Hemispheric lateralization of white matter microstructure in children and its potential role in sensory processing dysfunction.

Diffusion tensor imaging (DTI) studies have demonstrated white matter microstructural differences between the left and right hemispheres of the brain. However, the basis of these hemispheric asymmetries is not yet understood in terms of the biophysical properties of white matter microstructure, especially in children. There are reports of altered hemispheric white matter lateralization in ASD; however, this has not been studied in other related neurodevelopmental disorders such as sensory processing disorder (SPD). Firstly, we postulate that biophysical compartment modeling of diffusion MRI (dMRI), such as Neurite Orientation Dispersion and Density Imaging (NODDI), can elucidate the hemispheric microstructural asymmetries observed from DTI in children with neurodevelopmental concerns. Secondly, we hypothesize that sensory over-responsivity (SOR), a common type of SPD, will show altered hemispheric lateralization relative to children without SOR. Eighty-seven children (29 females, 58 males), ages 8-12 years, presenting at a community-based neurodevelopmental clinic were enrolled, 48 with SOR and 39 without. Participants were evaluated using the Sensory Processing 3 Dimensions (SP3D). Whole brain 3 T multi-shell multiband dMRI (b = 0, 1,000, 2,500 s/mm2) was performed. Tract Based Spatial Statistics were used to extract DTI and NODDI metrics from 20 bilateral tracts of the Johns Hopkins University White-Matter Tractography Atlas and the lateralization Index (LI) was calculated for each left-right tract pair. With DTI metrics, 12 of 20 tracts were left lateralized for fractional anisotropy and 17/20 tracts were right lateralized for axial diffusivity. These hemispheric asymmetries could be explained by NODDI metrics, including neurite density index (18/20 tracts left lateralized), orientation dispersion index (15/20 tracts left lateralized) and free water fraction (16/20 tracts lateralized). Children with SOR served as a test case of the utility of studying LI in neurodevelopmental disorders. Our data demonstrated increased lateralization in several tracts for both DTI and NODDI metrics in children with SOR, which were distinct for males versus females, when compared to children without SOR. Biophysical properties from NODDI can explain the hemispheric lateralization of white matter microstructure in children. As a patient-specific ratio, the lateralization index can eliminate scanner-related and inter-individual sources of variability and thus potentially serve as a clinically useful imaging biomarker for neurodevelopmental disorders.

The Effect of Size and Asymmetry at Birth on Brain Injury and Neurodevelopmental Outcomes in Congenital Heart Disease.

Poor and asymmetric fetal growth have been associated with neonatal brain injury (BI) and worse neurodevelopmental outcomes (NDO) in the growth-restricted population due to placental insufficiency. We tested the hypothesis that postnatal markers of fetal growth (birthweight (BW), head circumference (HC), and head to body symmetry) are associated with preoperative white matter injury (WMI) and NDO in infants with single ventricle physiology (SVP) and d-transposition of great arteries (TGA). 173 term newborns (106 TGA; 67 SVP) at two sites had pre-operative brain MRI to assess for WMI and measures of microstructural brain development. NDO was assessed at 30 months with the Bayley Scale of Infant Development-II (n = 69). We tested the association between growth parameters at birth with the primary outcome of WMI on the pre-operative brain MRI. Secondary outcomes included measures of NDO. Newborns with TGA were more likely to have growth asymmetry with smaller heads relative to weight while SVP newborns were symmetrically small. There was no association between BW, HC or asymmetry and WMI on preoperative brain MRI or with measures of microstructural brain development. Similarly, growth parameters at birth were not associated with NDO at 30 months. In a multivariable model only cardiac lesion and site were associated with NDO. Unlike other high-risk infant populations, postnatal markers of fetal growth including head to body asymmetry that is common in TGA is not associated with brain injury or NDO. Lesion type appears to play a more important role in NDO in CHD.

Correcting for prematurity affects developmental test scores in infants born late and moderately preterm.

BACKGROUND: Corrected age is typically applied when assessing the development of children born <32 weeks of gestation. There is no consensus as to whether corrected age should be applied when assessing children born late/moderately preterm (LMPT; 32-36 weeks of gestation). AIMS: This study explored the impact of corrected age on developmental test scores in infants born LMPT. STUDY DESIGN: 221 LMPT infants were assessed at two years corrected age using the Bayley-III cognitive and language scales, from which cognitive and language composite scores were derived (Normative Mean 100; SD 15). Assessments were then re-scored using chronological age. Bayley-III composite scores <80 were used to define developmental delay. Paired sample t-tests were used to assess the difference in mean test scores derived using corrected versus chronological age, and McNemar's tests to assess the difference in the proportion of infants with developmental delay using corrected versus chronological age. RESULTS: Mean corrected age scores were significantly higher than chronological age scores (cognitive: 2.1 points; 95% CI 1.6, 2.5; language 2.5; 95% CI 2.1, 2.8). Overall, significantly more LMPT infants were classified with developmental delay when chronological (18.3%) versus corrected (15.0%) age was used (p=0.016). CONCLUSIONS: Correcting for prematurity results in significantly higher developmental test scores and a significantly lower prevalence of developmental delay in LMPT infants and may affect eligibility for intervention services. Researchers and clinicians should be aware that the use of corrected age may impact on developmental test scores at both an individual and population level among infants born LMPT.