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Study of botulinum toxin injections to treat pain in patients with piriformis muscle syndrome

Verified siteRegistered drugNo placebo
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What is this trial about?

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

This study focuses on Piriformis Muscle Syndrome, a condition where the piriformis muscle in the buttock region causes pain and discomfort along the sciatic nerve. The research evaluates the effectiveness of XEOMIN, which contains botulinum toxin, compared to placebo in treating this condition. The medication is specifically designed for patients who have not found relief through conventional treatments like physiotherapy, muscle relaxants, or pain medications.

The purpose of the study is to determine if a single injection of botulinum toxin can reduce sciatic pain in people with Piriformis Muscle Syndrome. During the study, participants will receive one injection of either XEOMIN or placebo into the affected muscle. The injection will be guided by ultrasound or computed tomography to ensure accurate placement. The treatment's effects will be monitored over six months, with particular attention to pain levels after six weeks.

The medication being tested, XEOMIN, is administered as a solution for injection into the muscle. Each dose contains up to 200 units of botulinum toxin. Some patients may receive a second injection after 12 weeks if needed. Throughout the study, participants will be asked to report their pain levels and overall quality of life through various assessment tools.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment

    Your sciatic pain intensity will be measured using a visual scale from 0 to 100 (where 0 means no pain and 100 means worst possible pain)

    You will be asked about the average intensity of your pain over the last 24 hours

    Your buttock pain will also be measured using the same scale

    You will complete quality of life questionnaires

  2. Step 2

    Treatment injection

    You will receive a single injection into the muscle, guided by ultrasound or CT scan

    The injection will contain either botulinum toxin or an inactive substance

    Neither you nor your doctor will know which substance you receive

  3. Step 3

    Follow-up visits

    You will attend follow-up visits at 6, 12, 18, and 24 weeks after the injection

    At each visit, your pain levels will be reassessed

    You will complete questionnaires about your quality of life, physical functioning, anxiety, depression, and disability

    Your ability to sit comfortably will be evaluated

    Any use of pain medications will be recorded

    Any side effects will be monitored

  4. Step 4

    Potential second injection

    At 12 weeks after the first injection, your doctor will evaluate if you need a second injection

    The total study duration will be 6 months from your first injection

Who can join the trial?

8 criteria

  • You must be between 18 and 80 years old
  • You must have been diagnosed with piriformis muscle syndrome affecting one side of your body for at least 3 months
  • Your diagnosis must be confirmed with a score of 8 or higher on the Clinical Scoring System for Piriformis Muscle Syndrome
  • Your sciatic pain level must be at least 4 points on a pain scale when the study begins
  • Previous treatments (such as physiotherapy, muscle relaxants, and pain medications) must have been unsuccessful in treating your condition
  • You must not have a herniated disc (bulging disc) in your lower back that could explain your pain, as confirmed by MRI or CT scan
  • You must be willing to provide written informed consent to participate in the study
  • You must have health insurance coverage through the social security system

Who cannot join the trial?

15 criteria

  • Age below 18 years or above 65 years
  • Known allergy or sensitivity to botulinum toxin
  • Previous treatment with botulinum toxin in the past 6 months
  • Pregnancy or breastfeeding
  • Neuromuscular junction disorders (conditions affecting nerve and muscle connections)
  • Active infection at the injection site
  • Use of medications that could interact with botulinum toxin
  • Presence of bleeding disorders or use of blood thinners
  • History of back surgery in the past year
  • Uncontrolled medical conditions that could affect study participation
  • Radiculopathy (nerve root compression) confirmed by imaging
  • Participation in another clinical trial within the past 30 days
  • Inability to follow study procedures or attend follow-up visits
  • History of substance abuse that could interfere with the study
  • Mental conditions that could affect ability to provide informed consent
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Investigated drugs

Botulinum toxin is a medication that helps relax muscles by blocking nerve signals. In this trial, it is injected directly into the piriformis muscle (a muscle in the buttocks region) under ultrasound or CT guidance. The medication is used to treat piriformis muscle syndrome, a condition that causes pain in the buttocks and along the sciatic nerve. This treatment aims to reduce pain and improve quality of life for patients suffering from this condition.

What is already known about the treatment

Botulinum toxin - A highly purified protein that is injected directly into the piriformis muscle under ultrasound or CT guidance to treat piriformis muscle syndrome. This neurotoxin works by blocking nerve signals to muscles, causing temporary muscle relaxation and reducing pressure on the sciatic nerve. It belongs to the class of neuromuscular blocking agents and has been extensively studied in clinical settings for various muscular conditions. The medication is administered as a single-dose injection and is particularly effective in managing chronic muscle-related pain conditions where conventional treatments have not provided adequate relief.

Investigated diseases

Piriformis Muscle Syndrome - A neuromuscular condition where the piriformis muscle, located deep in the buttock, compresses or irritates the sciatic nerve. The condition typically causes pain, tingling, and numbness that begins in the buttocks and can extend down the back of the leg along the sciatic nerve pathway. Symptoms often worsen with prolonged sitting, climbing stairs, or performing squatting movements. The condition can develop gradually over time and may be related to muscle spasm, tightening, or swelling of the piriformis muscle. In some cases, anatomical variations in how the sciatic nerve passes through or around the piriformis muscle can contribute to the development of symptoms.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-517948-66-00Protocol codePHRCN/2019/AD-01Estimated enrolment108 patientsSponsorCentre Hospitalier Universitaire De Nimes

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).