Sphincterotomy is the Gold-Standard Treatment of Chronic Anal Fissure: But How Should it be Done?

Abstract

A chronic anal fissure is one of the most encountered anorectal diseases in the clinical practice of general surgery. After all the medical therapies have failed, lateral internal sphincterotomy is still the main-stay treatment for chronic anal fissure. The optimal and standardized sphincterotomy has the utmost importance in preventing postoperative incontinence and recurrence, which are consequences of either extreme or insufficient sphincterotomy. Therefore, the lateral internal sphincterotomy technique has been evolved within years with the initial proposition of controlled-sphincterotomy and improvement of this technique with the addition of sphincterotomy up to the dentate line. This chapter focuses on the chronic anal fissure in the era of spasm-controlled lateral internal sphincterotomy.

1. Introduction

An anal fissure is one of the most encountered anorectal diseases by general surgeons, although the true prevalence is unknown [1]. It is described as a tear developing in the squamous epithelium of the anoderm and is located between the dentate line and the anal verge [2].

This condition is often related to chronic constipation and difficulty of defecation and rarely can result from Crohn’s disease, tuberculosis, and Acquired Immune Deficiency Syndrome (AIDS). The most common location of the fissure is the posterior midline (90%), followed by the anterior midline (1–10%), and lateral (1%). Lateral fissures can be associated with an underlying disease and should be thoroughly investigated. Typical symptoms are anal pain during defecation, bleeding, pruritus, and soiling.

An anal fissure can be described as acute and chronic according to the duration of symptoms. An acute fissure is a superficial lesion that usually occurs after constipation/diarrhea and can be healed with conservative management in 4 to 6 weeks. In contrast, chronic anal fissure is a deeper lesion surrounded by scar tissue caused by chronic inflammation. Chronic inflammation can cause skin tags in the anoderm adjacent to the fissure and hypertrophic papilla in the anal canal. Medical treatment is often ineffective for chronic fissures, and the patient’s symptoms are prolonged to 6 to 8 weeks.

2. Pathogenesis

The triggering factor is usually thought to be trauma to the anoderm from the passage of hard stool or chronic irritation from diarrhea, but the exact etiology of anal fissure remains unclear. Two major hypotheses have been proposed regarding the development of chronic fissures: the presence of hypertonicity in the internal anal sphincter and relatively decreased tissue perfusion in the posterior midline [3, 4, 5] (Figure 1).

Figure 1.

Operative image of a patient with chronic anal fissure shows the spasm in the sphincter complex even under sedation.

It has also been suggested that hypertonicity may result in pressure on the perpendicular vessels in the internal anal sphincter muscle and may compromise perfusion to the posterior midline even more [6]. Therefore, most of the medical and surgical treatments have been developed to decrease the internal sphincter’s tonicity. Regardless of these hypotheses, hypertonicity may not be found in all patients with chronic anal fissures. Also, constipation and hard bowel movements have only been reported in 13% of these patients [7, 8].

3. Clinical presentation and diagnosis

Patients usually present with moderate to severe anal pain, described as “like passing broken glass,” aggravated by defecation, and lasts several minutes to hours afterward [9]. Although bleeding occurs less commonly in anal fissures than hemorrhoidal diseases, patients may notice a small amount of bright-red blood on the toilet paper resulting from chronic ulceration in the epithelium (Figure 2).

Figure 2.

Chronic anal fissure presenting with bleeding.

Based on these predominant symptoms, an acute or chronic anal fissure can be diagnosed during the first interrogation. Nevertheless, the clinician should always consider an underlying cause of chronic constipation related to the fissure, such as rectocele, diverticular disease, and colorectal cancer.

On physical examination, the location, depth, and the number of fissures should be noted in addition to the presence of skin tags and chronic inflammation surrounding the lesion (Figure 3). Initially, a digital rectal examination may not be performed due to severe pain in an acute anal fissure; in that case, a detailed examination under anesthesia with anoscope and rectosigmoidoscopy may be required [10].

Figure 3.

Physical examination involves the inspection of number of fissures and the presence of skin tags. a) Multiple skin tags b) multiple chronic fissures in the posterior, lateral, and anterior of the anal canal.

