Concurrent decrease of brain white matter tracts' thicknesses and fractional anisotropy after antenatal...

Area of Science:

• Neuroscience
• Medical Imaging
• Developmental Biology

Background:

• Hypoxia-ischemia (H-I) is a major cause of neonatal brain injury.
• Cerebral palsy is often associated with white matter (WM) damage.
• Rabbit models offer insights into human neonatal brain development and injury.

Purpose of the Study:

• To investigate the extent of gray and white matter (WM) injury after global antenatal hypoxia-ischemia (H-I).
• To correlate H-I with muscle hypertonia in a rabbit model of cerebral palsy.
• To assess microstructural changes in the brains of affected newborns.

Main Methods:

• Global fetal H-I induced via uterine ischemia in rabbit dams at embryonic day 22.
• Ex vivo high-resolution diffusion tensor imaging (DTI) on a 14 Tesla magnet.
• Voxel-wise comparison using Tract-Based Spatial Statistics (TBSS) of fractional anisotropy (FA) and WM tract thickness in hypertonic, nonhypertonic, and control neonates.

Main Results:

• Significant reduction in WM fractional anisotropy (FA) observed in multiple tracts (corpus callosum, periventricular WM, hippocampus, cingulum, internal capsule, optic tract) in hypertonic neonates.
• Significant reduction in WM tract thickness noted in the corpus callosum, periventricular WM, and cingulum in the hypertonic group.
• WM injury was widespread, affecting motor, limbic, and commissural fibers.

Conclusions:

• Global antenatal H-I leads to extensive WM injury in newborn rabbits with hypertonia.
• WM injury is characterized by decreased FA and reduced WM volumes compared to nonhypertonic controls.
• The findings highlight the broad impact of H-I on neonatal brain development and microstructure.