Family doctor

What is Polymyalgia Rheumatica (PMR)?

PMR is a syndrome that causes severe pain and stiffness in the muscles of the neck, shoulders and buttock area. The condition usually affects older people and is seen in approximately 2 percent of people over the age of 50, commonly females and those of northern European descent.

The exact cause of PMR is unknown but sufferers may have a genetic predisposition. Specific genes have been associated with the condition. Research is suggesting that an abnormality in the immune system may lead to the body's defences harming its own cells by mistake.

Diagnosing PMR

The diagnosis of PMR is based on:

1) Clinical features - these include pain and stiffness in the neck, shoulders, and pelvic area, and systemic symptoms such as fatigue, weight loss, and fever. The patient may have difficulty getting out of bed in the morning. Activities such as brushing hair and doing up bra straps may become much more difficult. The stiffness eases during the day. Symptoms usually occur on both sides of the body (bilaterally). Despite the pain and stiffness, muscle strength is not usually altered.

2) Blood tests - the ESR (erythrocyte sedimentation rate) is usually very raised and is the most useful test. Patients may also have an anaemia, and a raised liver enzyme called alkaline phosphatase.

Because the symptoms of PMR mimic many other illnesses, these "differential diagnoses" must be excluded before making a diagnoses of PMR. These include an under-active thyroid gland, arthritis, muscle diseases, infections and some cancers. Investigations include blood tests and a chest x-ray.

Associated condition

Giant Cell Arteritis (GCA) 15-20% of patients with PMR also have GCA. GCA results in inflamed thickened arteries (blood vessels). This can result in tenderness over some arteries, commonly on the face and in the temple area. The artery may become partially blocked causing pain such as headache. Complete blockage of the artery may cause a lack of blood supply resulting in very serious conditions such as blindness, stroke or heart attack. Patients with symptoms suggestive of GCA need a biopsy of their temporal artery. The biopsy reveals a narrow artery in 60-80% of patients.

GCA is treated with higher doses of steroids.

Treatment of PMR

PMR fortunately responds dramatically to medications called corticosteroids. They are usually given orally in the form of prednisone 10-20 mg. daily. The dose is gradually reduced each month and is increased if the symptoms return. Most patients require treatment for 2 to 4 years. Relapses are more likely in the first 18 months of treatment.

Treatment should be monitored with symptoms and regular blood tests and prednisone should always be reduced slowly under close medical supervision.

Patients are at risk of the side effects of steroids such as osteoporosis. Medicines such as vitamin D and bisphosphonates are often given to preserve bone.

References

BMJ 1995;310;1057-1059BMJ 1997;314;1329