SciaticaSciaticaNCT06783439
Ultrasonographic Evaluation of the Sciatic Nerve in Patients With Piriformis Syndrome
An observational study of Sciatica and Piriformis Muscle Syndrome, run by Istanbul University - Cerrahpasa at 1 site in Turkey (Türkiye).
Trial summary
Piriformis syndrome (PS) is defined as a neuropathy of entrapment resulting from compression and irritation of the sciatic nerve at the level of the piriformis muscle (PM) at the pelvic outlet, causing sciatica radiating to the leg. Read more about this study
- Who is it for?
- Ages 18 to 70 years
- Conditions the study is for
- Sciatica, Piriformis Muscle Syndrome
- What is being tested?
- Ultrasound
- Type of treatment
- Injection or infusion
- How many people
- 19 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Dec 2024to 1 Apr 2025
- How long will I take part?
- 1 Day
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 70 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Patients aged between 18 and 70 years with unilateral hip and/or leg pain, positive FAIR (flexion, adduction, internal rotation) test, and tenderness to palpation in the PM will be included in our study.
Who may be able to join
- Patients aged between 18 and 70 years with unilateral hip and/or leg pain
- Positive FAIR (flexion, adduction, internal rotation) test
- Tenderness to palpation in the Piriformis muscle
Who cannot join
- Patients with a history of previous surgery involving the lumbar and/or hip region
- A history of malignancy or infection in the pelvic region
- Body mass index (BMI) Greater than 30 kg/m2
- Psychiatric diseases
- Vascular disease
- Uncontrolled diabetes, hypertension or heart failure,
- Disc pathologies that may cause radiculopathy
- History of rheumatic disease.
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
İstanbul Üniversitesi - Cerrahpasa (IUC)
Istanbul
About this study
Piriformis syndrome (PS) is defined as a neuropathy of entrapment resulting from compression and irritation of the sciatic nerve at the level of the piriformis muscle (PM) at the pelvic outlet, causing sciatica radiating to the leg. The neuropathic component of PS is the compression of the sciatic nerve in or around the PM, while the primary cause of the somatic component is myofascial pain of the PM. PS accounts for 6-8% of all hip and sciatic pain cases. It is more common in middle-aged patients, and the most common etiological cause is trauma. There are various methods for the diagnosis of Piriformis Syndrome. Clinically, tenderness on palpation of the PM is the most common symptom. The FAIR test (passive flexion abduction and internal rotation of the hip), the Freiberg test (forceful internal rotation of the thigh in the supine position), the Pace test (abduction of the leg against resistance while sitting) and the Beatty maneuver (active abduction of the thigh on the affected side in the lateral decubitus position) are maneuvers that help in diagnosis. It is known that there is a delay in proximal nerve conduction (H-reflex) on the pathological side compared to the healthy side in the FAIR maneuver on EMG in PS, and it is not a sufficient test for diagnosis alone. Some studies have reported increased piriformis thickness on the pathological side in MRI. None of these clinical and imaging methods are sufficient for diagnosis alone, and today ultrasonography (US) has become one of the most important imaging methods for musculoskeletal clinicians in the diagnosis of PS. Imaging with US and the diagnostic injection test applied to the piriformis muscle with US guidance are quite important for diagnosis. There are a number of studies in the literature evaluating PM with US. These studies have shown that the piriformis muscle thickness and echogenicity increase on the pathological side. However, there is a lack of studies in the literature focusing on the evaluation of the sciatic nerve with US in patients with PS. Our aim in this study is to compare the thickness of the PM and the sciatic nerve by measuring US on both the pathological and painless sides in patients with unilateral hip pain who were diagnosed with PS clinically, to record the variations present in the sciatic nerve, and to determine whether the myofascial pain or the neuropathic component is dominant in the disease.
Read the detailed description
The sciatic nerve is the largest nerve in the body and is formed by the ventral roots of the lumbosacral plexus (L4-S3), passes through the foramen ischiadicum majus under the piriformis muscle (PM) and enters the gluteal region. It is controversial whether anatomical variations in the sciatic nerve and PM predispose to the development of Piriformis syndrome (PS). The sciatic nerve passes under the PM as a single branch in almost 90% of cases. However, there are some variations where it passes above and through the muscle or divides into tibial and peroneal branches, with one branch passing under the piriformis. There are a number of studies in the literature evaluating the PM with US. These studies have shown that the PM thickness and echogenicity increase on the pathological side. In addition, it has been mentioned that the sciatic nerve has a coarse and blurry image in patients complaining of sciatic pain. In one study, cross-sectional area measurement was performed instead of PM thickness measurement. However, this was criticized in later studies, and it was stated that it was difficult to calculate muscle volume exactly with two-dimensional US due to the irregular shape of the PM, which is anatomically pear-shaped, and that thickness measurement would provide more accurate results instead of cross-sectional area. In the first study in the literature focusing on the sciatic nerve in PS and the neuropathic pain it causes, it was found that the sciatic nerve was significantly enlarged (75%) on the symptomatic side and had decreased echogenicity in some patients when compared to healthy volunteers.
