Anal Fissure (cont.)
Thomas P. Sokol, MD, FACS, FASCRS
Thomas P. Sokol, MD, FACS, FASCRS
Thomas P. Sokol, MD received his medical degree from the University of Health Sciences/The Chicago Medical School in 1980. He went on to his general surgical residency at Harbor/UCLA Medical Center and then to the Carle Clinic/ University of Illinois for Fellowship Training in Colon and Rectal Surgery.
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How are anal fissures treated?
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The goal of treatment for anal fissures is to break the cycle of spasm of the anal sphincter and its repeated tearing of the anoderm.
General treatment. In acute fissures, medical (nonoperative) therapy is successful in the majority of patients. Of acute fissures, 80%-90% will heal with conservative measures as compared with chronic (recurrent) fissures, which show only a 40% rate of healing. Initial treatment involves adding bulk to the stool and softening the stool with psyllium or methylcellulose preparations and a high fiber diet. Additionally, patients are advised to avoid "sharp" foods that may not be well-digested (i.e., nuts, popcorn, tortilla chips), increase their liquid intake, and, at times, take stool softeners (docusate or mineral oil preparations). Sitz baths (essentially soaking in a tub of warm water) are encouraged, particularly after bowel movements, to relax the spasm, to increase the flow of blood to the anus, and to clean the anus without rubbing the irritated anoderm.
Anesthetics and steroids. Topical anesthetics (for example, Xylocaine, lidocaine, tetracaine, pramoxine) are recommended especially prior to a bowel movement to reduce the pain of defecation. Often, a small amount of a steroid is combined in the anesthetic cream to reduce inflammation. The use of steroids should be limited to two weeks because longer use will result in thinning of the anoderm (atrophy), which makes it more susceptible to trauma. Oral medications to relax the smooth muscle of the internal sphincter have not been shown to aid healing.
Nitroglycerin. Because of the possibility that spasm of the internal sphincter and reduced flow of blood to the sphincter play roles in the formation and healing of anal fissures, ointments with the muscle relaxant, nitroglycerin (glyceryl trinitrate), have been tried and found to be effective in healing anal fissures. Glycerin trinitrate (nitroglycerin) has been shown to cause relaxation of the internal anal sphincter and to decrease the anal resting pressure. When ointments containing nitroglycerin are applied to the anal canal, the nitroglycerin diffuses across the anoderm and relaxes the internal sphincter and reduces the pressure in the anal canal. This relieves spasm of the muscle and also may increase the flow of blood, both of which promote healing of fissures. Unlike Nitropaste, a 2.0% concentration of nitroglycerin that is used on the skin for patients with heart disease and angina, the nitroglycerin ointment used for treating anal fissures contains a concentration of nitroglycerin of only 0.2%. One randomized, controlled trial has demonstrated the healing of anal fissures in 68% of patients with nitroglycerin as compared to 8% of patients treated with placebo (inactive treatment). Other studies have shown a 33%-47% recurrence rate of fissures following treatment with nitroglycerin. The presence of a sentinel pile is associated with a lower healing rate with nitroglycerin treatment.
The dose of nitroglycerin often is limited by side effects. The usual side effects are headache (due to dilation of blood vessels in the head) or light-headedness (due to a drop in blood pressure). This author recommends that a small amount of ointment be applied to a cotton-tipped swab with the swab then inserted into the anus only for the depth of the cotton-tipped portion of the swab. Ointment smeared around the outside of the anus does not reach the anoderm where its effects are important, yet the nitroglycerin will be absorbed and produce side effects.
Nitroglycerin is more rapidly absorbed if blood flow in the anoderm is high. For this reason, it is recommended that nitroglycerin not be applied within 30 minutes of a bath since the warm water of the bath enlarges (dilates) the blood vessels in the skin and anoderm and increases their flow of blood. Additionally, the first application of nitroglycerin should be at bedtime while the patient is lying down in order to prevent falls due to light-headedness.
The side effects of nitroglycerin often are self-limited, that is, they become less with repeated use. Caffeine can help reduce or prevent headaches. However, if side effects are pronounced, nitroglycerin should be discontinued. Drugs for impotence (for example, sildenafil (Viagra)), should not be used together with nitroglycerin since they increase the risk of developing low blood pressure.
Calcium channel blocking drugs. As is the case with nitroglycerin, ointments containing calcium channel blocking drugs (for example, nifedipine [Adalat] or diltiazem [Cardizem]) relax the muscles of the internal sphincter. They also expand the blood vessels of the anoderm and increase the flow of blood. Nifedipine ointment (2%) is applied in a manner similar to nitroglycerin ointment, but seems to produce fewer side effects. Although healing of chronic fissures has been reported in up to 67% of patients treated with calcium channel blockers, they are most effective with acute fissures.
