Head injury and brain ischaemia--implications for therapy.

Brain ischaemia is a frequent and important sequel to brain injury. Areas of ischaemic brain damage are an almost invariable finding at postmortem in patients who have sustained severe head injury— that is, injury associated with coma (Graham, Adams and Doyle, 1978). Sequential computerized tomography of the head in disabled survivors of severe head injury frequently reveals sizeable cerebral infarcts (Miller et al., 1980). Traumatic brain laceration results also in ischaemia in the territory of divided vessels. Herniation of the medial temporal lobe of the brain through the tentorial hiatus and downward axial shift of the brain stem produce stretching and distortion of the brain arterial supply with ischaemia and infarction in the brain stem and occipital lobes (Miller and Adams, 1984). Brain ischaemia may therefore be the single most important mechanism in the production of secondary brain dysfunction and damage after severe head injury.