- Conditions
- Sciatica, Piriformis Muscle Syndrome
- Being tested
- Ultrasound
- Keywords
- Piriformis Muscle Syndrome, Sciatica
- Medical subject headings
- Sciatica, Piriformis Muscle Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
UltrasoundOther
The ultrasound probe will be placed parallel to the body of the piriformis muscle on an imaginary line drawn from the sacrum to the greater trochanter of the femur. This area is also the sensitive area of the patients during the examination with pressure, and when the US probe is in this position, the subcutaneous fat tissue, gluteus maximus muscle, piriformis muscle, and the upper and lower borders of the sciatic nerve will be displayed in order from superficial to deep. First, the maximum thickness of the piriformis muscle body will be measured, then the thickness of the sciatic nerve will be measured, and the same measurements will be applied to the patient's asymptomatic hip, and the measurements will be recorded.
| Study group | Role | What they receive |
|---|---|---|
| symptomatic hip | Patients aged between 18 and 70 years with unilateral hip and/or leg pain, positive FAIR (flexion, adduction, internal rotation) test, and tenderness to palpation in the PM will be included in our study. Receives: Other: Ultrasound | |
| asymptomatic hip | Patients aged between 18 and 70 years with unilateral hip and/or leg pain, positive FAIR (flexion, adduction, internal rotation) test, and tenderness to palpation in the PM will be included in our study. Receives: Other: Ultrasound |
What is being measured
The primary outcome is the main question the study is designed to answer.
numeric scale
Tenderness in the piriformis muscle will be assessed by palpation using the numerical scale (NRS). The numerical scale is a pain score and is evaluated between 0 and 10.
Measured: five months
Sciatic nerve thickness (measurement with US)
Sciatic nerve thickness will be measured with ultrasound on the symptomatic and asymptomatic sides in the same patient.
Measured: five months
Piriformis muscle thickness (measurement with US)
Piriformis muscle thickness will be measured with ultrasound on the symptomatic and asymptomatic sides in the same patient.
Measured: five months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 Jan 2025
- Study start1 Dec 2024
- Primary completion1 Apr 2025
- Study completion1 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SciaticaStudies of the same condition, open and under way.
- More trials run by Istanbul University - CerrahpasaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case only
- Time perspective
- Cross-sectional
- Enrolment
- 19 participants (actual)
- Target duration
- 1 Day
Sponsor and investigators
- Lead sponsor
- Istanbul University - Cerrahpasa
- Sponsor type
- University, hospital or other
- Collaborators
- Istanbul Physical Medicine Rehabilitation Training and Research Hospital
- Responsible party
- Principal investigator, Busra Sezer Kıral, Istanbul University - Cerrahpasa
- Investigators
- Selim Sezikli, Principal investigator, Istanbul Physical Medicine Rehabilitation Training and Research Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06783439
- Sponsor's protocol ID
- 2024-69
- Other IDs
- Istanbul PMR
- Acronym
- Sciatica
- Status last verified
- Feb 2026
- First submitted
- 7 Jan 2025
- Last updated
- 3 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Ultrasonographic Evaluation of the Sciatic Nerve in Patients With Piriformis Syndrome
- ClinicalTrials.gov ID
- NCT06783439
- Acronym / sponsor ID
- Sciatica / 2024-69
- Conditions
- Sciatica, Piriformis Muscle Syndrome
- Keywords
- Piriformis Muscle Syndrome, Sciatica
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 19 participants (actual)
- Lead sponsor
- Istanbul University - CerrahpasaUniversity, hospital or other
- Collaborators
- Istanbul Physical Medicine Rehabilitation Training and Research Hospital
- Study start
- 1 Dec 2024 (actual)
- Primary completion
- 1 Apr 2025 (actual)
- Study completion
- 1 Apr 2025 (actual)
- First posted
- 20 Jan 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Piriformis syndrome (PS) is defined as a neuropathy of entrapment resulting from compression and irritation of the sciatic nerve at the level of the piriformis muscle (PM) at the pelvic outlet, causing sciatica radiating to the leg. The neuropathic component of PS is the compression of the sciatic nerve in or around the PM, while the primary cause of the somatic component is myofascial pain of the PM. PS accounts for 6-8% of all hip and sciatic pain cases. It is more common in middle-aged patients, and the most common etiological cause is trauma. There are various methods for the diagnosis of Piriformis Syndrome. Clinically, tenderness on palpation of the PM is the most common symptom. The FAIR test (passive flexion abduction and internal rotation of the hip), the Freiberg test (forceful internal rotation of the thigh in the supine position), the Pace test (abduction of the leg against resistance while sitting) and the Beatty maneuver (active abduction of the thigh on the affected side in the lateral decubitus position) are maneuvers that help in diagnosis. It is known that there is a delay in proximal nerve conduction (H-reflex) on the pathological side compared to the healthy side in the FAIR maneuver on EMG in PS, and it is not a sufficient test for diagnosis alone. Some studies have reported increased piriformis thickness on the pathological side in MRI. None of these clinical and imaging methods are sufficient for diagnosis alone, and today ultrasonography (US) has become one of the most important imaging methods for musculoskeletal clinicians in the diagnosis of PS. Imaging with US and the diagnostic injection test applied to the piriformis muscle with US guidance are quite important for diagnosis. There are a number of studies in the literature evaluating PM with US. These studies have shown that the piriformis muscle thickness and echogenicity increase on the pathological side. However, there is a lack of studies in the literature focusing on the evaluation of the sciatic nerve with US in patients with PS. Our aim in this study is to compare the thickness of the PM and the sciatic nerve by measuring US on both the pathological and painless sides in patients with unilateral hip pain who were diagnosed with PS clinically, to record the variations present in the sciatic nerve, and to determine whether the myofascial pain or the neuropathic component is dominant in the disease.
