Affiliations: [a] Department of Neurology, Medical University of South Carolina, Charleston, SC, USA
| [b] Department of Psychology, University of South Carolina, Columbia, SC, USA
| [c] Department of Communications Sciences and Disorders, University of South Carolina, Columbia, SC, USA
Correspondence:
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Corresponding author: Leonardo Bonilha MD PhD, Department of Neurology, Medical University of South Carolina, Columbia, SC, USA. Tel.: +1 843 792 3383; Fax: +1 842 792 8626; E-mail: bonilha@musc.edu.
Abstract: Purpose:Post-stroke aphasia is typically associated with ischemic damage to cortical areas or with loss of connectivity among spared brain regions. It remains unclear whether the participation of spared brain regions as networks hubs affects the severity of aphasia. Methods:We evaluated language performance and magnetic resonance imaging from 44 participants with chronic aphasia post-stroke. The individual structural brain connectomes were constructed from diffusion tensor. Hub regions were defined in accordance with the rich club classification and studied in relation with language performance. Results:Number of remaining left hemisphere rich club nodes was associated with aphasia, including comprehension, repetition and naming sub-scores. Importantly, among participants with relative preservation of regions of interest for language, aphasia severity was lessened if the region was not only spared, but also participated in the remaining network as a rich club node: Brodmann area (BA) 44/45 - repetition (p = 0.009), BA 39 - repetition (p = 0.045) and naming (p < 0.01), BA 37 - fluency (p < 0.001), comprehension (p = 0.025), repetition (p < 0.001) and naming (p < 0.001). Conclusions:Disruption of language network structural hubs is directly associated with aphasia severity after stroke.
Keywords: Connectome, magnetic resonance imaging, diffusion tensor imaging, structural networks, hubs, rich club, aphasia, stroke, language performance
