An atypical presentation of giant cell arteritis.

emergency department with difficulty walking, dizziness and double vision that had lasted for one week. He had previously experienced several weeks of temporal head ache and weight loss. Abnormal findings on neur o logic examination included upbeat nystagmus, gaze palsy when looking to the right and gait ataxia. Diffusion-weighted magnetic resonance imaging (MRI) showed multiple, small, acute and subacute infarcts in the pons, cerebellar hemispheres and occipital lobes. A computed tomography (CT) angiogram showed bilateral concentric thickening of the walls of the vertebral arteries extracranially (Figure 1) with irregular, concentric stenoses of these arteries from the subclavian artery to the upper cervical vertebrae. The radiologic differential diagnosis included bilateral dissection of the vertebral arteries, but it did not include giant cell arteritis. Our patient was given treatment with intravenous heparin, followed by warfarin for the presumed dissection. After four weeks in hospital, he was discharged to a stroke rehabilitation facility. Six weeks after being discharged from hospital, the patient was readmitted with a decreased level of consciousness, dysarthria and worsening ataxia. A diffusion-weighted MRI showed new infarcts in the pons, cerebellum and midbrain. A magnetic resonance angiogram showed severely diminished blood flow in his basilar artery, as well as extensive multifocal areas of diminished flow within the vertebral arteries. A new, moderately severe, area of stenosis within the petrous portion of his left internal carotid artery was evident (Figure 2). The rapid progression of changes in the large vessels led to the consideration of vasculitis as a possible diagnosis. Our patient’s erythrocyte sedi mentation rate was 30 mm/h (the upper limit of normal varies between laboratories, but it is 6 mm/h at our institution) and his C-reactive protein level was 25 (normal < 8) mg/L. When adjusted for age, the erythrocyte sedimentation rate could be interpreted as normal (upper limit of normal of the the age-adjusted rate for men is calculated as age in years ÷ 2; for women, it is calculated as [age in years + 10] ÷ 2). His hemoglobin level was normal, and laboratory markers of systemic vasculitis were negative. Given the initial involvement of large, extra cranial arteries, our patient’s advanced age and his continued weight loss, giant cell arteritis rather than primary central nervous system angiitis became our working diagnosis. Treatment Cases