Early neurological deterioration following thrombolysis for minor stroke with isolated internal carotid artery occlusion.

BACKGROUND Better understanding the incidence, predictors and mechanisms of early neurological deterioration (END) following intravenous thrombolysis (IVT) for acute stroke with mild symptoms and isolated internal carotid artery occlusion (iICAo) may inform therapeutic decisions. METHODS From a multicenter retrospective database we extracted all patients with both NIHSS<6 and iICAo (i.e. not involving the Willis circle) on admission imaging, intended for IVT alone. END was defined as ≥4 NIHSS points increase within 24hrs. END and no-END patients were compared for i) pre-treatment clinical and imaging variables, and ii) occurrence of intracranial occlusion, carotid recanalization and parenchymal hemorrhage on follow-up imaging. RESULTS Seventy-four patients were included, among whom 22 (30%) patients experienced END. Among pre-treatment variables, supra-bulbar carotid occlusion was the only admission predictor of END following stepwise variable selection (OR=4.0; 95%CI 1.3-12.2; P=0.015). On follow-up imaging, there was no instance of parenchymal hemorrhage but an intracranial occlusion was now present in 76% vs. 0% of END and no-END patients, respectively (P<0.001), and there was a trend towards higher carotid recanalization rate in END patients (29% vs. 9%, P=0.07). As compared to no-END, END was strongly associated with poor 3-month outcome. CONCLUSIONS END is a frequent and highly deleterious event after IVT for minor stroke with iICAo, and is of thrombo-embolic origin in 3 out of 4 patients. The strong association with iICAo site -largely a function of underlying stroke etiology- may point to a different response of the thrombus to IVT. These findings suggest END may be preventable in this setting.