The piriformis muscles are one of several sets of muscles that rotate your hips outwards, helping to keep you stable and upright when moving around. There are two of these muscles, one running across from either side of the sacrum to the top of each thigh bone. Piriformis syndrome occurs when one of these muscles tightens and irritates the sciatic nerve.
Causes of Piriformis Syndrome
The piriformis muscles run over the sciatic nerve, and can easily put pressure on it if they become too tight or go into spasm from strain to overuse. This irritates the nerve, causing pain. In around 15 per cent of people, the sciatic nerve actually runs directly through the piriformis muscle: these people are particularly predisposed to piriformis syndrome.
Symptoms and Diagnosis of Piriformis Syndrome
You will feel a dull, annoying pain in your buttock that usually radiates down your leg, often accompanied by tingling or numbness. This tends to get worse when you sit down, particularly for any length of time, or climb stairs or a steep slope. You may also have difficulty walking. Some sufferers experience pain in the rectum when defecating. Your specialist is likely to be able to diagnose the condition from a description of your symptoms and a physical examination, but he may also arrange an MRI scan to rule out other possible causes of your pain.
Risks and Recovery for Piriformis Syndrome
With suitable physical therapy and exercises, most people make a full recovery within 4-8 weeks. Any activities involving strenuous, repeated forward movements of the legs, such as running, cycling, and rowing, can put particular strain on the piriformis muscles, so you should exercise caution when performing them. If your symptoms are very severe and persist after a range of methods have failed to bring you relief, you may be offered a piriformis block injection into the muscle.