Anorectal reflex following sphincter-saving operations

Application of laparoscopic modified Bacon operation in patients with low rectal cancer and analysis of the changes in anal function: A retrospective single-center study

Purpose

To investigate the value of modified Bacon operation in patients with low rectal cancer.

Methods

Retrospective analysis of 60 patients treated with laparoscopic surgery for low rectal cancer in the Department of Colorectal and Anal Surgery, Jingzhou Hospital affiliated to Yangtze University, from 2019 to 2022, divided into observation and control groups based on the method of the operation (laparoscopic modified Bacon operation group and laparoscopic Dixon operation with prophylactic ileostomy group). We compared the variations between the two groups.

Results

The length of the abdominal surgical incision was shorter in the observation group than in the control group(P<0.05). In the observation group, the length of hospital stay after the first operation was shorter(P<0.05), the both operations time and the second intraoperative bleeding were less(P<0.05), the DET score at one week after the first operation and the VAS after both operations were fewer than in the control group(P<0.05), the postoperative rate of ischemic necrosis of the exposed bowel was higher(P<0.05), and the anal function was poorer in the short term after the second operation compared with the control group(P<0.05), but there was no significant difference between the anal function at 6 months after the second operation compared with the control group(P>0.05).12 months after the second operation, the anal function has recovered to the preoperative level in the observation group(P>0.05).

Conclusion

The laparoscopic modified Bacon operation has smaller abdominal wounds, which reduces postoperative pain; it does not require the use of staplers, which reduces the patient's financial burden; no postoperative anastomotic leakage occurs, and a more satisfactory anal function can be obtained.

Can anal manometry predict anal incontinence after fistulectomy in males?

BACKGROUND

Disordered continence is frequently reported after operations for anal fistulae and pre-operative anorectal physiology may be carried out prior to surgery to improve functional outcome. Elderly patients and multiparous females are at higher risk for incontinence, whereas males under 60 have stronger sphincters. The aim of this study was to investigate the predictive role of anal manometry and the causes of postoperative soiling and its effect on the quality of life in males with intact sphincters undergoing excision of either trans or supra sphincteric fistulae.

METHODS

Thirty-eight patients (median age 47 years) were analysed retrospectively. None had previous anal surgery and all were fully continent. Five had Crohn's disease. Anal pressures and rectal sensation were evaluated prior to fistulectomy by means of anal manometry in all cases and after surgery in those who had postoperative incontinence. A cutting seton was used in 17 patients, a rectal advancement flap in 15 and a double rectal-cutaneous flap in six. None had a lay-open. The intersphincteric plane was explored and drained in all cases. A previously described incontinence grading and score was used to assess postoperative soiling. The median follow-up was 22 (range 5-89) months. The patients with postoperative anal incontinence were evaluated with the Gastrointestinal quality of Life Index Questionnaire (0:poor, 4:good) at a median follow-up of 49 months.

RESULTS

Twenty-nine (76%) patients were continent after surgery, whereas 9 (24%) complained of some degree of anal incontinence (minor in 4, severe in 1, the 1-6 incontinence score being 3.7 +/- 1.3 (mean +/- s.d.m.). Their Quality of life score was 3.8 +/- 0.5 (mean +/- sdm). None of them had Crohn's disease, five had frequent diarrhoea, four had a reintervention for either anal fissure or recurrent fistula (two), three had a postseton anal deformity. No difference was found between continent and incontinent patients as far as pre-operative anal pressures were concerned, but the maximum rectal volume threshold was significantly higher in incontinent patients, 165 +/- 67 vs. 123 +/- 49 ml of air (P = 0.04).

CONCLUSIONS

Sphincter division, diarrhoea and anal deformity may cause soiling after fistulectomy in males and it does not severely affect quality of life. Surgery rather than manometry may predict it and rectal sensation may play a role which needs further investigation.

