Structural and Functional Correlates of Hand Recovery Following Childhood Stroke

Following stroke in children, there is a wide range of motor recovery. This study examined the role of the corticospinal tract (CST) and its association with motor outcome of the hand in children following arterial ischemic stroke (AIS). The corticospinal tract was assessed several ways, using the appropriate imaging modalities.The primary hypothesis was that the extent of motor recovery in the stroke affected hand would be associated with two factors: 1) the extent of anatomical damage to the stroke affected corticospinal tract, and, 2) the extent and pattern of functional reorganization within the motor system. Children with AIS in the middle cerebral artery territory, occurring after the age of 2, were assessed for motor function with the validated Pediatric Stroke Outcome Measure. The presence of corticospinal tract damage was determined using conventional MRI to assess Wallerian degeneration, and diffusion tensor imaging (DTI) to quantify damage at the microstructural level. These measures were done in chronic phase following stroke. In the acute phase, (1 - 10 days post stroke), the presence of diffusion weighted imaging (DWI) signal abnormalities in the corticospinal tract were determined. Finally, neural activation patterns were evaluated using functional MRI to assess the location and extent of functional reorganization of the hand following stroke. These activation patterns were also assessed to determine the association with corticospinal tract integrity, and motor outcome. We found the integrity of the CST shows an association with motor outcome of the hand in pediatric stroke patients. Greater damage to the CST was associated with a greater motor deficit, suggesting that the level of motor skill recovery achieved in pediatric stroke patients relates to the gross morphological, and microstructural status of the CST. Integrity of the fibers in the CST also showed an association with the brain activation patterns. Greater damage to the CST was associated with a larger volume of activations during stroke affected hand use in the stroke affected hemisphere, and more severe outcome. The current study suggests that a structural and functional relationship exists in children with variable recovery of hand function following stroke. The use of complementary imaging techniques was effective in evaluating this relationship.Ph.D