Background Contrast-induced encephalopathy (CIE) is an increasingly observed complication following neurointervention, but remains poorly defined with limited evidence for clinical decision-making. We sought to characterize the stereotypical clinical features of CIE in a nationwide, multicenter cohort.

Methods A multicenter cohort study was conducted between 10 neurovascular sites across Australia. Patients were screened according to the previously proposed Australian diagnostic criteria. Descriptive analysis was conducted to characterize the clinical course and outcomes of CIE, and associations between clinical and radiological variables on patient outcomes were analyzed using Fisher’s exact and χ2 tests.

Results A total of 56 patients (median age 65 years) were included. The median contrast volume was 170 mL (IQR 140–229). Median time to symptom onset was 6 hours (IQR 1–12), with frequent symptoms including motor deficit (55.4%), dysphasia (39.3%), and confusion (35.7%). Common radiological findings included sulcal effacement (45.5%) and subarachnoid contrast staining (30.9%) on CT. Hemianopia (p=0.001) and cortical blindness (p=0.018) were associated with posterior circulation interventions, while motor deficit was correlated with anterior circulation interventions (p=0.001). At discharge, 87.5% of patients achieved complete resolution of symptoms, of which 69.4% achieved complete recovery within 72 hours.

Conclusion CIE is a recognized complication of neurointervention. Symptoms occur within hours of contrast administration and correlate with the territory of contrast administration. Most patients achieve complete symptom resolution. Ongoing investigation is required to further define CIE as a clinical entity.