Nitric oxide synthase and VIP distribution in enteric nervous system in idiopathic chronic constipation

Idiopathic chronic constipation has been correlated to neural abnormalities that consist of a reduced number of myenteric plexus neurons and a decreased concentration of VIP-positive nerve fibers within the circular muscle. Recent studies hypothesized the involvement of nitric oxide in motility disorders of the human gut. To date, no information is available on nitric oxide involvement in idiopathic chronic constipation. The density of VIP- and nitric oxide-producing neurons was evaluated by immunocytochemistry using anti-VIP and anti-nitric oxide synthase antibodies in five patients with idiopathic chronic constipation. A low total neuron density was found at the myenteric plexus. The density of VIP-positive neurons was low while that of nitric oxide synthase-positive neurons was high at both plexuses. Our data confirm that idiopathic slow-transit chronic constipation is due to abnormal neurogenic factors. The presence of numerous nitric oxide synthase-positive neurons, all along the colon and at both plexuses, supports the hypothesis that an excessive production of nitric oxide may cause the persistent inhibition of contractions.

Nerve regeneration across colorectal anastomoses after low anterior resection in a canine model

The disappearance and subsequent return of the recto-anal inhibitory reflex following low anterior resection was investigated using manometric and histological studies. Ten female greyhound dogs were randomised into 2 groups. All underwent low anterior resection. Five had stapled EEA anastomosis of the rectum and 5 were handsewn. The recto-anal inhibitory reflex was measured before and after surgery using a microtransducer tipped catheter. Six months postoperatively the recto-anal inhibitory response was again measured and the animals sacrificed. The colorectal anastomoses were examined histologically using light microscopy to determine the pattern of innervation at the anastomotic site. Manometric studies showed the recto-anal inhibitory reflex present in all cases pre-operatively, in only 1 case on the tenth postoperative day and was present in eight cases after 6 months. Histological examination of longitudinal sections across the anastomoses showed clear evidence of regenerating nerve trunks at the anastomotic site in both stapled and handsewn groups. We conclude that the return of the recto-anal inhibitory reflex is associated with regeneration of intramural autonomic nerves across the anastomotic scar.

The results of pouch surgery after ileo-anal anastomosis for inflammatory bowel disease: the manometric assessment of pouch continence and its reservoir function

Anal sphincter function after restorative proctocolectomy has mainly been investigated by anal manometry. A significant decrease of basal pressure up to 45%, has been recorded postoperatively, possibly due to sphincter stretch during endoanal mucosectomy. Both abdominal mucosectomy and anastomosis at the level of the anorectal ring have been reported to prevent anal sphincter damage and lead to better continence. The striated sphincter is not significantly affected by the surgical procedure. Pouch-anal inhibitory reflex is partly maintained in the presence of a rectal cuff which leaves the ganglionic plexus unaltered; a satisfactory continence is also retained in the absence of the reflex when the rectum is totally excised. Pouch capacity, compliance and motility have been investigated by endoluminal balloon and probes. Pouch emptying has been studied by a "porridge" test, by a semi-solid medium labelled with technetium-99, and by other methods. A more effective storage function is achieved by large capacity reservoirs which lower the bowel frequency. The motor response to pouch distension, to a meal, and to pharmacological stimuli is usually counteracted by sphincter contraction. Ileal hypermotility may lead to fecal leakage mainly in the presence of weak sphincters. Poor pouch emptying may be related to an anal stricture.

Functional assessment of coloanal anastomosis with reservoir and excision of the anal transition zone

