409 Diffusion MRI to investigate atypical corticospinal tract microstructure and motor impairments in hemiplegic cerebral palsy

Abstract

OBJECTIVES/GOALS: Hemiplegic cerebral palsy (HCP) limits the functional ability of one side of the body, but motor impairments are very heterogeneous among children with this diagnosis. The purpose of this study was to evaluate the CST using DTI and tractography analyses as it relates to quantitative measures of the severity of weakness and mirror movements in HCP. METHODS/STUDY POPULATION: Preliminary results include five participants with HCP (2M, 16±7.8 years) and six controls (2M, 12±3.5 years). DTI data were collected using a spin-echo echo-planar imaging sequence with diffusion weighting of b=1000 s/mm2 in 60 different directions and 8 scans without diffusion weighting (b=0 s/mm2). Images were processed with steps of brain extraction, denoising, motion and eddy current correction, and fit with tensors to generate maps of diffusivity metrics. Anatomical landmarks were used to guide probabilistic tractography of the CST for analyses in both the lesioned and non-lesioned hemispheres. To quantify grasp weakness and mirroring severity, participants completed a bilateral assessment of grip strength using handheld force measurement devices and custom MATLAB data acquisition software. RESULTS/ANTICIPATED RESULTS: DTI is a feasible method to evaluate CST microstructure in HCP and typically developing pediatric participants. Spearman correlation analyses, using age and sex as covariates, revealed that for the lesioned hemisphere CST, there were significant positive correlations between grasp weakness severity and mean diffusivity (MD) (Ï=0.66, p=0.038) and between grasp weakness severity and axial diffusivity (AD) (Ï =0.68, p=0.030). There was not a significant correlation between grasp weakness severity and fractional anisotropy (FA) (Ï =-0.47, p=0.166). For the non-lesioned hemisphere CST, there was a significant positive correlation between mirroring severity and radial diffusivity (RD) (Ï =0.70, p=0.023). There was not a significant correlation between mirror movement severity and FA (Ï =-0.41, p=0.2361). DISCUSSION/SIGNIFICANCE: The correlations demonstrated here show a potential relationship between CST microstructure and the severity of hand impairments in HCP. While these relationships between CST diffusivity properties and hand function are preliminary, they provide the first steps to better understand underlying neural mechanisms for motor impairments in HCP.