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Poster B45, Thursday, August 16, 3:05 – 4:50 pm, Room 2000AB

The progression of leukoaraiosis and the integrity of perilesional tissue predict changes in language abilities

Alexandra Basilakos1, Lisa Johnson1, Leonardo Bonilha2, Brielle Stark1, Chris Rorden1, Grigori Yourganov1, Julius Fridriksson1;1University of South Carolina, 2Medical University of South Carolina

The presence of leukoaraiosis in stroke survivors may be an indicator of worse recovery outcomes. Leukoaraiosis is the result of macrostructural changes in the brain's white matter attributed to ischemic changes, artherosclerotic disease, and reductions in cerebral blood flow. Although lesion volume often accounts for the greatest amount of variance in aphasic outcomes, no study has investigated the concomitant effect of leukoaraiosis in long-term outcomes in chronic post-stroke aphasia. Accordingly, this study investigated the extent that the progression of leukoaraiosis, in addition to changes in perilesional grey and white matter (GM, WM), predict changes in language abilities. Methods: Behavioral testing and neuroimaging data from 38 participants (11F, mean age at first test=58.1,SD=10) in the chronic stage of stroke recovery were obtained from two time points (mean months post-onset, MPO, at time 1=40.6,SD=50; MPO at time 2=70.5, SD=60). The Western Aphasia Battery (WAB) aphasia quotient (AQ) was used to measure aphasia severity at both time points, and proportional change in WAB AQ and WAB subscores (spontaneous speech, repetition, naming, comprehension) served as the primary dependent measures for all analyses. All participants had T1 and T2 scans from the time of behavioral testing. The Fazekas scale was used to rate leukoaraiosis in the contralesional hemisphere on all T2 scans. Raters were blind to time point and participant test scores. GM and WM volumes were obtained from all T1 scans using SPM12's unified segmentation-normalization procedures. An in-house script estimated perilesional tissue, with the following procedures: i) hand-drawn lesions were dilated 5mm in each dimension, and the original lesion was subtracted from the dilated volume, leaving a "shell" 5mm in thickness; ii) a brain mask was constructed so only voxels inside the brain were analyzed; iii) GM and WM volumes inside each 5mm shell were estimated for each participant for each scanning session. Changes in overall Fazekas scores and perilesional GM and WM volumes between scanning sessions were entered as independent variables in a series of stepwise multiple regression analyses predicting language changes. Analyses were controlled for months between scanning sessions. Results: Regression models were significant for predicting proportional changes in spontaneous speech [F(2,37)=6.7, p=0.003, adjusted R2=.24], comprehension [F(2,37)=5.3,p=0.01, adjusted R2=.19], repetition [F(1,37)=4.9,p=0.03, adjusted R2=.10], and naming [F(1,37)=9,p=0.008, adjusted R2=.16]. The model predicting change in AQ was not significant. Increased perilesional GM in ventral stream areas (B=0.56,p=0.001), together with increased perilesional WM (B=0.38, p=0.22), were the best predictors of improvements in spontaneous speech. The progression of leukoaraiosis (B=-0.49,p=0.005), along with increased perilesional GM in dorsal stream areas (B=.40, p=0.029) accounted for the greatest amount of variance in changes in comprehension. The progression of leukoaraiosis was the only significant predictor of declines in repetition (B=-0.35, p=0.33) and naming performance (B=-0.43,p=0.008). Conclusions: Results suggest that in addition to perilesional changes, the progression of leukoaraiosis accounts for a significant amount of variance in aphasic performance over time. Future studies that relate brain damage to impairments should consider including measures of white matter integrity, as overall brain health contributes to lesion-symptom predictions.

Topic Area: Language Disorders