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Study on Treating Chronic Anal Fissure in Patients Using Ultrasound-Guided Injections of Botulinum Toxin A

Registered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on the treatment of chronic anal fissure, a condition characterized by a long-lasting tear in the lining of the anus, which can cause pain and discomfort. The study will use a treatment involving Botulinum Toxin Type A, a substance commonly known for its ability to relax muscles. In this trial, the Botulinum Toxin Type A will be administered as a powder that is mixed into a solution for injection.

The purpose of the study is to determine if using an ultrasound-guided technique to inject the Botulinum Toxin Type A is more effective and safer than the standard method. The ultrasound guidance helps in precisely locating the injection site, potentially improving the treatment's effectiveness and safety. The study aims to establish a new technique that complements the existing one, making it more precise without increasing risks.

Participants in the study will receive injections of Botulinum Toxin Type A, and their progress will be monitored over a period of time. The study will assess the effectiveness of the treatment by measuring pain levels and any changes in symptoms. The goal is to see if this new method of injection can provide better relief for those suffering from chronic anal fissures.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Upon joining the study, an initial assessment is conducted to confirm the diagnosis of chronic anal fissure. This condition is characterized by a fissure that has persisted for more than six weeks despite various treatments.

    Eligibility is determined based on the presence of specific symptoms such as indurated edges or sentinel polyps.

  2. Step 2

    Informed consent

    Participants are required to sign an informed consent form, acknowledging their understanding of the study and its procedures.

  3. Step 3

    Treatment administration

    The treatment involves ultrasound-guided inter-sphincteric injections of botulinum toxin type A. This is a solution for injection, specifically designed to treat chronic anal fissures.

    The injection is administered through a technique that uses an endorectal ultrasound probe to precisely locate the infiltration site, aiming to enhance the effectiveness and safety of the treatment.

  4. Step 4

    Monitoring and evaluation

    Participants are monitored for changes in symptoms and any side effects. The effectiveness of the treatment is assessed using the VAS scale for pain and the Wesner scale for fecal incontinence.

    Quality of life is evaluated using the FIQL scale, and the thickness of the external anal sphincter is measured with endorectal ultrasound.

  5. Step 5

    Follow-up

    Regular follow-up appointments are scheduled to track progress and address any concerns. The study aims to standardize the injection technique and improve treatment outcomes.

Who can join the trial?

7 criteria

  • Participants must be of legal age, which means they are considered adults by law.
  • Participants must sign an informed consent form, which is a document that explains the study and confirms their agreement to participate.
  • Participants must have a diagnosis of chronic anal fissure. This is a small tear in the lining of the anus that has been present for more than 6 weeks.
  • The chronic anal fissure must not have improved despite trying various treatments like hygiene changes, dietary adjustments, relaxing treatments, or medications such as nitroglycerin (NTG) or calcium blockers.
  • The fissure should show signs of being chronic, such as having indurated edges (hardened edges), visible IAF fibers (internal anal sphincter fibers), or a sentinel polyp (a small growth) that has persisted for more than 6 weeks.
  • Both male and female participants are eligible to join the study.
  • The study does not include vulnerable populations, which means groups that might need special protection or care.

Who cannot join the trial?

4 criteria

  • Individuals who do not have a chronic anal fissure cannot participate. A chronic anal fissure is a long-lasting tear in the lining of the anus.
  • Participants must be within the specified age range. If you are outside this range, you cannot join the study.
  • Both males and females are eligible, so gender is not a reason for exclusion.
  • Vulnerable populations, such as those who cannot give informed consent, are not included in this study.
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Investigated drugs

Botulinum Toxin A is used in this clinical trial to treat chronic anal fissures. The trial aims to determine if injecting this medication with the help of ultrasound guidance is more effective and safer than the standard injection method. Botulinum Toxin A works by relaxing the muscles around the fissure, which can help reduce pain and promote healing. The study focuses on whether the precise location of the injection, controlled by ultrasound, improves the treatment's effectiveness and safety.

What is already known about the treatment

Botulinum Toxin A – This medication is administered through ultrasound-guided inter-sphincteric injections, specifically targeting chronic anal fissures. Currently, it is being studied in clinical trials to determine if this method is more effective and safer than traditional techniques. The main therapeutic use of Botulinum Toxin A in this context is to relieve pain and promote healing of anal fissures. At the molecular level, it works by blocking the release of neurotransmitters that cause muscle contractions, leading to muscle relaxation. It is classified pharmacologically as a neuromuscular blocker.

Investigated diseases

Chronic anal fissure – This condition involves a small tear in the lining of the anus, which can cause pain and bleeding during bowel movements. It often results from passing hard or large stools and can lead to a cycle of discomfort and muscle spasms in the anal area. Over time, the fissure may become chronic if it does not heal properly, leading to persistent symptoms. The condition can cause a noticeable crack or ulcer in the anal skin, which may be visible upon examination. Chronic anal fissures can also lead to the development of a skin tag near the tear, known as a sentinel pile. The condition is often associated with discomfort, itching, and a feeling of tightness in the anal region.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-520748-13-01Protocol codeFAC-BOTOXEstimated enrolment50 patientsSponsorHospital Universitario de Burgos

sourced from the EU Clinical Trials Register and site verification

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