The Strategy of Endovascular Treatment for Ruptured Vertebral Artery Dissecting Aneurysm, Based on Its Location Relating to the Position of the Posterior Inferior Cerebellar Artery Origin

Objective: We evaluated the outcomes of endovascular therapy for ruptured vertebral artery dissecting aneurysm (VADA), focusing on its location relating to the posterior inferior cerebellar artery (PICA) origin. Materials and Methods: Patients with ruptured VADA, treated in our hospital from January 2007 to July 2015, were divided into four groups with respect to the location of the PICA origin. In seven patients, the dissecting segment involved the origin of the PICA (PICA origin type). In all, 10 patients had dissection distal to the origin of the PICA (PICA distal type). In the remaining two patients, there was no definite PICA (non-PICA type). There were no patients with dissection proximal to the origin of the PICA (PICA proximal type). The postoperative course was retrospectively compared between the groups. Results: Endovascular parent artery occlusion just proximal to the PICA origin was performed in the PICA origin group, whereas parent artery occlusion involving the whole dissected segment was performed for the other groups. In the PICA origin group, although re-bleeding had occurred in one patient, the modified Rankin scale score 3 months after the surgery, was less than 3 in all patients. Cerebral infarctions occurred in six patients in the PICA distal group and two patients in the non-PICA group. All two patients in the non-PICA group experienced medullary infarction, which occurred in only one patient in the PICA distal group. Conclusion: Parent artery occlusion just proximal to the PICA in the PICA origin group is effective, but frequent follow-up is necessary to evaluate increase in the blood flow to the residual dissection due to newly developed collaterals. Embolization in the short segment is advised in the PICA distal group to minimize the risk of cerebral infarction due to occlusion of the perforating arteries. Avoiding medullary infarction in treating the non-PICA group remains a challenge.