Piriformis syndrome occurs when the piriformis muscle spasms and irritates or compresses the sciatic nerve. It often causes symptoms similar to sciatica, though it is not caused by a spinal problem like sciatica is.
The piriformis is a small muscle located deep in the buttock, behind the gluteus maximus. It runs diagonally from the lower spine to the upper surface of the femur, with the sciatic nerve running underneath or through the muscle. The piriformis muscle helps the hip rotate, turning the leg and foot outward.
As a result of overuse, injury, or strain, the piriformis muscle can tighten, swell, or spasm. Sports that involve repetitive forward movement of the legs, or problems in surrounding joints like the sacroiliac joints are typical causes of piriformis syndrome.
The location of the piriformis muscle near the sciatic nerve means that when the piriformis muscle is irritated or injured, it can affect the sciatic nerve as well.
Symptoms of piriformis syndrome include tenderness and pain in the buttock area, accompanied by sciatica-like pain, numbness, and weakness that runs down the back of the thigh, calf, and foot. Pain from piriformis syndrome is often worse when walking up stairs, after sitting, or while walking or running.
Piriformis syndrome is often confused with other conditions, especially lumbar spine conditions. Attaining a proper diagnosis of piriformis syndrome is important when considering treatment for low back and leg pain.