Detailed description
The sciatic nerve is the largest nerve in the body and is formed by the ventral roots of the lumbosacral plexus (L4-S3), passes through the foramen ischiadicum majus under the piriformis muscle (PM) and enters the gluteal region. It is controversial whether anatomical variations in the sciatic nerve and PM predispose to the development of Piriformis syndrome (PS). The sciatic nerve passes under the PM as a single branch in almost 90% of cases. However, there are some variations where it passes above and through the muscle or divides into tibial and peroneal branches, with one branch passing under the piriformis. There are a number of studies in the literature evaluating the PM with US. These studies have shown that the PM thickness and echogenicity increase on the pathological side. In addition, it has been mentioned that the sciatic nerve has a coarse and blurry image in patients complaining of sciatic pain. In one study, cross-sectional area measurement was performed instead of PM thickness measurement. However, this was criticized in later studies, and it was stated that it was difficult to calculate muscle volume exactly with two-dimensional US due to the irregular shape of the PM, which is anatomically pear-shaped, and that thickness measurement would provide more accurate results instead of cross-sectional area. In the first study in the literature focusing on the sciatic nerve in PS and the neuropathic pain it causes, it was found that the sciatic nerve was significantly enlarged (75%) on the symptomatic side and had decreased echogenicity in some patients when compared to healthy volunteers.
Study design
- Observational model
- Case only
- Time perspective
- Cross-sectional
- Target follow-up
- 1 Day
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| symptomatic hip | – | Other: UltrasoundPatients aged between 18 and 70 years with unilateral hip and/or leg pain, positive FAIR (flexion, adduction, internal rotation) test, and tenderness to palpation in the PM will be included in our study. |
| asymptomatic hip | – | Other: UltrasoundPatients aged between 18 and 70 years with unilateral hip and/or leg pain, positive FAIR (flexion, adduction, internal rotation) test, and tenderness to palpation in the PM will be included in our study. |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Patients aged between 18 and 70 years with unilateral hip and/or leg pain, positive FAIR (flexion, adduction, internal rotation) test, and tenderness to palpation in the PM will be included in our study.
Key inclusion criteria (3 listed)
- Patients aged between 18 and 70 years with unilateral hip and/or leg pain
- Positive FAIR (flexion, adduction, internal rotation) test
- Tenderness to palpation in the Piriformis muscle
Key exclusion criteria (8 listed)
- Patients with a history of previous surgery involving the lumbar and/or hip region
- A history of malignancy or infection in the pelvic region
- Body mass index (BMI) Greater than 30 kg/m2
- Psychiatric diseases
- Vascular disease
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| UltrasoundThe ultrasound probe will be placed parallel to the body of the piriformis muscle on an imaginary line drawn from the sacrum to the greater trochanter of the femur. This area is also the sensitive area of the patients during the examination with pressure, and when the US probe is in this position, the subcutaneous fat tissue, gluteus maximus muscle, piriformis muscle, and the upper and lower borders of the sciatic nerve will be displayed in order from superficial to deep. First, the maximum thickness of the piriformis muscle body will be measured, then the thickness of the sciatic nerve will be measured, and the same measurements will be applied to the patient's asymptomatic hip, and the measurements will be recorded. | Other | asymptomatic hip, symptomatic hip |
Primary outcome
numeric scale
Time frame: five months
Tenderness in the piriformis muscle will be assessed by palpation using the numerical scale (NRS). The numerical scale is a pain score and is evaluated between 0 and 10.
Sciatic nerve thickness (measurement with US)
Time frame: five months
Sciatic nerve thickness will be measured with ultrasound on the symptomatic and asymptomatic sides in the same patient.
Piriformis muscle thickness (measurement with US)
Time frame: five months
Piriformis muscle thickness will be measured with ultrasound on the symptomatic and asymptomatic sides in the same patient.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Mar 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Selim Sezikli principal investigator
Istanbul Physical Medicine Rehabilitation Training and Research Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Sciatica and Piriformis Muscle Syndrome, run by Istanbul University - Cerrahpasa at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 3 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
numeric scale (time frame: five months). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Mar 2026.