Lesions in putative language and attention regions are linked to more severe strokes in patients with higher white matter hyperintensity burden
Authors: Bonkhoff Anna K. , Hong Sungmin , Bretzner Martin , Schirmer Markus D. , Regenhardt Robert W. , Arsava E. Murat , Donahue Kathleen L. , Nardin Marco J. , Dalca Adrian V. , Giese Anne-Katrin , Etherton Mark R. , Hancock Brandon L. , Mocking Steven J. T. , McIntosh Elissa C. , Attia John , Benavente Oscar R. , Cole John W. , Donatti Amanda , Griessenauer Christoph J. , Heitsch Laura , Holmegaard Lukas , Jood Katarina , Jimenez-Conde Jordi , Kittner Steven J. , Lemmens Robin , Levi Christopher R. , McDonough Caitrin W. , Meschia James F. , Phuah Chia-Ling , Rolfs Arndt , Ropele Stefan , Rosand Jonathan , Roquer Jaume , Rundek Tatjana , Sacco Ralph L. , Schmidt Reinhold , Sharma Pankaj , Slowik Agnieszka , Söderholm Martin , Sousa Alessandro , Stanne Tara M. , Strbian Daniel , Tatlisumak Turgut , Thijs Vincent , Vagal Achala , Wasselius Johan , Woo Daniel , Zand Ramin , McArdle Patrick F. , Worrall Bradford B. , Jern Christina , Lindgren Arne G. , Maguire Jane , Golland Polina , Bzdok Danilo , Wu Ona , Rost Natalia S. 
Published: November 2021

Objective

To examine whether high white matter hyperintensity (WMH) burden is associated with greater stroke severity and worse functional outcomes in lesion pattern-specific ways.

Methods

MR neuroimaging and National Institutes of Health Stroke Scale data at index stroke, as well as modified Rankin Scale (mRS) at 3-6 months post-stroke were obtained from MRI-GENIE study of acute ischemic stroke (AIS) patients. Individual WMH volume was automatically derived from FLAIR-images. Stroke lesions were automatically segmented from DWI-images, spatially normalized and parcellated into atlas-defined brain regions. Stroke lesion effects on AIS severity and unfavorable outcomes (mRS>2) were modeled within a purpose-built machine learning and Bayesian regression framework. In particular, interaction effects between stroke lesions and a high versus low WMH burden were integrated via hierarchical model structures. Models were adjusted for the covariates age, age2, sex, total DWI-lesion and WMH volumes, and comorbidities. Data were split into derivation and validation cohorts.

Results

A total of 928 AIS patients contributed to stroke severity analyses (mean age: 64.8(14.5), 40% women), 698 patients to functional outcome analyses (mean age: 65.9(14.7), 41% women). Individual stroke lesions were represented in five anatomically distinct left-hemispheric and five right-hemispheric lesion patterns. Across all patients, acute stroke severity was substantially explained by three of these patterns, that were particularly focused on bilateral subcortical and left-hemispherically pronounced cortical regions. In high WMH burden patients, two lesion patterns consistently emerged as more pronounced in case of stroke severity: the first pattern was centered on left-hemispheric insular, opercular and inferior frontal regions, while the second pattern combined right-hemispheric temporo-parietal regions. Bilateral subcortical regions were most relevant in explaining long term unfavorable outcome. No WMH-specific lesion patterns of functional outcomes were substantiated. However, a higher overall WMH burden was associated with higher odds of unfavorable outcomes.

Conclusions

Higher WMH burden increases stroke severity in case of stroke lesions involving left-hemispheric insular, opercular and inferior frontal regions (potentially linked to language functions) and right-hemispheric temporo-parietal regions (potentially linked to attention). These findings may contribute to augment stroke outcome predictions and motivate a WMH burden and stroke lesion pattern-specific clinical management of AIS patients.