What is the success rate of Botox (Botulinum toxin) injection for treating anal fissure?

From the Guidelines

Botox (Botulinum toxin) injections for treating anal fissures have a success rate of approximately 75%–95%. The treatment works by temporarily paralyzing the internal anal sphincter muscle, reducing spasm and pain, which allows the fissure to heal 1. A typical regimen involves injecting botulin toxin directly into the internal anal sphincter, with the optimal location of injection still being a topic of debate. Key points to consider when using Botox for anal fissure treatment include:

• High cure rates with low morbidity
• Temporary relief, with potential for recurrence
• Sphincter-preserving, making it an attractive option for patients with pre-existing continence issues
• Generally mild and temporary side effects, including minor incontinence, bruising, or pain at the injection site
• Useful for patients who have failed conservative treatments but wish to avoid surgery, such as lateral internal sphincterotomy (LIS) 1. Some of the key benefits of Botox injections for anal fissures include:
• Rapid symptom relief
• High success rates
• Low risk of permanent complications
• Outpatient procedure with minimal recovery time
• Suitable for patients who are not good candidates for surgery or have failed other treatments. However, it's essential to weigh these benefits against the potential drawbacks, including:
• Temporary nature of the treatment, with possible recurrence
• Need for repeated injections
• Potential for minor side effects
• Limited long-term data on relapse rates and effects on continence. Given the available evidence, Botox injections can be considered a viable treatment option for anal fissures, particularly for patients who have failed conservative treatments and wish to avoid surgery 1.

From the Research

Success Rate of Botox Injection for Anal Fissure

The success rate of Botox injection for treating anal fissure has been studied in several clinical trials.

• A study published in the Irish Journal of Medical Science in 2004 found that Botox injection healed anal fissures in approximately 73-96% of cases 2.
• Another study published in Diseases of the Colon and Rectum in 2003 reported a healing rate of 73.8% after a single Botox injection, which increased to 86.9% after a second injection 3.
• A dose-finding study published in Colorectal Disease in 1999 found that 78% of patients with chronic anal fissures were healed after 3 months of treatment with Dysport, a type of botulinum toxin 4.
• A study published in Postgraduate Medicine in 2016 reported that 59% of patients with anal fissure experienced relief of anal pain after Botox treatment 5.
• A randomized controlled trial published in the World Journal of Surgery in 2010 found that lateral internal sphincterotomy had a higher healing rate than Botox injection, but Botox injection had a lower rate of anal incontinence 6.

Factors Affecting Success Rate

The success rate of Botox injection for anal fissure may depend on several factors, including:

• Dose and frequency of injection: Studies have shown that higher doses of Botox may be more effective, but also increase the risk of side effects 3, 4.
• Type of botulinum toxin used: Different types of botulinum toxin, such as Botox and Dysport, may have different efficacy and safety profiles 4.
• Patient selection: Patients with uncomplicated chronic anal fissures may be more likely to respond to Botox treatment than those with complicated or recurrent fissures 6.

Side Effects and Complications

Botox injection for anal fissure is generally well-tolerated, but may cause side effects such as:

• Temporary fecal incontinence: Reported in up to 10% of patients 3, 5.
• Pain: May occur at the injection site or in the anal region 3, 5.
• Bleeding: Rarely reported, but may occur at the injection site 3.