Piriformis syndrome is an irriation of the sciatic nerve as it passes next to or through the piriformis muscle. The piriformis muscle is a flat, pyramid-shape structure. It starts along the anterior (front) part of the sacrum and inserts or attaches on the greater trochanter of the femur. That’s a bony bump at the top of the upper thigh bone.
The muscle is close enough to the sciatic nerve that the muscle can put pressure on the nerve when it contracts or if the muscle builds up muscle bulk from repetitive overuse. In about 10 per cent of all cases, the sciatic nerve actually runs through the piriformis muscle. Anytime the muscle contracts, the nerve gets squeezed.
Symptoms include aching, burning, or sharp pain in the area controlled by the sciatic nerve. The pain starts in the mid-buttocks on one side and can shoot down the upper leg. Symptoms may go down as far as the knee but only occasionally go past the knee.
Besides repetitive overuse of the muscle, other potential causes include myofascial trigger points, anatomic variations, postural factors, and a difference in leg length. The risk of developing piriformis syndrome increases any time someone stands on one leg more than the other, sits on one foot, sits crossed-leg, or stands habitually with the hip turned out (external rotation. Walking with the leg too close to the other leg and with internal rotation of the leg can also increase the strain on this muscle resulting in piriformis syndrome.
The main symptom of piriformis syndrome (sciatica) can also be caused by tumors, lumbosacral strain, lumbar disc herniation, and spinal stenosis (narrowing of the spinal canal around the spinal cord). So the diagnosis of piriformis syndrome must rule out the possibility of any of these as the real cause of your buttock pain. If you have already been evaluated and told that you have piriformis syndrome, then it’s likely these other possible causes of the buttock pain have been set aside.