Syndrome, piriformis: Irritation of the sciatic nerve caused by compression of the nerve within the buttock by the piriformis muscle. Typically, the pain of the piriformis syndrome is increased by contraction of the piriformis muscle, prolonged sitting, or direct pressure applied to the muscle. Buttock pain is common. The piriformis syndrome is one of the causes of sciatica.
The piriformis muscle begins at the front surface of the sacrum (the V-shaped bone between the buttocks at the base of the spine) and passes through the greater sciatic notch to attach to the top of the thigh bone (femur) at its bony prominence called the greater trochanter. The gluteus maximus muscle covers over the piriformis muscle in the buttocks.
The doctor can often detect tenderness of the piriformis muscle during a rectal examination.
The piriformis syndrome is treated with rest and measures to reduce inflammation of the piriformis muscle and its tendon. Treatments include piriformis stretching exercises, physical therapy, anti-inflammatory medications, and pain medications. With persistent symptoms, further treatment can include local injection of anesthetic and cortisone medication.
Rarely, for severe cases, surgery is performed to relieve the pressure irritating the sciatic nerve. During surgical operations, the piriformis muscle is either thinned, elongated, divided, or removed.