Two Inflammatory Conditions—Polymyalgia Rheumatica and Giant Cell Arteritis—Share Clinical Connection

That such a symptom is swiftly—and often spectacularly—abolished with low-dose corticosteroids is a distinguishing hallmark of PMR (See Figures 1 and 2, at right). That such a response could not be validated as a criterion that discriminates PMR from comparator diseases in the recently published “2012 Provisional Classification Criteria for Polymylagia Rheumatica” is surprising.⁵ Granted that these criteria are for classification, not diagnosis, the fact remains that the brisk therapeutic response to low-dose corticosteroids is clinically remarkable. It is has been argued that the use of this response for diagnosis of PMR is an exercise in tautology; I’m no logician, but I believe that, until we have a reliable biomarker (or biomarkers) for PMR, clinicians will continue to assess corticosteroid responsiveness in the diagnosis of a patient with suspected PMR.⁶

Figure 1: PMR: Inability to abduct actively the arms above 90º in a patient presenting with two weeks of proximal achiness and protracted morning stiffness.

Figure 2: PMR: Painless active abduction of the shoulders after one week on prednisone 10 mg/day.

PMR: Troubles with the Taper

The initial treatment of the patient with PMR is the easy part; the hard part can be the subsequent treatment. Even at low doses, the side effects of corticosteroids (CS) can be formidable, such as the well-recognized bone loss, and also ones less documented in the usual litany of toxicities, such as widespread capillary fragility—not an uncommon problem in the older adult on concurrent treatment with aspirin, warfarin, or other anticoagulants. Furthermore, the need for prolonged treatment with CS in the treatment of PMR is not uncommon; relapses during the CS taper are usual, rather than exceptional. Why PMR is monophasic in some patients and polyphasic in others—with recurrences seen even years after CS have been discontinued—is unknown.⁷ The benefit of steroid-sparing medications in the taper of CS—viz., methotrexate—is unfortunately marginal, so the goal of treatment centers on identifying the lowest dose of CS that keeps the given individual patient comfortable, with periodic efforts to accomplish a complete taper of the drug. Owing to the exquisite sensitivity to CS exhibited by many patients with PMR, the use of 1-mg decrements may facilitate this process.

The taper of CS can be problematic for several reasons. It may not be a problem per se, but simply part and parcel of the natural history of PMR, which, as noted above, is marked by relapses and recurrences. The diagnosis may have been just plain wrong—e.g., multifocal osteoarthritis or fibromyalgia may have been mistaken for PMR. Or, symptoms referable to commonplace local problems—nodal osteoarthritis, rotator cuff pathology, OA at the hips—may recrudesce during the taper of CS, which must be distinguished from bona fide flares of PMR. Or, signs of explicit synovitis may be recurrent, and raise consideration for so-called “late onset rheumatoid arthritis” or “elderly onset rheumatoid arthritis.”