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

Risk factors for severe low anterior resection syndrome in patients with rectal cancer undergoing sphincter‑preserving resection: A systematic review and meta‑analysis

The present study aimed to evaluate the incidence and risk factors of severe low anterior resection syndrome (LARS) in patients with rectal cancer undergoing sphincter-preserving resection, and to provide the clinical basis and reference for the treatment of rectal cancer and the prevention of LARS. Studies on the incidence and risk factors for severe LARS in patients with rectal cancer undergoing sphincter-preserving resection were searched using PubMed, Embase, Cochrane Library, Scopus and Web of Science, according to the inclusion and exclusion criteria. After evaluating the study quality and extracting relevant data, RevMan 5.2 and STATA software were used to conduct a meta-analysis. A total of 12 articles were considered eligible for the present meta-analysis. Within these articles, there were 3,877 cases of sphincter-preserving resection for rectal cancer and 1,589 cases of severe LARS; the incidence of severe LARS was 40.99%. The results of the meta-analysis revealed that sex [female; odds ratio (OR), 6.54; 95% CI, 3.63-11.76; Z, 6.27; P<0.00001], radiotherapy and chemotherapy (OR, 3.45; 95% CI, 2.29-5.21; Z, 5.91; P<0.00001), total mesorectal excision (TME; OR, 4.39; 95% CI, 3.32-5.79; Z, 10.41; P<0.00001), and distance between tumor and anal margin (OR, 2.74; 95% CI, 0.86-8.72; Z, 1.70; P<0.00001) may be the risk factors for severe LARS.

Abnormal gastrointestinal motility is a major factor in explaining symptoms and a potential therapeutic target in patients with disorders of gut-brain interaction

The objective of this article is to review the evidence of abnormal gastrointestinal (GI) tract motor functions in the context of disorders of gut-brain interaction (DGBI). These include abnormalities of oesophageal motility, gastric emptying, gastric accommodation, colonic transit, colonic motility, colonic volume and rectal evacuation. For each section regarding GI motor dysfunction, the article describes the preferred methods and the documented motor dysfunctions in DGBI based on those methods. The predominantly non-invasive measurements of gut motility as well as therapeutic interventions directed to abnormalities of motility suggest that such measurements are to be considered in patients with DGBI not responding to first-line approaches to behavioural or empirical dietary or pharmacological treatment.

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.

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.