Piriformis Syndrome
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Direct answer
Piriformis syndrome is sciatica-like pain from irritation or compression of the sciatic nerve by the piriformis muscle, felt deep in the buttock and often down the back of the thigh. It is a diagnosis of exclusion, made only after lumbar disc disease, sacroiliac pathology and hip disease have been ruled out. Physiotherapy, stretching and image-guided injection are the usual first steps, and surgical release is reserved for refractory cases.
What you must remember
- Anatomy: the sciatic nerve usually passes below the piriformis, but in some people it runs through the muscle, which predisposes to compression.
- Symptoms: deep buttock pain, often with radiation down the posterior thigh, worse on prolonged sitting and climbing stairs.
- Provocation: pain reproduced by hip flexion, adduction and internal rotation, which is the basis of the FAIR test.
- Freiberg sign: buttock pain on forced internal rotation of the extended hip.
- Diagnosis: clinical and of exclusion; MRI rules out lumbar disc, sacroiliac and hip causes, and nerve conduction studies are often normal.
- Typical patient: an active adult such as a runner or cyclist, sometimes after a fall onto the buttock or a period of unusual exertion.
- Management: stretching, physiotherapy, activity change and NSAIDs first, then image-guided injection, with surgical release for refractory disease.
A stepwise approach to buttock pain with sciatic features
Buttock pain with sciatic features is reached by elimination, because the piriformis is only one of several sources. The sequence below narrows the field before the muscle is blamed.
- Examine the spine first: a neurological examination with dermatomal sensation, reflexes and power, supported by MRI when needed, decides whether a lumbar disc is responsible.
- Exclude the sacroiliac joint: sacroiliac pain can mimic piriformis pain, so the joint is examined on its own with provocation tests.
- Exclude the hip: range of movement and imaging look for intra-articular pathology such as femoroacetabular impingement or osteoarthritis.
- Apply the FAIR test: flexion, adduction and internal rotation of the hip reproduce deep buttock pain in piriformis syndrome.
- Perform the Freiberg sign: pain on forced internal rotation of the extended hip supports piriformis involvement.
- Treat in stages: physiotherapy with stretching, activity modification and NSAIDs come first, followed by image-guided injection if symptoms persist.
- Operate rarely: surgical release of the piriformis is considered only when conservative care and injection both fail.
Where the exam tries to catch you
Piriformis questions usually test whether the student excludes the spine before blaming the muscle.
- Trap: diagnosing piriformis syndrome from buttock pain without a neurological examination Correct: a lumbar disc must be excluded first, because disc prolapse commonly causes sciatica with objective neurological signs.
- Trap: expecting nerve conduction studies to confirm piriformis syndrome Correct: these studies are often normal, so the diagnosis stays clinical and of exclusion.
- Trap: confusing the FAIR test with the Freiberg sign Correct: the FAIR test combines flexion, adduction and internal rotation with the hip flexed, whereas the Freiberg sign uses forced internal rotation of the extended hip.
Frequently asked questions
Which test reproduces pain in piriformis syndrome?
The FAIR test, which combines flexion, adduction and internal rotation of the hip, reproduces deep buttock pain in piriformis syndrome. A positive test supports the diagnosis but does not by itself exclude a lumbar disc or sacroiliac cause.
What is the Freiberg sign in piriformis syndrome?
The Freiberg sign is buttock pain on forced internal rotation of the extended hip. It is one of the classic clinical signs of piriformis involvement that exam stems quote.
Why is piriformis syndrome a diagnosis of exclusion?
Piriformis syndrome mimics lumbar disc prolapse, sacroiliac joint pain and hip pathology, so these conditions must be excluded first. Only after they are set aside does piriformis irritation become the working diagnosis.
How is piriformis syndrome treated initially?
Stretching, physiotherapy, activity modification and NSAIDs are the usual first steps in piriformis syndrome. Image-guided injection follows when symptoms persist, and surgical release is reserved for refractory cases.