Piriformis syndrome (PS) is a neuromuscular condition where the piriformis muscle – one of the deep gluteal muscles – presses on and compresses the sciatic nerve causing pain, tingling and numbness in the buttock area, and down the path of sciatic nerve to the thigh and leg. Sciatic nerve runs under the piriformis muscle (Fig. 1) and may be irritated when the muscle is too tight or shortened due to spasms. Piriformis syndrome is to be differentiated from sciatica which shows similar symptoms but has different causes.

Fig. 1 : Piriformis syndrome. Posterior view of the pelvis showing location of piriformis muscle and sciatic nerve. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.

 

 

 

 

Diagnosis is difficult as it produces similar symptoms as sciatica and is commonly done by exclusion of sciatica caused by compression of sciatic nerve roots by a herniated disc.

Fig. 2 : Sciatica caused by compression of spinal nerve roots by a herniated disc. Lateral view of the lumbar spine. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.  

 

 

 

 

Causes and Risk factors

–  Anatomical abnormality of the nerve/muscle relation. Some people are more likely to get PS than others.

– Tightness or spasm of piriformis muscle due to overuse injury. This commonly happens in sport activities that put pressure on the piriformis muscle such as bicycling, running without proper stretching, or any activity that involves repeated movements of the leg performed in sitting position.

Treatment

– Conservative treatment includes stretching exercises, massage, avoidance of causative activities.

– Physical therapy that strengthens the gluteus maximus, gluteus medius, and biceps femoris is usually recommended to reduce strain on the piriformis muscle.

– Relief of symptoms may be achieved with anti-inflammatory drugs or muscle relaxants.