Should we care about the internal anal sphincter?

TMEM16A in smooth muscle cells acts as a pacemaker channel in the internal anal sphincter

Maintenance of fecal continence requires a continuous or basal tone of the internal anal sphincter (IAS). Paradoxically, the basal tone results largely from high-frequency rhythmic contractions of the IAS smooth muscle. However, the cellular and molecular mechanisms that initiate these contractions remain elusive. Here we show that the IAS contains multiple pacemakers. These pacemakers spontaneously generate propagating calcium waves that drive rhythmic contractions and establish the basal tone. These waves are myogenic and act independently of nerve, paracrine or autocrine signals. Using cell-specific gene knockout mice, we further found that TMEM16A Cl- channels in smooth muscle cells (but not in the interstitial cells of Cajal) are indispensable for pacemaking, rhythmic contractions, and basal tone. Our results identify TMEM16A in smooth muscle cells as a critical pacemaker channel that enables the IAS to contract rhythmically and continuously. This study provides cellular and molecular insights into fecal continence.

Review article: pathogenesis of Crohn's perianal fistula-understanding factors impacting on success and failure of treatment strategies

BACKGROUND

Evidence from groups who have studied fistula aetiology and extrapolation from interventional studies supports a multifactorial hypothesis of Crohn's perianal fistula, with several pathophysiological elements that may contribute to fistula formation, persistence and resistance to treatment.

AIM

An evidence synthesis of current understanding of pathophysiological factors underlying Crohn's perianal fistula is presented, exploring the fundamental reasons why some treatments succeed and others fail, as a means of focussing clinical knowledge on improving treatment of Crohn's perianal fistula.

METHODS

Evidence to support this review was gathered via the Pubmed database. Studies discussing pathophysiological factors underpinning perianal fistula, particularly in Crohn's disease, were reviewed and cross-referenced for additional reports.

RESULTS

Pathophysiological factors that impact on success or failure of interventions for Crohn's perianal fistulae include the high-pressure zone, obliterating the dead space, disconnecting the track from the anus, removing epithelialisation, eradicating sepsis and by-products of bacterial colonisation, correcting abnormalities in wound repair and removing the pro-inflammatory environment which allows fistula persistence. Most current interventions for Crohn's perianal fistulae tend to focus on a single, or at best two, aspects of the pathophysiology of Crohn's anal fistulae; as a result, failure to heal fully is common.

CONCLUSIONS

For an intervention or combination of interventions to succeed, multiple factors must be addressed. We hypothesise that correct, timely and complete attention to all of these factors in a multimodal approach represents a new direction that may enable the creation of an effective treatment algorithm for Crohn's anal fistula.

Successful Treatment of Passive Fecal Incontinence in an Animal Model Using Engineered Biosphincters: A 3-Month Follow-Up Study

Fecal incontinence (FI) is the involuntary passage of fecal material. Current treatments have limited successful outcomes. The objective of this study was to develop a large animal model of passive FI and to demonstrate sustained restoration of fecal continence using anorectal manometry in this model after implantation of engineered autologous internal anal sphincter (IAS) biosphincters. Twenty female rabbits were used in this study. The animals were divided into three groups: (a) Non‐treated group: Rabbits underwent IAS injury by hemi‐sphincterectomy without treatment. (b) Treated group: Rabbits underwent IAS injury by hemi‐sphincterectomy followed by implantation of autologous biosphincters. (c) Sham group: Rabbits underwent IAS injury by hemi‐sphincterectomy followed by re‐accessing the surgical site followed by immediate closure without implantation of biosphincters. Anorectal manometry was used to measure resting anal pressure and recto‐anal inhibitory reflex (RAIR) at baseline, 1 month post‐sphincterectomy, up to 3 months after implantation and post‐sham. Following sphincterectomy, all rabbits had decreased basal tone and loss of RAIR, indicative of FI. Anal hygiene was also lost in the rabbits. Decreases in basal tone and RAIR were sustained more than 3 months in the non‐treated group. Autologous biosphincters were successfully implanted into eight donor rabbits in the treated group. Basal tone and RAIR were restored at 3 months following biosphincter implantation and were significantly higher compared with rabbits in the non‐treated and sham groups. Histologically, smooth muscle reconstruction and continuity was restored in the treated group compared with the non‐treated group. Results in this study provided promising outcomes for treatment of FI. Results demonstrated the feasibility of developing and validating a large animal model of passive FI. This study also showed the efficacy of the engineered biosphincters to restore fecal continence as demonstrated by manometry. Stem Cells Translational Medicine2017;6:1795–1802

Stapled haemorrhoidopexy: is it time to move on?

