An adult case of congenital external carotid-jugular arteriovenous fistulawith reversible circulatory insufficiency in the cerebellum and lower brain stem

A 27-year-old man with congenital external carotid-jugular arteriovenous fi stula presented with a diminished level of consciousness and an ataxic gait . Axial fluid-attenuated inversion-recovery (FLAIR) MR imaging revealed ven ous congestion, a dilated right jugular vein, and an area of high signal in tensity in the brain stem and cerebellum. Angiography showed a dilated righ t external carotid artery and jugular vein and the presence of a fistula. A fter coil embolization of the fistula, axial MR FLAIR images showed only a few areas of high signal intensity in the brain stem and cerebellum. The ca usal factor was venous congestion in the inferior petrosal sinus and basila r plexus due to high blood pressure in the jugular vein. This case is prese nted for its unusual clinical and radiologic findings.