Chiasmal Stroke in Patient With Atrial Fibrillation and Complete Occlusion of Right Internal Carotid Artery

Abstract

Fabian et al (1) recently published a case of “Chiasmal stroke following open-heart surgery” in the Journal, which described a 62-year-old man with total loss of vision in his right eye and loss of the temporal half of the vision in the left eye, and an otherwise normal neurologic examination. We report another case of chiasmal stroke. A 59-year-old man with probable myocarditis and a several month history of intermittent shortness of breath was diagnosed with atrial fibrillation with rapid ventricular rate and started on anticoagulation. Eight days later he experienced sudden complete vision loss in the right eye and loss of the temporal half of the visual field in the left eye. He was found to have an atrial thrombus and complete occlusion of his right internal carotid artery. Three days after acute vision loss, visual acuity was of no light perception, right eye, and 20/30, left eye. The right pupil was amaurotic. All other aspects of the examination, including appearance of the optic nerves, were normal. Automated perimetry demonstrated complete temporal field loss in the left eye respecting the vertical median (Fig. 1). His neurologic examination was normal.FIG. 1: Complete temporal visual field loss is present in the left eye.The day after vision loss, MRI of the brain showed an abnormality in the anterior chiasm on the right (Fig. 2). In addition, there was occlusion of the right internal carotid artery, an acute small left cerebellar infarct, and white matter changes consistent with small vessel ischemia.FIG. 2: Chiasmal infarction. A. Diffusion-weighted imaging shows bright signal (arrowhead) in the anterior chiasm on the right and apparent diffusion coefficient map (not shown) confirmed restricted diffusion. B. Coronal fluid-attenuated inversion recovery (FLAIR) image reveals a signal abnormality (arrow) in the same location.This patient had normal laboratory values for rapid plasma reagin and anti-neutrophil cytoplasmic antibody. Acute chiasmal infarction is a rare event, presumably because of its redundant and complex blood supply. To date, the only other report of chiasmal infarct was in a patient with acquired immunodeficiency syndrome, mucormyosis, and diabetes mellitus (2). We believe that the cause of our patient's infarction was stroke, with embolus from a left atrial thrombus.