The pattern of irreversible brain changes after cardiac arrest in humans.

Irreversible brain damage resulting in sustained post-arrest coma is a most serious complication of CA in resuscitated patients. In this study we present the neuropathological examination performed on 17 brains of patients who had remained unconscious for variable post-resuscitation periods and died after survival time ranging from 1 day to 36 days following cardiac arrest. Two main types of irreversible brain lesions were observed. The first one consisted of primary ischaemic selective disseminated neuronal death appearing in the form of acidophilic neurones with consecutive neuronal loss and reactive astroglial activation in the brain regions vulnerable to ischaemia or in more widespread distribution. The second included microinfarcts or confluent areas of pancellular necrosis associated with perivascular and diffuse tissue sponginess and was considered as secondary to post-resuscitation systemic and regional circulatory disturbances. These lesions showed multifocal, perivascular and laminar distribution with apparent predilection to the cortical border zones of arterial supply territories and were associated with disintegration and loss of GFAP-reactive astrocytes. Continuity between the areas of selective neuronal loss and focal tissue pannecrosis with corresponding patchy disappearance of GFAP- and VIM-positive astrocytes indicates the contribution of astroglia in the progression of postischaemic brain lesions. Both types of changes, evaluated in the neocortex and hippocampus, were more intensive and heterogeneous in the patients dying after prolonged coma duration than in those with recovery of consciousness within the first days after resuscitation.