High-resolution colon manometry in patients suffering from LARS symptoms after surgery for rectal cancer.

Survival rates after rectal cancer and oncological outcomes have improved significantly over the years. Improved imaging, neoadjuvant therapy and standardized surgery all add to an improved oncological outcome. Radical surgery - a total mesorectal excision (TME) - remains the gold standard treatment. Because of the excision of the rectum, the rectal reservoir as such is lost. As a consequence, a low anterior resection - although nerve- and sphincter sparing - may result in debilitating functional consequences concerning bowel function. These bowel symptoms are commonly referred to as the Low Anterior Resection Syndrome (LARS); a complex syndrome consisting of a multitude of possible bowel symptoms, with consequences for the patient’s quality of life.
Notwithstanding the overwhelming use of ‘LARS’ as a term to describe these bowel symptoms (such as: incontinence for flatus or feces, frequent bowel movements, urgency and clustering of defecation), the exact pathophysiological mechanisms still remain poorly understood. It is hypothesized that the etiology of LARS is multifactorial, and relates to neo-rectal capacity and compliance, sphincter function, pelvic floor function, colonic motility and postprandial response. Based on these hypotheses, first it was explored if the creation of a rectal neo-reservoir would prevent LARS. However, evidence shows that a rectal neo-reservoir does not contribute to long term differences concerning bowel complaints, questioning its contribution to LARS/postoperative bowel function. However, the creation of a neo-rectum has been suggested to delay motility patterns; i.e. when stool reached the rectum, a delay of defecation was observed. Second, it has been demonstrated that, along with TME, a high ligation of the inferior mesenteric artery and the inferior mesenteric vein at the inferior border of the pancreas, could result in altered colonic motility and consequently affect postoperative function (LARS) due to autonomic denervation. To our knowledge, the impact of the mechanisms associated with radical surgery on colonic motility has only been scarcely investigated. Therefore, the innovative technique of high-resolution colon manometry (HRCM) can provide valuable insights into colonic motility patterns. Recently, a consensus statement on terminology and definitions of these patterns was published, giving an overview of the current knowledge. A recent study of Keane et al. using HRCM, demonstrated that in patients who underwent distal colorectal resection (on average 6.8 years before), LARS was associated with altered colonic motility.

The rationale of this study was to investigate the alteration of colonic motor patterns in the early postoperative stage and between patients with no or minor LARS-symptoms (LARS-score < 30) compared to patients experiencing major LARS complaints (LARS-score ≥ 30). Consequently, the aim of this study was to investigate colonic motor patterns with HRCM and to assess the effect of hindgut denervation on the presence of coordinated proximal to distal contractions in rectal cancer patients suffering from varying degrees of LARS after TME.

The   morning after    an    overnight fast   of  no    less   than    12 h,     subjectswere    expected at  the    endoscopy unit   of  the    University Hospitals of  Leuven. Loperamide hydrochloride was    discontinued for   1 day.    Bowel     preparation consisted of   one-   liter  of   water   enemas (Moviprep) at  two   timepoints the   day    before the   HRCM. The   colonoscopy was  performed under conscious sedation (up to 5 mg midazolam). A high-resolution manometry (HRM) catheter (10-   F   solid    state    catheter containing 40   pressure sensors spaced 2.5   cm    apart,    Unisensor AG,)   was    clipped into   the  mucosa of   the  caecum. Two   hours     later,    subjectswere positioned in a semi-recumbent pose on a bed and colonic pres-sure   recordings started for   3 h.    The   subject subsequently received a standardized meal,    based    on    the   habitual Belgian lunch,    and   the    re-cording of  colonic pressures continued for   two   more     hours.     At  this   point,    bisacodyl (10  mg)    was   administered intraluminally, thereafter,pressure recording continued for   a   maximum of  1 h.   When     the   meas-urement was finished, the HRM was removed with a gentle pull. 

High resolution colon manometry