Anal Fissure (cont.)
How are anal fissures treated?
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 (e.g., 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. Smearing
ointment around the outside of the anus does not allow the ointment to 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 (e.g., 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 (e.g., 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.
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.
- Anal fissures are cracks or tears in the anus and anal
canal. They may be acute or chronic.
- Anal fissures are caused primarily by trauma, but
several non-traumatic diseases are associated with anal fissures and should be
suspected if fissures occur in unusual locations.
- The primary symptom of anal fissures is pain during and
following bowel movements. Bleeding, itching, and a malodorous discharge also
may occur.
- Anal fissures are diagnosed and evaluated by visual
inspection of the anus and anal canal. Endoscopy and, less commonly,
gastrointestinal x-rays may be necessary.
- Anal fissures are initially treated conservatively by
adding bulk to the stool, softening the stool, consuming a high fiber diet,
avoiding "sharp" or poorly digested foods, and utilizing sitz baths.
- Ointments containing anesthetics, steroids,
nitroglycerin, and calcium channel blocking drugs are used for treating anal
fissures that fail to heal with less conservative management.
- Injections of botulinum toxin may be effective when
ointments are not effective. (The cost of treatment would be substantially
reduced if the toxin were packaged in smaller doses.)
- Surgery by lateral sphincterotomy is the gold standard for curing anal
fissures. Because of complications, however, it is reserved for patients who
are intolerant of non-surgical treatments or in whom non-surgical treatments
have proven to be ineffective.
Last Editorial Review: 8/4/2005
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