It has been suggested that polymyalgia rheumatica (PMR) and temporal arteritis are clinical syndromes that form part of the spectrum of giant cell arteritis (GCA), so are different manifestations of the same disease process. Although GCA, including temporal arteritis, is linked with PMR, both conditions can occur in isolation.
PMR and GCA are unlikely to occur in people aged under 50 years. The incidence varies between 10–50 cases per 100,000, and there is a peak incidence between 60 and 75 years of age.
These conditions are almost always confined to white populations, with a higher incidence in Scandinavia and northern Europe. The number of people at risk is expected to double in the next 25 years as the average age of the population increases.
PMR, an inflammatory disease, usually presents with proximal girdle stiffness ('girdle' refers to muscles that encircle the neck, shoulders or pelvis) and pain that is usually sudden in onset and quickly becomes bilateral. However, muscle strength is usually not reduced.
For a diagnosis of GCA to be made, the American College of Rheumatology criteria, issued in 1990, suggest the presence of three or more of the following:
- Age 50 years or older.
- New-onset localised temporal headache.
- Temporal artery tenderness or decreased temporal artery pulse.
- ESR ≥50mm/h.
- Positive histology on temporal artery biopsy.
There may also be myalgia, systemic malaise and fever.
GCA most commonly affects the branches of the internal and external carotid arteries. This can lead to jaw claudication and headache (30-80% of cases), and visual disturbances (20% of cases) such as amaurosis fugax, hallucination, diplopia or irreversible visual loss.
PMR and GCA are clinical diagnoses without gold standard serological or histological tests, excluding temporal artery biopsy for GCA.
Some other conditions may mimic GCA and PMR, such as fibromyalgia. The difference is important because GCA can rapidly lead to blindness through ocular ischaemia and requires higher doses of corticosteroid medication. GCA is linked with PMR in about 25% or more of cases, but the relationship is unknown.
A raised ESR continues to be the universal diagnostic parameter and one by which response to steroids is judged and the condition monitored. However, 5–20% of cases may have an ESR within the normal range. If a patient appears clinically to have PMR, CRP should be measured because this may be raised in those with a normal ESR. Measurement of plasma viscosity may also be considered.
Oral corticosteroids are the mainstay of treatment. Although there are no widely accepted standard treatment protocols in relation to dose or duration of treatment, guidelines from the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) recommend starting corticosteroid therapy with 12.5-25mg/day of prednisolone or the equivalent (see resources), or 40-60mg daily for GCA where temporal arteritis is suspected.
Ocular involvement in GCA is a treatable medical emergency and steroids should be started immediately, without awaiting biopsy results, to prevent possible blindness.
The steroid dose should be adjusted depending on the patient's response and taking into account the associated risks and side-effects of steroid treatment (see box). Essentially, the dose can be reduced once symptoms ease and ESR normalises. If symptoms start to relapse, dose reduction has been too quick.
|Side effects of steoids|
Acute side effects include:
Long-term side effects include:
For most patients, remission of PMR is achieved with a starting dose of prednisolone at 15mg/day. There should, usually, be a dramatic response to treatment within a few days. The dose needs to be reduced at approximately 1mg/month until 10mg per day is reached and reduced by 1mg every two months until treatment is stopped and the condition adequately controlled.
There is, however, no absolute consensus on this and the dose may need to be increased where symptoms are not controlled within the first week and a diagnosis of GCA considered.
Where a long-term corticosteroid is being prescribed prevention against potential osteoporosis should also be considered.
In GCA, steroids may be required for three to four years. Relapses are most likely in the first 18 months of treatment and may occur in a third or more of patients. In such cases, the dose should be increased to be equal to or greater than that given before relapse, depending on the severity of symptoms.
Cerebrovascular accidents and visual loss are potential causes of morbidity in GCA due to cranial ischaemia. Research suggests that low-dose aspirin in addition to corticosteroid therapy may lessen the risk of these complications and this is recommended by EULAR.
Optimal management of PMR and GCA should take into account research indicating an increased incidence of large artery complications, including aortic aneurysm, aortic dissection and large artery stenosis.
- Professor Rodger Charlton is a GP and professor of undergraduate primary care education at the University of Leicester
This is an updated version of an article that was first published in June 2012.
- Dasgupta B, Borg FA, Hassan N et al. BSR and BHPR guidelines for the management of polymyalgia rheumatica. Rheumatology 2010; 49: 186-90.
- Dasgupta B, Borg FA, Hassan N et al. BSR and BHPR guidelines for the management of giant cell arteritis. Rheumatology 2010; 49: 1594-7.
- Charlton R. Optimal management of giant cell arteritis and polymyalgia rheumatica. Ther Clin Risk Manag 2012; 8: 173-9.
- Saad ER. Polymyalgia Rheumatica Treatment & Management. Available from: http://emedicine.medscape.com/article/330815-treatment (accessed 18.04.17).