PURPOSE: The purpose of this study was to describe the MRI findings of polymyalgia rheumatica(PMR), with emphasis on muscular abnormalities of the shoulder and pelvic girdle.
MATERIALS AND METHODS: Since January 2005, PMR was diagnosed in 14 patients by using clinical diagnostic criteria in our institution. MR images of 7 shoulder girdles and 12 pelvic girdles were evaluated retrospectively with regard to the presence, frequency and pattern of muscular abnormalities and the presence of other inflammatory conditions including tenosynovitis, bursitis and arthritis.
RESULTS: Muscular involvement rate of the shoulder and pelvic girdles were 28.6 % and 75%, respectively. Iliopsoas muscle was most commonly involved, and hip rotator muscles and gluteus maximus muscle were followed in order of frequency. Most common pattern of muscular involvements was the juxta-entheseal myopathy which was defined as abnormal infiltrations around the site of bone attachment of the muscles. In small number of patients, a pattern of myopathy with prominent thickening of intermuscular septum and a pattern of non-specific myositis-like myopathy were found. Additional abnormalities including arthritis (58.3%) and bursitis (83.3%) were found in the MR studies.
CONCLUSION: MRI in patients with PMR revealed characteristic features of muscular involvement, in addition to various bursitis and arthritis. This study suggest that juxta-entheseal myopathy in shoulder and pelvis may contribute to the diffuse pain and stiffness in these areas observed in patients with PMR.
REFERENCES: 1. Salvarani C, et al. Polymyalgia rheumatica and giant-cell arteritis. Lancet. 2008;372: 234-245 2. May DA, et al. Abnormal signal intensity in skeletal muscle at MR imaging: patterns, pearls, and pitfalls. Radiographics. 2000;20: S295-315 3. Lovitt S, et al. MRI in myopathy. Neurol Clin. 2004;22: 509-538 4. Soubrier M, et al. Polymyalgia rheumatica: diagnosis and treatment. Joint Bone Spine. 2006;73: 599-605
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