Prognostic Significance of Infarct Size and Location: The Case of Insular Stroke

Carlos Laredo,Yashu Zhao,Salvatore Rudilosso,Ángel Chamorro,Xabier Urra,Arturo Renú,José Carlos Pariente

doi:10.1038/s41598-018-27883-3

Abstract

The prognostic relevance of strokes in different locations is debated. For example, insular strokes have been associated with increased mortality, but this association could reflect their greater severity. In two independent cohorts of patients with supratentorial ischemic stroke (n = 90 and 105), we studied the prognostic consequences of lesion size and location using voxel-based lesion-symptom mapping before and after volume control, which better accounts for total lesion volume. Strokes affecting the insula were larger than non-insular strokes (28 vs 2cc and 25 vs 3cc, p < 0.001 in both cohorts). A number of supratentorial areas (mainly in the left hemisphere), including the insula, were associated with poor functional outcome in both cohorts before (4014 voxels) and after volume control (1378 voxels), while the associations with death were greatly reduced after volume control (from 8716 to 325 voxels). Exploratory analyses suggested that the method of lesion volume quantification, the National Institutes of Health Stroke Scale hemispheric bias and patient selection can result in false associations between specific brain lesions and outcomes. In conclusion, death in the first months after stroke is mainly explained by large infarct volumes, whereas lesions of specific supratentorial structures, mostly in the left hemisphere, also contribute to poor functional outcomes.

Highlights

Overall, there are conflicting results in the literature regarding the prognostic relevance of lesions in different brain areas, including the involvement and laterality of insular lesions
Used conventional voxel-based lesion symptom mapping (VLSM) in magnetic resonance imaging (MRI) images, and VLSM after volume control (VC), to better account for the effects related to total lesion size[43]
The lesion overlays in both cohort 1 (C1) and cohort 2 (C2) showed that patients with poor outcomes had larger lesions compared with patients with better outcomes, and this was apparent in the case of death: the lesions were homogeneously distributed over the entire hemispheric territory in patients who died (Fig. 1a)

Summary

Introduction

There are conflicting results in the literature regarding the prognostic relevance of lesions in different brain areas, including the involvement and laterality of insular lesions. Recent studies have reopened the discussion on the clinical relevance of insular involvement in stroke patients[25,40,41,42], suggesting that the use of variable techniques to adjust for the influence of infarct size could explain some of the current discrepancies. We tried to overcome some of the limitations of previous reports on the contribution of stroke size and specific supratentorial lesions to death and poor functional outcome. We were able to describe the contribution of the size of the stroke and the lesion of specific brain areas to the occurrence of death and poor functional outcome in patients with ischemic stroke

Methods

Results

Conclusion