This is an uncommon disorder in which the piriformis muscle in the buttocks irritates the sciatic nerve. The piriformis muscle is a narrow muscle located in the buttocks.

Symptoms of this disorder include pain, tingling, and numbness in the buttocks and down the leg. Symptoms may get worse after sitting for prolonged periods, or after activity which uses your buttock muscles. Stretching exercises, massage, and anti-inflammatory drugs can be effective treatments for less severe cases.
It most commonly affects older adults.