Figure 13. Traumatic vascular dissection of the supraclinoid internal carotid artery.

CTA (A) performed the day after injury shows asymmetric narrowing and luminal irregularity of the left internal carotid artery (ICA) (arrow) just beyond the anterior clinoid process concerning for traumatic dissection. Note the air-hemorrhage level within the left sphenoid sinus (A) which should raise suspicion anterior skull base fracture (not shown) and potential injury to the adjacent carotid artery. Dissection of the left supraclinoid ICA was confirmed the same day on digital subtraction angiography (B), which again revealed an irregular, narrowed lumen (arrow). Time of flight MR angiogram (C) performed 3 days after injury shows a narrowed irregular lumen of the left supraclinoid ICA (arrow). T1WI (D) from the same examination reveals subtle T1-shortening (arrow) in the left ICA wall, consistent with early subacute methemoglobin blood products within a dissecting intramural hematoma. Noncontrast CT (E) and diffusion weighted MRI (F) obtained 2 and 3 days after injury, respectively, show that the patient's dissection was complicated by an acute left middle cerebral artery territory embolic infarction.