Behavior of Extracranial-to-Intracranial Extended Arterial Dissections of the Vertebral Artery.

Background: Vertebral artery dissections (VADs) may extend from the extracranial to the intracranial vasculature (e+iVAD). We evaluated how the characteristics of e+iVAD differed from those of intracranial VAD (iVAD).

Methods And Results: From 2002 to 2019, among consecutive patients with cervicocephalic dissection, those with iVAD and e+iVAD were included, and their clinical characteristics were compared. In patients with unruptured dissections, a composite clinical outcome of subsequent ischemic events, subsequent hemorrhagic stroke, or mortality was evaluated. High-resolution magnetic resonance images were analyzed to evaluate intracranial remodeling index. Among 347 patients, 51 (14.7%) had e+iVAD and 296 (85.3%) had iVAD. The hemorrhagic presentation occurred solely in iVAD (0.0% versus 19.3%), whereas e+iVAD exhibited higher ischemic presentation (84.3% versus 27.4%; <0.001). e+iVAD predominantly presented steno-occlusive morphology (88.2% versus 27.7%) compared with dilatation patterns (11.8% versus 72.3%; <0.001) of iVAD. The ischemic presentation was significantly associated with e+iVAD (iVAD as a reference; adjusted odds ratio, 3.97 [95% CI, 1.67-9.45]; =0.002]). Patients with unruptured VAD showed no differences in the rate of composite clinical outcome between the groups (log-rank, =0.996). e+iVAD had a lower intracranial remodeling index (1.4±0.3 versus 1.6±0.4; <0.032) and a shorter distance from dural entry to the maximal dissecting segment (6.9±8.4 versus 15.7±7.4; <0.001).

Conclusions: e+iVAD is associated with lower rates of hemorrhages and higher rates of ischemia than iVAD at the time of admission. This may be explained by a lower intracranial remodeling index and less deep intrusion of the dissecting segment into the intracranial space.