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NCT Number: NCT07624045

Efficacy of Botulinum Toxin Versus Placebo on Pain and Health Related Quality of Life of Patients With Piriformis Muscle Syndrome

Piriformis muscle syndrome (PMS) is characterized by symptoms caused by compression or irritation of the sciatic nerve by the piriformis muscle as it exits the sciatic notch. PMS commonly evokes the symptoms of sciatica and is likely underdisagnosed. Patients who experience pain related to piriformis syndrome will complain of aggravated pain after prolonged periods of sitting or upon rising from a seated position. Around 98% of patients evoke positional buttock pain, especially during prolonged sitting (car journeys, for example). This is less true for sciatic pain radiation, which is still found in 63% of cases, systematically associated with the notion of buttock pain. Treatments for PMS aim to reduce or eliminate sciatic pain and also control buttock pain. Reducing these pains can improve the physical condition and emotional state of the patient. Several approaches have been proposed including physical therapy (massage-physiotherapy, self-rehabilitation techniques) combined with the use of anti-inflammatory drugs, analgesics and muscle relaxants to reduce inflammation, spasm and pain. Many patients do not respond to conventional care. Surgery may be considered only in those cases who do not improve with conservative therapy or injections. However, decompressive surgery is an invasive treatment, indicated in case of complete failure of all medical strategies, with physical and functional consequences. In recent years, several published studies showed the use of botulinum toxin (BT) injection as a new therapeutic option to reduce buttock and sciatic pain induced by PMS. The study team previously observed the efficacy of BT/A1 administration into the piriformis muscle in patients who were previously treated with medication and rehabilitation protocols with no pain improvement. Pain relief was considered as "very good" or "good" for 77% of the patients, "average" for 7.4% and "poor" for 15.6%. No adverse events were reported. More recently, Fishman and colleagues reported the results of a randomized, double-blind, controlled study including 56 patients and comparing physical therapy, incobotulinum toxin A and placebo. Data are sparse concerning BT injection for PMS and no multicenter randomized clinical trial have been performed. Two out of three randomized trials (Fishman 2004, 2017) are based on highly selected patients (3 standard deviations or more beyond on the prolongation of the posterior tibial or fibular nerve H-reflex in FAIR test). Therefore, BT efficacy may be overestimated and remains to be evaluated among unselected PMS patients, regardless of analgesic treatments or physical therapy. Finally, no randomized studies have reported the heatlh-related quality of life of PMS patients.

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Key information

Conditions

Piriformis Muscle Syndrome Mononeuropathies Nerve Compression Syndromes Nervous System Diseases Neuralgia Neurologic Manifestations Neuromuscular Diseases Pain Pathological Conditions, Signs and Symptoms Pelvic Pain Peripheral Nervous System Diseases Sciatic Neuropathy Signs and Symptoms

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Centre Hospitalier Universitaire de Nîmes, Nîmes, Gard, France

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Objective clinical diagnosis of unilateral piriformis syndrome for at least 3 months (as assessed by Clinical Scoring System for the Diagnosis of Piriformis Muscle Syndrome: score of 8 or greater
  • Absence of herniated lumbar disc which can explain radiating pain (MRI or computed tomography (CT) of the lumbar spine)
  • Patients not responding to conventional care (physiotherapy, muscle relaxants, analgesics)
  • Baseline sciatic pain intensity of at least 4 points on visual analog scale
  • Provision of written informed consent
  • Patients affiliated to social security system (health insurance coverage).

