Computed tomography in the assessment of raised intracranial pressure in non-traumatic coma

Cranial computed tomography (CT) scans and invasive intracranial pressure (ICP) measurements were reviewed for 34 children with non-traumatic coma from various causes. CT scan features including focal or generalised changes in density were noted and changes in cerebrospinal fluid (CSF) spaces were graded and correlated with the level of maximum ICP in the first 12 hours of treatment and monitoring. Seven patients had normal findings and 27 had abnormal scans. Nineteen of the 27 patients with abnormal scans had generalised abnormalities with varying degrees of loss of CSF space. Seventeen of these 19 patients had pressures greater than 15 mmHg. The highest pressures being found in those with the greatest degree of CSF space obliteration. In the remaining 8 patients, who had focal abnormalities either within the basal ganglia or cerebral hemisphere, there was no relationship between local CSF space obliteration and the level of ICP. In the 7 patients with normal scans three had ICPs of 20 mmHg or greater in the first 12 hours of monitoring and a further two also developed an ICP of this level 13-36 hours after the initiation of monitoring. In non-traumatic coma of various causes there is an association between loss of CSF space and increased ICP. However, there were two important exceptions to this; firstly in patients with focal abnormalities either within the basal ganglia or cerebral hemisphere, in whom the loss of adjacent CSF spaces was not a good indicator of generalised raised ICP; secondly some patients with normal scans, in whom this finding did not indicate normal ICP nor ensure that it remained at this level.