Abstract 3444: Characteristics and Prognostic Significance of Pseudodissection Phenomenon Associated with Acute Distal Internal Carotid Artery Occlusion

Abstract

Background: Acute stroke from intracranial internal carotid artery (ICA) occlusion can occasionally resemble angiographic cervical ICA dissection which may cause delays in endovascular acute stroke treatment. Objective: To determine the angiographic characteristics of the phenomemon of “pseudodissection” and its clinical implications in acute stroke endovascular treatment. Material and Methods: Retrospective analysis of angiographic and clinical data of 31 patients with acute stroke from ICA occlusion, treated with endovascular therapy at two University affiliated institutions was performed. Pseudodissection was defined as angiographic appearance of typical ICA dissection with evidence of normal inner vascular wall upon further catheter exploration. A cadaver model was then created duplicating intracranial ICA occlusion to demonstrate out hypothesis. Results: Angiographic appearance pseudodissection was identified in 7 out of 31 patients (22.6%). Six patients had guide catheters placed proximal to pseudodissection in anticipation of stent placement for treatment of dissection. All 7 patients had further exploration of the presumed dissected segment (6 microcatheter, 1 diagnostic catheter) which demonstrated normal vascular inner wall. The location of the clot was more common in the petro-cavernous segment in the pseudodissection patients (5/7, 71%). Carotid terminus clot was more common in non pseudodissection patients compared to pseduodissection patients (18/24, 75% versus 2/7, 29% respectively, p < 0.0001). Recanalization was less common in pseudodissection patients compared to non pseudodissection patients (3/7 and 21/24 respectively, p 0.029). We then created a cadaver model with intracranial ICA occlusion at the level of posterior communicating artery to demonstrate the phenomenon of pseudodissection as result of lack of contrast runoff in a closed vessel system. Conclusion: Early recognition of pseudodissection in the ICA is important in the setting of acute stroke to avoid delay in treatment of intracranial ICA occlusion. This phenomenon is probably seen in the setting of distal ICA occlusion which prohibits any fluid transit through the vessel.