Exclusion criteria

  • Bilateral piriformis muscle syndrome.
  • History of piriformis syndrome surgery.
  • History of botulinum toxin administration.
  • Any treatment (general or local) likely to interfere with botulinum toxin or evaluation of the primary endpoint (Corticosteroids, aminoglycosides).
  • Corticosteroids in the past 3 weeks.
  • Signs of severe fibrosis (on MRI or CT) of the piriformis muscle.
  • Other causes of sciatic pain (lumbar root compression, inflammatory, infectious or neoplasic pelvic disease, particularly for inflammatory sacroiliac pain).
  • Hip prosthesis on the same side as piriformis syndrome; knee prosthesis is tolerated.
  • Contraindication to BT injection:
  • History of intolerance, hypersensitivity or known allergy to any botulinum toxin product or excipients;
  • Patients with myasthenia gravis or other diseases of the neuromuscular junction;
  • Patients with Lambert-Eaton Syndrome;
  • Patients with neurological disorders such as dysphagia, swallowing disorders or aspiration pneumonia;
  • Current infection at the proposed injection site;
  • Long-term anticoagulant therapy ;
  • Antibiotics and vaccination are prohibited for 15 days before and after BT injection
  • Pregnant or breastfeeding women. Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant must use an effective method of contraception (oral contraceptives, contraceptive injections, intrauterine devices, method of double-barrier contraceptive patches). The contraception should be maintained throughout the study.
  • Patients unable to complete the patient diary.
  • Inability to understand the reasons for the study; psychiatric disorders judged by the investigator to be incompatible with inclusion in the study.
  • Patients with legal disability or limited legal capacity.
  • Patients judged as noncompliant.

Treatment and study plan

Botulinum Toxin - A injections

Drug

Incobotulinumtoxin type A (200 U in 2 mL of preservative-free normal saline) will be injected in equally divided doses (1mL; 100 U for incobotulinumtoxin A) into 2 locations in the affected buttock region

Placebo

Drug

Placebo (normal saline solution and excipients described in Xeomin) will be injected in equally divided doses (1mL) into 2 locations in the affected buttock region

Primary outcomes

  1. Change in sciatic pain

    Time frame: From baseline to Week 6

    Measured on a 0 (no pain) to 10 (worst pain) visual analog scale

Secondary outcomes

  1. Change in buttock pain intensity

    Time frame: From baseline to Week 6

    Measured on a 0 (no pain) to 10 (worst pain) visual analog scale

  2. Health-related quality of life

    Time frame: Baseline

    EuroQol-5 Dimension questionnaire measuring five items representing the five dimensions, and a visual analog scale graduated from 0 to 100 (100 referring to the "best possible state of health"). For each dimension, patients indicate their current state of health to generated a 5-digit number describing the health status (e.g., health status "11111" indicates the absence of problems in each dimension)

  3. Health-related quality of life

    Time frame: Week 6

    EuroQol-5 Dimension questionnaire measuring five items representing the five dimensions, and a visual analog scale graduated from 0 to 100 (100 referring to the "best possible state of health"). For each dimension, patients indicate their current state of health to generated a 5-digit number describing the health status (e.g., health status "11111" indicates the absence of problems in each dimension)

  4. Health-related quality of life

    Time frame: Week 12

    EuroQol-5 Dimension questionnaire measuring five items representing the five dimensions, and a visual analog scale graduated from 0 to 100 (100 referring to the "best possible state of health"). For each dimension, patients indicate their current state of health to generated a 5-digit number describing the health status (e.g., health status "11111" indicates the absence of problems in each dimension)

  5. Health-related quality of life

    Time frame: Week 18

    EuroQol-5 Dimension questionnaire measuring five items representing the five dimensions, and a visual analog scale graduated from 0 to 100 (100 referring to the "best possible state of health"). For each dimension, patients indicate their current state of health to generated a 5-digit number describing the health status (e.g., health status "11111" indicates the absence of problems in each dimension)

  6. Health-related quality of life

    Time frame: Week 24

    EuroQol-5 Dimension questionnaire measuring five items representing the five dimensions, and a visual analog scale graduated from 0 to 100 (100 referring to the "best possible state of health"). For each dimension, patients indicate their current state of health to generated a 5-digit number describing the health status (e.g., health status "11111" indicates the absence of problems in each dimension)

