Piriformis syndrome

Piriformis syndrome is a condition which is believed to result from nerve compression at the sciatic nerve by the piriformis muscle. It is a specific case of deep gluteal syndrome.

The largest and most bulky nerve in the human body is the sciatic nerve. Starting at its origin it is 2 cm wide and 0.5 cm thick. The sciatic nerve forms the roots of L4-S3 segments of the lumbosacral plexus. The nerve will pass inferiorly to the piriformis muscle, in the direction of the lower limb where it divides into common tibial and fibular nerves. Symptoms may include pain and numbness in the buttocks and down the leg. Often symptoms are worsened with sitting or running.

Causes may include trauma to the gluteal muscle, spasms of the piriformis muscle, anatomical variation, or an overuse injury. Few cases in athletics, however, have been described. Diagnosis is difficult as there is no definitive test. A number of physical exam maneuvers can be supportive. Medical imaging is typically normal. Other conditions that may present similarly include a herniated disc.

Treatment may include avoiding activities that cause symptoms, stretching, physiotherapy, and medication such as NSAIDs. Steroid or botulinum toxin injections may be used in those who do not improve. Surgery is not typically recommended. The frequency of the condition is unknown, with different groups arguing it is more or less common.