Background Despite its low incidence, basilar artery occlusion (BAO) remains a major therapeutic challenge since severe disability and death occur in about 80% of patients. Specific site of BAO (proximal, middle, or distal) has rarely been reported as a prognostic factor in reperfusion therapy. We aimed to explore the relationship between site-specific BAO and clinical outcomes in patients treated with reperfusion therapies.

Methods We performed a single-centre retrospective study of all consecutive patients with acute BAO admitted to the University Medical Centre Ljubljana between January 2013 and August 2022 who were treated with reperfusion therapies. Patients were grouped according to the location of BAO and compared for baseline characteristics, differences in stroke aetiology, type of reperfusion therapy, success of recanalization, and clinical outcome after 90 days evaluated by the modified Rankin Scale (mRS) score. Statistical analysis was performed with the two-sided ANOVA t-tests for continuous measures, Chi-squared (χ2) tests for categorical measures and a multivariate ordinal logistic regression analysis.

Results The study included 103 patients (47% females, median age 74 years; confidence interval (CI) 72 to 98). Proximal BAO was found in 13%, middle in 13%, and distal in 74% of patients. Cardioembolic etiology was more common in distal (=0.01), and atherosclerotic etiology in proximal and middle BAO occlusions (P=0.02). While distal BAO was more likely to be recanalized using intravenous thrombolysis (IVT) compared with other sites of occlusion (P=0.05), we found no difference between different occlusion sites and the success of endovascular treatment (EVT). Lower age (odds ratio (OR) 0.89; CI 0.84 to 0.95; P<0.01) and shorter time to intervention (OR 0.71; CI 0.53 to 0.95; P=0.02), regardless of it being IVT or EVT, were predictors of an excellent clinical outcome (mRS 0–2). Distal occlusion (OR 28; CI 2.7 to 300; p<0.01) was a strong predictor of a favorable clinical outcome (mRS 0–3).

Conclusion Prompt reperfusion, regardless of it being IVT or EVT, increases the chance of excellent clinical outcomes in patients with acute BAO. Distal BAO is more often associated with a favorable clinical outcome compared with the proximal and middle segments.