Sciatica vs piriformis syndrome: how to tell the difference

Both lumbar radiculopathy (the clinical form of "sciatica") and piriformis syndrome produce pain, tingling, or numbness that runs from the buttock into the posterior thigh and leg. The symptoms can be clinically indistinguishable from self-report alone. Differentiation requires examination.

True lumbar radiculopathy involves compression or irritation of a lumbar nerve root, typically from a disc herniation, foraminal narrowing, or in rare cases tumour. The nerve root affected determines the distribution: L4 (inner knee and shin), L5 (outer shin and top of foot), S1 (outer foot and small toe).

Key features: pain that changes with lumbar spine movement (flexion or extension relieves or provokes it), positive straight leg raise (SLR) at a low angle, possible neurological signs (reflex change, weakness, dermatomal numbness).

Piriformis syndrome involves compression of the sciatic nerve by the piriformis muscle in the deep gluteal space. Key differentiating features: symptoms worsen with sustained sitting (compressing the piriformis region) but not with lumbar movement, positive hip external rotation provocation tests, normal or negative SLR, and lumbar imaging that does not explain the symptoms.

The FAIR test (hip flexion, adduction, internal rotation in supine) compresses the piriformis against the sciatic nerve and typically reproduces the symptoms.

The treatment for lumbar radiculopathy and piriformis syndrome are different. Neural mobilisation (nerve glides) for radiculopathy addresses the nerve's mobility in the lumbar canal. Deep gluteal soft tissue work and hip loading for piriformis syndrome addresses the compression at the hip.

Treating lumbar radiculopathy with piriformis release produces no benefit. Treating piriformis syndrome with lumbar treatment produces no benefit. The clinical assessment determines which is the correct target.