Hypothesis of Pathophysiology

Various causes (including reduction of the rectal ampulla, iatrogenic internal sphincter lesions, auto-nomic nerve lesions, influence of chemoradiation) could play a role in determining this dysfunction.

A sphincter-saving RR significantly reduces the rectal ampulla; frequently, excision of the entire rectum is necessary, and coloanal anastomosis is performed [5, 23-27]. Even if a colonic pouch is constructed, FI may still occur [5, 23, 28]. However, the role of methods of reconstruction appears essential. At present, the J-pouch remains the gold standard for routine clinical practice, thanks to good results at long-term follow-up, but the transverse coloplasty and side to end anastomosis assure a superposable intestinal function in many trials [29-34].

The transanal introduction of a stapler or anal dilatation may be a cause of iatrogenic lesion of the internal anal sphincter in a high percentage of patients (18% at endoanal ultrasound evaluation) [2, 35, 36], but the external sphincter does not appear lesioned by the procedure. Internal anal sphincter fragmentation can cause a decrease of resting anal pressure. On the other hand, transabdominal anastomosis minimized the risk of sphincter damage and showed a good degree of continence [36-38].

Despite the warning that great care should be taken regarding nerve sparing, sympathetic and parasympathetic fibers can be interrupted, with significant deregulation of the nervous inputs and outputs to and from the pelvis, particularly the remaining rectum, anus, and perirectal structures [11]. On the other hand, the preservation of autonomic nerve structures during total mesorectal excision (TME) can decrease the risk of FI and urogenital disturbances. The pelvic organs are innervated by sympathetic and parasympathetic nerve fibers. The sympathetic supply arises from L1 to L3, which contribute to the superior hypogastric plexus that extends to the sacral promontory. This plexus gives origin to the right and left hypogastric nerves. The parasympa-thetic nerve fibers arise from S2 to S4. They emerge through the sacral foramina (nerves erigentes) and join the sympathetic hypogastric nerves to constitute the right and left inferior pelvic plexuses sited at the pelvic sidewall anteriorly and laterally to the lower third of the rectum. From each pelvic plexus, nerve fibers (both sympathetic and parasympathetic) reach the pelvic viscera.

Identification of the nerve fibers is more difficult for the parasympathetic nerves that extend deep into the pelvis, whereas visualization of the sympathetic system is easier. However, damage could occur along the entire nerve fiber branchings: periaortic/pericav-al, superior hypogastric plexus, hypogastric nerves, S2-S4 parasympathetic nerves, inferior pelvic plexuses, and distal nerve fibers. Other factors can also influence nerve sparing: male gender, tumor size, intraoperative blood loss, and surgeon expertise. When urinary incontinence and/or disturbances of sexual function occur as secondary effects of nerve damage, they contribute to worsening of the patient's clinical condition [39].

Pelvic radiotherapy can play an important role in the pathogenesis of functional disturbances of continence [40-42]. In patients treated with pelvic radiotherapy for prostate, gynecological, bladder, anal, or rectal cancer, the incidence of FI is 3-53% [43]. This is despite progress in irradiation procedure. The patient's age and presence of "anal symptoms" are described as risk factors. In their review article, Putta and Andreyev [43] assessed that rectal cancer seems to present the highest incontinence rate, probably due to the additive effects of surgery to those of radiotherapy. In this work, only 8-56% of incontinent patients were found affected in their quality of life. The authors interpreted this finding because patients "do not feel or seem ill, will not report symptoms, as they believe they are inevitable consequences of radiotherapy treatment, of being old, or that there is nothing that can be done". With the aim of investigating bowel dysfunctions, Peeters et al. [44] sent a questionnaire to 597 patients enrolled in the prospective randomized TME trial (5x5 Gy before TME surgery vs. TME surgery alone), with a median follow-up of 5.1 years after the treatment. Irradiated patients compared with nonirradiated patients reported increased rates of FI (62% vs. 38%, respectively; p<0.001), pad wearing as a result of incontinence (56% vs. 33%, respectively; p<0.001), anal blood loss (11% vs. 3%, respectively; p=0.004), and mucus loss (27% vs. 15%, respectively; p=0.005). Satisfaction with bowel function was significantly lower and the impact of bowel dysfunction on daily activities was greater in irradiated patients compared with patients who underwent TME alone. Pollack et al. [45] recently reported results of a randomized trial within the Stockholm Radiotherapy Trials on 64 patients submitted to low anterior resection with or without preoperative radiotherapy (21 and 43 patients, respectively) followed up with quality-of-life questionnaires, clinical examination, anorectal manometry, and endoanal ultrasound. An impaired anorectal function was common after low anterior resection for rectal cancer, and the risk was increased after radiotherapy. Irradiated patients had significantly more symptoms of FI (57% vs. 26%, p=0.01), soiling (38% vs. 16%; p=0.04), and bowel movements per week (20 vs. 10; p=0.02). Significantly lower resting (35 mmHg vs. 62 mmHg; p<0.001) and squeeze pressures (104 mmHg vs. 143 mmHg; p=0.05) and more scarring of the anal sphincters (33% vs. 13%; p=0.03) were documented in irradiated patients. A

worse quality of life affected incontinent patients.

Multiple factors are supposed to produce the effects of radiotherapy on the pelvic structures involved in the continence mechanisms, including radiotherapy dose as well as physical, patient-related, treatment, and genetic factors [43]. Effects could be found on both anal canal structures and the rectum. In most studies, anal maximum resting pressure decreased following pelvic irradiation [46-54], hypo-thetically due to damage of endovascular cushions, internal anal sphincter thinning or atrophy, or both. However, disagreement exists on manometric assessment of resting pressure, as it was unchanged in other reports [50, 55-57]. Even if pressure increment due to squeezing is decreased in most studies [47,48, 50, 51-54, 57, 58] and thickness of the external anal sphincter has been reported after radiotherapy for prostate cancer [54], the influence of pudendal neuropathy in a change of muscle morphology is unclear. A significant prolonged pudendal nerve terminal motor latency (PNTML) has been observed in patients treated with neoadjuvant chemoradiation (irrespective to the inclusion or not of the anal canal to the irradiation field) and is associated to the FI severity score [57]. Moreover, being that the puden-dal nerve is also responsible for anal sensitivity, damage to it can be a significant cause of fecal seepage.

A lumbosacral plexopathy may be a concomitant cause of incontinence and can cause perianal anesthesia and alterations to the pudendal nerve [59]. Myenteric plexus degeneration within the bowel wall has been thought to influence continence [46]. The rectal sensation to distension is primarily transmitted along the S2, S3, and S4 parasympathetic nerves, which traverse the pelvic splanchnic nerves. Damage to these nerves induced by radiotherapy could alter rectal compliance. Regarding rectal physiology, most studies report a significant decrease in threshold volume and maximum tolerated volume in incontinent patients following pelvic irradiation [46-52, 54, 56, 58]. Moreover, radiotherapy induces an inflammatory response within the pelvic vessels and an increased secretion of growth factors, with consequent damage to the microcircle of the rectum.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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