A case is reported of a 53-year-old woman who was hit by a bullet which penetrated the skull base and caused a left carotid-cavernous fistula of the direct type and a pseudoaneurysmal dilation of the high cervical portion of the left internal carotid artery. The fistula was successfully embolized by positioning a balloon into the fistula itself by means of the Debrun technique: unexpectedly the size of the pseudoaneurysm decreased after the embolization; the possible explanations for this event are discussed.