Establishment of a blunt impact-induced brain injury model in rabbits.

Objective: To establish an animal model to replicate the blunt impact brain injury in forensic medicine.

Methods: Twenty-four New Zealand white rabbits were randomly divided into control group (n equal to 4), minor injury group (n equal to 10) and severe injury group (n equal to 10). Based on the BIM-II Horizontal Bio-impact Machine, self-designed iron bar was used to produce blunt brain injury. Two rabbits from each injury group were randomly selected to monitor the change of intracranial pressure (ICP) during the impacting process by pressure microsensors. Six hours after injury, all the rabbits were dissected to observe the injury morphology and underwent routine pathological examination.

Results: Varying degrees of nervous system positive signs were observed in all the injured rabbits. Within 6 hours, the mortality rate was 1/10 in the minor injury group and 6/10 in the severe injury group. Morphological changes consisted of different levels of scalp hematoma, skull fracture, epidural hematoma, subdural hematoma, subarachnoid hemo- rrhage and brain injury. At the moment of hitting, the ICP was greater in severe injury group than in mild injury group; and within the same group, the impact side showed positive pressure while the opposite side showed negative pressure.

Conclusions: Under the rigidly-controlled experimental condition, this animal model has a good reproducibility and stable results. Meanwhile, it is able to simulate the morphology of iron strike-induced injury, thus can be used to study the mechanism of blunt head injury in forensic medicine.