Epidemiology
- Sex: ♀ > ♂ (3:1)
- Age of onset: >70 years (rarely seen in patients < 50 years)
Tip
Women of advanced age are particularly prone to the disease.
Etiology
Association with giant cell arteritis (GCA): Approx. 10% of individuals with polymyalgia rheumatica also have GCA.
Pathophysiology
Clinical features
- History:
- Subacute onset of bilateral pain & morning stiffness (> 45–60 min) involving the shoulder (most common), hip girdle, and/or neck.
- Functional impairment: Difficulty abducting arms (e.g., combing hair, putting on a coat) or rising from a seated position.
- Systemic symptoms: Low-grade fever, fatigue, malaise, anorexia, weight loss.
- Physical Exam:
- Decreased active ROM due to pain.
- Passive ROM is preserved.
- No true muscle weakness (normal objective motor strength testing; weakness is pain-limited).
- Normal muscle bulk without atrophy.
- Mild localized tenderness over shoulders/hips without joint deformity or warmth.
Diagnostics
- Diagnostic Strategy: Clinical diagnosis based on classic symptom distribution, age ≥ 50, markedly elevated inflammatory markers, and rapid response to corticosteroids.
- Initial/Key Labs:
- Markedly elevated ESR (usually > 40–50 mm/hr, often > 100 mm/hr) and/or elevated CRP.
- Normal Creatine Kinase (CK) and aldolase (critical to exclude myopathy).
- Normocytic normochromic anemia (anemia of chronic disease).
- Negative/non-elevated RF, anti-CCP, and ANA (to rule out RA/SLE).
- Normal TSH (to rule out hypothyroid myopathy).
- Imaging (optional/adjunctive):
- Musculoskeletal US or MRI: Demonstrates bilateral subacromial/subdeltoid bursitis, biceps tenosynovitis, or hip trochanteric bursitis.
- Biopsy:
- Muscle biopsy: Normal (not indicated).
- Temporal artery biopsy: Indicated only if concomitant signs/symptoms of GCA are present (e.g., headache, jaw claudication, vision loss).
| Feature | PMR | RA |
|---|---|---|
| Age | 60 to 80 years | 30 to 50 years |
| Female predominance | 2 to 3 times as likely | 2 times as likely |
| Morning stiffness | always | always |
| Onset of symptoms | days to few weeks | weeks to months |
| Predominant joints | shoulders, hips | small joints of hands, feet |
| Extra-articular feature | giant-cell arteritis | subcutaneous nodules |
| Joint swelling | unusual | always |
| Elevated ESR, CRP | 80% to 90% | 70% to 80% |
| Positive RF, anti-CCP | not present | 50% to 70% |
| Response to low-dose steroid | rapid, very good | equivocal after a few weeks |
Link to original
Feature Fibromyalgia (FM) Polymyositis (PM) Polymyalgia Rheumatica (PMR) Demographics F, 20–55 yo F > M, > 40 yo Age > 50 yo (peak 70s) Core Symptom Widespread chronic pain, fatigue, insomnia Painless proximal muscle weakness Proximal morning stiffness/pain (shoulders, hip girdle) Strength Normal Decreased (proximal) Normal (pain-limited ROM) CK / Aldolase Normal Markedly elevated (↑↑) Normal ESR / CRP Normal Normal or mild ↑ Markedly elevated (↑↑, ESR > 50) Diagnostic Test Clinical Muscle biopsy (CD8+ endomysial) Clinical + rapid steroid response 1st-Line Tx Exercise, Duloxetine, TCAs, Pregabalin High-dose prednisone (± MTX/AZA) Low-dose prednisone (10–20 mg) Key Association IBS, tension headaches, depression Interstitial lung disease, malignancy Giant Cell Arteritis (GCA)
Treatment
- First-Line: Low-dose oral prednisone (10–20 mg/day). c
- Expect rapid response in 1–3 days.
- Taper slowly over 1–2 years.
- Second-Line (Steroid-Sparing): Methotrexate or Sarilumab (IL-6 inhibitor) for frequent relapses.
- Prophylaxis: Calcium + Vitamin D ± Bisphosphonates for steroid-induced bone loss.
Complications
- Progression to GCA: Risk of irreversible vision loss (amaurosis fugax).
- Steroid Toxicity: Osteoporosis/fractures, secondary diabetes, Cushingoid features.
- Relapse: Common during steroid taper (treat by returning to prior effective dose).