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Pain in the Piriformis? A New Test Can Tell

The next time something annoys you, don't think of it as a pain in the butt; think of it as a "pain in the piriformis." The piriformis is a muscle in the buttock that passes through the same opening in the pelvis bone as the sciatic nerve. When the piriformis is tight or contracted, it can put pressure on the sciatic nerve. This causes a painful condition called sciatica.

Piriformis syndrome is just one of the causes of sciatica. Piriformis syndrome has several symptoms. Besides pain in the buttock and down the leg, there may be difficulty walking. Stooping or squatting tends to bring on the pain. So does lifting the leg while lying flat on the back.

Doctors would like to find a test for sciatic nerve pain that's caused by piriformis syndrome. This would help direct treatment and suggest when surgery may be beneficial. The problem is that people with unbearable pain sometimes have imaging tests such as MRI (magnetic resonance imaging) that come back normal. Other people have MRI and other tests that suggest a piriformis problem, but no pain or symptoms.

A new test called the FAIR test may be just what the doctor ordered. FAIR stands for Flexion, Adduction, and Internal Rotation. These are all movements of the hip and leg. The test is done with the person lying on the painfree side at the edge of a bed or table. The hip and knee of the painful leg are on top and bent. The foot of the leg on top is hooked behind the knee of the leg on the bottom. The knee on top moves down toward the floor.

In this position, the piriformis muscle presses on the sciatic nerve and may slow the speed at which the nerve can send a signal. To do the test, electrodes are placed on the lower leg, and an electrical signal is sent to the sciatic nerve. How fast the nerve passes the signal to the muscle is measured by how long it takes for the muscle to signal pain or contract. The results are compared to those of people without sciatica.

A group of doctors used this test to check for piriformis syndrome. Patients with very slow reflexes on this test were treated for piriformis syndrome. More than 80 percent of patients with positive FAIR tests improved with physical therapy.

Piriformis syndrome as a cause of sciatic nerve pain has been so hard to test, doctors have wondered if such a problem actually exists. A new test is available to measure how much pressure the piriformis muscle places on the sciatic nerve. The test is a good predictor of whether physical therapy or surgery can change the effect of the piriformis on the sciatic nerve. Information from this test will help doctors decide how to treat patients with sciatica from piriformis symdrome.

Loren M. Fishman, MD, et al. Piriformis Syndrome: Diagnosis, Treatment, and Outcome--A 10-Year Study. In Archives of Physical Medicine and Rehabilitation. March 2002. Vol. 83. No. 3. Pp. 295-301.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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