Polymyalgia rheumatica is a common rheumatological disorder, which is characterised by shoulder and hip girdle pain.
Polymyalgia rheumatica (PMR) is a common systemic inflammatory disease that is one of the most common indications for long-term steroids. It is characterised by myalgia and muscles stiffness with preponderance to the neck, shoulder and pelvic girdle.
Similar to giant cell arteritis (GCA), PMR is predominantly a disease of older adults and rarely presents before 50 years old. The peak prevalence is estimated between 70-80 years. Women are 2-3 times more likely to be affected than men.
The exact cause of PMR is currently unknown.
Similar to GCA, the aetiology of PMR remains unknown. There appears to be a pro-inflammatory response with elevated levels of IL-6, an increase in certain T-cell subsets and subclinical arterial inflammation in some patients.
Both genetic and environmental factors have been linked with the aetiology of PMR:
Despite its name, the predominant sites of inflammation in PMR are proximal articular and periarticular structures.
The name PMR implies a myopathic process, however, the muscle in PMR is normal on histopathological assessment. The predominant site of inflammation includes bursae and tendons. Bursae are fluid-filled sacs that counteract the friction associated with tendons. Despite the site of inflammation, patients still present with generalised muscle stiffness and pain, particularly in the shoulder and pelvic girdles.
There are characteristic sites in the upper and lower extremities associated with PMR:
The hallmark of PMR is symmetrical muscle aching, worse in the morning, that affects the shoulders, hips, neck and torso.
PMR should be suspected in any patient aged 50 years and older who present with two weeks of typical symptoms.
PMR is closely linked with GCA. It is estimated that 10% of patients with PMR will develop GCA. Therefore, it is essential to assess for features of GCA including unilateral headache, visual changes, jaw claudication, temporal artery tenderness, scalp pain and constitutional symptoms.
GCA is a medical emergency because without prompt recognition and treatment it can lead to visual loss. For more information, see our notes on giant cell arteritis.
The diagnosis of PMR is based on identifying typical clinical features and assessing response to corticosteroids.
The diagnosis of PMR should be considered if:
NOTE: these represent the core inclusion criteria as recommended by the British Society of Rheumatology (BSR)
A rheumatology referral should be considered in patients who present with atypical features:
Due to the often vague presentation and association with constitutional symptoms, it is important to exclude an alternative diagnosis such as underlying malignancy, infection or systemic inflammatory disorders.
It is essential to screen for, and diagnose, GCA if present. Early diagnosis and treatment of GCA is essential to prevent long-term complications such as loss of sight (~1/5th).
For information on the diagnosis and treatment of GCA, see our notes on giant cell arteritis.
Investigations are useful to exclude an alternative diagnosis in patients presenting with bilateral shoulder/pelvic pain.
Usually a series of routine blood tests are enough to rule out alternative diagnoses before initiating treatment.
More specialist tests may be needed depending on the clinical presentation. These include blood tests to screen for malignancy or inflammatory conditions and the use of imaging to exclude structural pathologies or active inflammation (i.e. synovitis).
Corticosteroids form the cornerstone of treatment in patients with suspected or confirmed PMR.
Following clinical assessment and routine blood tests, if PMR is felt the most likely diagnosis, patients can be started on oral prednisolone at 15 mg daily. After initiation of treatment patients should be reviewed in one week to assess the response to treatment.
After initiation, prednisolone should be reduced once symptoms are fully controlled. This is usually after a period of 3-4 weeks. Tapering may be required over a long period (1-2 years) due to the risk of relapse on stopping too early.
Consider in patients with atypical symptoms, problems with steroid tapering, long-term steroid use (>2 years), recurrent flares or steroid-associated side-effects.
Occasionally, steroid-sparing agents such as methotrexate may be used, particularly with steroid-related side-effects. However, the majority of patients should achieve disease control on low dose prednisolone.
In patients with PMR and suspected GCA, treatment should follow that of GCA with prompt initiation of high-dose corticosteroids to prevent complications such as sight loss. Patients should be advised about GCA symptoms and told to seek urgent medical attention if they develop.
Steroids can be associated with numerous complications including steroid-induced hyperglycaemia, mood changes, insomnia, gastrointestinal bleeding, immunosuppression, weight gain, cushingoid appearance, osteoporosis and adrenal cortex suppression.
Patients starting steroids will usually need a long course with slow tapering over several months or years. Therefore, from the outset the following should be considered:
In addition, patients should be given a steroid emergency card that acts as a reminder of the key side-effects and risks of steroids, including not to stop abruptly due to risk of adrenal insufficiency.
Patents should be assessed after one week of treatment to assess for a response and then three-monthly within the first year.
The majority of patients respond well to steroids and have a good longterm outcome.
Up to 45% of patients may not respond to steroids within the first 3-4 weeks of treatment and a more extended course of steroids may be needed.
Thankfully, there is no increased mortality associated with PMR, but relapse is common and patients may develop morbidity associated with side-effects from corticosteroids.
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