Characterization of "Perfusion Scotoma" in Acute Ischemic Stroke Following Endovascular Treatment

CT-perfusion (CTP) may underestimate the size of the ischemic core, a phenomenon known as "perfusion scotoma". We aimed to investigate the prevalence of perfusion scotoma, characterize its baseline predictors, and explore its association with functional outcomes in a real-world population of stroke patients treated with endovascular treatment (EVT).

Data were obtained from a prospective EVT registry, selecting patients with successful recanalization (final mTICI ≥2b), a good quality baseline CTP, and an available 24-hour non-contrast CT. Ischemic core underestimated volume (ICuV) was calculated as the difference between follow-up infarct volume and CTP-estimated ischemic core. The primary outcome was the presence of perfusion scotoma, defined as ICuV ≥10 mL. Baseline characteristics with p value <0.20 in univariable comparisons were entered in a backward stepwise, multivariable logistic regression analysis to identify factors independently associated with perfusion scotoma.

A total of 464 patients of 672 (69%) were included in the analysis. The median age was 74 years (IQR=68-83), 215 (46.3%) were males, and 116 (25%) had a perfusion scotoma. Perfusion scotoma was independently associated with male sex (adjusted OR 1.62 [95%CI 1.01-2.51]; p=0.04), more distal site of occlusion (adjusted OR 1.60 [95%CI 1.10-2.34]; p=0.01; per each 1-point increase: terminal ICA to M1 to M2), lower ASPECTS at admission (adjusted OR 0.64 [95%CI 0.54-0.76]; p<0.001; per each 1-point increase), and longer onset-to-CT time (adjusted OR 1.05, [95%CI 1.01-1.10]; p=0.03; per each 1-hour increase). The optimal onset-to-CT time cutoff to distinguish between patients without and with perfusion scotoma was 420 minutes. Perfusion scotoma was associated with 90-day ordinal mRS (adjusted common OR [acOR] 3.16 [95%CI 2.12-4.76]).

Perfusion scotoma occurred in 1 out of every 4 patients. Baseline predictors included male sex, lower ASPECTS, more distal vessel occlusion, and longer onset-to-CT time. Perfusion scotoma was associated with poorer functional outcomes.