Conservation of the anal transition zone (ATZ) has been deemed necessary for continence after coloanal anastomosis (CAA) with reservoir. Therefore, we have studied functional and manometric results after CAA with reservoir and excision of the ATZ in 18 consecutive patients (mean age, 65.2 years; ten males and eight females), 17.4 months after closure of a temporary loop colostomy (Study 1). Twelve of the 18 initial patients were studied again 30.2 months after closure (Study 2). In Study 1, all patients underwent 1) a standardized interview, 2) a manometric study with measurement of anal pressure at rest (PR), voluntary contraction (VC), inhibitor anal reflex (IAR), conscious sensation (CS), and maximum tolerable volume (MTV), and 3) a liquid continence test (LCT) with measurement of colonic reservoir pressure during infusion. In Study 2, patients underwent all the same tests except the LCT. Results were compared with those of six controls (mean age, 65.8 years; two females and four males). In Study 1, 14/18 patients were continent; PR, VC, and CS did not differ among continent patients, incontinent patients, and controls. MTV was significantly lower in incontinent patients (mean +/- SD, 165 +/- 46.5 ml) than in continent patients and controls (mean +/- SD, 261 +/- 50.8 ml vs. 250.7 +/- 83 ml). IAR was not observed in continent or incontinent patients but was observed in controls. Contraction waves in the colonic reservoir during LCT were more frequent in incontinent patients (4/4) than in continent patients (4/14), and their amplitudes were higher (119 vs. 32 mm Hg). In Study 2, 12/12 patients were continent; PR and MTV remained unchanged except in the two initially incontinent patients, in whom MTV was increased. VC was slightly increased (94.7 vs. 116 mm Hg). IAR remained absent in all patients. We conclude that 1) excision of the ATZ did not increase the risk of incontinence, and 2) poor functional results were mainly due to small MTV and contraction waves in the colonic reservoir.

Alterations in anorectal function after anterior resection for cancer of the rectum

We have evaluated by means of a clinical and functional study the alterations in anorectal function of a group of 50 consecutive patients who have undergone an anterior resection of the rectum. Results are correlated with the anastomosis location and the time passed after the operation. According to research data this operation changes the patient's defaecation habits and the manometric and radiological parameters of anorectal function. These alterations are more evident in patients with a low anastomosis. The qualitative characteristics of defaecation did not change significantly in relation to the time passed since operation. However, there was a significant increase in compliance 6 months after operation, and the threshold rectal volume and the maximum tolerated volume also showed a significant increase 12 months following operation.

A comparison of simultaneous longitudinal and radial recordings of anal canal pressures

A new anal manometry perfusion catheter is described that offers the capability of simultaneous linear longitudinal pressure measurements. The authors studied 20 control subjects with this catheter and with a four-quadrant perfusion catheter. An asymmetry of basal, squeeze, and relaxation pressures was found. The highest basal pressures were in the middle of the anal canal, regardless of quadrant orientation. Using the radial perfusion catheter, the squeeze pressure profile was consistent with a double-loop external sphincter mechanism. Using the linear perfusion catheter, the internal sphincter relaxation pressures show a greater negative deflection at the proximal portions of the sphincter, which was not achieved at points distally in the same quadrant. This implies that during reflex relaxation, pressure is maintained in the distal anal canal so that patients remain continent during sensory sampling of rectal contents. The authors believe this is the first time this same-quadrant longitudinal asymmetry of relaxation has been shown with a single rectal balloon stimulus.

Preoperative and postoperative evaluation by manometric study of the anal sphincter after coloanal anastomosis for carcinoma

The purpose of the present study was to pre- and postoperatively evaluate the anal sphincter after coloanal anastomosis in 20 patients with carcinoma of the rectum at 5.5 to 8 cm from the anal verge. The 20 patients matched age and sex with the controlled subjects. Of the 20 patients, 17 with normal preoperative manometric studies when compared with control subjects underwent a coloanal anastomosis as described by Castrini, and three patients with preoperative incontinence underwent abdominoperineal resection. Manometric studies preoperatively, and postoperatively at three and 12 months, indicated a statistically significant decrease in squeezing pressure, and rectal compliance at three months that almost normalized by 12 months. The rectal compliance correlated with the number of bowel movements per day at three months (four to five per day) and at 12 months (two to three per day). The rectoanal reflex and length of pressure zone have remained unchanged. Results seem to indicate that anal continence can be preserved after coloanal anastomosis.

Investigations of the anal sphincter before and after restorative proctocolectomy

Twenty-eight patients who underwent sphincter-saving proctocolectomy and formation of an ileoanal reservoir had clinical evaluation of resting and maximal anal sphincter pressures and perfused catheter manometry. The clinical estimate of resting tone, heretofore believe to be a good predictive parameter of postoperative function, was inaccurate. This suggests the advisability of manometric evaluation. There were significant changes in sphincter pressures postoperatively. Operation did not effect the preoperative electromyographic findings of the puborectalis muscle and external sphincter in our small postoperative population. The mechanism by which operation might influence these parameters has been discussed. Factors such as parity and the descending perineum syndrome may effect continence. Due to the length of time the sphincter is required to function in these patients and the multiplicity of factors involved, we believe that long-term studies are needed.

