Repeated Traumatic Brain Injury Affects Composite Cognitive Function in Piglets

Cumulative effects of repetitive mild head injury in the pediatric population are unknown. We have developed a cognitive composite dysfunction score that correlates white matter injury severity in neonatal piglets with neurobehavioral assessments of executive function, memory, learning, and problem solving. Anesthetized 3- to 5-day-old piglets were subjected to single (n=7), double one day apart (n=7), and double one week apart (n=7) moderate (190 rad/s) rapid non-impact axial rotations of the head and compared to instrumented shams (n=7). Animals experiencing two head rotations one day apart had a significantly higher mortality rate (43%) compared to the other groups and had higher failures rates in visual-based problem solving compared to instrumented shams. White matter injury, assessed by beta-APP staining, was significantly higher in the double one week apart group compared to that with single injury and sham. Worsening performance on cognitive composite score correlated well with increasing severity of white matter axonal injury. In our immature large animal model of TBI, two head rotations produced poorer outcome as assessed by neuropathology and neurobehavioral functional outcomes compared to that with single rotations. More importantly, we have observed an increase in injury severity and mortality when the head rotations occur 24 h apart compared to 7 days apart. These observations have important clinical translation to infants subjected to repeated inflicted head trauma.