Polymyalgia Rheumatica and Giant-Cell Arteritis(3)

Clinical Manifestations

Polymyalgia Rheumatica

The combination of persistent pain for at least one month with aching and morning stiffness in the neck, shoulder girdle, and pelvic girdle that lasts at least 30 minutes and an increase in the erythrocyte sedimentation rate to at least 40 mm per hour is strongly suggestive of polymyalgia rheumatica.^17,18 Patients with polymyalgia rheumatica have bilateral discomfort involving the proximal limb and joint areas. The musculoskeletal pain worsens with movement of the affected area and typically interferes with usual daily activities.

On examination, limitation of active and, often, passive movements of the shoulders due to pain is present. Shoulder pain is the presenting finding in the majority of patients (70 to 95 percent). The hips and neck are less frequently involved (between 50 and 70 percent). In both the shoulder and pelvic girdles the pain usually radiates distally toward the elbows and knees. The discomfort may begin on one side, but it soon becomes bilateral. Systemic symptoms and signs are present in approximately one third of patients and include fever, malaise or fatigue, anorexia, and weight loss. The diagnosis is usually made within two to three months after the onset of symptoms.^17,39,40

The prominent and diffuse shoulder discomfort may be due more to periarticular structures than to the glenohumeral joint itself. Physical examination reveals little evidence of swelling or tenderness of proximal joints that could account for the patients' often marked symptoms. An MRI study of patients with polymyalgia rheumatica identified subdeltoid and subacromial bursitis as more prominent and common than joint synovitis and bicipital tenosynovitis³⁵ (Figure 2).

Distal manifestations are present in about half of the cases.^4,8,41,42 They include nonerosive, self-limited, asymmetric peripheral arthritis (predominantly affecting the knees and wrists), carpal tunnel syndrome, and swelling and pitting edema of the dorsum of the hands and wrists (Figure 3A), as well as of the ankles and the tops of the feet.

Giant-Cell Arteritis

The onset of giant-cell arteritis tends to be gradual, but it can be abrupt. Systemic symptoms are present in about half of patients.^39,43 Although the fever is usually low grade, it can reach 39?to 40癈 in about 15 percent of patients and may be the presenting clinical manifestation.⁴⁴

A headache is probably the most frequent symptom and occurs in two thirds of patients.^39,45 The pain is frequently marked and tends to be located over the temporal or occipital areas but may be less well defined. Scalp tenderness is usually confined to the temporal and, less commonly, the occipital arteries, but it may be diffuse. It is seen most often in those with headaches.

On physical examination, the frontal or parietal branches of the superficial temporal arteries may be thickened, nodular, tender, or occasionally erythematous (Figure 4A). Pulses may be decreased or absent. The occipital arteries and, less often, the postauricular or facial arteries may be enlarged or tender. Nearly half of patients suffer from jaw claudication.⁴³ Occasionally, intermittent claudication may occur in the muscles of the tongue or those involved in swallowing. In rare cases, more marked vascular narrowing may lead to infarction of the scalp or the tongue.

Permanent partial or complete loss of vision in one or both eyes occurs in up to 20 percent of patients and is often an early manifestation of the disease.^43,45,46,47 Affected patients typically report partially obscured vision ("a shade covering one eye"), which may progress to total blindness. If untreated, the other eye is likely to become affected within one to two weeks. Once established, visual impairment is usually permanent. Amaurosis fugax is an important visual symptom that precedes permanent visual loss in 44 percent of patients.⁴⁷ Diplopia or visual hallucinations occur less frequently.^46,47,48 Visual loss is caused by ischemia of the optic nerve or tracts as a result of arteritis of the branches of the ophthalmic or posterior ciliary arteries and, less commonly, by occlusion of the retinal arterioles. The early funduscopic findings consist of ischemic optic neuritis with a slight pallor and edema of the optic disk and scattered cotton-wool patches and small hemorrhages. These retinal changes usually follow the loss of vision.

Approximately 30 percent of patients have neurologic manifestations.⁴⁹ The most common are neuropathies (14 percent), including mononeuropathies and peripheral polyneuropathies of the arms or legs.⁵⁰ Less common neurologic findings are transient ischemic attacks or strokes in the territory of the carotid or vertebrobasilar artery.

