Diffusion tensor imaging of callosal motor fibres correlates with functional impairment in children with periventricular leukomalacia

Purpose: Diffusion tensor imaging (DTI) of transcallosal motor fibers is a potential paradigmatic parameter for hand motor function. We aimed to evaluate the microstructure (DTI), interhemispheric inhibitory competence as measured by transcranial magnetic stimulation (TMS) and hand motor function in children with mild cerebral palsy compared to normal controls.

Methods: We examined 8 children (mean age 15.1±2.3) with known mild bilateral cerebral palsy and periventricular leukomalacia (PVL) and 12 healthy age-matched controls (mean age 15.3±2.7). Relative and fractional anisotropy (RA, FA) values were calculated for the callosal motor fibers and correlated to parameters of interhemispheric inhibitory competence and degree of mirror movements as measured by a computer-based hand motor function test..

Results: Anisotropy values were significantly lower in children with PVL as compared to age-matched healthy controls (p=0.008). FA and RA values in transcallosal motor fibers correlated with parameters of hemispheric inhibitory competence (R=0.58; p=0.035) and with degree of mirror movements (R=0.53; p=0.021). Mirror movements were elevated in the PVL group by the factor 2.

Conclusion: Anisotropy values of transcallosal motor fibers appear to correlate with functional impairment of hand motor function in children with PVL.