). Severe and mild LARS had significant differences using the two evaluation methods. There was a significant negative correlation between LARS and MRI-RC score (P < 0.001), and they had a negative correlation with defecation rate (P = 0.028).

CONCLUSION

MRI defecography and standard LARS score can both be used as an evaluation index to study the pathogenesis of LARS.

Development and Validation of a Post-Radiotherapy Prediction Model for Bowel Dysfunction After Rectal Cancer Resection

BACKGROUND & AIMS

The benefit of radiotherapy for rectal cancer is based largely on a balance between a decrease in local recurrence and an increase in bowel dysfunction. Predicting postoperative disability is helpful for recovery plans and early intervention. We aimed to develop and validate a risk model to improve the prediction of major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy using perioperative features.

METHODS

Eligible patients more than 1 year after restorative resection following radiotherapy were invited to complete the low anterior resection syndrome (LARS) score at 3 national hospitals in China. Clinical characteristics and imaging parameters were assessed with machine learning algorithms. The post-radiotherapy LARS prediction model (PORTLARS) was constructed by means of logistic regression on the basis of key factors with proportional weighs. The accuracy of the model for major LARS prediction was internally and externally validated.

RESULTS

A total of 868 patients reported a mean LARS score of 28.4 after an average time of 4.7 years since surgery. Key predictors for major LARS included the length of distal rectum, anastomotic leakage, proximal colon of neorectum, and pathologic nodal stage. PORTLARS had a favorable area under the curve for predicting major LARS in the internal dataset (0.835; 95% CI, 0.800-0.870, n = 521) and external dataset (0.884; 95% CI, 0.848-0.921, n = 347). The model achieved both sensitivity and specificity >0.83 in the external validation. In addition, PORTLARS outperformed the preoperative LARS score for prediction of major events.

CONCLUSIONS

PORTLARS could predict major bowel dysfunction after rectal cancer resection following radiotherapy with high accuracy and robustness. It may serve as a useful tool to identify patients who need additional support for long-term dysfunction in the early stage.

CLINICALTRIALS

gov, number NCT05129215.

Inhibited postprandial retrograde cyclic motor pattern in the distal colon of patients with diarrhea-predominant irritable bowel syndrome

Patients with irritable bowel syndrome (IBS) have recurrent lower abdominal pain, associated with altered bowel habit (diarrhea and/or constipation). As bowel habit is altered, abnormalities in colonic motility are likely to contribute; however, characterization of colonic motor patterns in patients with IBS remains poor. Utilizing fiber-optic manometry, we aimed to characterize distal colonic postprandial colon motility in diarrhea-predominant IBS. After an overnight fast, a 72-sensor (spaced at 1-cm intervals) manometry catheter was colonoscopically placed to the proximal colon, in 13 patients with IBS-D and 12 healthy adults. Recordings were taken for 2 h pre and post a 700 kcal meal. Data were analyzed with our two developed automated techniques. In both healthy adults and patients with IBS-D, the dominant frequencies of pressure waves throughout the colon are between 2 and 4 cycles per minute (cpm) and the power of these frequencies increased significantly after a meal. Although these pressure waves formed propagating contractions in both groups, the postprandial propagating contraction increase was significantly smaller in patients compared with healthy adults. In healthy adults during the meal period, retrograde propagation between 2 and 8 cpm was significantly greater than antegrade propagation at the same frequencies. This difference was not observed in IBS-D. Patients with IBS-D show reduced prevalence of the retrograde cyclic motor pattern postprandially compared with the marked prevalence in healthy adults. We hypothesize that this reduction may allow premature rectal filling, leading to postprandial urgency and diarrhea.NEW & NOTEWORTHY Compared with healthy adults this study has shown a significant reduction in the prevalence of the postprandial retrograde cyclic motor pattern in the distal colon of patients with diarrhea-predominant irritable bowel syndrome. We hypothesize that this altered motility may allow for premature rectal filling which contributes to the postprandial urgency and diarrhea experienced by these patients.

Hyperactive Distal Colonic Motility and Recovery Patterns Following Right Colectomy: A High-Resolution Manometry Study

BACKGROUND

Postoperative ileus results in morbidity, prolonged hospitalization, and increased health care expenditure. However, the underlying abnormalities in motility remain poorly understood. Recent high-resolution manometry studies demonstrated that the distal colon becomes hyperactive with a cyclic motor pattern postoperatively, but they did not track this activity beyond 16 hours after surgery.

OBJECTIVE

This study used high-resolution manometry to evaluate distal colonic motility during the first 4 days after right-sided colectomy.

