ABSTRACT
Objective To study the characteristics of craniocerebral injury caused by the handgun bullet impacting on the bulletproof helmet.Methods Fourteen healthy landrace pigs were involved and randomly divided into injury group(n =9)and control group(n =5).The landrace pigs of the injury group were shot vertically on the head under the protection of helmet plate with 9 mm handgun bullet at velocity of 360 m/s.While the landrace pigs of the control group were dealt with the same process as the injury group except for use of unarmed handgun bullet of the same ammunition dose.The changes of vital sign in the early period and the retina injury at two hours after injury were observed.Porcine cerebrospinal fluid (CSF)at pre-injury and at three hours post-injury were obtained for investigating the levels of neuron specific enolase(NSE)andαⅡ-spectrin protein.Then,the landrace pigs were sacrificed and dissected to examine the general morphological changes of the brain.The brain cortex was taken,fixed and stained with hematoxylin-eosin for microscopic observation.Results The landrace pigs in the injury group manifested decrease of the blood pressure and increase of the heart rate and respiratory rate in the early stage after injury.General morphological observation found retinal hemorrhage(3/9),skull fracture(3/9)and brain surface damage including local impact lesion(9/9)and contrecoup lesion(9/9),with severe impact lesion than contrecoup lesion.Optical microscopic observation revealed acute injury of the cerebral cortex neuron both on the impact and contrecoup locations.The concentrations of NSE and αⅡ-spectrinwere significantly increased in CSF three hours after injury(P ＜ 0.05).Conclusions The handgun bullet impacts on the pig head protected by the bulletproof helmet may induce blunt craniocerebral injury in the early period,with severe impact lesion than contrecoup lesion.Therefore,traumatic brain injury of the soldiers armed with the helmets should be stressed and managed early.