From the Guidelines
Polymyalgia rheumatica (PMR) is an inflammatory disorder that causes muscle pain and stiffness, primarily affecting the shoulders, neck, upper arms, hips, and thighs, and its diagnosis relies on a combination of clinical symptoms, laboratory findings, and exclusion of other conditions, with a rapid response to low-dose corticosteroids being both therapeutic and diagnostic 1. The hallmark symptoms of PMR include bilateral shoulder and/or hip girdle pain and morning stiffness lasting more than 45 minutes. Some key points to consider in the diagnosis of PMR include:
- Laboratory tests typically show elevated inflammatory markers, particularly erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), though these are not specific to PMR 1.
- A baseline laboratory dataset should be documented in each patient before prescribing therapy, including rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies (ACPA), C-reactive protein and/or erythrocyte sedimentation rate (ESR), blood count, glucose, creatinine, liver function tests, bone profile, and dipstick urinalysis 1.
- Ultrasound may reveal bursitis or tenosynovitis around affected joints, supporting the diagnosis.
- It's essential to rule out other conditions that can mimic PMR, such as rheumatoid arthritis, polymyositis, and various malignancies.
- PMR is also associated with giant cell arteritis in about 15-30% of cases, so patients should be monitored for symptoms like headache, jaw claudication, and visual disturbances 1. The diagnosis of PMR remains primarily clinical, as there is no definitive test for PMR, and a combination of clinical evaluation, laboratory tests, and imaging studies is used to support the diagnosis 1.
From the Research
Definition of Polymyalgia Rheumatica
Polymyalgia rheumatica (PMR) is a relatively common syndrome of the elderly characterized by severe pain and stiffness in the neck, shoulder, and pelvic girdles, along with increased acute phase reactants 2. It is an inflammatory condition of unknown etiology characterized by aching and stiffness in the shoulder and in the pelvic girdles and neck 3.
Diagnostic Criteria
The current diagnostic criteria for PMR include:
- Severe pain and stiffness in the neck, shoulder, and pelvic girdles
- Increased acute phase reactants, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)
- However, a normal ESR does not exclude a diagnosis of PMR, as some patients may have a normal or slightly increased ESR at the time of diagnosis 2, 4
- C-reactive protein and interleukin-6 seem to be more sensitive indicators of disease activity both at diagnosis and during relapse/recurrence 3
Diagnostic Methods
Diagnostic methods for PMR include:
- Clinical evaluation, including medical history and physical examination
- Laboratory tests, such as ESR and CRP
- Imaging studies, such as ultrasound and 18-fluorodeoxyglucose positron emission tomography associated with total body computed tomography (18-FDG PET/CT) 4
- Arthroscopic, radioisotopic, and magnetic resonance imaging studies to evaluate synovitis in proximal joints and periarticular structures 3
Key Considerations
Key considerations in diagnosing PMR include:
- PMR should be suspected in older patients with bilateral shoulder and hip stiffness that is worse in the morning and improves with use 5
- Other conditions, such as giant cell arteritis (GCA) and elderly-onset rheumatoid arthritis (EORA), should be considered in the differential diagnosis 6, 3
- A thorough evaluation, including laboratory tests and imaging studies, is necessary to confirm the diagnosis of PMR 2, 4, 3