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[Rhizomelic pseudopolyarthritis: update]
1Service de rhumatologie, Hôtel-Dieu, CHU, 1, place Alexis-Ricordeau, 44093 Nantes, France. yves-laborie@chu-nantes.fr
Purpose:
Update of recent works on polymyalgia rheumatica (PMR). CURRENT KNOWLEDGE ANS KEY POINTS: In polymyalgia rheumatica (PMR) unassociated with giant cell arteritis (GCA) (twice as frequent as GCA without PMR) several recent works demonstrated by MRI or echography that synovitis and/or subacromial bursitis accounted for most of the painful shoulders and could be relieved by steroid injections. Peripheral synovitis can also occur in 10-20% of PMR, and lead to consideration of other diagnoses, mostly RA or the RS3PE syndromes for those cases of PMR with peripheral edema. PMR with asymmetrical onset are often difficult to diagnose early, and the classification criteria for PMR are not widely accepted. When clinical signs suggestive of GCA are lacking, temporal biopsy is positive in only 1 to 5% of PMR cases. Several studies on PMR with so-called 'normal' ESR (below 30 mm, first hour) have cast doubts on the value of this biological sign (although 'normal ESR' should only stand for values below 11 mm). Hence it would be worthwhile to study whether CRP and even SAA deserve to be added to future sets of criteria for PMR. A defect in hypothalamic axis response is often noticed and could play a part in PMR pathogenesis, thus explaining why PMR is quite exclusively noticed after ages 50 or 60. Two-thirds of patients can stop prednisone within 2 years after the onset of treatment. The lack of a prompt response within the first days should suggest differential diagnoses, including some myelodysplastic disorders.
Future Prospects And Projects:
The search for genetic factors common or specific to PMR and GCA could enhance our understanding of these overlapping syndromes. Studies of the transcriptosomes of lymphocytes infiltrating the target tissues (arterial wall in GCA, synovium in PMR) might also prove informative. Controlled studies of new biological treatments like cytokine inhibitors (anti-TNF-alpha, anti-interferon gamma) could demonstrate a clear sparing effect in steroids, a goal not yet achieved by the use of current DMARDs, including MTX.
Insights
Recent studies highlight synovitis and bursitis as key causes of shoulder pain in polymyalgia rheumatica (PMR), treatable with steroids. Research also questions the reliability of erythrocyte sedimentation rate (ESR) and suggests exploring genetic factors and new treatments for PMR.
Area of Science:
- Rheumatology and Immunology
- Musculoskeletal Disorders
- Inflammatory Conditions
Context:
- Polymyalgia rheumatica (PMR) is an inflammatory condition primarily affecting individuals over 50.
- PMR often co-occurs with giant cell arteritis (GCA), but is more common independently.
- Recent research focuses on understanding the underlying mechanisms and diagnostic challenges of PMR.
Purpose:
- To review recent advancements in understanding polymyalgia rheumatica (PMR).
- To discuss the role of synovitis and bursitis in PMR-related shoulder pain, and their response to steroid injections.
- To evaluate the diagnostic utility of erythrocyte sedimentation rate (ESR) and explore potential new biomarkers like C-reactive protein (CRP) and serum amyloid A (SAA).
Summary:
- Recent imaging studies (MRI, echography) reveal synovitis and subacromial bursitis as primary causes of shoulder pain in PMR, responsive to steroid therapy.
- Peripheral synovitis occurs in 10-20% of PMR cases, sometimes mimicking rheumatoid arthritis (RA) or RS3PE syndromes.
- The diagnostic criteria for PMR require refinement, with questions raised about the sole reliance on ESR, especially 'normal' values, and the low yield of temporal artery biopsy in PMR without GCA symptoms.
Impact:
- Findings suggest a need to reconsider diagnostic criteria for PMR, potentially incorporating CRP and SAA.
- Understanding the hypothalamic axis defect in PMR pathogenesis may explain its age distribution.
- Future research directions include investigating genetic links between PMR and GCA, analyzing tissue transcriptomes, and exploring novel biologic therapies like cytokine inhibitors for steroid-sparing effects.