Piriformis Syndrome is a painful condition that affects the buttock, but it can also mimic hip pain. This condition is due to irritation of the branches of the sciatic nerve because of abnormalities of the piriformis muscle. The piriformis muscle is injured by trauma, or irritated from prolonged sitting. Piriformis syndrome affects women more than men, mainly because of differences in the female anatomy. The syndrome is sometimes confused with pudendal neuralgia.
Anatomy
The piriformis muscle attaches to the pelvis at the sacrum and at its other end to the upper end of the femur bone. This muscle allows for external rotation, abduction and extension of the hip.
The sciatic nerve usually leaves the pelvis beneath the piriformis muscle, but variations exist, some of which increases the risk of pressure and trauma on the nerve.
How do you know if you have piriformis syndrome?
Common symptoms include lower back pain, buttock pain, numbness, difficulty with ambulation and difficulty with activities such as standing, sitting, squatting, passing motion. Women may find it difficult intercourse painful.
The buttock pain can shoot into the hip area, or down the posterior thigh and the lower leg. Some patients may experience leg swelling and difficulty with sex. Sometimes an affected person may walk with a limp with the foot externally rotated.
What types of piriformis syndrome are there?
In what is known as ‘primary piriformis syndrome’ (15% of patients), there is an anatomical cause such as a split piriformis muscle or split sciatic nerve, or an abnormal passage of the sciatic nerve.
In ‘secondary piriformis syndrome’,
- 50% are caused by trauma to the buttocks which leads to inflammation and muscle spasm. This then results in nerve compression. This trauma can be due to accidents, surgery, over-exercise and abnormal lumbar or sacroiliac joints.
- Piriformis syndrome may also be caused by changes in the biomechanics of the lower limb, lower back and pelvis that can lead to shortening of the piriformis muscle. The shortened muscle then compresses and irritates the sciatic nerve.
- Overuse of the piriformis muscle in long-distance walking, running or by prolonged sitting can lead to ‘microtrauma’ of the muscle which then compresses the sciatic nerve.
Do I need a scan or X-ray?
A CT scan or MRI will be useful to exclude that the pain is not originating from the spine or the hip joint. Sometimes a nerve study called ‘electromyography’ may be useful to exclude a herniated disc that may produce similar symptoms.
How do you treat piriformis syndrome?
Conservative treatment with medications such as non-steroidal anti-inflammatory drugs can be tried first. Other medications include muscle relaxants and drugs that treat pain from the nerve. This can be tried along with physiotherapy and changes to lifestyle. In some people, psychotherapy may be required especially if the condition has been longstanding.
If conservative measures fail, injections of medications such as local anaesthetics, steroids, and botox into the affected piriformis muscle can be very effective. This is commonly done under ultrasound guidance. We recommend trying conservative treatment for a maximum of 1-2 months before proceeding with injections because of the increased risk of the condition becoming chronic and harder to treat if left for too long.
If simple injections fail to relieve the pain from piriformis syndrome, pulse radiofrequency to the affected nerve can be tried before open surgery. Abscesses and haematomas may need to be drained if it is the cause. Incisions of the piriformis muscle may be required to reduce the tension and pressure on the sciatic nerve. The obturator internus muscle must be considered as a cause of buttock pain if targeted treatments to the piriformis fails to work.