Polymyalgia Rheumatica (PMR)
Causes and Risk Factors
The exact cause is unknown.
Risk factors:
- Advanced age
- Usually >65 y/o (peak incidence: 70-80 y/o)
- Uncommon in <50 y/o
- Females
- Northern European ancestry
Clinical Features
PMR should be suspected in >50 y/o with at least 2 weeks of:
- Bilateral shoulder and/or pelvic pain
- Pain worsens with movement and affects sleep
- Usually unilateral initially but quickly becomes bilateral
- Shoulder pain may radiate to the elbows, which is the presenting feature in 70-95% cases
- Stiffness lasts >45 min after waking or resting
- May cause difficulty in turning over in bed / rising from bed or chair / raising arms above shoulder height
Additional features:
- Systemic features (e.g. fever, fatigue, anorexia, weight loss, depression)
- Peripheral MSK signs
- Carpal tunnel syndrome
- Asymmetric peripheral arthritis
- Oedema of the hands, wrists, feet, ankles
- Bilateral upper arm tenderness
Muscle strength is usually preserved in PMR, pain and stiffness may make strength testing difficult.
True muscle weakness is not typical, but prolonged symptoms and reduced activity may lead to disuse muscle atrophy and secondary weakness.
Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are closely associated [Ref]
- 16-21% of patients with PMR have GCA
- 40-60% of patients with GCA have PMR
See the Giant Cell Arteritis (GCA) article for additional information.
Investigation and Diagnosis
There are no clear diagnostic criteria for PMR; NICE CKS states that PMR can be diagnosed if ALL of the following are present:
- Presence of core clinical features
- PMR mimics excluded
- A +ve response to steroids
A work-up for PMR would include:
| Tests to support PMR | Most useful test: ESR and/or CRP
Serum creatine kinase would be normal in PMR |
| Tests to exclude PMR mimics |
|
The following PMR mimics must be excluded:
- Giant cell arteritis – as treatment with immediate high-dose steroids is necessary and is strongly associated with PMR
- Active infection / cancer
- Arthritis
- Thyroid disease
- Statin-induced myalgia
- Myositis
Management
Giant cell arteritis should be excluded prior to starting oral prednisolone treatment for PMR, as giant cell arteritis would require urgent treatment with a higher dose of steroid treatment (in fact IV steroids if there are any visual changes) and it is associated with PMR, as discussed above.
Patients should be advised to seek urgent medical attention if they develop symptoms of giant cell arteritis. Symptoms of giant cell arteritis should also be reviewed at every follow-up. See the Giant Cell Arteritis (GCA) for more information.
1st line: oral prednisolone (15 mg daily)
- Treatment is typically required for 1-2 years
- The steroid dose should be tapered down slowly once symptoms are fully controlled
PMR usually responds well to steroids. If symptoms do not improve significantly and ESR/CRP do not normalise within 1 month despite an appropriate dose, reconsider the diagnosis and refer to a specialist.