4. Non-operative management

Usual recommendations for acute anal fissure include increased fiber and fluid ingestion, the use of local anesthetic ointments, warm daily sitz-bath, and stool softeners. Although almost half of the acute fissures heal with these conservative treatments, the success rate is as low as 30% in chronic fissures [10, 11, 12]. Given the cost-effectiveness and potential risk of incontinence with surgery, international guidelines still recommend topical and botulinum toxin injection as first-line therapy.

4.1 Nitrates

The mechanism of nitrates is based on the release of nitric oxide, which influences the relaxation of the internal anal sphincter muscle [13, 14]. Its commonly used form is glyceryl trinitrate (GTN) in 0.2–0.4% doses, and it is applied topically two to three times a day. The topical application of GTN has been reported to decrease anal resting pressures and promote healing in anal fissure compared to placebo; however, 50% of patients’ disease has recurred in the long term [11]. Major side-effects and reasons for discontinuing the treatment are headaches and light-headedness [15, 16].

4.2 Calcium-channel blockers

Topical application of calcium-channel blockers has been proven to effectively heal anal fissures with a lower risk of side effects [17]. Topically applied 0.5% nifedipine has been found to have healing rates of 93% in a duration of 19-month follow-up [18]. Also, Khan et al. have proved significantly higher healing rates (80.4%) with 2% topical diltiazem compared to GTN application [19]. Similarly, 0.5% topical minoxidil has been shown as equally effective as diltiazem [20].

4.3 Botulinum toxin

Botulinum toxin is an exotoxin produced by Clostridium botulinum, and its injection prevents the release of acetylcholine from the presynaptic nerve terminals, thus results resulting in temporary muscle paralysis. The first use of botulinum toxin in treating anal fissure was described in 1993 by Jost and Schimrigk [21, 22].

Although there is no standardized treatment with botulinum toxin regarding the dose and injection site, it is commonly injected directly into the internal anal sphincter on either side of the midline, with doses varying from 5 to 100 units [23, 24]. Pilkington et al. have revealed no significant differences between unilateral and bilateral injections in healing and fissure pain relief in a randomized prospective study [25]. In a retrospective review of patients who have been treated with high-dose (80–100 IU) and low-dose (20–40 IU) botulinum toxin, recurrence rates have been found significantly lower in a high-dose group during a mean follow-up of 25 months [26]. However, a meta-analysis has demonstrated no dose-dependent efficiency [27].

Several comparative studies have investigated the healing rates and symptomatic relief after botulinum toxin and topical agents [28, 29, 30, 31, 32]. Sajid et al. have shown that botulinum toxin injection has had similar healing rates with GTN but fewer side effects [33]. Also, another study has demonstrated that overall cure rates have been similar between diltiazem (53%), GTN (54%), and botulinum toxin (51%) [34]. A guideline published in 2017 has stated that botulinum toxin injection has similar results with topical agents as first-line therapy and modest improvement in healing rates as second-line therapy following treatment with topical agents [10].

The significant drawbacks of botulinum toxin injection are the risk of incontinence and its temporary effectiveness that usually lasts 3–6 months [35, 36]. Moreover, there are still unanswered questions: the following step when botulinum toxin fails if the second injection should be performed, the interval for repeat injection, and the timing of surgery. A recent study has discussed some of those issues among colorectal surgeons on practice parameters of botulinum toxin treatment [37]. It has been shown that more than half of the clinicians perform the second injection in case of persistence of symptoms and recurrence, and the interval for repeat injection has usually been more than 2 months.

5. Surgical treatment of chronic anal fissure

Traditionally, lateral internal sphincterotomy (LIS) has been the gold-standard treatment for chronic anal fissure [38]. This technique decreases the pressure caused by the internal anal sphincter hypertonicity, normalizes the perfusion on the anoderm, alleviates the pain, and promotes fissure healing [3] (Figure 4). With trends toward topical agents and botulinum toxin injection, several studies have been conducted to compare the outcomes of these treatment methods [39, 40, 41, 42]. A randomized controlled trial by Mentes et al. has revealed that LIS is superior to botulinum toxin injection regarding healing and recurrence in the long term [43]. Similar results have been obtained by Arroyo et al., 1-year healing rates with botulinum toxin and LIS were 45% and 93%, respectively [44].

Figure 4.

Healing of the chronic anal fissure. a) Preoperative image, b) postoperative 6-month image.

