Piriformis syndrome

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Piriformis syndrome is a pain syndrome involving low back or buttock pain that is referred to the leg. It is named after the piriformis muscle, a muscle that originates from the anterior or front side of the sacrum bone in the lower back or buttocks. The sciatic nerve passes under the piriformis muscle in the majority of people, even piercing or splitting the muscle in as many as ¼ of the population. Piriformis syndrome is controversial as it is an often under-diagnosed cause of sciatica type pain.

Why It Occurs

Piriformis syndrome is a cause of low back pain that can affect a wide variety of patients often dependent on the underlying cause. The overuse syndrome often seems to affect those athletes involved in sports requiring long periods of running. For this reason runners are often victims of piriformis pain syndrome.

The etiology of the pain caused by piriformis syndrome is still somewhat controversial. Most physicians believe the symptoms of piriformis syndrome can be grouped into two different categories; primary piriformis syndrome and secondary piriformis syndrome. Primary piriformis syndrome symptoms are attributed more to an anatomic cause such as a split sciatic nerve, a split piriformis muscle, or another uncharacteristic sciatic nerve path as it passes by the piriformis muscle and exits the pelvis. Secondary piriformis syndrome is caused by traumatic and ischemic events. Only about 15% of cases of piriformis syndrome are a result of a primary cause. The majority are due to macro-trauma to the buttocks causing inflammation and muscle spasm with resulting nerve compression. Micro-trauma causes are usually in the form of overuse injuries such as from walking or running.