Piriformis syndrome is a rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve-the largest nerve in the body. The piriformis muscle is a narrow muscle located in the buttocks.

Compression of the sciatic nerve causes pain-frequently described as tingling or numbness-in the buttocks and along the nerve, often down to the leg. The pain may worsen as a result of sitting for a long period of time, climbing stairs, walking, or running.

Piriformis syndrome is also known as “wallet sciatica” or “fat wallet syndrome,” as the condition can be caused or aggravated by sitting with a large wallet in the affected side’s rear pocket.

The syndrome may be due to anatomical variations in the muscle-nerve relationship, or from overuse or strain.

The prognosis for most individuals with piriformis syndrome is good. Once symptoms of the disorder are addressed, individuals can usually resume their normal activities. In some cases, exercise regimens may need to be modified in order to reduce the likelihood of recurrence or worsening.

Generally, treatment for the disorder begins with stretching exercises and massage. Anti-inflammatory drugs may be prescribed. Cessation of running, bicycling, or similar activities may be advised. A corticosteroid injection near where the piriformis muscle and the sciatic nerve meet may provide temporary relief. In some cases, surgery is recommended.