What is Polymyalgia Rheumatica?
Polymyalgia rheumatica (PMR) is an inflammatory rheumatic disease affecting adults over age 50, characterized by bilateral shoulder pain and stiffness (with or without hip/neck involvement), elevated inflammatory markers, and dramatic response to glucocorticoids. 1
Clinical Presentation
PMR presents with a distinctive pattern of symptoms:
- Bilateral shoulder pain and stiffness (hallmark feature)
- Hip girdle and neck pain may accompany shoulder symptoms
- Pronounced morning stiffness lasting >45 minutes
- Onset is typically acute or subacute (developing over days to weeks) 2
- Systemic symptoms including fatigue, fever, and weight loss may occur, driven by IL-6 signaling 2
The disease is 2-3 times more common in women and almost exclusively affects those over 50 years of age, with peak incidence in the eighth decade 3, 4.
Pathophysiology
The underlying pathology involves:
- Synovial and periarticular inflammation
- Muscular vasculopathy
- Systemic IL-6-mediated inflammation 2
Age-related factors contributing to PMR development include immunosenescence/inflammaging, increased infection susceptibility, endocrine changes, and alterations in gut microbiota 4.
Diagnostic Features
PMR diagnosis relies on:
Laboratory findings:
- Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) 1
- ESR >40 mm/1st hour is associated with higher relapse rates 5
Clinical criteria:
- Age >50 years (mandatory)
- Bilateral shoulder pain/stiffness
- Elevated inflammatory markers
- Exclusion of other conditions 5
Imaging advances: Ultrasound, MRI, and PET-CT show promise for diagnosis and monitoring, though limited by availability and cost 2, 6.
Key Differential Considerations
PMR must be distinguished from:
- Giant cell arteritis (GCA) - can coexist with PMR in 16-21% of cases 2
- Rheumatoid arthritis (check RF/ACPA) 5
- Malignancy
- Infection
- Other inflammatory conditions
Critical caveat: PMR can appear as a side effect of cancer checkpoint inhibitor therapy 2.
Disease Course and Prognosis
- Relapses occur in 34-62% of patients 7
- Disease duration varies; many patients require treatment beyond 12 months 1
- GC-related adverse events occur in up to 85% of patients 7
- Female sex is associated with higher risk of GC side effects and relapse 5
Association with Giant Cell Arteritis
PMR and GCA share pathophysiological mechanisms and frequently overlap. Vigilance for GCA symptoms (new headache, jaw claudication, visual symptoms, scalp tenderness) is essential throughout PMR management as GCA requires urgent treatment to prevent irreversible ischemic complications 7.