DESIGN

An observational study of perioperative high-resolution colonic manometry using a 36-sensor catheter with 1-cm resolution.

SETTING

A single tertiary hospital.

PATIENTS

Adult patients undergoing elective laparoscopic or open right-sided colonic resection.

MAIN OUTCOME MEASURES

Occurrence of distal colonic motor patterns during the perioperative period, defined according to a published classification system. Clinical markers of gut recovery included time to first stool, oral diet, and prolonged postoperative ileus.

RESULTS

Seven patients underwent perioperative manometry recordings. Hyperactive cyclic motor patterns emerged intraoperatively and peaked in the first 12 hours postoperatively, occupying 81.8% ± 3.9% of the recording. This gradually returned to normal during the first 4 days, reaching 19.0% ± 4.4% ( p = 0.002). No patient had a bowel movement before this hyperactivity resolved. High-amplitude propagating sequences were absent in early postoperative recordings, and their return temporally correlated with the passage of stool. Abnormal high-amplitude repetitive 0.5 to 1 cycle per minute activity was observed in the left colon of 1 patient with prolonged ileus.

LIMITATIONS

The invasive nature of recordings limited this study to a small sample size.

CONCLUSIONS

Cyclic motor patterns are markedly hyperactive in the distal colon after right-sided colectomy and resolve during the first 4 postoperative days. High-amplitude propagating sequences are inhibited by surgery and gradually recover. Bowel function may not return until these changes resolve. Other abnormal repetitive hyperactive patterns could contribute to the development of prolonged ileus. See Video Abstract at http://links.lww.com/DCR/B967 .

MOTILIDAD HIPERACTIVA DEL COLON DISTAL Y PATRONES DE RECUPERACIN DESPUS DE COLECTOMA DERECHA UN ESTUDIO DE MANOMETRA DE ALTA RESOLUCIN

ANTECEDENTES:El íleo post-operatorio produce una morbilidad significativa, una hospitalización prolongada y un aumento del gasto sanitario. Sin embargo, las anomalías subyacentes en la motilidad siguen siendo poco conocidas. Estudios recientes de manometría de alta resolución demostraron que el colon distal se vuelve hiperactivo con un patrón motor cíclico en el post-operatorio, pero no registraron esta actividad más allá de las 16 horas posteriores a la cirugía.OBJETIVO:Utilizar la manometría de alta resolución para evaluar la motilidad del colon distal durante los primeros cuatro días después de la colectomía del lado derecho.DISEÑO:Estudio observacional de pacientes sometidos a manometría colónica perioperatoria de alta resolución mediante catéter de 36 sensores con 1 cm de resolución.AJUSTE:Un solo hospital terciario.PACIENTES:Pacientes adultos sometidos a resección laparoscópica o abierta de colon del lado derecho de forma electiva.PRINCIPALES MEDIDAS DE RESULTADO:AAparición de patrones motores del colon distal durante el período perioperatorio, definidos según un sistema de clasificación publicado. Los marcadores clínicos de recuperación intestinal incluyeron, tiempo hasta la primera evacuación, dieta oral e íleo posoperatorio prolongado.RESULTADOS:Siete pacientes fueron sometidos a registros de manometría perioperatoria. Los patrones motores cíclicos hiperactivos emergieron intraoperatoriamente y alcanzaron su punto máximo en las primeras 12 horas post-operatorias, ocupando 81,8 ± 3,9% del registro. Esto volvió gradualmente a la normalidad durante los primeros cuatro días, alcanzando el 19,0 ± 4,4% (p = 0,002). Ningún paciente tuvo una evacuación intestinal antes de que se resolviera esta hiperactividad. Las secuencias de propagación de alta amplitud estaban ausentes en las grabaciones post-operatorias tempranas y su retorno se correlacionó temporalmente con el paso de las heces. Se observó actividad anormal de alta amplitud repetitiva de 0,5-1 ciclo / minuto en el colon izquierdo de un paciente con íleo prolongado.LIMITACIONES:La naturaleza invasiva de las grabaciones limitó este estudio a un tamaño de muestra pequeño.CONCLUSIONES:Los patrones motores cíclicos son marcadamente hiperactivos en el colon distal después de la colectomía del lado derecho y se resuelven gradualmente durante los primeros cuatro días posoperatorios. Las secuencias de propagación de gran amplitud se inhiben mediante cirugía y se recuperan gradualmente. Es posible que la función intestinal no regrese hasta que estos cambios se resuelvan. Otros patrones hiperactivos repetitivos anormales podrían contribuir al desarrollo de íleo prolongado. Consulte Video Resumen en http://links.lww.com/DCR/B967 . (Traducción-Dr. Mauricio Santamaria ).

