Polymyalgia Rheumatica

Polymyalgia rheumatica (PMR) is a chronic inflammatory rheumatic disease of older adults characterised by pain and morning stiffness of the shoulder, neck and hip girdles with a markedly raised acute-phase response, and a dramatic response to corticosteroids.

It is a common musculoskeletal problem of older women (Kane's) and occurs almost exclusively in people over 50 years, with peak incidence in the seventh and eighth decades; women are affected two to three times as often as men.

PMR and giant cell arteritis have common clinical and epidemiological links but need not occur synchronously: roughly 40–50% of GCA patients have PMR features, and about 15–20% of PMR patients develop GCA.

Geriatric relevance: Pathy's lists PMR among the major causes of frailty, acting through pain, immobility and reduced food intake — and stresses that treatment with corticosteroids reverses the frailty it produces, yet this totally reversible condition is often misdiagnosed by clinicians.

Aetiology is unknown; there is a genetic association with HLA-DRB1*04, and environmental or infectious triggers have been proposed given seasonal and cyclical clustering.

The dominant mechanism is IL-6 driven systemic inflammation with dendritic cell and CD4+ T-cell activation. Unlike myositis, the muscle itself is normal — the pathology lies in peri-articular structures: subacromial and subdeltoid bursitis, glenohumeral synovitis, biceps tenosynovitis and trochanteric bursitis.

Ageing-related immunosenescence and inflammaging explain the restriction of PMR to older adults.

Cardinal symptoms: symmetrical aching and stiffness of the shoulder girdle (most common), neck and hip girdle, of relatively abrupt onset, worst in the morning and after rest, with morning stiffness lasting more than 45–60 minutes.

Functional impact: difficulty getting out of bed, standing up from a chair, lifting the arms to comb the hair, and turning over in bed — a classic geriatric presentation of "off legs" or "gone off her feet".

Constitutional symptoms (Kane's list): weight loss, fever, muscle pain, aching of the neck, shoulder and hip, and morning stiffness; also fatigue, malaise, anorexia, depression and low-grade pyrexia. PMR is a recognised cause of pyrexia of unknown origin in the elderly.

Examination: painful restriction of active shoulder and hip movement with preserved passive range; muscle strength is normal once pain is overcome, and there is no muscle wasting or tenderness disproportionate to pain. A peripheral asymmetrical arthritis, carpal tunnel syndrome and distal RS3PE-like pitting oedema may occur.

Always screen for GCA at every visit: headache, scalp tenderness, jaw claudication, visual symptoms, and temporal artery abnormality.

ESR and CRP are markedly elevated — ESR classically above 40 mm/hour. About 7–20% have a normal ESR at presentation, so a normal ESR with a typical picture and high CRP does not exclude PMR.

Normal creatine kinase, normal electromyography and normal muscle biopsy — the single most useful discriminator from inflammatory myopathy. Normocytic normochromic anaemia of chronic disease, thrombocytosis, raised alkaline phosphatase and hypoalbuminaemia are common. Rheumatoid factor and anti-CCP are negative.

Exclusion is essential before committing to long-term steroids: full blood count, renal and liver function, calcium, TSH, CK, protein electrophoresis, ANA, RF/anti-CCP, chest radiograph, and vitamin D. Consider PSA in men and imaging if malignancy is suspected.

Imaging: ultrasound showing bilateral subacromial/subdeltoid bursitis or biceps tenosynovitis supports the diagnosis and is part of the 2012 EULAR/ACR classification criteria (age ≥50, bilateral shoulder pain and raised ESR/CRP are mandatory, then scored on morning stiffness >45 minutes, hip involvement, absence of RF/anti-CCP, and absence of other joint involvement; ≥4 points without ultrasound, ≥5 with). PET-CT may show large-vessel uptake and detect coexisting GCA.

Differential diagnosis: late-onset rheumatoid arthritis, inflammatory myopathy, hypothyroidism, statin myopathy, osteoarthritis of the cervical spine and shoulders, rotator cuff disease, fibromyalgia, myeloma, occult malignancy, infective endocarditis, and Parkinson's disease.

Corticosteroids are the treatment — typically prednisolone 12.5–25 mg/day (commonly 15 mg). Response is dramatic: near-complete relief of symptoms within 24–72 hours. Failure to respond promptly should make you question the diagnosis.

Tapering: reduce to 10 mg/day over 4–8 weeks, then by 1 mg every 4 weeks, guided by symptoms rather than ESR alone. Most need 1–2 years of treatment; relapse occurs in over half during tapering.

Methotrexate has been used as a corticosteroid-sparing agent and may be useful for patients with frequent disease relapses and/or corticosteroid-related toxicity (Kane's) — typically 7.5–15 mg weekly with folic acid.

Infliximab has not been shown to be beneficial in terms of pain management or disease progression and is not currently recommended (Kane's, citing Hernández-Rodríguez).

Mandatory steroid-sparing co-prescription in the elderly: calcium and vitamin D, bone protection with a bisphosphonate, gastroprotection where NSAIDs or high steroid doses are used, glucose monitoring for steroid-induced diabetes, blood pressure and weight monitoring, and cataract and glaucoma surveillance. Consider Pneumocystis prophylaxis at high cumulative doses.

Escalate vigilance to GCA: because of the close association between PMR and temporal arteritis, any symptoms suggestive of temporal artery involvement — headache, jaw claudication, recent changes in vision — especially when the sedimentation rate is very high (>75 mm/hour), should prompt consideration of temporal artery biopsy (Kane's).

Non-drug care: graded exercise to prevent deconditioning and steroid myopathy, fall prevention, protein-adequate nutrition, and management of steroid-related mood change and insomnia.

Prognosis is good — most achieve remission and stop steroids within 1–3 years, though a minority need low-dose maintenance for longer. Morbidity in the elderly comes largely from cumulative glucocorticoid toxicity: osteoporotic fracture, diabetes, infection, cataract, skin fragility and steroid myopathy.