Relationship between intracranial pressure and water content of the brain in experimental brain oedema.

clinical states. It was demonstrated in polygraphic studies that the large plateau waves coincided with a reduction in local cortical blood flow and available oxygen. Clinical improvement after the administration of steroids was reflected in the record by the virtual disappearance of high pressure waves 12 hours after commencement of treatment. Similar records were obtained from patients with communicating hydrocephalus and 'benign intracranial hypertension'. Eleven cases of so-called normal pressure hydrocephalus were monitored. The majority had flat pressure recordings but a few showed levels above normal at certain periods. Operation was performed in eight patients, half of whom subsequently showed improvement in intellectual performance. Two of these cases had suffered a previous subarachnoid haemorrhage. The third group of cases were those with severe closed head injuries. Recordings were found to be particularly valuable where there was no evidence of an immediately remediable lesion since it was this group in which an insidious deterioration commonly occurred. On several occasions craniotomy had been undertaken because the recordings showed a rising ICP in the absence of clinical change. Examples were given in each group and the technical problems in relation to a fully reliable pressure transducer were described.