Long-term functional outcome after tubular laparoscopic sigmoid resection for diverticular disease

PURPOSE

Sigmoid resection for diverticular disease is a frequent surgical procedure in the Western world. However, long-term bowel function after sigmoid resection has been poorly described in the literature. This study aims to assess the long-term bowel function after tubular sigmoid resection with preservation of inferior mesenteric artery (IMA) for diverticular disease.

METHODS

We retrospectively identified patients who underwent sigmoid resection for diverticular disease between 2002 and 2012 at a tertiary referral center in northern Germany. Using well-validated questionnaires, bowel function was assessed for fecal urgency, incontinence, and obstructed defecation. The presence of bowel dysfunction was compared to baseline characteristics and perioperative outcome.

RESULTS

Two hundred and thirty-eight patients with a mean age of 59.2 ± 10 years responded to our survey. The follow-up was conducted 117 ± 32 months after surgery. At follow-up, 44 patients (18.5%) had minor LARS (LARS 21-29) and 35 (15.1%) major LARS (LARS ≥ 30-42), 35 patients had moderate-severe incontinence (CCIS ≥ 7), and 2 patients (1%) had overt obstipation (CCOS ≥ 15). The multivariate analysis showed that female gender was the only prognostic factor for long-term incontinence (CCIS ≥ 7), and ASA score was the only preoperative prognostic factor for the presence of major LARS at follow-up.

CONCLUSION

Sigmoid resection for diverticular disease can be associated with long-term bowel dysfunction, even with tubular dissection and preservation of IMA. These findings suggest intercolonic mechanisms of developing symptoms of bowel dysfunction after disruption of the colorectal continuity that are so far summarized as "sigmoidectomy syndrome."

Faecal incontinence is associated with an impaired rectosigmoid brake and improved by sacral neuromodulation

BACKGROUND

The rectosigmoid brake, characterised by retrograde cyclic motor patterns on high-resolution colonic manometry, has been postulated as a contributor to the maintenance of bowel continence. Sacral neuromodulation (SNM) is an effective therapy for faecal incontinence, but its mechanism of action is unclear. This study aims to investigate the colonic motility patterns in the distal colon of patients with faecal incontinence, and how these are modulated by SNM.

METHODS

A high-resolution fibreoptic colonic manometry catheter, containing 36 sensors spaced at 1-cm intervals, was positioned in patients with faecal incontinence undergoing stage 1 SNM. One hour of pre- and post meal recordings were obtained followed by pre- and post meal recordings with suprasensory SNM. A 700-kcal meal was given. Data were analysed to identify propagating contractions.

RESULTS

Fifteen patients with faecal incontinence were analysed. Patients had an abnormal meal response (fewer retrograde propagating contractions compared to controls; p = 0.027) and failed to show a post meal increase in propagating contractions (mean 17 ± 6/h premeal vs. 22 ± 9/h post meal, p = 0.438). Compared to baseline, SNM significantly increased the number of retrograde propagating contractions in the distal colon (8 ± 3/h premeal vs. 14 ± 3/h premeal with SNM, p = 0.028). Consuming a meal did not further increase the number of propagating contractions beyond the baseline upregulating effect of SNM.

CONCLUSION

The rectosigmoid brake was suppressed in this cohort of patients with faecal incontinence. SNM may exert a therapeutic effect by modulating this rectosigmoid brake.

Characterisation of parasympathetic ascending nerves in human colon

Background

In the human large bowel, sacral parasympathetic nerves arise from S2 to S4, project to the pelvic plexus ("hypogastric plexus") and have post-ganglionic axons entering the large bowel near the rectosigmoid junction. They then run long distances orally or aborally within the bowel wall forming "ascending nerves" or "shunt fascicles" running in the plane of the myenteric plexus. They form bundles of nerve fibres that can be distinguished from the myenteric plexus by their straight orientation, tendency not to merge with myenteric ganglia and greater width.

Aim

To identify reliable marker(s) to distinguish these bundles of ascending nerves from other extrinsic and intrinsic nerves in human colon.

Methods

Human colonic segments were obtained with informed consent, from adult patients undergoing elective surgery (n = 21). Multi-layer immunohistochemical labelling with neurofilament-H (NF200), myelin basic protein (MBP), von Willebrand factor (vWF), and glucose transporter 1 (GLUT1), and rapid anterograde tracing with biotinamide, were used to compare ascending nerves and lumbar colonic nerves.

