Table 1.

Denver dissection grading system in blunt blunt cerebrovascular injury and associated stroke rates. A grade I injury heals regardless of therapy. 70% of grade II dissections progress whilst on heparin therapy. Only 8% of pseudoaneurysms (grade III) healed with heparin, about 89% resolves after endovascular stenting. Occluded carotid arteries (grade IV) does not recanalize in the early post-injury period. Grade V injuries (transections) are lethal and refractory to intervention. Stroke risk increases with injury grade.

Grade	Type of Dissection	Stroke in Carotid Artery Dissection (%)	Stroke in Vertebral Artery Dissection (%)
I	Luminal irregularity or dissection with <25% luminal narrowing	3	19
II	intimal flap or intramural hematoma with luminal narrowing ≥ 25% or intraluminal thrombus	11	40
III	Pseudoaneurysm	33	13
IV	Total occlusion	44	33
V	Transection and free bleeding	100	N/A