Endovascular Treatment for Lateral Wall Paraclinoid Aneurysms and the Influence of Internal Carotid Artery Angle

Abstract

Lateral wall paraclinoid aneurysms (LPA) are a rare type of aneurysm located on the lesser curve side of the internal carotid artery (ICA) bend, at the level of the anterior clinoid process. The objective of this study was to assess the influence of flexion of the ICA on the morphology of aneurysms and outcome of endovascular treatment. Between 2003 and 2018, we treated 643 cases of unruptured paraclinoid aneurysms with endovascular therapy in our institution. Of those cases, aneurysms projecting laterally on preoperative angiography were defined as LPA. The degree of bending of the ICA (ICA angle) was measured and statistically analyzed in relation to the aneurysm characteristics and the occlusion status after treatment. In all, 43 aneurysms were identified. ICA angle was positively correlated with the maximum dome size of the aneurysm ( P <0.01) and the aspect ratio ( P <0.01), and negatively correlated with the volume coil embolization ratio ( P <0.01). Complete occlusion (CO) was achieved in 23 cases (53.5%) immediately after treatment, and in 35 cases (81.4%) at follow-up. The mean ICA angle in the incomplete occlusion group was significantly larger than in the CO group ( P = 0.01). Larger ICA angle resulted in recurrence, whereas smaller ICA angle was more likely to obtain progressive thrombosis ( P = 0.02). Endovascular treatment for LPA was safe and effective. The degree of flexion of the ICA may contribute to the level of hemodynamic stress on the aneurysm, its morphology, and the embolization effect.

A Case of Horizontal Stent-assisted Coiling for an Aneurysm Arising from Fenestration of the Vertebral Artery: A Technical Case Report

“…The wide angle between the two branches accentuates the terminal type of intracranial aneurysm, potentially leading to incomplete occlusion. [20][21][22] Therefore, we did not apply the Enterprise Vascular Reconstruction Device (Codman Neurovascular, Raynham, MA, USA), a widely recognized stent for providing vascular straightening, owing to its longitudinal stiffness. 23)…”

Increased Carotid Siphon Tortuosity Is a Risk Factor for Paraclinoid Aneurysms

“…Evidence from compelling neuroimaging results suggests a relationship between increased carotid siphon tortuosity and paraclinoid aneurysms. Sugiyama et al ( 28 ) compared the carotid siphon to a meandering river in the natural world and reported that meandering rivers experience less erosion on the side with the lesser curve when compared with the side with the greater curve. Also, the riverbed is more easily formed on the side with the lesser curve and it experiences a lower flow velocity.…”

Stent-assisted coiling of unruptured paraclinoid aneurysms with wide neck or unfavorable dome-to-neck ratio: Results of ventral wall vs dorsal wall with propensity score matching analysis

“…24 In addition, when we compared dorsal and ventral group aneurysms, statistically significant differences were found in terms of follow-up angiographic outcomes. Sugiyama et al 25 reported that the degree of flexion of the ICA may change the hemodynamic stress and long-term outcomes following embolization of paraclinoid aneurysms. Kim et al 26 showed that paraclinoid aneurysms at different locations had different hemodynamic stress and progressive embolization effect, which may be caused by the curvature and twist of vessels.…”