White Matter Integrity and Motor Function Disruption Due to Traumatic Brain Injury in Piglets: Impacts on Motor-Related Brain Fibers

Abstract

Pediatric traumatic brain injury (TBI) often induces significant disability in patients, including long-term motor deficits. Early detection of injury severity is key in determining a prognosis and creating appropriate intervention and rehabilitation plans. However, conventional magnetic resonance imaging (MRI) scans, such as T2 Weighted (T2W) sequences, do not reliably assess the extent of microstructural white matter injury. Diffusion tensor imaging (DTI) tractography enables three-dimensional reconstruction of specific white matter tracts throughout the brain in order to detect white matter injury based on anisotropic diffusion. The objective of this study was to employ DTI tractography to detect acute changes to white matter integrity within the intersecting fibers of key motor-related brain regions following TBI. Piglets were assigned to either the sham craniectomy group (sham; n = 6) or the controlled cortical impact TBI group (TBI; n = 6). Gait and MRI were collected at seven days post-surgery (DPS). T2W sequences confirmed a localized injury predominately in the ipsilateral hemisphere in TBI animals. TBI animals, relative to sham animals, showed an increased apparent diffusion coefficient (ADC) and decreased fractional anisotropy (FA) in fiber bundles associated with key brain regions involved in motor function. TBI animals exhibited gait deficits, including stride and step length, compared to sham animals. Together these data demonstrate acute reductions in the white matter integrity, measured by DTI tractography, of fibers intersecting key brain regions that strongly corresponded with acute motor deficits in a pediatric piglet TBI model. These results provide the foundation for the further development of DTI-based biomarkers to evaluate motor outcomes following TBI.