Review of Medical and Surgical Management of Chronic Anal Fissure

To determine which treatment modality has the best outcome for chronic anal fissures in terms of pain relief, fissure healing, and recurrence. The main symptoms are pain while the passage of stools is acute in primary fissures but often persists in case of longstanding fissures causing significant discomfort to the patient. The management of anal fissure has progressed immensely in the last decade due to a better understanding of its pathophysiology. The main aim of the treatment is to reduce the spasm of the internal anal sphincter, thereby reducing the anal canal pressure. The Conservative approach consists of topical nitrates, calcium channel blockers, and calcium channel blockers. It is often preferred over surgical alternatives as it is not invasive. Surgeries for chronic anal fissures include anal dilatation, posterior mid-line sphincterotomy, lateral internal sphincterotomy, fistulectomy, sphincterolysis, and advancement flap repair. This narrative review article aims to review all the existing and newer complex modalities available for the management of chronic anal fissures. Currently the initial management of fissures is pharmacological therapy with topical nitroglycerin or diltiazem or botulinum toxin A injection. The following line of treatment is surgical, which is lateral internal sphincterotomy. Non-surgical therapy often proves ineffective in providing relief and healing, frequently culminating in the recurrence of fissures. On the other hand, surgical therapy has postoperative drawbacks like intestinal incontinence, commonly gas, loose stool or rarely hard stool. There is inadequate data on the latest treatment modalities like fistulotomy, sphincterolysis, flap procedures, etc. They may be considered only when conventional therapy fails to provide relief. Review Article Madankar and Ali; JPRI, 33(61A): 49-57, 2021; Article no.JPRI.79838 50


BACKGROUND
An anal fissure is an ischemic ulcer in the longitudinal axis of the lower anal canal. It occurs most commonly in the posterior midline may be seen in the anterior midline (in females). Spasm and contracture of the internal anal sphincter have a principal role in the pathogenesis of this condition [1,2,3]. A fissure that doesn't heal in 3 months can be called chronic [1]. The symptoms include extreme pain during and after bowel movements, rectal bleeding, and constipation as patients hesitate to pass stools due to painfurther aggravating the symptoms [1]. The incidence is higher in young and working-age adults, making the treatment issues highly relevant [2].

OBJECTIVE
This article reviews the various treatment modalities available to manage chronic anal fissures.

DISCUSSION
Anal fissures are the result of increased internal anal sphincter tone. Acute anal fissures usually heal spontaneously within 6 weeks. Over the years, there have been many alterations in the hypotheses aiming to understand the pathophysiology of chronic anal fissures. The earliest theory proposed trauma as a cause due to the passage of hard stools; however, this only explained acute fissures, and their progression to chronic fissures remained unaccounted for [4]. The persistence of anal fissures was subsequently explained by two other factorsthe constant presence of anal sphincter hypertonia and ischemia preventing the healing of fissures [3,4]. The distal anal canal (posterior commissure) has been demonstrated to have a deficient blood supply and is the most common site for fissures [3,4].
Healing is more difficult in cases of chronic fissures. The goals of medical management are targeted, consisting of:  [3,4].
Most of the fissures usually resolve without surgical intervention. Healing is more prolonged in chronic fissures [4]. Surgical interventions for definitive management are considered when conservative therapy fails to provide relief. Surgeries aim to reduce the pressure of the anal canal and decrease the tone of the internal anal sphincter [1,2,3,4].

MEDICAL MANAGEMENT
The conservative treatment consists of:

High Fiber Diet or Fiber Supplements
A randomized control trial showed that consumption of 10g of unprocessed bran fiber daily along with warm sitz baths for 15 minutes daily after passing bowel movements gave quicker symptomatic relief and improved healing at three weeks as opposed to 2% lignocaine ointment or 2% hydrocortisone cream [4]. Dietary fiber is only shown to be effective only when consumed before stools are formed. It however, plays little to no role in relieving pre-existing constipation [5].

Sitz Baths
They help by improving hygiene, reducing pain, and relieving the anal sphincter spasm. Various RCTs have shown that sitz baths have no influential role in providing symptomatic relief to the patient or in accelerating wound healing [6,7]. However, sitz baths have been shown to improve patient satisfaction. There are few reported side effects like perianal skin rash [6]. No other severe complications have been reported. Thus, there is no solid proof for the role of sitz baths in treating anal fissures, although it may be used for patient satisfaction [6,7].

