Study on the Mechanism of Cerebral Contusion Based on Judicial Autopsy Report

摘要

Cerebral contusion is one of the symptoms observed when a human receives a heavy impact on the head, and considered to be caused by the negative pressure fluctuation inside a cranium. In order to know the mechanism of cerebral contusion, the impact experiment and finite element analysis of a water-filled acrylic container was carried out. In the analysis, mass and velocity of the impactor were changed, so as to keep the energy constant and intracranial pressure fluctuation inside the container was obtained. The frequency analyses were performed for the pressure fluctuations. It was shown that the higher frequency was excited and the negative pressure occurred at the impact side when the force duration was short, and consequently coup contusion was caused. 11 autopsied cases which had in-depth data were reconstructed by using finite element model of a human head. The autopsy reports included the data of the impact object, impact region, skull fracture region and lesion area of a brain. In analysis, the impact velocity was estimated so that the negative pressure could occur only at the lesion area of a brain. As a result of analysis, the force duration was short when the impact object was light weight with high velocity, the negative pressure occurred at the impact side and the positive pressure occurred at the opposite side of impact, and consequently coup contusion was obtained, the force duration was long when the impact object was heavy weight with low velocity, the positive pressure occurred at the impact side and the negative pressure occurred at the opposite side of impact, and consequently contrecoup contusion was obtained.