Large and small "holes" in the brain: reversible or irreversible changes in head injury.

We prospectively studied the frequency and course of large (greater than 25 cc) and small (less than 25 cc) areas of decreased density in 491 patients with severe closed head injury entered into the Traumatic Coma Data Bank (TCDB). The frequency of such areas and of subarachnoid haemorrhage on initial and subsequent CT scans were recorded. The frequency of large "holes" increased from 8 on the initial CT scan to 24 on scans done from day 4 to day 10. Half of these lesions either completely or almost completely resolved 14 days or more following injury. In patients with small "holes" the frequency increased from 24 to 77, but on scans performed 14 days or more following injury, 47% had completely disappeared. The presence of subarachnoid haemorrhage on the initial scan predicted the development of large areas of decreased density, but it did not predict the development of small areas of decreased density. The disappearance of a substantial number of these areas of decreased density ("holes") indicate that these areas do not necessarily represent areas of cerebral infarction. Patients with closed head injury are at risk for the development of what appear to be regional areas of cerebral ischaemia, but subarachnoid haemorrhage only predicts the development of large areas with these changes. Pharmacologic trials with calcium channel blocking agents or NMDA receptor antagonists in head injured patients appear warranted.