НЕВРОМОРФОЛОГИЯ И СЪДЕБНОМЕДИЦИНСКО ЗНАЧЕНИЕ НА ДИФУЗНАТА АКСОНАЛНА ЛЕЗИЯ

Abstract

NEUROMORPHOLOGY AND FORENSIC SIGNIFICANCE OF DIF-FUSE AXINAL LESION Summary With the introduction of the concept of focal and diffuse brain injuries in the past 20 years, it became clear that the outcome of a head injury does not depend so much on the extensity of the focal injury, as on the occurrence of diffuse brain injuries. Diffuse axonal injury (DAI) is a clinical-pathological entity clinically characterized by an immediate and prolonged unconsciousness after a mechanical impact to the head, typically without any lucid interval, lead-ing to severe brain failure, vegetative state and death, and pathologically de-fined by a diffuse damage of axonal fibres inside the white matter, including the fibre tracts and the brain stem. The aim of the present thesis is to perceive the incidence and distribu-tion of DAI in the overall pathology of closed head injuries, and to emphasize the significance of the complete forensic-neuropathological examination (FNE) in the process of its diagnosis. For this aim, we analyzed the appearance and distribution of DAI on 63 cases with fatal non-missile head injury. To all in-cluded cases a complete FNE was performed. According to our results, DAI has an incidence of about 30-50% in the pathology of the closed head injury. It is an acceleration-deceleration injury that typically occurs in road traffic accidents and in the falls from a consider-able height (above 2 meters) but is not typical for the cases of simple falls or assaults. Therefore, DAI is more characteristic for the traumatic events related with a longer duration of the acceleration forces, whereas the other acceleration injury – the acute subdural hematoma (ASDH) is more characteristic for the events with short duration of the acceleration forces. There is no statistically significant simultaneous occurrence of DAI and ASDH. Furthermore, DAI as a sole feature and the only explanation for the impairment of the brain function and also, as the cause of death, can be found in every fifth case of closed head injury and its presence can be detected only by a complete FNE. The most con-stant clinical parameter accompanying DAI is the immediate and deep coma. Our study revealed a clear correlation between the coma and the damage of axonal fibres of both traumatic and ischemic origin. By exploring the clinical-pathological correlations of DAI, we showed that DAI is not a significant factor to the short survival (i.e. to the fatal outcome) in the first 24 hours, but is a sig-nificant factor for the severity of the impairment of brain function. This finding is of a huge medico-legal importance. On the other hand, a verified presence of DAI upon the FNE, is an absolute sign of a vital reaction, and also for the time of survival of at least 2-3 hours. Finally, ß-APP immunohistochemistry proved to be an important tool in hands of the forensic neuropathologist which cer-tainly demonstrates that: there has been the injury of the brain; the origin of the axonal damage (is it traumatic or ischemic) and that the injury has occurred intra-vitaly, which is of a big medico-legal relevance. Also, the time course of the axonal pathology revealed by ß-APP expression can point to the age of the injury, which is also of a huge significance for forensic medicine.