Prognostic impact of infarction location on clinical outcome following endovascular treatment for posterior circulation stroke: a preliminary study

Abstract

This preliminary study looked at how the location of infarction in posterior circulation (PC) strokes affects clinical outcomes after endovascular treatment (EVT), with the aim of improving case selection. We retrospectively reviewed 42 patients with PC ischemic stroke who underwent urgent EVT over five years. Both clinical and radiological data were analysed. Based on diffusion-weighted imaging (DWI) and novel PC scores, patients were divided into three groups. These involved the non-brainstem group, which showed infarctions in the occipital lobe, thalamus, and cerebellum; the brainstem group, which included injuries in the midbrain, pons, and medulla; and the mixed group. Univariate and multivariate logistic regression analyses were used to compare safety and functional outcomes at three months after EVT, measured by the Modified Rankin Score (mRS). The mixed group had the most severe clinical presentations, as shown by higher NIHSS and novel PC imaging scores followed by brainstem group and then the non-brainstem group. Successful recanalization rates after EVT were similar across all groups (P = 0.840). However, patients without brainstem involvement had significantly better functional outcomes, including favorable (P-value: < 0.001), independent (P-value: 0.047), and outstanding (P-value: 0.006) mRS grades at three months. For safety outcomes, symptomatic intracerebral hemorrhage rates were similar among the groups (P = 0.275), but mortality was much higher in the mixed group (70%) and brainstem group (43.8%) than in the non-brainstem group (6.3%). After adjustment for other prognostic factors, a significant difference remained between the brainstem group and the non-brainstem group (aOR 37; 95% CI: 1.075–79.9; P-value: 0.021). Although successful recanalization was achieved in patients with PC stroke after EVT, infarction location—especially brainstem involvement—may be an associated factor to consider alongside other prognostic variables when deciding on EVT management. This is especially relevant because outcomes for brainstem lesions tend to be poor, even with EVT. However, the need for validation of these findings in larger cohorts is highly recommended.