The effects of mild germinal matrix-intraventricular haemorrhage on the developmental white matter microstructure of preterm neonates: a DTI study

Objectives: To evaluate white matter (WM) microstructural changes in preterm neonates (PN) with mild germinal matrix-intraventricular haemorrhage (mGMH-IVH) (grades I and II) and no other associated MRI abnormalities, and correlate them with gestational age (GA) and neurodevelopmental outcome. Methods: Tract-based spatial-statistics (TBSS) was performed on DTI of 103 patients studied at term-equivalent age, to compare diffusional parameters (fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD)) between mGMH-IVH neonates (24/103) and controls matched by GA at birth and sex. The relationship between DTI abnormalities, GA and neurodevelopmental outcome assessed with Griffiths’ Developmental Scale-Revised:0-2 was explored using TBSS and Spearman-correlation analysis (p <.05). Results: Affected neonates had lower FA, higher RD and MD of the corpus callosum, limbic pathways and cerebellar tracts. Extremely preterm neonates (GA < 29 weeks) presented more severe microstructural impairment (higher RD and MD) in periventricular regions. Neonates of GA ≥ 29 weeks had milder WM alterations (lower FA), also in subcortical WM. DTI abnormalities were associated with poorer locomotor, eye-hand coordination and performance outcomes at 24 months. Conclusions: WM microstructural changes occur in PN with mGMH-IVH with a GA-dependent selective vulnerability of WM regions, and correlate with adverse neurodevelopmental outcome at 24 months. Key Points: • DTI-TBSS analysis identifies WM microstructural changes in preterm neonates with mGMH-IVH. • Extremely preterm neonates with mGMH-IVH presented more severe impairment of WM microstructure. • Extremely preterm neonates with mGMH-IVH presented microstructural impairment of periventricular WM. • mGMH-IVH affects subcortical WM in preterm neonates with gestational age ≥ 29 weeks. • WM microstructural alterations are related to neurodevelopmental impairments at 24 months.