Surgical Treatment of Posterior Circulation Aneurysms – Anatomical Study and Surgical Technique

Abstract

Posterior circulation aneurysms represent 10–15% of intracranial aneurysms. The diagnosis is usually secondary to subarachnoid hemorrhage due to its initial asymptomatic presentation and higher risk of rupture compared with aneurysms in the anterior circulation. The surgical treatment of posterior circulation aneurysms is complex and challenging for neurosurgeons because of the particular anatomy of the posterior circulation with its close relation to the brainstem and cranial nerves and also because of the depth and narrowness of the surgical approach. Aneurysms from different locations have specific anatomical relationships and surgical approaches for better visualization and dissection. Therefore, a detailed anatomy knowledge of the posterior circulation is mandatory for an individualized preoperative planning and good neurological and angiographic outcomes. We selected the main aneurysm sites on the posterior circulation, such as: posterior inferior cerebellar artery, basilar trunk, basilar bifurcation, posterior cerebral artery (PCA) and superior cerebellar artery for a detailed description of the relevant anatomy related to aneurysm, and the main surgical approaches for its surgical treatment. Furthermore, we performed a literature review with the most recent outcomes regarding to the surgical treatment of posterior circulation aneurysms.

Management of a ruptured posterior inferior cerebellar artery (PICA) aneurysm with end-to-end in situ bypass: Case report

“…Saccular lesions are hemodynamically generated lesions that usually appear in bifurcations or curves of the vessels and can be treated surgically or endovascularly without sacrificing the parent vessel. Fusiform aneurysms appear spontaneously anywhere in the course of the vessel as a result of dissection [ 13 ].…”

“…Dissecting aneurysms of the PICA are very rare, present a high risk of bleeding, and are generally not amenable for clipping. Exclusion of these ruptured aneurysms can be performed by endovascular or microsurgical route, sacrificing the affected artery, or by revascularization of the PICA territory, which is only achieved by the microsurgical technique [ 2 , 4 , 5 , 11 , 13 ].…”

“…PICA aneurysms have a better application of the IC-IC bypass than any other aneurysms. This fact occurs due to the proximity of the two PICAs and their branches, allowing several possibilities for IC-IC bypass [ 1 , 2 , 13 ].…”

“…In the case reported, as it is a PICA-p3 segment PICA dissecting aneurysm, we opted for reanastomosis through in situ bypass to bypass the aneurysm. In cases with dominant PICA, it is preferable to avoid reanastomosis through the altero-lateral bypass of the two PICAs, due to the risk of compromising the dominant PICA and risk of ischemia in case the anastomosis is not satisfactory due to bypass occlusion or prolonged temporary clipping [ 1 , 2 , 13 ].…”

“…Emergency treatment is vitally important in patients with ruptured PICA aneurysms. Exclusion of these ruptured aneurysms can be performed endovascularly or microsurgically by sacrificing the parent artery, or by revascularization of the PICA territory which is only achieved by the microsurgical technique [ 1 , 2 , 4 , 13 ].…”