ＡＢＲと脳死 脳と側頭骨の病理組織学

Abstract

For assessing brain dead patients, auditory brain stem response (ABR) has been used as an objective measure. However, pathological findings of the brain and temporal bone have rarely been studied. In this report, both the neuropathology of the brain and temporal bone pathology were studied to elucidate the pathophysiology of the disappearance of ABR in brain death. In temporal bone pathology, generally, the more prolonged the disappearance of ABR, the more severely the inner ear structure was destroyed. In brain pathology, the more prolonged the disappearance of ABR, the more severely the cerebrum, cerebellum and brain stem degenerated. In the inner ear, the inner and outer hair cells disappeared and the stria vascularis separated due to autolysis. In the brain, cell layers of the cerebral cortex, granular cells of the cerebrum and neuronal cells of the dorsal cochlear nucleus disappeared due to ischemic changes. These pathological findings suggest that vascular circulation in the brain stem could be damaged at the beginning of brain death and cause irreversible changes in the brain stem resulting in autolysis of inner ear structures since the inner ear is supplied by the anterior inferior cerebellar artery. However, more extensive study is needed because exceptional cases with unusual pathology of the inner ear and brain do exist.