5.1 Techniques of lateral internal sphincterotomy

The main issue with LIS has been the risk of incontinence [45]. Garg et al. have reported incontinence rates as 14% during a follow-up of 2 years [46]. In this study, most patients complained of flatus incontinence (9%), followed by soiling/seepage (6%), incontinence to liquid stool (0.91%), and solid stool (0.63%).

Determining risk factors for incontinence after LIS include the history of vaginal delivery, female patients, anteriorly located fissures, age over 40–50, concomitant anorectal procedures (hemorrhoidectomy), and presence of incontinence in preoperative setting [46]. The effects of LIS on quality of life have been evaluated by using the Gastrointestinal Quality of Life Index (GQLI) and the Fecal Incontinence Quality of Life Scale (FIQLS) in a 1-year follow-up [47]. Moreover, GQLI scores have significantly improved after LIS, and only three patients (1.2%) experienced deterioration in FIQLS scores.

Although LIS has been performing for over decades, there has not been a standardized technique, and with increased reporting of incontinence, the search for optimal sphincterotomy regarding the level and degree of sphincter division has commenced. In the following sections, variations in sphincterotomy techniques will be discussed.

5.1.1 Open lateral internal sphincterotomy

The open technique involves a radial incision made on the intersphincteric groove and the dissection and division of the internal sphincter muscle to the level of the dentate line. The incision is usually left open for drainage (Figure 5).

Figure 5.

The steps of open lateral internal sphincterotomy. a) the circumferential incision is made in the intersphincteric groove, b) deepening the dissection with the help of retractors, c) the division of the internal sphincter muscle.

In a prospective randomized study, delayed healing and higher postoperative pain scores have been found in the open technique group [48]. Similar results have been obtained by Pernkoft and Kortbeek et al., who have reported lower complication rates with the closed technique [49, 50].

5.1.2 Closed lateral internal sphincterotomy

The closed technique involves the digital palpation of the sphincter complex, simultaneously inserting a blade into the intersphincteric groove and dividing the internal sphincter by moving the blade medially. The expected rate of division is 1/3 to 1/2 of the internal sphincter muscle.

Many authors have reported that the closed technique is effective and safe with a similar cure and fewer complication rates [51, 52]. In contrast, Wiley et al. has demonstrated similar incontinence rates between open and closed techniques, although overall, 6.8% of incontinence rates have been detected during a follow-up of 52 weeks [53]. Based on these contradicted results, it has been suggested that rather than an open or closed approach, the extent of sphincterotomy may influence the rates of incontinence and healing [54].

5.1.3 Radial vs. circumferential incision in lateral internal sphincterotomy

According to the surgeons’ experience and preference, open sphincterotomy can be performed with radial or circumferential incisions. Ersoz et al. has reported that the circumferential incision is associated with shorter healing time and fewer itching sensations than radial incisions [55]. Similar results about reduced time for wound healing with circumferential incision have also been proven by Kang et al. [56]. Both authors have suggested that the fecal material creates an outward force vector resulting in dilatation of the anal canal associated with more dehiscence in the radial incision.

5.1.4 Extent of sphincterotomy

Another attempt to decrease incontinence rates has been the proposal of performing sphincterotomy up to the height of the fissure apex instead of to the dentate line [57]. This technique initially showed high healing rates with significantly lower incontinence rates [58]. However, long-term follow-up results have demonstrated higher rates of treatment failure and slower effects on healing [59]. In another study evaluating the recurrence/persistence of fissure and incontinence rates, endoanal ultrasonography was performed after percutaneous and open sphincterotomy [60]. It has been confirmed that open and complete sphincterotomy is associated with lower recurrence rates but increased incontinence, while partial and percutaneous sphincterotomy has resulted in persistence and recurrence of the fissure. These results have supported that sphincterotomy should be complete but shorter, whether percutaneous or open sphincterotomy is performed.

Furthermore, the extent of sphincterotomy and its association with incontinence have been investigated between female patients and the control group by performing three-dimensional anal ultrasonography [61]. The extent of sphincterotomy has been directly related to incontinence, and it should be less than 25% of the total sphincter length (less than 1 cm in females) (Figure 6). Interestingly, this study has also demonstrated a significant decrease in anal resting pressure, whereas the maximum squeeze pressure has remained similar to preoperative measurements. A recent study has also reported supporting findings for dividing the internal sphincter by about 20% in female patients [62].

Figure 6.

