Carotid-cavernous fistula with brainstem congestion mimicking tumor on MRI.

Article abstract-A 65-year-old woman presented with a left abduction deficit and "red eye," mild proptosis, chemosis, arterialization of the conjunctival vessels, intention tremor, and bilateral pyramidal signs. MRI showed significant left-sided brainstem involvement that mimicked a tumor. Right hemiplegia ensued 1 week later. Venous congestion of the brainstem with hemiplegia resulting from shunting of blood flow from both carotid arteries is an extremely rare complication of carotid-cavernous fistula.