Stapled haemorrhoidectomy was proposed as an 'ideal' solution for symptomatic haemorrhoids, with minimal postoperative pain, no perianal wound requiring postoperative wound care and a relatively short operative time. Some randomised controlled trials and reviews confirmed these findings, claiming that stapled haemorrhoidopexy is the most effective and safe procedure for haemorrhoids. However, there are increasing number of publications highlighting that the technique is associated with serious and life threatening complications. Maybe it is now the time to accept that stapled haemorrhoidopexy has done its role in directing our attention to the fact that modern surgical treatment of haemorrhoids should avoid excision of anorectal skin but should instead aim at treatment intervention above the dentate line.

Revisiting an ancient treatment for transphincteric fistula-in-ano 'There is nothing new under the sun' Ecclesiastes 1v9

OBJECTIVE

The history of treatments for fistula-in-ano can be traced back to ancient times. Current treatment of transphincteric fistulae is controversial, with many options available. We reviewed the history of treatment using cutting setons and present our series of transphincteric fistulae in the light of the series in the literature.

DESIGN

Literature review and case series.

SETTING

Hospital based coloproctology service

PARTICIPANTS

140 consecutive patients presenting with fistula-in-ano were included.

MAIN OUTCOME MEASURES

The literature pertaining to treatment of transphincteric fistula was reviewed, along with the outcome of various treatment methods for this condition. Data were collected for 140 consecutive patients presenting with fistula- in-ano were assessed for fistula healing, recurrence and complications.

RESULTS

A total of 140 consecutive patients with fistula-in-ano were identified, of which 111 were cryptoglandular (79.3%). Eighty-one of these 111 were transphincteric (73.0%). At a median follow-up of 35 months (range, 2-83 months), 70 transphincteric fistulae had healed (86.4%), 10 were still undergoing treatment (12.3%) and one patient was lost to follow-up prior to treatment (1.2%). Two patients in this group required a stoma (2.5%), six patients developed recurrence (7.4%); three 'true' recurrences (3.7%). One (1.2%) developed a chronic fissure. There were no reported cases of incontinence.

CONCLUSIONS

The management of transphincteric fistula-in-ano is complex and controversial, for which no clear surgical procedure has gained acceptance as the gold standard. This study demonstrates that transphincteric fistulae can be successfully treated using cutting setons. A high healing rate (86.4%), low recurrence rate (7.4%) and a low complication rate (3.7%) are shown, which compares favourably with published rates over a long follow-up.

Rectal tone and compliance affected in patients with fecal incontinence after fistulotomy

AIM

To investigate the anal sphincter and rectal factors that may be involved in fecal incontinence that develops following fistulotomy (FIAF).

METHODS

Eleven patients with FIAF were compared with 11 patients with idiopathic fecal incontinence and with 11 asymptomatic healthy subjects (HS). All of the study participants underwent anorectal manometry and a barostat study (rectal sensitivity, tone, compliance and capacity). The mean time since surgery was 28 ± 26 mo. The postoperative continence score was 14 ± 2.5 (95%CI: 12.4-15.5, St Mark's fecal incontinence grading system).

RESULTS

Compared with the HS, the FIAF patients showed increased rectal tone (42.63 ± 27.69 vs 103.5 ± 51.13, P = 0.002) and less rectal compliance (4.95 ± 3.43 vs 11.77 ± 6.9, P = 0.009). No significant differences were found between the FIAF patients and the HS with respect to the rectal capacity; thresholds for the non-noxious stimuli of first sensation, gas sensation and urge-to-defecate sensation or the noxious stimulus of pain; anal resting pressure or squeeze pressure; or the frequency or percentage of relaxation of the rectoanal inhibitory reflex. No significant differences were found between the FIAF patients and the patients with idiopathic fecal incontinence.

