Polymyalgia rheumatica

Polymyalgia rheumatica is a disorder in which certain muscle groups become inflamed causing pain and stiffness. It is thought to affect one in 2,000 New Zealanders over 50 years old.

Although polymyalgia rheumatica is a long-term disease, it usually responds well to treatment and, unlike some other forms of rheumatism (diseases marked by inflammation and pain in the joints, muscles, or fibrous tissue) it does not cause any progressive disability or deformity.

Causes and risk factors

Polymyalgia rheumatica (PMR) is a complex condition the cause of which is unknown. It is possible that the way the immune system responds to certain viruses may trigger the disease. Developing PMR probably involves the interaction of a combination of genetic and environmental factors.

PMR almost exclusively occurs after the age of 50 years, with the average age of onset being 70 years. Women are two to three times more likely to develop the condition than men. PMR is more common in people of European ancestry, although it can occur in all ethnic groups.

PMR is sometimes associated with another condition called giant cell arteritis (also known as temporal arteritis). In this condition, arteries in the temples either side of the forehead and in other parts of the body become inflamed. If the arteries to the eyes are affected, this condition can lead to blindness. Approximately 15 per cent of people with PMR also have signs of giant cell arteritis and as many as 50 per cent of people with giant cell arteritis also have PMR. It is possible that PMR and giant cell arteritis are variations of the same disease.

Signs and symptoms

The most common symptoms of PMR are severe pain and stiffness in the muscles of the shoulders, neck, lower back, buttocks, and thighs. The muscles of the upper arms may also be affected but it is unusual for the muscles in the forearms, hands, legs, and feet to be affected.

The pain and stiffness are caused by mild inflammation in the joints and surrounding tissues. Other symptoms of PMR may include:

• Headache
• Fever and/or night sweats
• Fatigue and loss of energy
• Loss of appetite
• Depression
• Weight loss
• Mild anaemia.

In some cases, the onset of PMR can be sudden and dramatic, with severe symptoms literally appearing overnight. In other cases, the condition appears gradually over a period of several weeks. Symptoms are often worse in the morning, when they may be disabling, but tend to ease off by the afternoon. Symptoms are often more noticeable after a period of inactivity.

Pain in the jaw when chewing food and sudden loss of vision for 10 seconds (amaurosis) are important possible signs of giant cell arteritis, which is a more severe form of PMR and may indicate that urgent therapy with higher dose corticosteroids is required. Medical attention should be sought promptly in these situations.

Diagnosis

When the onset of the condition is sudden and dramatic, a diagnosis of PMR may be relatively easy to make. However, when symptoms develop gradually it may be less obvious that PMR is the cause.

The symptoms of PMR can be similar to those of certain other medical conditions including rheumatoid arthritis, osteoarthritis, polymyositis, and fibromyalgia. For this reason, it is important to rule out other possible causes for the symptoms before a diagnosis of PMR can be made.

There is no single test that will confirm whether a person has PMR. However, there are several blood tests that can help with the diagnosis by indicating the presence of inflammation or anaemia in the body.

To rule out rheumatoid arthritis, a substance in the blood called rheumatoid factor (RF) may be checked. RF will be elevated in people with rheumatoid arthritis; however, it is normal in people with PMR.

Treatment

The main aim of treatment is to control pain and improve muscle stiffness. PMR is usually treated with a corticosteroid medication (e.g., prednisone). High doses are given initially and then gradually decreased (or tapered) to the lowest possible dose at which symptoms are controlled. There is usually a quick response to corticosteroid treatment and symptoms tend to be dramatically decreased within a few days of starting the medication.

Corticosteroid doses will be tailored to the individual according to how well the symptoms are being controlled. Doses may need to be increased when the body is under stress, such as after surgery, injury, or during another illness.

Most people can stop taking corticosteroid medication within two years, though some people may need to take low doses for several years. When a person is free of symptoms and has not needed to take medication for a few months the disease is considered to be in remission.

Relapses (which is when symptoms return) may occur once corticosteroid treatment is stopped but symptoms will usually respond quickly if treatment is re-started. Many people will relapse during the tapering of the corticosteroids to find the lowest possible dose. These relapses are treated by increasing the drug dose for a while then gradually reducing the dose again.

While corticosteroids are effective in treating PMR, long-term use of the medication can produce side effects. These include:

• Increased susceptibility to infections
• Increased appetite or weight gain
• Thinning of the bones (osteoporosis), especially in women
• Puffiness of the face
• Thinning and easy bruising of the skin
• High blood pressure
• Diabetes
• Clouding of the lenses in the eyes (cataracts).

The need to manage the symptoms of the PMR needs to be balanced with the potential for side effects. It is important to never abruptly stop taking corticosteroid medication. The dose needs to be gradually reduced until at a level where the corticosteroid can be safely stopped.

Regular monitoring for side effects is required during corticosteroid treatment and dose reduction. Other treatments may be prescribed to manage reactions to corticosteroid medication (e.g., drugs that prevent bone thinning).

Methotrexate, which is a drug that suppresses the activity of the immune system, may be given with corticosteroids in some patients, usually people whose symptoms flare up or who do not respond adequately to corticosteroids. It may also be used to reduce the dosage of corticosteroid to minimise corticosteroid-related side effects.

Other factors that are important in managing PMR include:

Physical therapy or exercising regularly – particularly low-impact exercise and stretching

Eating a healthy, balanced diet.

Other medications that may be used to treat the condition include non-steroidal anti-inflammatory medications (NSAIDs). NSAIDs help to reduce inflammation and lessen pain but are not as effective as corticosteroids in providing symptom relief. Some people find alternative therapies such as acupuncture and massage are helpful in treating the symptoms of PMR.

Further support

Arthritis New Zealand provides support and education to people with PMR.

Freephone: 0800 663 463

Email: [email protected]

Website: www.arthritis.org.nz

References

Arthritis New Zealand (2015). Polymyalgia rheumatica (Pamphlet). Wellington: Arthritis Foundation of New Zealand. https://www.arthritis.org.nz/wp-content/uploads/2018/10/Polymyalgia-rheumatica.pdf

Mayo Clinic (2022). Polymyalgia rheumatica (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/polymyalgia-rheumatica/diagnosis-treatment/drc-20376545 [Accessed: 04/11/22]

Nesher, G., Breuer, G.S. (2016). Giant cell arteritis and polymyalgia rheumatica: 2016 Update. Rambam Maimonides Med J. 2016;7(4).

O’Toole, M.T. (Ed.) (2017). Polymyalgia rheumatica. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.

Saad, E.R. (2022). Polymyalgia rheumatic (Web page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. https://emedicine.medscape.com/article/330815-overview [Accessed: 04/11/22].

Last reviewed: November 2022