  7. Sciatic pain intensity

    Time frame: Baseline

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  8. Sciatic pain intensity

    Time frame: Week 3

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  9. Sciatic pain intensity

    Time frame: Week 6

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  10. Sciatic pain intensity

    Time frame: Week 9

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  11. Sciatic pain intensity

    Time frame: Week 12

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  12. Sciatic pain intensity

    Time frame: Week 15

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  13. Sciatic pain intensity

    Time frame: Week 18

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  14. Sciatic pain intensity

    Time frame: Week 21

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  15. Sciatic pain intensity

    Time frame: Week 24

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  16. Buttock pain intensity

    Time frame: Baseline

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  17. Buttock pain intensity

    Time frame: Week 3

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  18. Buttock pain intensity

    Time frame: Week 6

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  19. Buttock pain intensity

    Time frame: Week 9

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  20. Buttock pain intensity

    Time frame: Week 12

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  21. Buttock pain intensity

    Time frame: Week 15

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  22. Buttock pain intensity

    Time frame: Week 18

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  23. Buttock pain intensity

    Time frame: Week 21

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  24. Buttock pain intensity

    Time frame: Week 24

    Assessed on Visual Analog Scale value (0 = no pain, 10 = worst pain)

  25. Physical functioning

    Time frame: Baseline

    Brief Pain Inventory Short Form; 9-item questionnaire, where Worst Pain Score: 1 - 4 = Mild Pain; Worst Pain Score: 5 - 6 = Moderate Pain; Worst Pain Score: 7 - 10 = Severe Pain

  26. Physical functioning

    Time frame: Week 6

    Brief Pain Inventory Short Form; 9-item questionnaire, where Worst Pain Score: 1 - 4 = Mild Pain; Worst Pain Score: 5 - 6 = Moderate Pain; Worst Pain Score: 7 - 10 = Severe Pain

  27. Physical functioning

    Time frame: Week 12

    Brief Pain Inventory Short Form; 9-item questionnaire, where Worst Pain Score: 1 - 4 = Mild Pain; Worst Pain Score: 5 - 6 = Moderate Pain; Worst Pain Score: 7 - 10 = Severe Pain

  28. Physical functioning

    Time frame: Week 18

    Brief Pain Inventory Short Form; 9-item questionnaire, where Worst Pain Score: 1 - 4 = Mild Pain; Worst Pain Score: 5 - 6 = Moderate Pain; Worst Pain Score: 7 - 10 = Severe Pain

  29. Physical functioning

    Time frame: Week 24

    Brief Pain Inventory Short Form; 9-item questionnaire, where Worst Pain Score: 1 - 4 = Mild Pain; Worst Pain Score: 5 - 6 = Moderate Pain; Worst Pain Score: 7 - 10 = Severe Pain

  30. Perceived change in condition in response to therapy

    Time frame: Baseline

    Patient Global Impression of Improvement (PGI-I)

  31. Perceived change in condition in response to therapy

    Time frame: Week 6

    Patient Global Impression of Improvement (PGI-I)

  32. Perceived change in condition in response to therapy

    Time frame: Week 12

    Patient Global Impression of Improvement (PGI-I)

  33. Perceived change in condition in response to therapy

    Time frame: Week 18

    Patient Global Impression of Improvement (PGI-I)

  34. Perceived change in condition in response to therapy

    Time frame: Week 24

    Patient Global Impression of Improvement (PGI-I)

  35. Emotional distress

    Time frame: Baseline

    Hospital Anxiety and Depression Scale (HADS); 14 items, with responses scored on a scale of 0-3 (3 indicates higher symptom frequencies). Subscales (anxiety and depression) range from 0 to 21 whereby: normal 0-7, mild 8-10, moderate 11-14, and severe 15-21.

