[The piriformis syndrome]

Abstract

A rare mentioned and therefore and often overlooked cause of low back pain with sciatica. The piriformis muscle arises from the anterior surface of the sacrum and inserts on the superior border of the greater trochanter. Functionally, the piriformis muscle is an external rotator and abductor of the thigh. Muscle spasm or on inflammatory process set into motion by the spasm cause an epineurial irritation of the sciatic nerve. The symptoms present almost identically to lumbar disk syndrome, except for the consistent absence of true neurologic findings. Diagnosis is accomplished by rectal palpation of myofascial trigger points within the piriformis muscle, also pain and weakness on resistant abduction-external rotation of the thigh. The essential therapy is the injection of local anesthetic and a small dose of corticoid into the precise focal point of hyperirritability deep in the belly of the muscle. Recurrences are uncommon.