According to the Journal of the American Osteopathic Association (JAOA), 6 per cent of patients complaining of lower back pain are actually suffering from piriformis syndrome. Piriformis syndrome is most common in middle age. Women are more susceptible to the syndrome than men. This is likely because the wider girth of the female pelvis puts more strain on the muscles and nerves in that region.
The piriformis muscle begins at the sacrum bone at the spine base. The muscle ends at the greater trochanter bone at the top of the femur. The piriformis muscle rotates the leg and hip away from the body.
The location of the sciatic nerve can vary between individuals. The nerve may pass under the piriformis muscle or travel straight through it. Either placement can result in the nerve's irritation due to muscle movement, swelling or inflammation.
The irritation of the sciatic nerve is typically called sciatica. But sciatica can be caused by sources other than the piriformis muscle. The condition caused by the muscle is therefore called piriformis syndrome.
The pudendal nerve has branches in the regions of the rectum, perineum and the clitoris or penis. The rear end of the nerve exits at the base of the piriformis muscle. This placement makes the pudendal nerve susceptible to any irritations the muscle may be causing the sciatic nerve.
The most common piriformis syndrome symptom is a radiating pain that begins in the gluteal region and passes down the rear of the leg. This pain makes it difficult to sit or lie down for long periods of time. Walking and standing from a seated or crouching position may also be hard to accomplish without pain. Gentle movement will help the pain momentarily but will not make it go away completely. If the pudendal nerve is irritated, bowel movements may be difficult.
According to JAOA, the FAIR test is a sensitive and specific test for piriformis syndrome. FAIR stands for flexion, adduction and internal rotation. The test is done with the patient on his back on an examination table. The doctor will apply pressure and rotate the leg in a way that it would aggravate any pirformis syndrome symptoms present.
Advanced neurophysiological tests such as electromyography can be used to determine that the pain is not being caused by a source other than the piriformis muscle. X-rays are of little use because they only show what the muscles and nerves look like but not how they are interacting.
JAOA states that 79 per cent of patients with piriformis syndrome see a reduction of symptoms with the adoption of non-steroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, cold therapy and adequate rest. Stretches targeting the piriformis muscle can build strength in the area and decrease the chances of another flare up. If these methods do not alleviate the pain, surgery on the muscle is the final option.