Abstract P382: Assessing the Impact of Damage to Brainstem Tracts on Motor Ability in Ischemic Stroke Patients

Abstract

The extent of disruption to the corticospinal tract has been associated with motor impairment and worse recovery, but the role of other motor and sensorimotor tracts in impairment following brainstem stroke is poorly understood. Additionally, the impact of brainstem strokes on connectivity to distal cortical regions innervated by these tracts has not been well established. In 23 first-episode unilateral brainstem ischemic stroke patients, the extent of disruption to brainstem pathways was determined using the Dice score between binarized lesion masks obtained from T1 images and each of 23 brainstem tracts defined using a recently published high-resolution atlas of the brainstem based on connectome imaging data. Motor impairment was determined using the Fugl-Meyer assessment. White matter disruption due to the stroke was estimated using the Network Modification Tool 2.0 (NeMo) tool, which calculates the proportion of fiber tracts disrupted by the lesion in each voxel. Principal components analysis (PCA) was used to determine disruption patterns across patients. PCA of Dice scores identified one component which explained 65% of the variance, which corresponded to overlap with the corticospinal (CST), frontopontine (FPT), and parieto-occipito-temporo-pontine (POTPT) tracts, as well as the middle cerebellar peduncle. Component scores significantly correlated with Fugl-Meyer scores (corr. = -0.82, p < 0.01). PCA of cortical disconnectivity revealed one principal component which explained 75% of the variance, which correlated most highly with cortical regions connected to the CST, FPT, and the POTPT and whose scores also significantly correlated with Fugl-Meyer scores (corr. = -0.65, p < 0.01).