Poster B9, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
Long-range fiber damage in small vessel brain disease affects aphasia severity
Janina Wilmskoetter1, Barbara Marebwa1, Alexandra Basilakos2, Julius Fridriksson2, Chris Rorden3, Brielle C. Stark4, Lisa Johnson2, Gregory Hickok5, Argye E. Hillis6, Leonardo Bonilha1;1Department of Neurology, College of Medicine, Medical University of South Carolina, 2Department of Communication Sciences and Disorders, University of South Carolina, 3Department of Psychology, University of South Carolina, 4Department of Speech and Hearing Sciences, Indiana University, 5Department of Cognitive Sciences, University of California, Irvine, 6Department of Neurology, Johns Hopkins University
Background: We sought to determine the underlying pathophysiology relating white matter hyperintensities (WMH) to post-stroke outcomes. We hypothesized that: 1) WMH are associated with damage to a higher percentage of long-range compared to medium- and short-range intracerebral white matter fibers, and 2) the proportion of long-range fibers mediates the relationship between WMH and chronic post-stroke aphasia severity. Methods: We measured severity of periventricular (PVH) and deep white matter hyperintensities (DWMH), calculated percentages of short-, mid- and long-range white matter fibers, and determined aphasia severity of 48 individuals with chronic post-stroke aphasia. Correlation and mediation analyses were performed to assess the relationship between WMH, connectome fiber-length measures and aphasia severity. Results: We found that more severe PVH and DWMH correlated with a lower proportion of long-range fibers (r=-0.423, p=0.003; and r=-0.315, p=0.029; respectively), counterbalanced by a higher proportion of short-range fibers (r=0.427, p=0.002; and r=0.285, p=0.050; respectively). Mediation analyses revealed: 1) a significant total effect of PVH on WAB-AQ (standardized beta=-0.348, p=0.008), 2) a non-significant direct effect of PVH on WAB-AQ (p>0.05), 3) a significant indirect effect of more severe PVH on worse aphasia severity mediated by the lower percentage of long-range and higher percentage of short-range fibers (effect=6.5078, Bootstrapping: SE=3.5797, lower limit 95-CI=-0.5672, upper limit 95%-CI=15.0571). Conclusions: We conclude that small vessel brain disease seems to affect chronic aphasia severity through a change of the proportions of long- and short-range fibers. This observation provides insight into the pathophysiology of small vessel brain disease, and its relationship with brain health, stroke recovery and aphasia severity.
Themes: Disorders: Acquired, Language Production
Method: White Matter Imaging (dMRI, DSI, DKI)