Correlating early motor skills to white matter abnormalities in preterm infants using diffusion tensor imaging.

PURPOSE: Diffusion tensor imaging (DTI) can detect injury to specific white matter (WM) tracts involved with sensorimotor processing and may provide sensitive measures for latent or nascent motor skills. We hypothesized that DTI measures of WM fractional anisotropy (FA) could predict early motor scores on a standardized assessment in a cohort of preterm infants at risk for WM injury.

METHODS: In this prospective study, preterm infants (n= 26, 11 female, 15 male, mean gestational age 29.1 ± 2.5) underwent the Test of Infant Motor Performance (TIMP) at term and at 12 weeks corrected age (CA) and underwent an non-sedated magnetic resonance imaging (MRI) with DTI at a mean of 42 ± 1.5 weeks CA. Fractional anisotropy (FA) was measured by Voxelwise statistical analysis using Tract-Based Spatial Statistics (TBSS) in the specific regions of interest.

RESULTS: Significant differences were found between infants with poor versus average performance on motor assessments at 12-weeks and FA values in several left hemispheric WM tracts (p< 0.05). High FA of the left anterior limb of the internal capsule (ALIC) predicted mean increase in TIMP scores on specific items for head lift in prone and head lift turn to sound (p= 0.045 and p= 0.002).

CONCLUSION: Subtle WM injury, as indicated by low FA in left WM tracts, can predict outcomes of early motor skills performance testing at 3 months. Early DTI may identify infants with silent WM injury who need early intervention. Further studies may establish if individual tract FA improve after targeted treatment.