Background and purposeBetter 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.MethodsFrom a multicenter retrospective database, we extracted all patients with both National Institutes of Health Stroke Scale (NIHSS) score <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 24 h. 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.ResultsSeventy‐four patients were included, amongst whom 22 (30%) patients experienced END. Amongst pre‐treatment variables, suprabulbar carotid occlusion was the only admission predictor of END following stepwise variable selection (odds ratio = 4.0, 95% confidence interval: 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 toward higher carotid recanalization rate in END patients (29% vs. 9%, P = 0.07). As compared to no‐END, END was strongly associated with a poor 3‐month outcome.ConclusionsEarly neurological deterioration is a frequent and highly deleterious event after IVT for minor stroke with iICAo, and is of thromboembolic origin in three out of four 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.

Background: We recently reported a worrying 30% rate of early neurological deterioration (END) occurring within 24 hours following intravenous thrombolysis (IVT) in minor stroke with isolated internal carotid artery occlusion (ie, without additional intracranial occlusion), mainly due to artery-to-artery embolism. Here, we hypothesize that in this setting IVT—as compared to no-IVT—may foster END, in particular by favoring artery-to-artery embolism from thrombus fragmentation. Methods: From a large multicenter retrospective database, we compared minor stroke (National Institutes of Health Stroke Scale score <6) isolated internal carotid artery occlusion patients treated within 4.5 hours of symptoms onset with either IVT or antithrombotic therapy between 2006 and 2020 (inclusion date varied among centers). Primary outcome was END within 24 hours (≥4 National Institutes of Health Stroke Scale points increase within 24 hours), and secondary outcomes were END within 7 days (END 7d ) and 3-month modified Rankin Scale score 0 to 1. Results: Overall, 189 patients were included (IVT=95; antithrombotics=94 [antiplatelets, n=58, anticoagulants, n=36]) from 34 centers. END within 24 hours and END 7d occurred in 46 (24%) and 60 (32%) patients, respectively. Baseline clinical and radiological variables were similar between the 2 groups, except significantly higher National Institutes of Health Stroke Scale (median 3 versus 2) and shorter onset-to-imaging (124 versus 149min) in the IVT group. END within 24 hours was more frequent following IVT (33% versus 16%, adjusted hazard ratio, 2.01 [95% CI, 1.07–3.92]; P =0.03), driven by higher odds of artery-to-artery embolism (20% versus 9%, P =0.09). However, END 7d and 3-month modified Rankin Scale score of 0 to 1 did not significantly differ between the 2 groups (END 7d : adjusted hazard ratio, 1.29 [95% CI, 0.75–2.23]; P =0.37; modified Rankin Scale score of 0–1: adjusted odds ratio, 1.1 [95% CI, 0.6–2.2]; P =0.71). END 7d occurred earlier in the IVT group: median imaging-to-END 2.6 hours (interquartile range, 1.9–10.1) versus 20.4 hours (interquartile range, 7.8–34.4), respectively, P <0.01. Conclusion: In our population of minor strokes with iICAO, although END rate at 7 days and 3-month outcome were similar between the 2 groups, END—particularly END due to artery-to-artery embolism—occurred earlier following IVT. Prospective studies are warranted to further clarify the benefit/risk profile of IVT in this population.