Anatomic Feature and Preventive Strategy of Anterior Spinal Artery Occlusion in Endovascular Internal Trapping of Vertebral Artery Dissecting Aneurysms Distal to the Bifurcation of the Posterior Inferior Cerebellar Artery.

Background And Objectives: In endovascular internal trapping for intracranial vertebral artery dissecting aneurysms (VADAs) distal to the posterior inferior cerebellar artery bifurcation, anterior spinal artery (ASA) occlusion is a serious complication although it is relatively infrequent because of the presence of collateral blood vessels. In this article, we investigated the correlation between vascular anatomy and ischemic complications of the ASA.

Methods: We retrospectively evaluated 21 patients with ruptured PICA-distal type VADA treated by internal trapping at our affiliated institutions from 2008 to 2022. The parent arteries were embolized from the dilated segment to the normal vessel, with careful preservation of the perforating arteries and the ASA. Primary end points included ASA origin anatomy, ASA occlusion incidence, and ischemic complications in the medullary and spinal cord regions.

Results: The ASA originated from bilateral vertebral arteries (VAs), the contralateral VA, and the ipsilateral VA, in 7, 11, and 3 cases, respectively. Postoperative ASA occlusion was observed in 3 cases. In 2 of these cases, ischemic complications did not occur because of the presence of collateral flow from the ASA originating from the contralateral side. However, the third patient developed medullary cervical infarction because of occlusion of the ipsilateral ASA 5 hours after the treatment although the ASA had been preserved during intervention. In these 3 patients, the distance between the ASA and the distal coil end was shorter than that in nonobstructed cases. In addition, lateral medullary syndrome occurred in 1 case.

Conclusion: Cases of distal VADA with unilateral ipsilateral bifurcation of the ASA and proximity of the dissection site to the ASA origin carry the risk of severe medullary cervical infarction despite intraoperative preservation of the ASA. In such cases, strict postoperative management including antithrombotic therapy or alternative treatment modalities such as direct surgical VA trapping by clips should be considered.