Abstract TP94: White Matter Tract Integrity After Vascular Insult: Longitudinal Analysis of Hemorrhagic vs Ischemic Lesions

Abstract

Introduction: White matter tract (WMT) injury occurs in patients with acute cerebrovascular disorders. In this study, we elucidate longitudinal differences in mechanism of injury and repair between ischemic stroke (ISC) and intracerebral hemorrhage (ICH). Methods: Twenty patients (10 ISC and ICH) were prospectively imaged at 1, 3, and 12 months of onset on a 3T MRI. 3D anatomical and DTI images were obtained and integrity of the corticospinal tract (CST) assessed at the ipsi and contralesional posterior limb of internal capsule (PLIC). Fractional anisotropy (FA), mean diffusivity (MD) and pixel volume were recorded. A linear regression model was applied for statistical analysis. Results: ISC group had 4 men, 6 women whereas ICH group had 7 men, 3 women, both with average age 52. Baseline NIHSS in ISC was 11 (IQR=4.5-20) and ICH 6 (IQR=2-13). All lesions were unilateral, hemispheric, completely subcortical or with a significant subcortical component. The average lesion and hematoma volume at 1 month was 37 and 39 cc in ISC and ICH, respectively. The MD in the PLIC of the ISC increased from 1 to 3m (P <0.05) then plateaued, whereas it decreased in ICH over the entire 12m (Fig 1A). The rFA showed a similar pattern of initial injury and then improvement over time in both ISC and ICH (Fig 1B). The ISC group showed 12% WM atrophy in the PLIC at 12m, wheras 13% expansion (P < 0.05) in ICH over this period, after an initial contraction of 14% at 1m (fig 1C-D). Structural changes of the PLIC correlated with changes in mRS/NIHSS (p<0.05). Conclusions: ISC and ICH display unique patterns of WMT changes over one year in which ICH injury reflects a compression of the CST that resolves over time, while in ISC our data show degeneration and microstructural injury. These changes reflect different mechanisms of injury and remodeling on a cellular level. A better understanding of these changes could improve recovery therapies. Larger studies are needed to better characterize long term WMT changes in IS and ICH.