Botulinum toxin. Botulinum toxin (Botox) relaxes (actually paralyzes) muscles by preventing the release of acetylcholine from the nerves that normally causes muscle cells to contract. It has been used successfully to treat a variety of disorders in which there is spasm of muscles, including anal fissures. The toxin is injected into the external sphincter, the internal sphincter, the intersphincteric groove (an indentation just inside the anus that demarcates the dividing line between external and internal sphincters), or into the fissure itself. The dose is not standardized and has varied from 2.5 to 20 units of toxin in two locations (usually on either side of the fissure). The cost of a 100 unit vial of toxin is several hundred dollars and unused toxin cannot be saved. Thus, the expense for a single injection of toxin is high. In some series of patients but not all, the frequency of healing of fissures with botulinum toxin is high. When fissures recur after treatment, they usually heal again with a second injection. One representative study found that fissures healed in 87% of patients by six months after treatment with botulinum toxin. By 12 months, however, the healing rate had fallen to 75% and by 42 months to 60%. The primary side effect of botulinum toxin is weakness of the sphincters with varying degrees of incontinence (leakage of stool) that usually is transient. Other side effects are not common.
There is a great variability in the medical literature with respect to the effectiveness of drugs and botulinum toxin in the healing of anal fissures. Healing may be temporary and fissures may return with a hard bowel movement. Recurrent fissures often require a change to another form of treatment. Patients need to balance the effectiveness of treatment, short and long-term side effects, convenience, and expense in choosing their treatment. When patients are intolerant or unresponsive to non-surgical treatments, surgery becomes necessary.
Personal observation. The author has found that when there are enlarged internal hemorrhoids in addition to a fissure, that healing of the fissure is improved if the hemorrhoids are treated with sclerotherapy that shrinks them. After application of a topical anesthetic, if a patient can tolerate a gentle examination of the rectum with a finger and an anoscope can be inserted through the anus, enlarged hemorrhoids can be identified, and if present, treated with sclerotherapy. It is unclear if improvement in healing is caused by anal dilation with the finger or by shrinkage of the hemorrhoid.)
Surgical treatment. The Standard Task Force of the American Society of Colon and Rectal Surgeons has recommended a surgical procedure called partial lateral internal sphincterotomy as the technique of choice for the treatment of anal fissures. In this procedure, the internal anal sphincter is cut starting at its distal most end at the anal verge and extending into the anal canal for a distance equal to that of the fissure. The cut may extend to the dentate line, but not farther. The sphincter can be divided in a closed (percutaneous ) fashion by tunneling under the anoderm or in an open fashion by cutting through the anoderm. The cut is made on the left or right side of the anus, hence the name "partial lateral internal sphincterotomy." The posterior midline, where the fissure usually is located, is avoided for fear of accentuating the posterior weakness of the muscle surrounding the anal canal. (Additional weakness posteriorly can lead to what is called a keyhole deformity, so called because the resulting anal canal resembles an old fashioned skeleton key. This deformity promotes soilage and leakage of stool.)
Although many surgeons decline to cut out the fissure itself during lateral sphincterotomy, this author feels that this reluctance to remove the fissure is not always appropriate, and characteristics of the fissure itself should be taken into account. If the fissure is hard and irregular, suggesting anal cancer, the fissure should be biopsied. If the edges and base of the fissure are heavily scarred, there may be a problem after surgery with anal stenosis, a condition in which additional scarring narrows the anal canal and interferes with the passage of stool. In this case, it may be better to cut out the scarred fissure so that there is a chance for the wound to heal with less scarring and chance of stenosis. Finally, an associated large anal papilla or a large hemorrhoidal tag may interfere physically with wound healing, and removing them may promote healing.
Following surgery, 93%-97% of fissures heal. In one representative study, healing following surgery occurred in 98% of patients by two months. At 42 months following surgery, 94% of patients were still healed. Recurrence rates after this type of surgery are low, 0%-3%.
Failure to heal following surgery often is attributed to reluctance on the part of the surgeon to adequately divide the internal anal sphincter; however, other reasons for failure to heal, such as Crohn's disease should be considered as well. The risk of incontinence (leakage) of stool following surgery is low. It is important to distinguish between short-term and long-term incontinence. In the short-term (under six weeks), the sphincter is weakened by the surgery, so leakage of stool is not unexpected. Long-term incontinence should not occur after partial lateral internal sphincterotomy because the internal sphincter is less important than the external sphincter (which is not cut) in controlling the passage of stool. It is important to distinguish between incontinence to gas, a minimal amount of stool that, at most, stains the underwear (soiling), and loss of stool that requires an immediate change in underwear. In a large series of patients followed for a mean of five years after surgery, 6% were incontinent of gas, 8% had minor soiling, and 1% experienced loss of stool.
Anal surgical stretch. Several surgeons have described procedures that stretch and tear the anal sphincters for the treatment of anal fissures. Though anal stretching often is successful in alleviating pain and healing the fissure, it is a traumatic, uncontrolled disruption of the sphincter. Ultrasonograms of the anal sphincters following stretching demonstrate trauma that extends beyond the desired area. Because only 72% of fissures heal and there is a 20% incidence of incontinence of stool, stretching has fallen out of favor.
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