Early Subacute White Matter Hyperintensities and Recovery of Language After Stroke.

Background: White matter hyperintensities (WMH) are considered to contribute to diminished brain reserve, negatively impacting on stroke recovery. While WMH identified in the chronic phase after stroke have been associated with post-stroke aphasia, the contribution of premorbid WMH to the early recovery of language across production and comprehension has not been investigated.

Objective: To investigate the relationship between premorbid WMH severity and longitudinal comprehension and production outcomes in aphasia, after controlling for stroke lesion variables.

Methods: Longitudinal behavioral data from individuals with a left-hemisphere stroke were included at the early subacute (n = 37) and chronic (n = 28) stage. Spoken language comprehension and production abilities were assessed at both timepoints using word and sentence-level tasks. Magnetic resonance imaging (MRI) was performed at the early subacute stage to derive stroke lesion variables (volume and proportion damage to critical regions) and WMH severity rating.

Results: The presence of severe WMH explained an additional 18% and 25% variance in early subacute (t = -3.00, p = .004) and chronic (t = -3.60, P = .001) language comprehension abilities respectively, after controlling for stroke lesion variables. WMH did not predict additional variance of language production scores.

Conclusions: Subacute clinical MRI can be used to improve prognoses of recovery of aphasia after stroke. We demonstrate that severe early subacute WMH add to the prediction of impaired longitudinal language recovery in comprehension, but not production. This emphasizes the need to consider different domains of language when investigating novel neurobiological predictors of aphasia recovery.