GR.5 Incidence of orbital infarction syndrome following endovascular thrombectomy

Abstract

Background: Orbital infarction syndrome (OIS) is a rare entity defined as acute ischemia of intraorbital structures. Three case reports of OIS post-endovascular thrombectomy (EVT) have recently been published, two demonstrating absent choroid blush (CB) on digital subtraction angiogram (DSA). Our goals are to determine the true incidence of OIS post-EVT and to identify imaging findings (e.g. CB) that may alert neurologists to potential cases. Methods: A retrospective cohort study including all EVT patients from Health Sciences Center (HSC), Winnipeg in 2019-20 was performed. Patient charts were reviewed to determine the incidence of OIS. Pre- and post-EVT DSA images were reviewed, and the sensitivity and specificity of absent CB for OIS was calculated. Results: Out of 248 patients, 13 were excluded for incomplete charts, and 4 cases (1.7%) of OIS were discovered. During sensitivity/specificity analysis of absent CB for OIS, 51 patients were excluded for inadequate imaging. There were 4 true positives, 0 false-negatives, 113 true-negatives, and 67 false-positives; resulting in a sensitivity of 100% and worst-case scenario specificity of 63% (assuming all 51 indeterminate cases were false positives). Conclusions: OIS is rare post-EVT with an incidence of 1.7%. Absent CB is very sensitive for diagnosing OIS with lower specificity.