Piriformis Syndrome

Abstract

Piriformis syndrome is an entrapment neuropathy that presents as pain, numbness, paresthesias, and weakness in the distribution of the sciatic nerve. It is caused by compression of the sciatic nerve by the piriformis muscle as it passes through the sciatic notch. The piriformis muscle’s primary function is to rotate the femur externally at the hip joint; this muscle is innervated by the sacral plexus. With internal rotation of the femur, the tendinous insertion and belly of the muscle can compress the sciatic nerve; if this compression persists, it can cause entrapment of the nerve.

The symptoms of piriformis syndrome usually begin after direct trauma to the sacroiliac and gluteal region. Occasionally, the syndrome is the result of repetitive hip and lower extremity motions or repeated pressure on the piriformis muscle and underlying sciatic nerve. Abscess, tumor, or hematoma in this region can mimic the clinical presentation of piriformis syndrome.

Keywords

piriformis syndrome, hip pain, lumbar radiculopathy, sciatica, piriformis muscle, straight leg raising test, entrapment neuropathy, ultrasoind guided injection, diagnostic sonography, pirformis syndrome provocation test

ICD-10 CODEG57.00

Keywords

piriformis syndrome, hip pain, lumbar radiculopathy, sciatica, piriformis muscle, straight leg raising test, entrapment neuropathy, ultrasoind guided injection, diagnostic sonography, pirformis syndrome provocation test

ICD-10 CODEG57.00

The Clinical Syndrome

Piriformis syndrome is an entrapment neuropathy that presents as pain, numbness, paresthesias, and weakness in the distribution of the sciatic nerve. It is caused by compression of the sciatic nerve by the piriformis muscle as it passes through the sciatic notch ( Fig. 90.1 ). The piriformis muscle’s primary function is to rotate the femur externally at the hip joint; this muscle is innervated by the sacral plexus. With internal rotation of the femur, the tendinous insertion and belly of the muscle can compress the sciatic nerve; if this compression persists, it can cause entrapment of the nerve.

The symptoms of piriformis syndrome usually begin after direct trauma to the sacroiliac and gluteal region. Occasionally, the syndrome is the result of repetitive hip and lower extremity motions or repeated pressure on the piriformis muscle and underlying sciatic nerve. Abscess, tumor, or hematoma in this region can mimic the clinical presentation of piriformis syndrome ( Fig. 90.2 ).

Signs and Symptoms

Initial symptoms include severe pain in the buttocks that may radiate into the lower extremity and foot. Patients suffering from piriformis syndrome may develop an altered gait, leading to coexistent sacroiliac, back, and hip pain that confuses the clinical picture. Physical findings include tenderness over the sciatic notch. Palpation of the piriformis muscle reveals tenderness and a swollen, indurated muscle belly. A positive Tinel’s sign over the sciatic nerve as it passes beneath the piriformis muscle is often present. A positive straight leg raising test result suggests sciatic nerve entrapment. The piriformis muscle provocation test can help identify the piriformis muscle as the possible cause of sciatic nerve entrapment ( Fig. 90.3 ).