PMR attacks those of us who are over fifty years old, becomes more common with age, and affects more women to men. In the USA, 711000 people have PMR and the lifetime risk of developing PMR is 2.43% for women and 1.66% for men. Like most arthritis types, the cause of this devastating and common disease is not known but theories suggest that environmental triggers play a role because the incidence of PMR varies from country to country and region to region.
Even though PMR is included among the various types of arthritis, it is not a true arthritis because it does not cause joint inflammation or joint damage. Instead, the inflammation of PMR attacks the ligaments, membranes, and sinews that surround our joints, especially those of our hips, shoulders, and necks. Moreover, as the name ‘myalgia’ or ‘muscle ache’ suggests, PMR does not cause muscle inflammation; it only causes pain in multiple muscles groups and hence the prefix ‘poly’ or ‘many’.
One of the dangers of PMR is its association with brain artery inflammations. Patients who have brain artery inflammations, 40% to 60% have PMR and patients with PMR, 16% to 21% have brain artery inflammations. The dangers of brain artery inflammations are that they can cause multiple strokes and blindness, which is why they need to be considered medical emergencies.
Unlike most true arthritis types, there is no diagnostic test for PMR. The diagnostic criteria are clinical and include: a) age over 50, b) recent and persistent symptoms of 2 weeks to 2 months, c) head, neck, shoulder, and hip pains, d) prolonged morning stiffness of at least 30-60 minutes, e) low fever, depression, weight loss, f) elevated inflammation markers such as the ESR & CRP, and g) a very good response to cortisone, which is the most effective treatment to date.
If PMR is present without brain artery inflammations, the dose of cortisone is usually smaller and the response is more prompt. If it coexists with brain artery inflammations, the dose of cortisone is bigger and the response is slower. In both cases, treatment is prolonged, lasting one to two years for many. However, unlike most other types of arthritis, PMR is curable and most patients are able to eventually taper and stop their cortisone treatments. Relapses are common, however, and occur in up to 50% of patients, especially in women who were treated with too low a cortisone dose and for too short a time.
Prolonged cortisone treatment has many adverse effects such as stomach ulcers, cataracts, easy bruising, skin thinning, osteoporosis, weight gain, diabetes, high blood fats, infections, muscle damage, and nerve damage. To minimize these adverse effects, cortisone-sparing medicines such as methotrexate are sometimes used, but the results are unimpressive and inconsistent. At present, there is no medicine that can replace cortisone, which remains the treatment of choice. Other arthritis medicines such as aspirin, ibuprofen, or naproxen can be used as adjuncts, but are rarely enough when used alone.
Late-onset rheumatoid arthritis is a great mimicker of PMR. Up to 2% to 30% of patients initially diagnosed with PMR are reclassified as rheumatoid arthritis upon further follow-up. The clue is always joint damage, which is universal in untreated rheumatoid arthritis but absent in PMR. Unfortunately, modern medicines that are now being used to treat rheumatoid arthritis do not seem to help PMR.
PMR is a serious but curable disease and should always be treated by experienced physicians who know how much cortisone to use, how long the treatment should be, how slowly to taper the dose, and how to protect the patient from the many adverse effects of cortisone. Anyone, fifty years or older, who develops new onset neck, head, shoulder, and hip aches associated with prolonged morning stiffness should consult a physician if symptoms persist in spite of usual treatments.
In the elderly, new-onset headaches with declining vision are very dangerous, should be considered a medical emergency, and should be promptly investigated because they can be manifestations of brain artery inflammations. Delay in diagnosing pure PMR is not dangerous by itself, but delay in diagnosing brain artery inflammations can result in strokes, blindness, and death. Hence, since PMR frequently coexists with brain artery inflammations and with late-onset rheumatoid arthritis, which can cause joint damage, it is best to avoid diagnostic and therapeutic delays.