Pyriformis syndrome in a 10-year-old boy as a complication of operation with the patient in the sitting position.

We present a case of sciatic neuropathy due to the pyriformis syndrome after operation in the sitting position. Neither sciatic nerve injury nor the pyriformis syndrome has been reported after operation in the sitting position, although a low incidence of common peroneal nerve injury has been reported as a complication of operation on patients who are in the sitting position. The clinical findings of sciatic neuropathy, external rotation of the ipsilateral foot in the position of comfort, and a therapeutic response to local anesthetic injection into the pyriformis muscle are diagnostic of the syndrome. Nerve conduction studies should be performed to aid in the differentiation between a common peroneal and sciatic neuropathy. The syndrome may occur because of extreme flexion of the hips and prolonged pressure while in the sitting position, leading to pyriformis muscle trauma, resultant spasm, and sciatic compression. The prognosis is for complete recovery after symptomatic treatment with nonsteroidal antiinflammatory medication and physical therapy.