CONCLUSION

In patients with FIAF, normal motor anal sphincter function and rectal sensitivity are preserved, but rectal tone and compliance are impaired. The results suggest that FIAF is not due to alterations in rectal sensitivity and that the rectum is more involved than the anal sphincters in the genesis of FIAF.

Anorectal physiology and testing

A good understanding of anorectal physiology is essential for the diagnosis and appropriate treatment of various anorectal disorders, such as fecal incontinence, constipation, and pain. This article reviews the physiology of the anorectum and details the various investigations used to diagnose anorectal physiology disorders. These anatomic and functional tests include anal manometry, endoanal ultrasound, defecography, balloon expulsion test, magnetic resonance imaging, pudendal nerve terminal motor latency, electromyography, and colonic transit studies. Indications for investigations, steps in performing the tests, and interpretation of results are discussed.

Operative strategy for fistula-in-ano without division of the anal sphincter

INTRODUCTION

The treatment of perianal fistulas is diverse because no single technique is universally effective. Fistulotomy remains the most effective way of eradicating the pathology but it renders the patient at some risk of faecal incontinence, which many patients are reluctant to take. There are no data in the literature to indicate the healing rate of perianal fistulas when using an operative strategy that routinely avoids division of any part of the anal sphincter. The aim of this paper is to present the long-term results with an operative strategy that aims to avoid division of any part of the anal sphincter complex when treating all types of perianal fistulas, thereby minimising/eliminating the risk of postoperative incontinence.

METHODS

We report 54 consecutive cases of anal fistula that presented electively and as an emergency. Patients with known or subsequently diagnosed inflammatory bowel disease or malignancy were excluded from the study.

RESULT

Overall, 46 patients (37 male and 9 female) with a median age at presentation of 42 years (range: 19-73 years) were treated by lay-open of the subcutaneous tract of the perianal fistula and insertion of a loose seton for the part of the fistula tract related to the sphincter complex. The types of fistula treated were intersphincteric (89%), transsphincteric (4%) and high suprasphincteric (7%). The median length of time that the seton was left in place was 7 months (range: 1.5-24 months). The healing rate was 86% with a recurrence rate of 19% and a median follow-up duration of 42 months.

CONCLUSIONS

Patients who are reluctant to take any risk of faecal incontinence could be treated using an operative strategy that routinely avoids division of any part of the anal sphincter complex as this has a recurrence rate that compares well with other treatment modalities.

Fistulotomy or seton in anal fistula: a decisional algorithm

Fistula in ano is a common proctological disease. Several authors stated that internal and external anal sphincters preservation is in the interest of continence maintenance. The aim of the present study is to report our experience using a decisional algorithm on sphincter saving procedures that achieved us to obtain good results with low rate of complications. From 2008 to 2011, 206 patients underwent surgical treatment for anal fistula; 28 patients underwent perianal abscess drainage plus seton placement of trans-sphincteric or supra-sphincteric fistula (13.6 %), 41 patients underwent fistulotomy for submucosal or low inter-sphincteric or low trans-sphincteric anal fistula (19.9 %) and 137 patients underwent partial fistulectomy or partial fistulotomy (from cutaneous plan to external sphincter muscle plan) and cutting seton placement without internal sphincterotomy for trans-sphincteric anal fistula (66.50 %). Healing rates have been of 100 % and healing times ranged from 1 to 6 months in 97 % of patients treated by setons. Transient fecal soiling was reported by 19 patients affected by trans-sphincteric fistula (11.5 %) for 4-6 months and then disappeared or evolved in a milder form of flatus occasional incontinence. No major incontinence has been reported also after fistulotomy. Fistula recurred in five cases of trans-sphincteric fistula treated by seton placement (one with abscess) (1/28) (3.5 %) and four with trans-sphincteric fistula (4/137) (3 %). Our algorithm permitted us to reduce to 20 % sphincter cutting procedures without reporting postoperative major anal incontinence; it seems to open an interesting way in the treatment of anal fistula.