Measurement of sphincterotomy. a) Sphincterotomy is measured as 1 cm from the anal verge, b) the distance of sphincterotomy to the dentate line is shown as 2 cm.

5.1.5 Ultramodified internal sphincterotomy

Sungurtekin et al. has described a new technique called ultra-modified internal sphincterotomy, which involves an incision made in the base of the posterior fissure, identification of the internal and external sphincter under direct vision, division of previously measured 1 cm of internal sphincter bundle [63].

They have reported the results of this technique in comparison to the closed sphincterotomy. The anal resting pressures have decreased in both study groups; however, the decline in pressures has lasted for 24 months in closed technique and is attributed to iatrogenic damage in the internal anal sphincter. Moreover, the patient satisfaction and recovery rates have been higher in the ultramodified sphincterotomy group.

5.1.6 Spasm-controlled sphincterotomy

Previous findings have created a whole new perspective in the technique of sphincterotomy, suggesting that the sphincter division should be made in a tailored fashion by considering the differences in genders, anal calibers, and anal resting pressures.

A tailored, spasm-controlled sphincterotomy term by performing sphincterotomy according to the anal caliber was first proposed by Cho et al. [64]. A prospective comparative study has investigated the outcomes of spasm-controlled and up to the fissure apex sphincterotomy [65]. The spasm-controlled technique was performed by small serial sphincterotomies using an anal calibrator to achieve a 25–30 mm anal caliber, while fissure apex sphincterotomy was performed in a traditional way (Figure 7). Not surprisingly, the incontinence rates have been found significantly lower with described technique, and there was no significant difference in treatment failure (Figure 8).

Figure 7.

Anal calibrators are used to measure the anal caliber in the spasm-controlled technique. Small, medium and large calibrators are in the size of 5–15, 15–30, and 27–43 mm, respectively [65].

Figure 8.

In the spasm-controlled technique, anal calibrations are measured before and after sphincterotomy. a) Small anal calibrator is measured as 5–15 mm, b) anal caliber is measured about 12 mm in this patient with chronic anal fissure.

6. Tips and tricks

• Local or regional anesthesia are preferred in combination with sedative drugs. Regional anesthesia may be required for patients with high body mass index considering the difficulties in respiration with the prone position.

• Injecting local anesthetics consisting of lidocaine hydrochloride with adrenaline to the incision area enables a blood-free surgical area.

• The prone jack-knife position provides good exposure to the anal canal and sphincter complex.

• Anal caliber is measured with anal calibrators at the initial of the procedure.

• A circumferential 1 cm incision made on the right lateral of the anal canal is the chosen approach. Subcutaneous dissection is performed in the intersphincteric groove with the help of small retractors.

• The lateral internal sphincter muscle is divided under the direct vision as small bites at each time, and the anal caliber is repeatedly measured to obtain a predetermined anal caliber of 25–30 mm.

• The incision is partially closed using continuous 4–0 absorbable sutures.

• Fissurectomy might be performed in addition to sphincterotomy in patients with severe pain and soiling symptoms due to deep scar tissue.

• Large skin tags can also be excised for cosmetic and hygiene issues, if so, one should be avoided to excise a large amount of anoderm.

7. Conclusions

Lateral internal sphincterotomy is still the gold-standard treatment for chronic anal fissures when the first-line and second-line therapies such as topical nitrates, calcium-channel blockers, and botulinum toxin have failed. It is associated with increased healing rates and improved quality of life in patients with anal fissures. Therefore, surgical intervention can even be offered in select patients without first confirming the failure of pharmacological therapies.

The technique of lateral internal sphincterotomy has been evolved over the years in terms of approaches (open/closed), the level of division of the internal sphincter (complete/partial), and the extent of sphincterotomy (to the dentate line/up to the fissure apex). A tailored-fashion sphincterotomy that is based on the individual characteristics of each patient has come upfront in recent years. As a tailored-fashion technique, the spasm-controlled sphincterotomy has been performed as a safe and effective method with low rates of incontinence and treatment failure.

Determining an individualized technique, which involves objective methods to measure the sufficient level of sphincterotomy either by calibrators and a surgical measure or anal ultrasonography and manometry, has the utmost importance in preventing postoperative incontinence, increasing healing rates, and improving quality of life.

Conflict of interest

All authors declare that they have no conflict of interest.