Piriformis Syndrome
A non-discogenic cause of sciatic-type buttock and leg pain attributed to compression or irritation of the sciatic nerve by the piriformis muscle.
Overview
Piriformis syndrome is a controversial but clinically useful label for deep gluteal pain with radiating symptoms arising from sciatic nerve irritation in the infrapiriformis space. Anatomical variants, including the sciatic nerve passing through or splitting the piriformis, hypertrophy, and trauma are implicated. It remains a diagnosis of exclusion after discogenic and other causes of sciatica are ruled out.
Epidemiology
Piriformis syndrome is estimated to account for 6 to 8 percent of presentations of low back and buttock pain, although the true incidence is uncertain. Women are more commonly affected, with peak presentation in the fourth and fifth decades.
Symptoms
Deep buttock pain radiating down the posterior thigh, exacerbated by prolonged sitting, climbing stairs, or crossing the affected leg. Tenderness is maximal over the piriformis belly, and provocative tests such as FAIR (flexion, adduction, internal rotation), Pace, and Freiberg signs reproduce symptoms. A normal neurological examination helps distinguish from radiculopathy.