Topical Nitrates
Nitrates are a group of compounds that release NO, a vascular smooth muscle relaxant [1,8]. NO acts through production of cGMP. cGMP has various intracellular actions -one of which is the relaxation of smooth muscles [1]. GTN (Glyceryl trinitrate) is readily absorbed cutaneously and applied as a 0.2% paste to the perianal skin. It has been demonstrated to increase the endodermal blood flow and reduce the mean anal resting pressure [1,4]. The most prevalent negative effect of GTN medication is headache, which typically leads to treatment noncompliance [1,4]. Although the healing rates are low, effective symptomatic relief is achieved. It should also be noted that the treatment may take up to eight weeks to be effective [1,4,8].

Calcium Channel Blockers
Topical and local calcium channel blockers have the exact mechanism of action as nitrates. They are also reportedly not associated with headaches [1,4,8]. Topical diltiazem application has been proven to be effective in healing fissures with minimal side effects [1,4,8]. The main side effect observed with calcium channel blockers is itching, but it seldom leads to treatment discontinuation [4]. It can thus be considered as an effective conservative treatment alternative.

Botulinum Toxin
It is an exotoxin released by the C. botulinum bacterium [1,4]. When injected locally, the toxin attaches itself to the nerve terminals located at the presynaptic neuromuscular junction, stopping acetylcholine release and causing short-lasting muscle paralysis [1,4]. The exact role of BT injection in the anal fissure therapy protocol is unknown [1,4]. The transitory nature of the procedure makes it desirable to patients concerned about the chances for future incontinence, as well as individuals with significant levels of anxiety who are unable to consent to lateral internal sphincterotomy [4].
The pain was reportedly alleviated in 24 hours, and healing of fissures was observed in 12 weeks [1].
The BT injection can be done safely in the office, or it can be done as an outpatient treatment under anesthesia [4]. Although this has not been rigorously studied, proponents of doing this technique as an outpatient surgery suggest that including fissure debridement in the process may improve healing [4]. However, it is important to note that the effects of this procedure wear off in three months and if the causative factors have not been addressed by then, a high chance of recurrence is seen [4].
The summary of outcomes and recurrence rates of different pharmacological agents is listed below [9] (Table 1).

SURGICAL MANAGEMENT
Despite the availability of non-surgical treatments, surgery is still an effective and popular treatment for persistent anal fissures. It not only provides immediate clinical relief, but it also cures the fissure in up to 95% of patients. Anal dilation, posterior mid-line sphincterotomy, lateral internal sphincterotomy, fissurectomy, and advancement flap repair are the commonly employed surgical procedures. Postoperative incontinence is a concern associated with all surgical procedures.

Anal Dilatation
One of the first devised methods for the management of anal fissures was anal dilatation [1,4,9]. The technique varies, but it usually entails inserting four fingers into the anal canal and straining the sphincters for two to four minutes [1,4,9]. This procedure has been reported to heal up to 90% of fissures, but recurrence has been documented in 2.2 percent-56.5 percent of cases [1,4,9]. The dangers of incontinence have not been properly recognized until recently. The likelihood of incontinence after an anal stretch is substantially higher than after other treatment methods, with more than 50% of patients reporting continence impairment [4]. As seen on endoanal ultrasonography, incontinence is caused by sphincter disruption caused by anal strain [4]. Other methods for standardizing anal dilation or reducing trauma have not been broadly accepted. Because of these potential risks and the availability of better treatment modalities, anal dilatation as a management modality for anal fissures has now been deemed redundant [1,4,9].
Medication that lowers the internal anal sphincter tone can successfully reduce anal pressure, allowing in the recovery of chronic fissures. Unfortunately, this effect is reversible, and if the problem reappears, the medicine should be stopped, even if the fissure has healed completely. Sphincterotomy is the most efficient and successful way of management in individuals with chronic anal fissures as opposed to other surgical and pharmacological treatment options [1,4,9,10,11,[12][13][14][15][16].
A radial incision in the anoderm is made laterally to expose the internal sphincter muscle fibers during a lateral internal sphincterotomy [1,4,8,12]. The distal four-fifths of the internal anal sphincter muscle are then sharply divided with a scalpel or scissors under direct observation. The wound may be left open or closed primarily. The spasms associated with anal fissures are eased by partially splitting the internal anal sphincter. This promotes blood flow to the ischemic anal ulcer, which promotes healing. LIS provides the best results, accompanied by a positive rate of over 90%, but there is a possibility of fecal incontinence that must be considered. Infection, abscess, fistula, and hematoma are occasionally seen complications after LIS [1,4,9,11,12,13]. In spite of the high success rate of fissure recovery post sphincterotomy, between 1.6 and 6% of patients will experience recurrence. Inadequate sphincterotomy is the leading cause of recurrence. Sphincterotomy can be performed again in such instances.

