Abstract Body: Introduction
Cognitive and language trajectory has been extensively studied following ischemic stroke, with large epidemiological studies showing on average a decline in naming and cognition acutely followed by continued decline over time. We tested the hypothesis that average decline reflects a marked decline in patients who show progressive brain atrophy (even in the uninfarcted hemisphere), but improvement in other patients without progressive atrophy. We quantified atrophy in the right (non-infarcted) hemisphere in each individual over time, and examined its relationship to naming change over time.
Methods
Participants (n=71) in a longitudinal study of language and MRI over the first year after left hemisphere ischemic stroke were included if they completed an MRI and the Boston Naming Test (BNT) acutely and chronically (either 6m or 12m post-stroke). Stroke volumes were extracted from acute imaging, and atrophy was measured by comparing baseline scans to chronic scans for each individual. Pearson correlations between atrophy and change in BNT score were identified for each hemisphere.
Results
Left hemisphere stroke volume correlated with increased left hemisphere atrophy (likely reflecting Wallerian degeneration) (r=0.50, p=0.0001), but not with right hemisphere atrophy (Figure 1). Naming improved more with less right hemisphere atrophy, but the correlation was statistically significant only when 3 outliers were removed (r= 0.56; p=0.0057; Figure 2). Conversely, naming tended to improve less with less left hemisphere atrophy (NS; Figure 3), likely reflecting smaller strokes, with less room for improvement.
Conclusions
As right hemisphere atrophy is not significantly influenced by left hemisphere stroke volume, progressive decline in naming over the first year after stroke in a subset of patients with progressive right hemisphere atrophy likely points to a separate degenerative process. The subset of patients who show minimal right hemisphere atrophy show improvement, rather than continued decline, in naming over the first year after stroke.