|Diagnosis and Treatment of Polymyalgia Rheumatica|
Diagnosis and Treatment of Polymyalgia Rheumatica
Charles E. Keenan Jr., M.D.
A 66-year-old male presented with symptoms of fatigue, aching in the back, thighs and shoulders, and stiffness following any length of inactivity. Onset of syndrome was subtle, with progression over a two to three month period to the point of interfering with normal daily activities.
The patient had been physically active with regular cardiovascular and resistance exercise. Previous history included prostatectomy for prostate cancer, coronary artery disease, and osteoarthritis controlled with rofecoxib.
Presenting symptoms differed from those previously attributed to osteoarthritis. Laboratory analyses revealed an initial erythrocyte sedimentation rate (ESR) of 105, C-reactive protein (CRP) at 10.09, with a ferritin of 107. With an initial diagnosis of polymyalgia rheumatica, the patient was placed on 15 mg of prednisone. Dosage was reduced to 10 mg after one month of improvement, and then to 5 mg as a maintenance dosage.
Subsequent testing demonstrated a reduction of CRP to 0.97 and ESR to as low as 30. Improvement of presenting symptoms and dramatic response of ESR to prednisone confirmed the diagnosis of polymyalgia rheumatica.
Polymyalgia rheumatica, one of a heterogeneous group of inflammatory diseases, is common in the elderly population. The syndrome was first recognized by Barber in 1957. The average age at diagnosis is 70 years, with most patients of Caucasian European descent. Polymyalgia rheumatica afflicts twice as many women as men.1 The incidence of polymyalgia rheumatica is estimated to be 0.5 % in persons older than 50 years, with an annual incidence from 12 to 68 cases per 100,000 persons older than 50 years.2
Polymyalgia rheumatica is typically characterized by bilateral pain and stiffness of the shoulder and pelvic girdles, but symptoms can be more pervasive in the body. Proximal joint and muscular pain is most common; distal pain is atypical. Pain may or may not be worse at night, and morning stiffness can range from being uncomfortable to severely debilitating. Sleep may be affected, and the patient my present with varying degrees of fatigue and depression. Fever, if present, is low. Duration of symptoms at presentation generally exceeds one month.
In the majority of patients, ESR is elevated. However, ESR may be essentially normal particularly in younger, male patients. ESR offers the most useful laboratory determination of polymyalgia rheumatica diagnosis as well as that of the closely associated temporal arteritis. While CRP level may be elevated in patients with these conditions, it offers little diagnostic value over ESR. The Westegren ESR typically used to define polymyalgia rheumatica is 40 mm/hour while that of 100 mm/hour is common in temporal arteritis. Patients with isolated osteoarthritis should have a normal ESR.3
Polymyalgia rheumatica and temporal arteritis often overlap. Fifty to ninety percent of temporal arteritis patients may initially present with symptoms of polymyalgia rheumatica, while nearly 33% of those with polymyalgia rheumatica are found to have temporal arteritis upon temporal artery biopsy. Incidence of temporal arteritis is 18 cases per 100,000 persons over 50.4
Due to the diversity in presenting symptoms and difficulty of differential diagnosis, it has been suggested that rapid response to low-dose corticosteroids (15 mg/day of prednisone) could be considered supporting the diagnosis of polymyalgia rheumatica.
The etiology of polymyalgia rheumatica and temporal arteritis is not completely understood and may be similar or the same. Hypothesized triggering factors have included infections including influenza, hepatitis B or Borrelia burgdorferi. Clinical studies have not confirmed causation. In fact, it has been speculated that polymyalgia rheumatica may be a more intense and focal form of the same process.4
No specific antibodies have been identified with polymyalgia rheumatica. The increased incidence in white women of European origin indicates a genetic component, as does an association with the HLADR4 allele. The immune system has been implicated, as there have been increased numbers of circulating lymphoblasts in patients with polymyalgia rheumatica and reduced peripheral blood cytotoxic/suppressor T cell ratios; however, no persistent immune defects have been identified.5
Brooks and McGee list diagnostic criteria as pain and/or stiffness, elevated ESR, morning stiffness, exclusion of other diseases including rheumatic arthritis and systemic lupus or other connective tissue disorders, symptomatic response to low-dose oral corticosteroids (10-20 mg/day of prednisone), age over 50, duration of symptoms exceeding one month, systemic symptoms such as weight loss, fatigue, and fever, elevated acute phase reactant other than ESR, muscle tenderness, and time from onset to maximal symptoms of less than two weeks.6
Although symptoms can be and often are dramatic, physical examination is typically less impressive. There may or may not be tenderness in the paracervical musculature and shoulder joints. Synovitis may be easier to detect in the knees and sternoclavicular joints. True muscle weakness is not usually present. Rash, tendon crepitus, mucocutaneous abnormalities, and vascular changes are all usually absent in polymyalgia rheumatica.5
Patients with mild to moderate polymyalgia rheumatica symptoms may respond to nonsteroidal anti-inflammatory drugs (NSAIDS). If patients do not respond impressively to NSAIDS within four weeks, or if they present with severe symptoms initially, low dosages of corticosteroids are usually used. Dosages of 5-20 mg of prednisone or its equivalent in a single daily tablet are adequate. It is noteworthy that such low doses will not resolve temporal arteritis and may, therefore, contribute to the differentiation of that condition prior to biopsy.
Corticosteroid dosage is usually tapered within four weeks after initiation, if symptoms have quickly resolved and ESR and other laboratory abnormalities normalize. Dosage reduction depends on regular symptom review and lab testing. Gradual decrease in dosage is important and rate of reduction is generally as slow as 1 mg every two to four weeks. Any significant increase in ESR during tapering may require slower tapering of steroids. A rapid course of steroid reduction may be associated with flares of the underlying disease.
Many patients may be completely weaned from corticosteroids after about one year of therapy, though some will need a smaller maintenance dose. Others may be successfully removed from steroids earlier. Alternate-day corticosteroids seem to be less effective than single daily dosages. NSAIDS may be added to corticosteroids or used as maintenance.
Three subsets of patients have been described. The first group responds quickly to initial steroid therapy without flares after tapering. Required course of steroids is short. The second subset also responds well but has repeated flares and requires a longer course of steroids. The third group does not respond to initial steroid doses, and higher dosages are necessary. For such patients, more flares occur and a longer course of steroids will be needed.
Complete resolution may occur in some patients within a few months, but more typically after one to two years. There have been reports of patients requiring maintenance corticosteroid therapy for up to 10 years.
Regular follow-up by a physician is mandatory. This includes ESR testing and close questioning as to any symptoms suggesting arterial involvement. It is important for both patient and physician to recognize that most patients do well and that treatment is effective.