Fissurectomy
Fissurectomy is the surgical removal of an anal fissure [4, 9,13]. It is a procedure that involves removal of the anal fissure edges, curetting or excision of the fissure base, and maybe removal of sentinel skin tags and anal polyps to allow the anal fissure to heal [4, 9,13]. Scissors and diathermy are two methods for excising the fissure that have been documented [4]. Some approaches support primary defect closure, whereas others advocate healing by secondary intention [4,9].

Flap Anoplasty
Chronic anal fissures are also treated using flap anoplasty surgeries [4,9]. A local flap is created to cover the fissure defect in these treatments. Flap procedures are particularly beneficial in patients with normal anal pressures or in fissures owing to obstetric trauma, where there is commonly concomitant internal sphincter disruption, because they spare the disruption of the internal anal sphincter [4,9].

Sphincterolysis
Anal spasm in patients suffering with persistent anal fissures can be addressed by closed manipulation of the fibers of the internal anal sphincter. This technique is known as sphincterolysis. Ecchymosis, hematoma, and a submucous abscess were among the significant consequences. Within four weeks, the majority of the patients were completely healed. Thus, for the management of chronic anal fissure, manipulation of the internal anal sphincter fibers is a simple, safe, and effective approach [15].

Posterior Perineal Support Device
The usage of a device that supports the posterior perineum placed into a toilet seat to promote the

Fig. 2. Treatment algorithm for chronic anal fissures
healing rates of longstanding anal fissures was investigated in a recent study [4,9]. This posterior perineal support device is believed to counteract the posterior anal sphincter complex and mucosa's preferential overstretching, making defecation easier and less traumatizing [4,9].

Gonyautoxin Injection
Gonyautoxin is the newest pharmacological therapy to hit the market, and the preliminary results are promising, with a 100 percent recovery rate in just two weeks and no instances of incontinence [4,9]. Gonyautoxin acts by binding to voltage-gated sodium channels on excitable cells in a dose-dependent reversible manner, resulting in a blocking of neuronal transmission [10][11][12][13][14][15]. The effects are reversible and transient, and the mechanism is comparable to that of Botulinum toxin [4,9]. As a result, this does not fix the underlying issue of Botulinum toxin injection recurrence. Gonyautoxin, on the other hand, may help heal fissures in ways that have yet to be found [16][17][18][19][20][21][22].

CONCLUSION
Anal fissures are a very common pathology of the anorectal region with a high incidence in the working age group adults. It is associated with extreme pain and has a high morbidity resulting in poor quality of life and often disability. Medical management includes high fiber diet, sitz baths, topical CCB, or topical nitrates. The treatment of primary anal fissures is usually done in stages, with first-line medical therapy lasting up to 6-8 weeks. Though often preferred due to its noninvasive nature, it has a high recurrence rate and unsatisfactory relief of symptoms. As the statistics above demonstrate, no single standard pharmaceutical therapy has consistently demonstrated to be preferable to others. When conservative treatment fails, BT injection, which has few side effects and a high cure rate, may be tried. The limited lateral internal sphincterotomy is the best amongst surgical intervention, with no difference between open and closed procedures. If all other pharmacological therapies have failed or have been stopped due to problems, lateral internal sphincterotomy should be considered. The internal anal sphincter is separated up to the apex of the fissure, which helps in decreasing anal incontinence. Fecal incontinence caused by a restricted lateral internal sphincterotomy is rare and usually only lasts a few days.
The following is a brief summary of the treatment algorithm for chronic anal fissures [9] -CONSENT It is not applicable.

ETHICAL APPROVAL
It is not applicable.