Abstract 4033: Structural Integrity of the Corticospinal Tract Correlated with the Degree of Hand Recovery in Pediatric Patients Following Stroke

Abstract

Introduction: The objective was to investigate association of the corticospinal tract (CST) and the association with neurological outcome using Diffusion Tensor Imaging (DTI) to measure the structural integrity of the CST at the level of the cerebral peduncles and the descending CST (DCST) using a tractography based approach (Diffusion Tensor Tractography - DTT) in children with a range of recovery in hand function following arterial ischemic stroke. Methods: Structural integrity of the CST supplying the hand (DTI) and neurological outcome was evaluated in 11 patients and 8 controls. DTI: sequences were performed with 2 dimensional DW EPI, 25 directions, 1000 0b value, TR 8300 msec, TE ∼ 79msc, scan time: 5 minutes. CST integrity at the level of the peduncles was measured by drawing a region-of-interest (ROI) on the anterior cerebral peduncles (Kirton, 2007) and calculating Fractional Anisotropy ([FA], range 0=isotropic, 1=anisotropic) (FSL v4.1). Tract-based spatial statistics (TBSS) were used for CST reconstruction by drawing an ROI on single axial T1-weighted image in which the hand knob region was most noticeable as the initial seed point, and the second ROI on the single axial T1 weighted image in which the cerebral peduncle was most prominent. T-tests with Welch correction (for unequal variance) were used to compare the difference in the mean FA values of the ROIs between peduncles and the DCST in normal controls, and the stroke and non-stroke affected peduncles in patients. The correlation of the mean FA of the DCST and neurological outcome assessed with the sensori-motor subscale of the Pediatric Stroke Outcome Measure. Results: Patients and controls did not differ in age at acquisition (mean=9.61 vs 12.29). DTI: The mean FA values of the peduncles between patients and controls were found to differ between hemispheres (p= .006). The mean FA of the stroke affected (ipsilesional) (mean=.3912) peduncles were significantly lower than the non-affected peduncle (contralesional) (mean =.4336, p=.001). DTT: The tract based analyses also showed FA values (mean=.3197) in the stroke affected DCST were significantly lower than the unaffected (contralesional) DCST (mean=.4441). Correlation analysis a revealed a significant negative correlation between motor outcome and mean FA of the stroke affected DCST (P < 0.05) and the unaffected DCST (P < 0.05). Conclusions: Integrity of the fibers in the DCST shows an association with motor outcome of the hand in pediatric stroke patients. Greater damage to the DCST was associated with a greater motor deficit. The results of this study suggest that the level of motor skill recovery achieved in pediatric stroke patients relates to microstructural status of the DCST.