Myalgia in the Elderly: Arthritis . . . or Something Else?

Aging Matters

Strategies for Optimal Care of the Elderly


THE CASE: An 82-year-old woman complains that for the past 6 months, she has "not felt like herself." Previously, she was very active and energetic; in fact, 9 months earlier, she had vacationed in Hawaii. It now takes all of her energy just to get out of bed.

She has noticed pain, primarily in her hips, when she rises from a chair, and in her shoulders when she performs routine activities. These symptoms have been accompanied by an overwhelming sense of fatigue. She has lost 20 lb during this time, in large part because her fatigue and pain prevent her from preparing meals. She awakens frequently during the night and does not feel refreshed in the morning. She has become depressed because "it is so frustrating to be tired all the time."

This tired-appearing patient looks younger than her stated age. Her affect is flat, but she is alert and oriented. She reports pain when asked to rise from her chair as well as during upper extremity range of motion exercises. The remainder of her examination is unremarkable.

Laboratory studies reveal a mild anemia (hemoglobin level, 11.5 g/dL; hematocrit, 34%). The erythrocyte sedimentation rate (ESR) is 120 mm/h. The chemistry panel is normal.

In an older patient who presents with myalgia, which clues signal the presence of an acute, and possibly reversible, condition?

After presbyacusis, degenerative joint disease is the most common chronic medical disorder among persons older than 65 years.¹ In a patient like ours, therefore, complaints of neck, shoulder, and hip pain could be attributed to osteoarthritis. Her specific presentation and associated symptoms, however, suggest a more acute condition that, unlike degenerative joint disease, is reversible.   

CLINICAL PRESENTATION OF POLYMYALGIA RHEUMATICA
Polymyalgia rheumatica(PMR) is characterized by pain and stiffness accompanied by depression, fatigue, malaise, and sleep disorders. This acute inflammatory disease affects women twice as often as men. The incidence in persons older than 50 years is 52 per 100,000; it increases with age. The pathophysiology is unclear, but PMR is thought to be a synovitis characterized by T-cell and macrophage infiltration.²

The diagnostic criteria are listed in the Table. The constitutional symptoms of PMR, such as depression, are very common in elderly persons, which complicates making the diagnosis.

As with most geriatric syndromes, assessing impact on function is crucial. Functional impairments are among the most convincing evidence for a diagnosis of PMR. Patients may report that they need help getting out of bed in the morning because of stiffness ("gelling"). Gelling may also present as difficulty in getting out of a car or out of a chair after sitting for a while. Shoulder pain may make it difficult to comb the hair or put on a sweater.

PHYSICAL EXAMINATION
The results may be relatively normal, except for a flat affect that indicates depression. Low-grade fever may be present. Patients may interpret limited shoulder and neck range of motion as muscle weakness; however, true muscle weakness is generally not present. Rotation of the hips may elicit pain. Rash, Raynaud syndrome, and joint effusions are generally absent.

LABORATORY STUDIES
The most reproducible finding in PMR is an elevated ESR (Westergren method). It is usually higher than 50 mm/h and sometimes higher than 100 mm/h. The ESR may, however, be nearly normal in younger patients (those in their 50s and 60s) whose clinical picture suggests PMR. The level of C-reactive protein, a marker of inflammation, is also generally elevated.

Mild normochromic-normocytic anemia may also be present. Serum chemistry values are normal, as are kidney and liver function parameters. Autoantibodies (eg, antinuclear antibodies and rheumatoid factor [RF]) are found no more frequently in patients with PMR than in the general population. There are no radiologic findings that are pathognomonic of PMR.

DIFFERENTIAL DIAGNOSIS
A variety of alternative diagnoses need to be considered when a patient presents with myalgias and an elevated ESR. Some of the more likely possibilities include fibromyalgia, other connective tissue diseases, and endocrinopathies.³ Often, the most difficult condition to distinguish from PMR is fibromyalgia. Although patients with both syndromes experience pain, depression, fatigue, and sleep disorders, fibromyalgia generally affects younger persons and features distinctive trigger points. Sleep problems and depression often predate the pain of fibromyalgia, whereas they are likely to be concomitant with pain in PMR.

