Initial head computed tomographic scan characteristics have a linear relationship with initial intracranial pressure after trauma

BACKGROUND: Despite current recommendations by the Brain Trauma Foundation regarding the placement of intracranial pressure (ICP) monitoring devices, advances in computed tomographic (CT) scan technology have led to the suggestion that increased ICP may be predicted by findings on admission head CT scan and that patients without such findings do not require such monitoring. A linear relationship exists between characteristics of admission head CT scan and initial ICP level, allowing for selective placement of ICP monitoring devices. METHODS: From 1997 to 2001, a retrospective review of patients admitted with a Glasgow Coma Scale (GCS) score < 8 and head CT scan who underwent ventriculostomy placement at our institution, was conducted. Patients undergoing craniotomy with evacuation of mass lesions before ventriculostomy placement were excluded. Age, sex, mechanism of injury, anoxia, osmotic treatment, presence of drugs/alcohol, initial mean arterial pressure, initial GCS score, and initial ICP were recorded. Initial head CT scans were reviewed independently by two neuroradiologists who were blinded to ICP measurements, neurosurgical treatment, patient outcome, and each other's interpretation. Initial CT scans were evaluated and scored on a 1 (normal) to 3 (abnormal) scale with respect to ventricle size, basilar cistern size, sulci size, degree of transfalcine herniation, and gray/white matter differentiation. Initial ICP readings and CT scan findings were compared to determine whether a significant linear relationship existed between the above CT scan findings and ICPs. Logistic and univariate linear regression were used to compare averaged radiologist score versus dichotomized ICP at baseline. RESULTS: Initial head CT scan characteristics show a linear relationship to baseline ICPs. These findings are associative, but are not uniformly predictive. CONCLUSION: Therefore, the current Brain Trauma Foundation recommendation of ICP monitoring in those patients presenting with a GCS score < 8 with an abnormal CT scan or a normal CT scan with age > 40 years, systolic blood pressure < 90 mm Hg, or exhibiting posturing should be followed.