Piriformis syndrome !

Piriformis syndrome is buttock pain, often spreading down the thigh, blamed on the piriformis muscle irritating the sciatic nerve; it is debated.

Updated 2026-10-29

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What it is

Buttock pain, often spreading down the back of the thigh, attributed to irritation or compression of the sciatic nerve by the piriformis muscle. It is a diagnosis of exclusion and its existence and criteria are debated.

Who gets it

Its true frequency is unknown because no test confirms it; it is reported more often in women and in middle-aged adults, and it is now often grouped under deep gluteal syndrome.

Causes

Direct trauma or a fall onto the buttock
Muscle hypertrophy, spasm or overuse
Anatomical variants in which the sciatic nerve or part of it passes through or above the piriformis
Prolonged sitting on hard surfaces or on a wallet in the back pocket
Scarring after hip surgery

Risk factors

Prolonged sitting
Running or sports with repeated hip rotation
Buttock trauma
Leg length difference or altered gait

Pathophysiology

The sciatic nerve leaves the pelvis through the greater sciatic foramen, usually just below the piriformis. Spasm, swelling, scarring or a variant course can compress or stretch the nerve at this point, causing pain and sometimes sensory change along the sciatic distribution.

Classification

Primary: from anatomical variants of the muscle or nerve
Secondary: from trauma, mass, scarring or other causes
Considered one cause within deep gluteal syndrome

Symptoms and signs

Deep buttock pain, often one-sided
Pain spreading down the back of the thigh, usually not below the knee
Worse with sitting, climbing stairs or hip rotation
Tenderness over the piriformis near the sciatic notch

Diagnosis

Clinical: Tenderness at the piriformis and provocation tests that stretch or contract the muscle: FAIR (flexion, adduction, internal rotation), Freiberg, Pace and Beatty tests. No test is diagnostic alone.
Tests: Nerve conduction studies and EMG mainly exclude radiculopathy; an image-guided injection of local anesthetic into the muscle that relieves pain supports the diagnosis.
Imaging: Lumbar and pelvic MRI exclude disc herniation, stenosis, sacroiliac disease or masses; MR neurography can show the nerve and anatomical variants.

Differential diagnosis

Lumbar disc herniation with radiculopathy
Lumbar spinal stenosis
Sacroiliac joint pain
Greater trochanteric pain syndrome
Proximal hamstring tendinopathy
Pelvic mass or vascular lesion

Goal of treatment

Relieve pressure on the sciatic nerve and buttock pain, and restore normal sitting and activity, after other causes have been ruled out.

Treatment

Rehabilitation: Physiotherapy with piriformis stretching, hip strengthening and gait correction; this is the main treatment.
Medical: NSAIDs, muscle relaxants and neuropathic pain agents.
Procedure: Image-guided injection of local anesthetic with or without corticosteroid into the piriformis; botulinum toxin in refractory cases.
Surgical: Release of the piriformis tendon and freeing of the sciatic nerve in selected patients who fail other treatments.
Lifestyle: Avoiding long sitting on hard surfaces or with a wallet in the back pocket.

Complications

Chronic buttock and leg pain
Missed alternative diagnosis, such as radiculopathy or a mass
Nerve injury from injection or surgery

Prognosis

Most patients improve with physiotherapy and, when needed, injections. Surgery is uncommon.

Test yourself

Think of the answer, then tap the question to see it.

Which nerve is compressed in piriformis syndrome?

The sciatic nerve, as it leaves the pelvis below or through the piriformis.

Why is piriformis syndrome called a diagnosis of exclusion?

No test confirms it, so lumbar radiculopathy, stenosis, sacroiliac and hip causes must be ruled out first.

What does the FAIR test involve?

Hip Flexion, Adduction and Internal Rotation, which stretch the piriformis and reproduce buttock pain.

Which anatomical variant predisposes to piriformis syndrome?

The sciatic nerve, or one of its divisions, passing through or above the piriformis.

Which red flags point away from piriformis syndrome?

Saddle numbness, bladder or bowel problems, progressive weakness or systemic signs such as fever or weight loss.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Piriformis Syndrome (StatPearls (NCBI Bookshelf), 2023).

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Representative model, for educational purposes only.

Piriformis highlighted on the Durgical 3D model