350 - Perinatal Stroke: Understanding the Relationship Between Brain Lesion and Corticospinal Tract Development Using Lesion Segmentation and Diffusion Tensor Imaging Techniques

Poster Number: 350
Publication Number: 350.3214

Background: Cerebral Palsy (CP), a chronic neurological condition affecting motor function, is the most common childhood disability in the United States. CP is often caused by perinatal brain injury, including ischemic or hemorrhagic events that may affect the corticospinal tract (CST), the primary motor pathway for voluntary movements. The CST is bilaterally organized at birth and transitions to a contralateral dominant organization over the first two years of life. CST organization is often disrupted after early brain injury. Atypical CST organization has been associated with greater motor impairment in children with CP; however, the development of this connectivity pattern remains poorly understood.

Objective: Identify the relationship between brain lesion characteristics (lesion mechanism and size) and CST integrity to aid in early detection of CP.

Design/Methods: 3T structural and diffusion-weighted MRI were collected for 10 infants (age: 3.1-6.2 months; sex: 4F,6M) with perinatal brain injury in this prospective cross-sectional study. Brain lesions were characterized by mechanism (ischemic vs. hemorrhagic) using radiology reports, and corrected size (lesion/whole brain volume) from T1w manual segmentation using ITK-SNAP. Diffusion data were analyzed with probabilistic tractography using MRtrix3 to map the CST based on motor cortex and brainstem seeds. CST integrity was measured using fractional anisotropy (FA). FA for each hemisphere was calculated across streamlines as the average of the precise tract median.

Results: Bilateral CSTs were identified by tractography in eight infants; two only had tracts from the less-affected hemisphere. One infant with a bilateral lesion was excluded in hemisphere-specific analyses. Lesion mechanism was not associated with significant differences in lesion size, more-affected or less-affected hemisphere FA, or average FA (independent t-test, p > .20 for all). Spearman correlations between lesion size and FA were nonsignificant for the more-affected (ρ = -0.179, p = 0.702) or less-affected side (ρ = -0.383, p = 0.308). There was no significant difference in FA between more-affected and less-affected hemispheres (mean = 0.012, p > .05, paired t-test).

Conclusion(s): We found no significant relationships between lesion characteristics and CST FA in infants (3-6m) with brain injuries. For infants with bilateral CSTs, integrity was similar between hemispheres, suggesting that most retained age-typical CST projections. Future longitudinal analyses of lesion characteristics and CST integrity will be necessary to evaluate markers that may aid in early CP diagnosis.