Other connective tissue diseases, such as polymyositis and dermatomyositis, need to be excluded. Muscle weakness is more prominent than pain in patients with these 2 disorders; elevated muscle enzymes (creatine kinase, aldolase) strongly suggest the diagnosis. A classic dermatomyositis rash (erythema of the forehead, neck, shoulders, and trunk) clearly rules out PMR. A muscle biopsy confirms the diagnosis. Because approximately 13% of patients with polymyositis have a comorbid malignancy, differentiation from PMR is crucial.⁴

Rheumatoid arthritis (RA) can also masquerade as PMR, given that pain and morning stiffness are the key features of both conditions. However, patients with RA are likely to have synovitis of the distal joints--particularly the wrist and metacarpophalangeal joints. Elevated levels of RF may be present, but this finding does not clearly establish the diagnosis because it is neither sensitive nor specific. Generally, patients who have RA present with pain in specific joints, whereas those with PMR report generalized pain.

Occasionally, endocrinopathies present with a clinical picture similar to that of PMR, with pain and weakness as the primary complaints. The diagnosis can be made by ruling out hypothyroidism, hyperparathyroidism, and adrenal insufficiency with the appropriate laboratory studies.

TREATMENT
Once the diagnosis of PMR has been clearly established, prednisone, 15 mg/d, is usually the only therapy necessary to achieve a remarkable improvement in pain, fatigue, and overall quality of life. This effect is often seen within 48 to 72 hours and may be so dramatic that it has been described as a "Lazarus phenomenon."

After symptoms have been controlled and the ESR has been normalized—often within 1 month—the dose of prednisone can be tapered by 1 to 2.5 mg every 2 to 4 weeks. When a dose of 5 mg is reached, taper by 1 mg every 2 to 4 weeks. Most patients require low-dose corticosteroid therapy for about 12 months. A relapse during the tapering period requires elevation of the dosage to a previously successful level and a slower tapering schedule.

The prognosis for patients with PMR is excellent. There is no evidence of joint damage, and patients return to their previous functional level.However, PMR tends to recur, and patients are advised to contact their clinician if they notice the return of suggestive symptoms. At this point, an ESR is ordered and corticosteroid therapy is restarted. If a flare occurs shortly after the corticosteroids are tapered, the taper was done too quickly and a slower pace is recommended.

A small group of nonresponders to low-dose prednisone respond to methylprednisolone.³ With the exception of this group, a lack of response to low-dose prednisone generally indicates that other diagnoses in the differential must be reconsidered.

In 25% of patients, temporal arteritis (TA) coexists with PMR. TA is a much more significant vasculitis that involves the aorta and its proximal branches. Symptoms include headache, jaw claudication, and scalp tenderness, in addition to the constitutional symptoms seen in PMR. A temporal artery biopsy confirms the diagnosis. Treatment requires high dosages of corticosteroids (60 mg/d). Because TA may result in visual loss, hearing loss, or even sudden death from aortic dissection, prompt referral for biopsy and treatment is mandatory.

As is the case with any condition that involves corticosteroid treatment, patients with PMR require a bone density study and should be counseled regarding prevention and treatment of osteoporosis. Persons with diabetes require closer monitoring of blood glucose levels. Hypertension may be more difficult to control because of fluid retention.

OUTCOME OF THE CASE
After 48 hours of prednisone therapy, the patient called to report a "miraculous" recovery. At a follow-up visit after 4 weeks, she was virtually free of pain, fatigue, and depression. She was still having some difficulty in sleeping, and a low dose of trazodone was prescribed. After a dual energy x-ray absorptiometry scan revealed osteopenia, calcium, vitamin D, and risedronate were prescribed. The corticosteroid dose was reduced to 10 mg and will continue to be tapered.