Results

The rectosigmoid and rectal specimens had 6-11 ascending nerves spaced around their circumference. Distal colon specimens typically had 1-3 ascending nerves, with one located near the mesenteric taenia coli. No ascending nerves were observed in ascending colon specimens. GLUT1 antisera labelled both sympathetic lumbar colonic nerves and ascending nerves in the gut wall. Lumbar colonic nerves joined the myenteric plexus and quickly lost GLUT1 labelling, whereas GLUT1 staining labelled parasympathetic ascending nerves over many centimetres.

Conclusion

Ascending nerves can be distinguished in the colorectum of humans using GLUT1 labelling combined with NF200.

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.

The risk factors of low anterior resection syndrome after colorectal cancer surgery: A retrospective study of 566 patients in a single institution in China

PURPOSE

This study aims to identify the independent risk factors in the low anterior resection syndrome (LARS) after surgery for colorectal cancer (CRC).

METHOD

This was a retrospective, single-institution study in the Second Affiliation Hospital of Dalian Medical University, China. Patients underwent sphincter-preserving low anterior resection with total or partial mesorectal resection (with or without protective ileostomy) and completed a self-filled questionnaire over the phone to assess postoperative bowel dysfunction from January 2017 to December 2019. The predictors of LAR were evaluated using univariate and multivariate analyses.

RESULT

The study population was 566 patients, 264 (46.64%), 224 (39.58%), and 78 (13.78%) patients with no, minor, and major LARS, respectively. In the univariate analysis, independent factors such as tumor location and size, anastomotic height, protective ileostomy, post-operation chemoradiotherapy, tumor T stage, lymphatic nodal metastasis classification, surgery duration, and time interval for closure of stoma were significantly associated with LARS points while we found the tumor T stage and lymphatic nodal metastasis classification as the new independent risk factors compared with the last decade studies. In the multivariate analysis, factors such as low and middle tumor location and protective ileostomy, and post operation treatment, nodal metastasis classification were the independent risk factors for major LARS.

CONCLUSION

The new independence risk factors were tumor T stage and lymphatic nodal metastasis status in univariate analysis in our study, with anastomotic height, low and middle tumor location, protective ileostomy, post-operation chemoradiotherapy, nodal metastasis status increasing LARS point in multivariate analysis after surgery for CRC.

The Longitudinal Course of Low-anterior Resection Syndrome: An individual Patient Meta-analysis

OBJECTIVE

We aimed to better understand the longitudinal course of low anterior resection syndrome (LARS) to guide patient expectations and identify those at risk of persisting dysfunction.

SUMMARY BACKGROUND DATA

LARS describes disordered bowel function after rectal resection that significantly impacts quality of life.

METHODS

MEDLINE, EMBASE, CENTRAL, and CINAHL databases were systematically searched for studies that enrolled adults undergoing anterior resection for rectal cancer and used the LARS score to assess bowel function at ≥2 postoperative time points. Regression analyses were performed on deidentified patient-level data to identify predictors of change in LARS score from baseline (3-6months) to 12-months and 18-24 months.

RESULTS

Eight studies with a total of 701 eligible patients were included. The mean LARS score improved over time, from 29.4 (95% confidence interval 28.6-30.1) at baseline to 16.6 at 36 months (95% confidence interval 14.2%-18.9%). On multivariable analysis, a greater improvement in mean LARS score between baseline and 12 months was associated with no ileostomy formation [mean difference (MD) -1.7 vs 1.7, P < 0.001], and presence of LARS (major vs minor vs no LARS) at baseline (MD -3.8 vs -1.7 vs 5.4, P < 0.001). Greater improvement in mean LARS score between baseline and 18-24 months was associated with partial mesorectal excision vs total mesorectal excision (MD-8.6 vs 1.5, P < 0.001) and presence of LARS (major vs minor vs no LARS) at baseline (MD -8.8 vs -5.3 vs 3.4, P < 0.001).

CONCLUSIONS

LARS improves by 18 months postoperatively then remains stable for up to 3 years. Total mesorectal excision, neoadjuvant radiotherapy, and ileostomy formation negatively impact upon bowel function recovery.

Potential causes of the preoperative increase in the rectosigmoid cyclic motor pattern: A high-resolution manometry study

Background

Cyclic motor patterns (CMPs) are the most common motor pattern in the distal colon. This study used high‐resolution (HR) colonic manometry to quantify trends in distal colonic motor activity before elective colonic surgery, determine the effect of a preoperative carbohydrate load, and compare this with a meal response in healthy controls.

