Indication and Pitfall of Endovascular Treatments for Unruptured Dissecting Aneurysms

We reviewed 55 unruptured dissecting aneurysms treated in Nagoya University and its affiliated hospitals over the last 7 years, and investigated the indications and pitfalls of such endovascular treatments. Among 55 aneurysms, 38 were endovascularly treated. The aneurysms were located on the vertebral artery (VA) in 47, the anterior cerebral artery in 3, middle cerebral artery in 1, and the posterior cerebral artery (PCA) in 4. As for the clinical presentation, ischemic symptoms was found in 22 cases, and headaches without neurological symptoms occurred in 27 patients. Five patients had bilateral lesions, including 3 aneurysms with 1 ruptured on the contralateral side. Thirty aneurysms were treated with endovascular trapping. A worsening of ischemic symptoms by trapping of VA was experienced in 5 cases in which the posterior inferior cerebellar artery (PICA) was hypoplastic or the aneurysm located far from the PICA origin. Two of 14 patients during the follow-up period showed complete thrombosis with parent artery occlusion, and 1 aneurysm underwent a spontaneous reduction in size. No aneurysms recurred or ruptured after endovascular trapping. According to our analysis, endovascular treatments proved very useful in avoiding the rupture of dissecting aneurysms. However, dissecting aneurysms of VA with hypoplastic PICA should be carefully performed. The aneurysms with the tendency for spontaneous regression should be followed up without surgical sacrifice of the parent artery. A targeted treatment strategy is needed against unruptured lesions following multiple dissections with SAH as well as parent artery stenosis at the dissection site.