Respiratory tract findings, including cough with or without sputum, sore throat, and hoarseness, occur in about 10 percent of patients.⁵¹ Musculoskeletal manifestations are common in patients with giant-cell arteritis. Polymyalgia rheumatica is the most frequent, occurring in around 40 percent of patients, but distal symptoms, such as peripheral arthritis and swelling and pitting edema of the hands and feet, may occur in 25 percent of patients.⁵²

In approximately 10 to 15 percent of patients, the branches of the aortic arch, particularly the subclavian and axillary arteries, become narrowed and result in claudication of the arms.⁵³ Bruits may be heard on auscultation over the carotid, subclavian, axillary, and brachial arteries. Pulses in the neck or arms may be decreased or absent. Patients with such symptoms may have few of the usual symptoms of giant-cell arteritis, so the diagnosis may initially be overlooked.

Thoracic aortic aneurysm is 17 times as likely in patients with giant-cell arteritis as in those without the disease.¹⁶ This complication occurs as a late event, usually several years after the diagnosis and often after other symptoms have subsided. The aneurysm may rupture and result in death. A yearly chest radiograph is adequate to screen for thoracic aortic aneurysm.

Laboratory Findings

An erythrocyte sedimentation rate of at least 40 mm per hour is considered an important diagnostic finding in patients with polymyalgia rheumatica. Some studies have reported that 7 to 20 percent of patients with polymyalgia rheumatica have a normal erythrocyte sedimentation rate at the time of diagnosis.⁵⁴ A markedly elevated erythrocyte sedimentation rate is also a hallmark of giant-cell arteritis. The criteria of the American College of Rheumatology include an erythrocyte sedimentation rate of at least 50 mm per hour as one of the five criteria found to be useful in the classification of giant-cell arteritis.¹⁹ However, up to 22.5 percent of patients with giant-cell arteritis have a normal erythrocyte sedimentation rate before treatment.²¹

A recent population-based study from the Mayo Clinic has reported that 5.4 percent of patients had an erythrocyte sedimentation rate of less than 40 mm per hour at diagnosis and that 10.8 percent had an erythrocyte sedimentation rate of less than 50 mm per hour.²¹ Therefore, the finding of a normal erythrocyte sedimentation rate is not incompatible with a diagnosis of active polymyalgia rheumatica or giant-cell arteritis when other clinical findings suggest these diagnoses and should not constitute a reason to delay corticosteroid therapy if other features of polymyalgia rheumatica or giant-cell arteritis are present.

The C-reactive protein level has been found to be a more sensitive indicator of disease activity than the erythrocyte sedimentation rate both at diagnosis and during relapse.^54,55,56 Levels of interleukin-6 appear to be a sensitive indicator of active disease, but most clinical laboratories do not yet have the means to measure these levels.⁵⁶ Most patients have a mild-to-moderate anemia of chronic disease, and approximately one third of patients have mildly abnormal liver-function tests. Tests for rheumatoid factor and antinuclear antibodies are usually negative.^17,39,45

Imaging

Scintigraphy, MRI, and ultrasonography are all useful in identifying proximal synovitis in patients with polymyalgia rheumatica.^34,35,57 Ultrasonography and MRI studies have shown that subacromial and subdeltoid bursitis is the most frequent lesion, present in almost all patients with polymyalgia rheumatica (Figure 2A and Figure 2B), and that these two techniques are equally effective in confirming the presence of bilateral subacromial and subdeltoid bursitis in such patients.⁵⁷ We have found that ultrasonography of the shoulders is sometimes useful to confirm the diagnosis in patients with atypical cases.⁵⁸

MRI has demonstrated that tenosynovitis is the prominent lesion in patients with polymyalgia rheumatica who have swelling and pitting edema of the hands and feet⁵⁹ (Figure 3B). A role for color duplex ultrasonography in the diagnosis of giant cell arteritis has been proposed by Schmidt et al.,⁶⁰ who found that a dark halo around the lumen of temporal arteries was specific for the diagnosis of giant-cell arteritis (Figure 4B). However, we found that ultrasonography does not increase the diagnostic accuracy of a careful physical examination⁶¹; therefore, we do not routinely use this technique.

If a diagnosis of extracranial giant-cell arteritis is suspected, arteriography, computed tomography (CT), and magnetic resonance angiography are the required diagnostic tests. On arteriography, the typical finding is bilateral stenosis or occlusion of the subclavian, axillary, and proximal brachial arteries, and these arteries have a smooth, tapered appearance (Figure 5A). Femoral arteries and their branches are less commonly involved. The best imaging technique to detect aortic aneurysms or dissections is CT (Figure 5B) or MRI (Figure 5C). The finding of a thickened aortic wall on CT or MRI is a direct indication of inflammation of the aortic wall (Figure 5C) and thus of active disease.⁶²