Right Hemispheric Homologous Language Pathways Negatively Predicts Poststroke Naming Recovery

Background and Purpose - Stroke is the leading cause of disability in United States, and aphasia is a common sequela after a left hemisphere stroke. Functional imaging and brain stimulation studies show that right hemisphere structures are detrimental to aphasia recovery but evidence from diffusion tensor imaging is lacking. We investigated the role of homologous language pathways in naming recovery after left hemispheric stroke. Methods - Patients with aphasia after a left hemispheric stroke underwent naming assessment using the Boston Naming Test and diffusion tensor imaging at the acute and chronic time points. We analyzed diffusion tensor imaging of right arcuate fasciculus and frontal aslant tracts. We used Wilcoxon rank-sum test to evaluate structural lateralization patterns and partial Spearman correlation/multivariate generalized linear model to determine the role of right arcuate fasciculus and frontal aslant tracts in naming recovery after controlling for confounders. Results were corrected for multiple comparisons. Results - On average, the structural integrity of left language pathways deteriorated more than their right homologs, such that there was rightward lateralization in the chronic stage. Regression/correlation analyses showed that greater preservation of tract integrity of right arcuate fasciculus was associated with poorer naming recovery. Conclusions - Our study provides preliminary evidence that preservation of right homologs of language pathways is associated with poor recovery of naming after a left hemispheric stroke, consistent with previous evidence that maintaining greater reliance on left hemisphere structures is associated with better language recovery.