FIG 1. 27-year-old man with congenital external carotid–jugular arteriovenous fistula who presented with a diminished level of consciousness and an ataxic gait.

A, Axial FLAIR MR images (6000/120) on the day of hospital admission show venous congestion, a dilated right jugular vein, and an area of high signal intensity in the brain stem and cerebellum. A small infarction is visible in the temporal lobe.

B and C, Angiograms, frontal (B) and lateral (C) views, 1 day after admission show a dilated right external carotid artery and internal jugular vein and the presence of a fistula.

D, Brain CT studies 5 hours after angiography show congestion and edema.