Methods

Fiber‐optic HR colonic manometry (36 sensors, 1 cm intervals) was used to investigate distal colonic motor activity in 10 adult patients prior to elective colonic surgery, 6 of whom consumed a preoperative carbohydrate drink (200 kCal). Data were compared with nine healthy volunteers who underwent HR colonic manometry recordings while fasted and following a 700 kCal meal. The primary outcome was the percentage of recording occupied by CMPs, defined as propagating contractions at 2–4 cycles per minute (cpm). Secondary outcomes included amplitude, speed, and distance of propagating motor patterns.

Results

The occurrence of CMPs progressively increased in time periods closer to surgery (p = 0.001). Consumption of a preoperative drink resulted in significantly increased CMP occurrence (p = 0.04) and propagating distance (p = 0.04). There were no changes in amplitude or speed of propagating motor patterns during the preoperative period. The increase in activity following a preoperative drink was of similar magnitude to the colonic meal response observed in healthy controls, despite the lesser caloric nutrient load.

Conclusion

Distal colonic CMP increased in occurrence prior to surgery, amplified by ingestion of preoperative carbohydrate drinks. We hypothesize that anxiety, which is also known to rise with proximity to surgery, could play a contributing role.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.

Improvement of low anterior resection syndrome beyond 2 years after total mesorectal excision

AIM

Bowel dysfunction after sphincter-preserving proctectomy, also known as low anterior resection syndrome (LARS), has significant impact on survivors of rectal cancer. This study aimed to assess the temporal change of LARS beyond 2 years after proctectomy, which has not been fully studied.

METHODS

We longitudinally enrolled consecutive patients who had received total mesorectal excision in a tertiary academic medical center, with preoperative neoadjuvant therapy if indicated. LARS score was longitudinally assessed by two serial follow-ups, with a fixed interval of 18 months.

RESULTS

Overall, 107 patients responded for the first follow-up after a median of q20 months, 96 of whom responded for the second follow-up after a median of 38 months. At the first follow-up, 48 patients (44.9%) reported major LARS, compared with 23 (24.0%) at the second follow-up (p < 0.001). Mean LARS score improved from 27.3 to 18.6, mostly from "urgency" (12.2 vs. 6.2, p < 0.001) and "clustering of stools" (9.7 vs. 7.7, p = 0.001). Anastomosis less than 3 cm from the anal verge was independently associated with LARS improvement.

CONCLUSION

Bowel dysfunction continues to improve 2 years after total mesorectal excision, with most symptom relief in urgency and stool clustering, especially in patients with lower anastomosis.

Intraoperative serosal extracellular mapping of the human distal colon: a feasibility study

BACKGROUND

Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping.

METHODS

HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed.

RESULTS

Eleven patients (33-71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10-180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded.

CONCLUSIONS

Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period.

NEW FINDINGS

The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans.

Improving Global Surgical Oncology Benchmarks: Defining the Unmet Need for Cancer Surgery in Ghana

BACKGROUND

The Lancet Commission on Global Surgery (LCoGS) recommended an annual surgical rate at which low- and middle-income countries (LMICs) could achieve most of the population-wide benefits of surgery. However, condition-specific guidelines were not proposed. To inform rates of surgery for cancer, we sought to assess the current met and unmet need for oncologic surgery in Ghana.

METHODS

Data on all operations performed in Ghana over a one-year period (2014-15) were obtained from representative samples of 48/124 first-level and 12/16 referral hospitals and scaled-up for nationwide estimates. Procedures for cancer were identified by indication. Using modified LCoGS methodology with disease prevalence, Ghana's annual rate of cancer surgery was compared to that of New Zealand to quantify current unmet needs.

RESULTS

232,776 surgical procedures were performed in Ghana; 2,562 procedures (95%UI 1878-3255) were for cancer. Of these, 964 (37%) were surgical biopsies. The annual rate of procedures treating cancer was 2115 surgeries/100,000 cancer cases, or 21% of the New Zealand benchmark. Cervical, breast, and prostate cancer were found to meet 2.1%, 17.2%, and 32.1% of their respective surgical need.

CONCLUSIONS

There is a large unmet need for cancer surgery in Ghana. Cancer surgery constitutes under 2% of the total surgeries performed in Ghana, an important proportion of which are used for biopsies. Therapeutic operative rate is deficient across most cancer types, and may lag behind improvements in screening efforts. As cancer prevalence and diagnosis increase in LMICs, cancer-specific surgical capacity must be increased to meet these evolving needs.