Comparative study between the characteristics of facial nerve jnjury resulted from gun-shot and that from blast / 实用口腔医学杂志

ABSTRACT

Objective: To study the difference between the facial nerve injury by gun-shot and that by blast. Methods: 40 adult dogs were divided into 2 groups, with 20 dogs in each. In the blast group, the impact wave was simulated by detonator blast in the distance of 10 cm over the dog's masseter. At the same time,a steel ball was projected to the dog's face by a rifle to imitate segments in blast. In the gun-shot group, only the steel ball was used. Then the facial nerve was taken at the time of immediateness, 6 hours, 1 day, 3 days and 7 days following the injury for HE or immunocytochemical staining. And the facial nerve conduction velocity was examined 6 hours, 3 days and 7 days after injury.Results: The facial nerve edema was found in both groups just after injury. There was scattering hemorrhage and little hematoma below the spineurium in the gun-shot wound, as well as the diffusing bleeding and larger hematoma in blast wound. In the blast group, the severe edema could be found by light microscope in the whole extracranial facial nerve. Axonal fragments, infiltrating imflammatory cells and few neurofilament protein NF positive axons were observed. In the gun-shot group, only scattering damage was found within 2 cm from the wound track.Conclusion: The facial nerve injury by gun-shot bacomes less severe with the increase of distance from the wound track, but the blast injury is wider and more severe.