Piriformis syndrome is a neuromuscular disorder that is caused when the piriformis muscle compresses the sciatic nerve. The piriformis muscle is a flat, band-like muscle located in the buttocks near the top of the hip joint. This muscle is important in lower body movement because it stabilizes the hip joint and lifts and rotates the thigh away from the body. This enables us to walk, shift our weight from one foot to another, and maintain balance. It is also used in sports that involve lifting and rotating the thighs — in short, in almost every motion of the hips and legs.

The sciatic nerve is a thick and long nerve in the body. It passes alongside or goes through the piriformis muscle, goes down the back of the leg, and eventually branches off into smaller nerves that end in the feet. Nerve compression can be caused by spasm of the piriformis muscle.

Piriformis syndrome usually starts with pain, tingling, or numbness in the buttocks. Pain can be severe and extend down the length of the sciatic nerve (called sciatica). The pain is due to the piriformis muscle compressing the sciatic nerve, such as while sitting on a car seat or running. Pain may also be triggered while climbing stairs, applying firm pressure directly over the piriformis muscle, or sitting for long periods of time. Most cases of sciatica, however, are not due to piriformis syndrome.

If pain is caused by sitting or certain activities, try to avoid positions that trigger pain. Rest, ice, and heat may help relieve symptoms.

Since piriformis syndrome is usually caused by sports or movement that repeatedly stresses the piriformis muscle, such as running or lunging, prevention is often related to good form. Avoid running or exercising on hills or uneven surfaces. Warm up properly before activity and increase intensity gradually. Use good posture while running, walking, or exercising. If pain occurs, stop the activity and rest until pain subsides.