Computed tomographic brain density measurement as a predictor of elevated intracranial pressure in blunt head trauma

Abstract

There are no independent computed tomography (CT) findings predictive of elevated intracranial pressure (ICP). The purpose of this study was to evaluate brain density measurement on CT as a predictor of elevated ICP or decreased cerebral perfusion pressure (CPP). A prospectively collected database of patients with acute traumatic brain injury was used to identify patients who had a brain CT followed within 2 hours by ICP measurement. Blinded reviewers measured mean density in Hounsfield Units (HU) within a 100-mm2 elliptical region at four standardized positions. Brain density measurement was compared for patients with an ICP of 20 or greater versus less than 20 mm Hg and CPP of 70 or greater versus less than 70 mm Hg. During a 2-year period, 47 patients had ICP monitoring after brain CT. Average age was 40 +/- 18 years old; 93.6 per cent were male; mean Injury Severity Score was 25 +/- 10; and Glasgow Coma Scale was 6 +/- 4. There was no difference in brain density measurement for observer 1, ICP less than 20 (26.3 HU) versus ICP 20 or greater (27.4 HU, P = 0.545) or for CPP less than 70 (27.1 HU) versus CPP 70 or greater (26.2, P = 0.624). Similarly, there was no difference for observer 2, ICP less than 20 (26.8 HU) versus ICP 20 or greater (27.4, P = 0.753) and CPP less than 70 (27.6 HU) versus CPP 70 or greater (26.2, P = 0.436). CT-measured brain density does not correlate with elevated ICP or depressed CPP and cannot predict patients with traumatic brain injury who would benefit from invasive ICP monitoring.