Background The association between pretreatment brain stem infarction and thrombectomy outcomes remains to be elucidated in patients with acute basilar artery occlusion (BAO). We aimed to assess the association between pretreatment pontine infarction and extremely poor outcome in patients who underwent endovascular thrombectomy due to acute BAO.

Methods We retrospectively reviewed data from a stroke database to identify patients with acute BAO who underwent thrombectomy between January 2011 and August 2019. Patient characteristics, pretreatment diffusion-weighted imaging (DWI) data, and outcomes were evaluated. The largest infarct core was expressed as the percentage of infarct core area in each brain stem region on the DWI slice displaying the largest lesion. Extremely poor outcome was defined as a 90-day modified Rankin Scale score of 5 or 6.

Results A total of 113 patients were included, 37 of whom had extremely poor outcome. Among the 15 patients with extensive pontine infarction (largest pontine infarct core of ≥70%), 93.3% had extremely poor outcome. Multivariate logistic regression analysis revealed that the following variables were independent predictors of extremely poor outcome: extensive pontine infarction (adjusted OR 22.494; 95% CI 2.335 to 216.689; p=0.007), posterior circulation ASPECTS on DWI (adjusted OR per 1-point decrease 1.744; 95% CI 1.197 to 2.541; p=0.004), age (adjusted OR per 1-year increase 1.067; 95% CI 1.009 to 1.128; p=0.023), and baseline NIHSS (adjusted OR per 1-point increase 1.105; 95% CI 1.004 to 1.216; p=0.040).

Conclusion Our results showed that a large pontine infarct core of ≥70% on pretreatment DWI was strongly associated with extremely poor outcome among patients treated with endovascular thrombectomy for acute BAO.