141 - Piriformis Block

Abstract

Piriformis syndrome is caused by compression of the sciatic nerve by the piriformis muscle as the nerve passes through the sciatic notch. This entrapment neuropathy manifests as pain, numbness, paresthesias, and associated weakness in the distribution of the sciatic nerve. These symptoms often begin as severe pain in the buttocks that radiates into the lower extremity and foot. Patients who have piriformis syndrome may develop altered gait, which in turn may result in the development of coexistent sacroiliac, back, and hip pain, which further confuses the clinical picture. If the condition is not treated, progressive motor deficit of the gluteal muscles and lower extremity can result. The symptoms of piriformis syndrome usually begin after direct trauma to the sacroiliac and gluteal region and occasionally as a result of repetitive hip and lower extremity motions or repeated pressure on the piriformis muscle and underlying sciatic nerve. Rarely, occult tumors in this anatomic area can also compress the sciatic nerve as it passes through the sciatic notch and produce symptoms identical to those of piriformis syndrome. Piriformis muscle anomalies or sciatic nerve abnormalities can also result in compression of the sciatic nerve, as can acute injury to the nerve as it passes through, over, or under the piriformis muscle. Pathologic elements adjacent but unrelated to the piriformis muscle can also cause symptoms that mimic piriformis syndrome.