Anorectal function after low anterior resection for carcinoma

Anorectal function was studied in 13 patients with carcinoma of the rectum 6-12 cm from the anal verge, which was treated by low anterior resection (LAR), and in 13 age- and sex-matched control subjects. Patients were studied before and 3 and 12 months after operation. Anal resting and squeeze pressures were the same in patients and control subjects and were decreased only moderately after surgery, with a slight increase in maximum squeeze pressure 12 months after operation. Three of the patients had an inverse rectoanal reflex before operation, and two had no reflex at all. After operation, only two patients showed a normal rectoanal inhibitory reflex, and none gained a normal reflex within 12 months after surgery. Rectal compliance was significantly reduced before operation, compared to control subjects, and was still significantly lower 3 months after operation. After 12 months, however, rectal compliance had returned to preoperative level in all but two patients with coloanal anastomosis, who still emptied the bowel 4-5 times daily.

Clinical and manometric evaluation of continence after the Bacon two-stage pull-through procedure

Twenty-eight patients who underwent the Bacon pull-through operation were evaluated for continence by clinical and radiologic means. Six patients were available for anal manometry. Eighty-three percent of those patients followed for function did not have the sensation to defecate spontaneously. They had normal functioning of the external sphincter, failure of reflex inhibition of the internal sphincter, and decreased rectal compliance secondary to fibrosis of the presacral space. These factors created a distal high-pressure zone which, when combined with sensory loss due to transection of the levators, rendered the patient continent but without the ability to defecate spontaneously unless an enema was administered.

[Electrical and motor activity of the rectum following low anastomosis]

Electrical and motor activity of smooth muscle of the canine rectum was registered by transanal recording following low rectum anastomosis. The relaxation reflex of the anal canal had disappeared distal of the anastomosis in the first postoperative week, and electrical slow waves and pressure waves were desynchronized proximal and distal of the anastomosis. The resting pressure of the rectal wall had increased above preoperative values. After wound healing had accomplished the relaxation reflex and the synchronization of electrical and mechanical activity proximal and distal of the anastomosis did occur again. It is concluded that the rectal wall provides the pathways for the relaxation reflex of the anal canal. After wound healing has finished these pathways are restored across the anastomosis.

Anal sphincter function and rectal reservoir after sphincter saving operations for carcinoma of the rectum

Anal sphincter function and rectal reservoir were studied in 27 patients after low anterior resection, in 6 after Welch or Turnbull type pull-through surgery and in 3 after Bacon type pull-through surgery. Sixteen patients who had undergone right hemicolectomy served as a control group. Anal sphincter function immediately after low anterior resection was diminished, but improved during the following 6 months. Rectal capacity was much reduced immediately after surgery, but increased with time, and the neorectum could to some extent adapt to its new role as a reservoir. After pull-through operations, anal canal pressure and rectal compliance were significantly lower than after low anterior resection or right hemicolectomy. These findings may explain the increased frequency of bowel action after pull-through operations.

Physiologic status of the anorectum following sphincter-saving resection for carcinoma of the rectum

The physiologic status of the anorectum after low anterior resections or pull-through operations of the rectum was evaluated clinically and by manometric studies. It was demonstrated that the presence of a normal anal resting pressure and an anorectal reflex were important to achieve postoperative continence after sphincter-saving operations. In patients with anastomotic leaks and poor function, a marked high-pressure zone in the anal canal and an anorectal reflex were not found, but as local inflammation resulting from the anastomotic leak disappeared, these parameters returned to normal. A normal anorectal reflex was found in one of three patients after Bacon-type pull-through operations, but the remaining two showed an increase of anal canal pressure during colonic distention. These results indicate that an elevation of anal-canal pressure in response to colonic distention plays a significant role in fecal continence at the time of "a sense of urgency" if internal sphincter function is impaired.