Botulinum Toxin Injection

Botulinum toxin (Botox) is a relatively new treatment for patients with an anal fissure, anismus, or chronic pelvic pain caused by levator ani syndrome. Widely known as a safe and effective cosmetic therapy, Botulinum toxin can be used to treat these conditions when conservative and medical therapies have failed.

In patients with an anal fissure, Botulinum toxin temporarily relaxes the anal sphincter muscles and improves the blood supply to the area, thereby improving pain and muscle spasms and allowing the fissure to heal. Successful healing occurs in roughly half the patients with anal fissure who receive this treatment.

Some patients with anismus benefit from an injection of Botulinum toxin into the puborectalis muscle. The first injection helps make the diagnosis. If this injection helps, a repeat injection is given. It is this repeat injection that gives long-term benefit.

In patients with chronic pelvic pain caused by levator ani syndrome, Botulinum toxin works by reducing muscle spasm and tenderness in the culprit pelvic floor muscles. The pain is caused by knots in multiple muscles, and it is believed that Botulinum toxin helps relax these knots and allow the muscles to function normally.

If you are having this injection for an anal fissure, here is a small risk (around 2.5%) of minor incontinence in the week following the injection, mainly in patients who already have weak anal muscles, but normal continence resumes when the effects of the injection wear off.

Botulinum toxin injection is done as an openprocedure. For anal fissure, it involves 1–2 injections into the internal anal sphincter muscle directly through the anal skin. If an anal fissure is found to have overlying scar tissue, this is removed at the same time to aid healing. For anismus, it involves 1–2 injections into the external anal sphincter muscle and a part of the pelvic floor called the puborectalis muscle directly through the anal skin. For chronic pelvic pain caused by levator ani syndrome, the procedure involves multiple injections into the pelvic floor muscles. The whole procedure takes approximately 15–30 minutes. You will have the opportunity to discuss fully all the risks and benefits of this procedure with me before signing your consent form.

Botulinum toxin injection is done as a day-stay procedure under general anaesthesia, where you will be asleep and feel no pain. You will need to fast from midnight on the night before if your surgery is scheduled for the morning, or from 7 am if it scheduled for the afternoon.

No special bowel preparation is necessary before your procedure unless you are also having a colonoscopy in the same sitting. You will receive an enema one hour or so before your surgery, unless you have a fissure that makes this too painful.

You will be given an injection of local anaesthetic before you leave the operating theatre to keep you pain-free in the 6 hours after your surgery. After the operation you will be transferred to the recovery area and then to the ward.

Botulinum toxin injection is only painful in patients with an anal fissure where scar tissue needs to be removed from the fissure site. This will become apparent after the procedure when your local anaesthetic wears off, and will get better, but may take up to 2–4 weeks to resolve completely.

You should be able to go home the same day, but sometimes patients may need to stay longer. You should not drive after your surgery, so a friend or relative will need to take you home.

It is important to keep your bowel movements soft and regular while you are recovering from this procedure. To prevent constipation, eat foods high in fibre, and drink plenty of water (6–8 glasses a day). Analgesia and laxatives will be given to you to take home. It is best to keep up with these until your bowels are moving and any discomfort is manageable. Laxatives may need to be continued for up to 4 weeks after surgery.

You can expect minor bleeding after your procedure. A sanitary towel changed twice daily will help to prevent staining of underwear. Generally, use water to wash the anus twice a day and after every bowel movement.

Exactly when patients can resume driving after this procedure is determined on a case-by-case basis and will be discussed with you after your surgery. This is normally 1–2 weeks. Please let your insurance company know when you have been given the all-clear to resume driving.

Patients are usually able to return to normal activities as pain allows after Botulinum toxin injection, including going back to work. Just like when it is used to smooth out wrinkles in cosmetic surgery, the beneficial effects of the injection start to appear 1–2 weeks after the procedure, with full effects often felt at 6 weeks.

A follow-up appointment in the clinic will be arranged for 1–2 weeks after your surgery to check your wound and discuss further management if necessary.