Polymyalgia Rheumatica: Diagnosis and Management

Introduction

Polymyalgia rheumatica (PMR) is an inflammatory condition affecting older adults, characterised by pain and stiffness of the shoulder and hip girdles. It is closely related to giant cell arteritis (GCA) - the two conditions overlap substantially in their population, their inflammatory profile, and quite possibly their underlying pathology, and are considered part of the same spectrum of disease.¹

It is a favourite exam topic for two reasons: the diagnosis rests on recognising a specific pattern (proximal pain and stiffness, not weakness, in an older patient) and confirming it with a dramatic steroid response, and every case must be actively screened for coexisting GCA, since the consequence of missing it - blindness - is so severe.

Aetiology

The precise cause of PMR remains unclear, but it shares genetic and demographic associations with GCA, and IL-6 driven inflammation is thought to be central to both conditions - which is also why the same biologic (tocilizumab) has activity in both.

• Age over 50, with incidence rising steeply thereafter - average age at diagnosis is around 70
• Female sex (roughly 2-3x)
• Northern European / Scandinavian ancestry
• Association with giant cell arteritis - up to 20% of patients with PMR have or go on to develop GCA

Clinical features

• Bilateral shoulder pain and stiffness - the dominant symptom, often the presenting complaint
• Hip girdle and proximal thigh pain and stiffness, and sometimes neck involvement
• Morning stiffness lasting more than 45 minutes, with marked difficulty getting out of bed, dressing, or rising from a chair
• Symptoms worsen with rest/inactivity and improve somewhat with movement, though never fully, unlike simple mechanical stiffness
• Systemic features - low-grade fever, fatigue, weight loss, and low mood are common and can dominate the presentation
• No true muscle weakness - power is preserved once pain is controlled; the apparent 'weakness' patients describe is pain-limited effort, not a myopathic process

A minority of patients develop mild peripheral synovitis - typically asymmetrical involvement of the wrists or knees - and PMR overlaps clinically with RS3PE syndrome (remitting seronegative symmetrical synovitis with pitting oedema), which causes marked swelling of the hands and feet in a similar patient group.

Examination

• Active and passive range of movement of the shoulders and hips is often reduced by pain rather than true mechanical restriction
• Muscle bulk and power are preserved on formal testing once pain is accounted for - a genuinely weak muscle points away from PMR
• Peripheral joints - check the wrists, hands and knees for the mild synovitis or pitting oedema described above
• Temporal arteries - palpate for tenderness, thickening or reduced pulsation, and examine for scalp tenderness, as part of the routine GCA screen
• General examination for lymphadenopathy, hepatosplenomegaly, or a mass, if malignancy is a differential concern

Differential diagnosis

• Elderly-onset rheumatoid arthritis - can mimic PMR closely; look for symmetrical small-joint synovitis and check RF/anti-CCP
• Inflammatory myopathy (polymyositis/dermatomyositis) - true weakness and a markedly raised CK, unlike PMR
• Hypothyroidism - can cause proximal aching and stiffness; check TFTs
• Multiple myeloma and other malignancy - can present with bone pain and a raised ESR mimicking PMR; consider serum protein electrophoresis if the picture is atypical or the response to steroids is poor
• Osteoarthritis of the shoulders and hips - mechanical, non-inflammatory, normal inflammatory markers
• Fibromyalgia - diffuse pain in a younger patient, normal inflammatory markers, and no meaningful steroid response
• Adhesive capsulitis (frozen shoulder) - usually unilateral or asymmetrical, without systemic features or a raised ESR/CRP

Investigations

• ESR and CRP - typically raised, though a minority (up to 10-20%) of genuine PMR have normal inflammatory markers at presentation
• FBC - normocytic anaemia of chronic disease is common
• LFTs - a raised alkaline phosphatase is a recognised association
• Creatine kinase - normal in PMR; a raised CK should prompt reconsideration of an inflammatory myopathy
• Rheumatoid factor and anti-CCP - negative; used to help exclude elderly-onset rheumatoid arthritis
• TFTs - to exclude hypothyroidism as a mimic
• Serum protein electrophoresis - if myeloma is a concern, particularly with atypical features or bone pain
• Shoulder or hip ultrasound - can show bursitis and tenosynovitis supporting the diagnosis where the clinical picture is unclear, and contributes to the EULAR/ACR classification criteria

Classification

The 2012 EULAR/ACR provisional classification criteria require age 50 or over, bilateral shoulder pain, and an abnormal CRP or ESR, plus a scoring system across the following domains, with ultrasound findings (if performed) adding further points:

Management

Corticosteroids are first-line and highly effective, typically starting at prednisolone 15 mg daily.² NSAIDs are not recommended as primary treatment and offer little benefit over the dramatic response seen with steroids.

Response is reassessed after about a week; a good response confirms the diagnosis and treatment continues with a slow taper, guided by symptoms and inflammatory markers, typically over 1-2 years in total - for example, reducing to 12.5 mg after around 3 weeks, then 10 mg after a further 4-6 weeks, then by roughly 1 mg every 4-8 weeks thereafter, adjusted to the individual response.

• Relapse during tapering is common and is managed by returning to the last effective dose, then attempting a slower taper
• Bone protection - bisphosphonate, calcium and vitamin D from the outset, since a prolonged steroid course is expected from diagnosis
• Methotrexate - considered as a steroid-sparing agent for patients with relapsing disease, a high risk of steroid-related complications, or comorbidities (diabetes, osteoporosis) that make prolonged steroid exposure particularly hazardous
• Physiotherapy supports recovery of function and mobility as symptoms settle

Complications

Untreated or undertreated, PMR causes significant pain, functional impairment and reduced quality of life in older patients who are often already vulnerable to deconditioning and falls. The principal long-term burden, however, comes from treatment itself: osteoporosis and fragility fracture, diabetes, weight gain, cataracts, hypertension and increased infection risk from a prolonged corticosteroid course, which is why bone protection and steroid-sparing strategies are built into management from the start rather than added as an afterthought. The most serious missed complication is undiagnosed coexisting GCA, with its risk of irreversible visual loss.

Red flags

Prognosis

Most patients respond well to corticosteroids and are eventually able to stop treatment altogether, typically after one to two years, though a minority have a more prolonged or relapsing course requiring longer treatment or steroid-sparing therapy. Overall prognosis for the condition itself is good; the main determinants of morbidity are the cumulative effects of corticosteroid treatment and, where present, coexisting or subsequently developing GCA.