What Is Piriformis Syndrome?
The piriformis muscle, a flat, band-like structure located near the top of the hip joint in the buttocks, is involved in significant lower body movement, and used extensively in sports such as running and biking. It overlies the sciatic nerve, the long main nerve that extends down the back of the leg. The sciatic nerve branches out into smaller nerve endings in the feet. The sciatic nerve innervates the hamstring muscles and all of the muscles below the knee. It also provides feeling to the feet. Nerve compression can occur from spasm of the piriformis muscle or from an odd anatomic structure of the muscle. Piriformis syndrome is characterized by pain, tingling, numbness and weakness of the leg and foot. Approximately 6% of lower back pain and sciatica cases seen in a general practice may be caused by piriformis syndrome.2
Piriformis Syndrome Signs and Symptoms
Piriformis syndrome is characterized by pain, tingling or numbness in the buttocks. The term “sciatica” is used when the pain extends down the sciatic nerve. The cause of this pain is due to the piriformis muscle compressing the sciatic nerve, and is exacerbated by sitting or in the case of sports, such as running. Pain may also be present during other activity (climbing stairs), long periods of time sitting, or present on applying direct pressure to the piriformis muscle. Most cases of sciatica, however, are not due to piriformis syndrome,1 but rather, from disc disease of the back. This is what makes the diagnosis so tricky.
This syndrome was first identified in 1928, and used to explain sciatica before lumbar disc herniation was introduced in 1934. Today, the term piriformis syndrome is commonly used to explain all cases of sciatica that are not of disc origin.
Piriformis Syndrome Diagnosis
Diagnosis of piriformis syndrome is traditionally difficult, because symptoms can be similar in other conditions, such as a herniated disc. There is no definitive test for piriformis syndrome. Often, the syndrome is due to trauma to the area, or repetitive, intense activity such as long-distance running, or prolonged sitting. In some cases, a contracted piriformis muscle can be found on a physical exam. However, an MRI can be a valuable noninvasive diagnostic test, typically revealing an enlarged piriformis muscle2 Many doctors never consider piriformis syndrome as a possible diagnosis, and many who are aware of it are uncertain how to properly diagnose and treat it.2
Piriformis Syndrome Treatment
Suggested treatment for piriformis syndrome usually entails avoiding certain activities that trigger pain, and ice or heat to relieve symptoms. An exercise program, including stretching, may be prescribed, and some recommend anti-inflammatory medication or other muscle relaxers. Some success has also been reported with Botox injections.
For patients with symptoms resistant to these conservative treatments, surgical release of the piriformis muscle is often recommended and has been reported to be effective in relieving the symptoms.2 Surgical decompression through a limited muscle-splitting approach has been used with good or excellent results in 80% of patients.1
When non-operative treatment has been exhausted, patients may qualify for operative intervention, which involves decompression of the sciatic nerve in the buttocks. This can often be performed as a day procedure (without overnight stay) and with the aid of an endoscope. In the right population, it can be extremely effective in mitigating piriformis syndrome.
The above procedure is performed by very few surgeons in the country, however it is done at The Institute for Advanced Reconstruction.
Outcomes for Peripheral Nerve Entrapment Syndromes, Robert J. Spinner, M.D., Clinical Neurosurgery, Vol. 53, 2006