Polymyalgia rheumatica

Definition

Polymyalgia rheumatica (PMR) is an inflammatory syndrome of older age with severe pain and stiffness of the proximal muscles (shoulder and hip girdle, neck), without true muscle weakness or atrophy, and with nonspecific systemic symptoms. It is closely related to giant cell arteritis; some authorities consider both to be different aspects of the same disease process.

Occurrence & epidemiology

PMR affects adults over 50 and is more common than giant cell arteritis. 40–60 % of people with giant cell arteritis also have PMR, whereas only a few people with PMR develop giant cell arteritis.

Aetiopathogenesis

The cause is unknown. Shoulder symptoms result mainly from proximal bursitis (subdeltoid, subacromial), less often from bicipital tenosynovitis or joint synovitis. The close association with giant cell arteritis suggests a shared inflammatory mechanism.

Clinical features

• Bilateral pain of the shoulder and hip girdles, back, and neck.
• Morning stiffness lasting more than 60 minutes; pain wakes patients at night and is worst in the morning, sometimes so severe that getting out of bed and simple activities are hardly possible.
• Subjective weakness due to pain, but no objective muscle weakness.
• Systemic symptoms such as malaise.
• Giant cell arteritis may develop at onset or years later: new headache, pain on chewing, and visual disturbances are warning signs.

Diagnosis

• The diagnosis is clinical and requires exclusion of other causes.
• ESR: markedly elevated in more than 80 %, often above 100 mm/h, usually above 50 mm/h (Westergren); CRP also elevated.
• Complete blood count, TSH, and creatine kinase: thyroid function tests, muscle enzymes, electromyography, and muscle biopsy are normal in PMR.
• In about 80 %, chronic small-joint synovitis, erosions, rheumatoid nodules, and rheumatoid factor are absent; some joint swelling may be present.
• Pain on palpation and on active and passive range of motion of the shoulders, even when distracted; no monoclonal gammopathy.

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Further reading (open access)

1. MSD Manual Professional: Polymyalgia Rheumatica
2. MSD Manual Professional: Giant Cell Arteritis

Cross-references