POLYMYALGIA RHEUMATICA

Polymyalgia rheumatica is a syndrome consisting of pain and stiffness in pelvic and shoulder girdles, very rapid erythrocyte sedimentation rate, and a prompt response to a small dose of corticosteroid. For reasons unknown, it is a disease of older patients. The diagnosis is made with reluctance in anyone less than 50 years old, and most patients are over age 60. It is seen more often in women than in men (2.5:1). Almost all patients affected are Caucasian.

Patients experience pain in the neck, back, shoulders, upper arms, and thighs. The onset may be gradual but at other times is so abrupt that patients go to bed well and awaken in the morning stiff and sore as though they had chopped wood or shoveled snow. Morning stiffness and jelling after prolonged sitting are essential features of the history. Patients graphically describe how a spouse has to pull them out of bed or, if they are alone, how it is necessary for them to wiggle like a snake and then push themselves up from a kneeling position. Although such a story may initially suggest weakness, the limitation is actually due to pain and stiffness rather than lack of strength. Some patients experience widespread symptoms and complain that they hurt all over. In others the pain and stiffness is in either shoulders or hips, but in all it is symmetric. Low grade fever, malaise, apathy, and weight loss are sometimes present. Carpal tunnel syndrome has been noted.

Despite the severity of complaints, the physical examination of these patients is surprisingly normal. Tenderness or limitation of shoulder and hip motion may be detected; effusions are present in the knees at times. Muscle strength is normal when tested. Radiographs are unremarkable. The clue to the diagnosis is the erythrocyte sedimentation rate, which is usually elevated, often very high, and may exceed 100 mm per hour (Westergren method). Slight anemia may be present. Rheumatoid factor and antinuclear antibodies are not present, and serum complement is normal. Serum levels of muscle enzymes, electromyograms, and muscle biopsies are normal. Arthroscopy and biopsy of the shoulder show that the symptoms of pain and stiffness are due to synovitis.

Although polymyalgia rheumatica appears to be a distinct clinical entity, it is obvious from this description that it is not a specific one, and as such it is often necessary to exclude other diseases in order to make the diagnosis. The sedimentation rate indicates that this is an inflammatory disease and serves to separate it from osteoarthritis or the functional musculoskeletal pain of fibrositis. Difficulty in getting out of bed or rising from a chair may suggest the weakness of polymyositis, but, as mentioned, muscles are normal. The common diagnostic problem is to differentiate polymyalgia rheumatica from the onset of rheumatoid arthritis. Patients with rheumatoid arthritis tend to have synovitis of the distal joints-wrists, metacarpophalangeal, and metatarsophalangeal. When present, the rheumatoid factor is helpful, but at times the diagnosis only becomes evident with follow-up visits.

The response of the pain and stiffness of polymyalgia rheumatica to 10 to 20 mg of prednisone may truly be described as dramatic. Many patients are well by the next day; improvement is so invariable that if it does not appear within one week, the original diagnosis should be questioned. After two to four weeks, the dose can be tapered and patients remain free of symptoms on 5 to 7.5 mg of prednisone daily, without risk of steroid side effects. The duration that therapy will be required is uncertain. Some patients can stop after one year, but others will have to continue. The duration can be determined only by attempting to withdraw the drug and observing for a recurrence of stiffness and pain. Aspirin and other nonsteroidal anti-inflammatory drugs provide partial relief but are not so effective as small doses of steroid.

GIANT CELL ARTERITIS

Since the recognition that any of the larger arteries may be involved, the term giant cell arteritis has been preferred to the original names temporal or cranial arteritis. In contrast to polyarteritis, smaller arterioles are not affected; thus pulmonary and renal complications are not seen, and stroke or myocardial infarction does not occur more frequently than would be expected in this age group.

Clinical manifestations may conveniently be divided into localized or systemic. Local manifestations depend on the artery involved. Inflammation of the temporal artery produces severe headache, most often in one temple. The artery may be tender and swollen. Sudden unilateral blindness is due to occlusion of the terminal branches of the ophthalmic artery. Since blindness is irreversible, this is the most dreaded complication of the disease. Pain in the masseter muscles with chewing is attributed to involvement of the facial artery. This "jaw claudication" is a pathognomonic symptom of giant cell arteritis. Transient diplopia from ischemia of extraocular muscles is important to recognize, since it may lead to early diagnosis, steroid treatment, and preservation of vision. Arteritic involvement of the aorta can cause aortic arch syndromes with claudication in the arms and unequal pulses or, rarely, aneurysm formation. Systemic manifestations include fever, anemia, weight loss, and malaise. Some or all of these may be present in varying degree. If headache and other cranial symptoms are either not present or minimal and if systemic symptoms predominate, the patients may present such diagnostic problems as fever of unknown origin, unexplained anemia, or possible occult carcinoma.

As with polymyalgia rheumatica, the only laboratory abnormality is the rapid erythrocyte sedimentation rate. Anemia is usually mild but can be more significant with hematocrit as low as 28 per cent. Red blood cell indices are normal, and t ere is a i ure to uti ize iron espite t e presence o norma stores in the marrow. Tests of liver function, particularly the alkaline phosphatase, may show slight to moderate abnormalities, but biopsy of the liver shows normal tissue or slight fatty changes.

The diagnosis is established by biopsy of the temporal artery, which is safe and convenient to perform as an office procedure. The characteristic histologic picture shows zones of inflammatory infiltrate composed of histiocytes, lymphocytes, and giant cells surrounding markedly fragmented internal elastic lamina with intervening segments of normal artery. When headache, visual symptoms, or other signs of cranial artery involvement are present, the diagnosis may be suspected and the biopsy is usually positive. However, the characteristic arteritis has also been found in some patients with polymyalgia rheumatica, fever, or other systemic symptoms even when the temporal artery appears clinically normal.

Giant cell arteritis responds well to steroid treatment, but higher doses are needed to suppress the inflammation. When cranial arteritis is diagnosed or even suspected, treatment should be started immediately with at least 50 mg of prednisone in order to preserve vision. If the diagnosis is proved by biopsy, this dose should be continued for four weeks before gradual reduction is instituted with the aim of achieving the same maintenance dose and duration of therapy as described for polymyalgia rheumatica. Such a program carries a risk of steroid toxicity, particularly osteoporosis and vertebral collapse, which must be balanced against the risk of blindness. If the patient has been treated with high-dose steroid for one month, it is preferable to follow the clinical response as the dose is tapered. The risk of steroid toxicity from treating the sedimentation rate is greater than the risk of a complication of arteritis in a patient whose sedimentation rate increases somewhat as the steroid dose is lowered.

The nature of the relation between polymyalgia rheumatica and giant cell arteritis is uncertain. Both are diseases of older patients, the vast majority of whom are Caucasian. Both frequently are seen in the same patient. Sixty per cent of patients with giant cell arteritis experience polymyalgia rheumatica at some time during their illness. Conversely, of patients with polymyalgia rheumatica and normal-appearing temporal arteries, only 10 per cent show arteritis on biopsy. The majority of polymyalgia patients respond well to lowdose prednisone and never develop clinical evidence of arteritis.