From the Guidelines
Rhizomelic pseudopolyarthritis, more commonly known as polymyalgia rheumatica (PMR), is an inflammatory disorder that causes muscle pain and stiffness, primarily in the shoulders, neck, and hips, and differs significantly from rheumatoid arthritis (RA) in terms of its clinical presentation, treatment, and outcomes. PMR typically affects people over 50 years old and causes morning stiffness lasting more than 45 minutes, shoulder and hip pain, and elevated inflammatory markers like ESR and CRP 1. The treatment of choice for PMR is low-dose corticosteroids, typically prednisone starting at 12.5-25mg daily, with dramatic improvement usually occurring within 24-48 hours of starting treatment 1. This rapid response to steroids is actually considered a diagnostic feature of PMR. Unlike rheumatoid arthritis, PMR doesn't cause permanent joint damage, doesn't typically affect small joints like fingers and wrists, and doesn't produce rheumatoid factor or anti-CCP antibodies in blood tests 1. While RA requires long-term disease-modifying antirheumatic drugs (DMARDs), PMR is usually treated with a steroid taper over 1-2 years, sometimes with methotrexate added as a steroid-sparing agent 1. PMR can be associated with giant cell arteritis in about 15% of cases, which requires immediate medical attention if symptoms like headache, jaw claudication, or visual changes develop 1.
Some key differences between PMR and RA include:
- Age of onset: PMR typically affects people over 50 years old, while RA can occur at any age
- Clinical presentation: PMR causes muscle pain and stiffness in the shoulders, neck, and hips, while RA typically affects the small joints of the hands and feet
- Treatment: PMR is usually treated with low-dose corticosteroids, while RA requires long-term DMARDs
- Outcomes: PMR does not cause permanent joint damage, while RA can lead to significant joint damage and disability if left untreated or undertreated 1.
Overall, the treatment of PMR should focus on relieving symptoms and improving quality of life, while also monitoring for potential complications like giant cell arteritis.
From the Research
Definition and Characteristics of Rhizomelic Pseudopolyarthritis
- Rhizomelic pseudopolyarthritis, also known as polymyalgia rheumatica (PMR), is a condition characterized by bilateral hip and shoulder pain, predominantly in the shoulder girdle, with a varying degree of alteration of the general condition 2.
- The erythrocyte sedimentation rate (ESR) is often markedly increased, and the dramatic effect of corticosteroids in low dosage confirms the diagnosis 2.
- PMR can be associated with giant cell arteritis (GCA), and the therapeutic approach is strongly influenced by the risk of complications, notably ocular involvement 2.
Differences between Rhizomelic Pseudopolyarthritis and Rheumatoid Arthritis
- A comparative retrospective study found no significant clinical or biological differences between polymyalgia rheumatica and rheumatoid arthritis in the elderly 3.
- However, 70% of rheumatoid arthritis patients had one or more susceptibility alleles (shared epitope hypothesis), compared to 50% in polymyalgia rheumatica 3.
- PMR is often distinguished from rheumatoid arthritis by its lack of specific diagnostic criteria and the absence of significant peripheral synovitis, although peripheral synovitis can occur in 10-20% of PMR cases 4.
- The presence of mitochondrial myopathy, as diagnosed by muscle biopsy, may also be a distinguishing feature of PMR, with 19 out of 24 patients fulfilling the criteria for mitochondrial myopathies in one study 5.