Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 75-year-old woman is evaluated for a sudden loss of vision in the left eye that began 30 minutes ago. She has a 2-week history of fatigue; malaise; and pain in the shoulders, neck, hips, and lower back. She also has a 5-day history of mild bitemporal headache.

On physical examination, temperature is 37.3 °C (99.1 °F), blood pressure is 140/85 mm Hg, pulse rate is 72/min, and respiration rate is 16/min. BMI is 31. The left temporal artery is tender. Funduscopic examination reveals a pale, swollen optic disc. Range of motion of the shoulders and hips elicits moderate pain.

Laboratory studies:

Hemoglobin	9.9 g/dL (99 g/L)
Leukocyte count	7300/µL (7.3 × 109/L)
Platelet count	456,000/µL (456 × 109/L)
Erythrocyte sedimentation rate	116 mm/h

Which of the following is the most appropriate next step in this patient’s management?

A) Brain MRI
B) High-dose intravenous methylprednisolone
C) Low-dose oral prednisone
D) Temporal artery biopsy

MKSAP Answer and Critique

The correct answer is B) High-dose intravenous methylprednisolone. This item is available to MKSAP 15 subscribers as item 10 in the Pulmonary and Critical Care Medicine section. More information about MKSAP 15 is available online.

This patient’s headache, temporal artery tenderness, acute visual loss, fever, and mild anemia are strongly suggestive of giant cell arteritis (GCA). Immediate high-dose intravenous methylprednisolone is indicated for this patient. Pain in the shoulder and hip girdle accompanied by a significant elevation in the erythrocyte sedimentation rate is consistent with polymyalgia rheumatica, which is present in approximately 33% of patients with GCA. Anterior ischemic optic neuropathy usually causes acute and complete visual loss in patients with GCA, and funduscopic examination of these patients typically reveals a pale, swollen optic nerve.

Rarely, patients with GCA regain vision if treated immediately with high doses of an intravenous corticosteroid such as methylprednisolone (1 g/d or 100 mg every 8 hours for 3 days) followed by oral prednisone (1 to 2 mg/kg/d). More importantly, this aggressive regimen helps to prevent blindness in the contralateral eye. Therefore, although temporal artery biopsy is the gold standard for diagnosing GCA, diagnostic testing should not precede treatment in patients whose clinical presentation is suspicious for this condition.

Even in the absence of visual loss, GCA is a medical emergency. In a patient whose condition is suspicious for GCA but who does not have visual loss, immediate initiation of high-dose oral prednisone before diagnostic testing is performed also is indicated. Whether intravenous corticosteroid therapy is more effective than oral administration of prednisone for patients with GCA and visual loss remains uncertain. Nevertheless, intravenous therapy seems reasonable in this circumstance and is recommended by many experts, even though rigorous studies have not validated this approach. However, it is clear that low-dose oral prednisone, which is an adequate treatment for isolated polymyalgia rheumatica, does not sufficiently treat GCA.

A process in the brain is unlikely to cause monocular visual loss, and patients with GCA typically have normal findings on brain MRI. Therefore, this study would most likely be unhelpful in this patient.

In patients whose condition raises a strong suspicion of GCA, temporal artery biopsy should be performed after corticosteroid therapy is begun. Corticosteroid therapy will not affect the results of temporal artery biopsy as long as biopsy is performed within 2 weeks of initiating this therapy; positive biopsy results have been seen as late as 6 weeks after institution of high-dose corticosteroid therapy, but the yield of biopsy is higher when this study is performed sooner.

Key Point

• In patients whose clinical presentation is suspicious for giant cell arteritis, corticosteroid therapy should be instituted immediately, before diagnostic testing is performed.

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