Piriformis syndrome
Compression of the sciatic nerve

Piriformis syndrome is characterized by pain in the buttock area. The symptoms occur when the deeper buttock muscle irritates a nerve that runs from the back to the leg. This may also result in symptoms that radiate into the leg.

The diagnosis is difficult to make. The symptoms are often confused with other conditions.

Description of condition

The sciatic nerve (also called the ischiadic nerve) is the large hip nerve that runs from the buttock into the leg. Before the nerve enters the leg it must first move past a deeper buttock muscle: the piriformis. The nerve may become compressed or irritated here. It is thought that this is caused by a shortened piriformis, swelling or increased muscle tension.

Cause and history

The symptoms occur after an accident or fall on the buttock, or may be the result of an anatomical abnormality. This is because the sciatic nerve does not run past the piriformis in the same way for everyone. The nerve may run under the muscle (in 85 % of cases) or partially through the muscle (in 15 % of cases) or partially over the muscle (in 0.5 % of cases).

Signs & symptoms

• Pain in the buttock area.
  
• Sitting makes the symptoms worse.
  
• There is deep pressure pain in the middle of the buttock.
  
• The symptoms may increase during cycling or running.
  
• Sometimes the pain radiates along the nerve into the leg.
  
• The (passive) inward rotation of the hip can be painful.
  
• Flexing the hip with the knee extended may provoke symptoms (SLR test).
  
• This is not normally associated with back pain.

Diagnosis

It is often difficult to make this diagnosis. Therefore, there is still a lack of clarity and much discussion. The symptoms can also often be mistaken for other conditions.

There are few, if any, good additional examinations that can confirm the diagnosis. Therefore, it is often referred to as a clinical diagnosis. This implies that a physician or physiotherapist makes the diagnosis, without additional examinations. Through the patient's story and various physical tests, a clinical diagnosis can be made.

Direct pressure on the opening through which the nerve runs is painful. There are also a number of physical tests that can induce the symptoms. If some of these tests are positive and there is pressure pain at the opening then the diagnosis is made.

An MRI scan, nerve examination (EMG) or ultrasound examination often shows no problems with the nerve or piriformis. Hence, additional scans are usually not useful.

Treatment

Physiotherapy can decrease the muscle tension (tonicity) of the piriformis. Mobilization techniques are used to increase the free space for the sciatic nerve. In addition, exercise therapy is used.

Other forms of treatment include medication, an injection or - in rare cases - a surgical procedure.

Exercises

There are several exercises you can do for piriformis syndrome. Look here for the exercise program with exercises for the piriformis syndrome.

You can check your symptoms using the online physiotherapy check or make an appointment with a physiotherapy practice in your locality.

References
Hopayian, K., Song, F., Riera, R. & Sambandan, S. (2010). The clinical features of the piriformis syndrome: A systematic review. Eur Spine J. 2010 Dec;19(12):2095-109.
Schünke, M., Schulte, E. & Schumacher, U. (2005). Prometheus. Algemene anatomie en bewegingsapparaat. Houten: Bohn Stafleu Van Loghum.