  36. Emotional distress

    Time frame: Week 6

    Hospital Anxiety and Depression Scale (HADS); 14 items, with responses scored on a scale of 0-3 (3 indicates higher symptom frequencies). Subscales (anxiety and depression) range from 0 to 21 whereby: normal 0-7, mild 8-10, moderate 11-14, and severe 15-21.

  37. Emotional distress

    Time frame: Week 12

    Hospital Anxiety and Depression Scale (HADS); 14 items, with responses scored on a scale of 0-3 (3 indicates higher symptom frequencies). Subscales (anxiety and depression) range from 0 to 21 whereby: normal 0-7, mild 8-10, moderate 11-14, and severe 15-21.

  38. Emotional distress

    Time frame: Week 18

    Hospital Anxiety and Depression Scale (HADS); 14 items, with responses scored on a scale of 0-3 (3 indicates higher symptom frequencies). Subscales (anxiety and depression) range from 0 to 21 whereby: normal 0-7, mild 8-10, moderate 11-14, and severe 15-21.

  39. Emotional distress

    Time frame: Week 24

    Hospital Anxiety and Depression Scale (HADS); 14 items, with responses scored on a scale of 0-3 (3 indicates higher symptom frequencies). Subscales (anxiety and depression) range from 0 to 21 whereby: normal 0-7, mild 8-10, moderate 11-14, and severe 15-21.

  40. Disability for low back pain

    Time frame: Baseline

    Oswestry Disability Index (ODI): range 0 to 100. Zero is equated with no disability and 100 is the maximum disability possible.

  41. Disability for low back pain

    Time frame: Week 6

    Oswestry Disability Index (ODI): range 0 to 100. Zero is equated with no disability and 100 is the maximum disability possible.

  42. Disability for low back pain

    Time frame: Week 12

    Oswestry Disability Index (ODI): range 0 to 100. Zero is equated with no disability and 100 is the maximum disability possible.

  43. Disability for low back pain

    Time frame: Week 18

    Oswestry Disability Index (ODI): range 0 to 100. Zero is equated with no disability and 100 is the maximum disability possible.

  44. Disability for low back pain

    Time frame: Week 24

    Oswestry Disability Index (ODI): range 0 to 100. Zero is equated with no disability and 100 is the maximum disability possible.

  45. Tolerance of the sitting position

    Time frame: Baseline

    Time between the beginning of the sitting position and the onset or worsening of the pain

  46. Tolerance of the sitting position

    Time frame: Week 6

    Time between the beginning of the sitting position and the onset or worsening of the pain

  47. Tolerance of the sitting position

    Time frame: Week 12

    Time between the beginning of the sitting position and the onset or worsening of the pain

  48. Tolerance of the sitting position

    Time frame: Week 18

    Time between the beginning of the sitting position and the onset or worsening of the pain

  49. Tolerance of the sitting position

    Time frame: Week 24

    Time between the beginning of the sitting position and the onset or worsening of the pain

  50. Consumption of painkillers

    Time frame: Week 24

    Number of level 1 to 3 analgesics, non-steroidal anti-inflammatory drugs and muscle relaxants

  51. Number of patients requiring a second injection botulinum toxin in each arm

    Time frame: Week 12

    Number

  52. Side effects of injection

    Time frame: Week 24

    Side effects of the injection or attributable to the study drug

Study contacts

Contact information is provided by the study sponsor or research team.

Arnaud Dupeyron

CONTACT

[email protected]

04.66.68.34.59

Sponsors and collaborators

Lead sponsor

Centre Hospitalier Universitaire de Nīmes

Other

Registry information

Official study title

A Phase IIb, Randomized, Double-blind, Multicenter Study Evaluating the Efficacy of Botulinum Toxin Versus Placebo on Pain and Health Related Quality of Life of Patients With Piriformis Muscle Syndrome

Acronym: PiriTox

Important dates

Study start
2026
Primary completion
2029
Study completion
2029
First posted
Jun 3, 2026
Registry last updated
Jun 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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