DIFFUSION RESTRICTION IN REMOTE DESCENDING CORTICOSPINAL TRACTS PREDICTS MOTOR OUTCOME IN NEONATAL ARTERIAL ISCHEMIC STROKE

Objectives: The neonatal period is the most common time for arterial ischemic stroke (AIS) in children. Most children are left with motor deficits but accurate predictors of outcome are lacking. Diffusion-weighted MR imaging (DWI) may detect descending corticospinal tract (DCST) changes distal from AIS location that may represent pre-Wallerian degeneration (WD) (DeVries, 2005). Our aim was to quantify DWI changes in the DCST and correlate them with motor outcome.

Methods: Fourteen consecutive neonates with AIS, acute DWI, and no other neurological insult were included. A system of quantitative measures of DWI signal change through the DCST (internal capsule to medullary pyramids) was developed using Image J software. Motor outcomes were scored using the PSOM at a minimum follow-up of 12 months and correlations to the DCST measures were sought using Fisher's exact test.

Results: DWI signal in the DCST was quantifiably different from the contralateral side in 9 of 14 neonates. Locations included the internal capsule and cerebral peduncle as well as pontine and medullary DCST. Motor outcome was highly correlated with involvement of the middle third of the cerebral peduncle (p=0.003), the percentage of peduncle affected (p=0.005), and the length of DCST affected (p=0.04). All patients with poor outcome had >25% of the peduncle and >20mm of DCST affected, while neither of these were seen in any child with good outcome. All children without DCST DWI signal had normal outcome while all of those with poor outcome demonstrated WD of the peduncle on follow-up. DWI signal differences were often not evident on visual inspection alone. Conclusion: Computer-assisted quantification of DWI signal in the DCST remote from the area of infarction appears to predict motor outcome in neonatal AIS.