Diagnosing Amaurosis Fugax with Emergency Ultrasound

A 66-year-old man with a history of hypertension presented to the emergency department with transient visual loss in his right eye. Physical examination revealed visual acuity of 20/30 in the unaffected eye and 20/40 in the affected eye with corrective lenses. With the exception of unilateral quadrantonopia in the affected eye on visual field testing, the physical exam, including a full neurologic examination, revealed no additional abnormalities.

Given the history of transient visual loss followed by a visual field deficit, the emergency physician suspected amaurosis fugax and performed a bedside ultrasound of the right carotid artery using a 12-3 MHz linear array transducer (Model HD11XE, Philips, Andover, MA). This exam was performed by placing the transducer over the right anterior neck and obtaining grayscale views of the common carotid artery in both longitudinal and transverse planes (Video Clips S1 and S2, available as supporting information). The exam demonstrated a near-complete occlusion of the distal common carotid artery, with fresh thrombus and reversal of diastolic flow (Figure 1). Noncontrast computed tomography revealed no acute abnormality, and the patient was admitted to the neurology service where angiography confirmed the severe carotid stenosis. The patient underwent an uncomplicated carotid end-arterectomy.

Figure 1.  Spectral Doppler image demonstrating reversal of diastolic flow in the distal common carotid artery. Note the high-velocity flow toward the transducer (above the baseline) in systole (s) and low-velocity flow away from the transducer (below the baseline) in diastole (d).