Head computed tomography scans in trauma patients with seizure disorder: Justifying routine use

Hypotheses: A majority of trauma patients with known seizure disorder with seizure activity were noncompliant with their medications, normal neurologic examination findings would predict negative results of head computed tomography (CT) scans, and the yield of CT scans would be insufficient to justify their routine use. Design: Retrospective consecutive case series. Main Outcome Measures: Blood levels of antiepileptic drugs, predictive values and receiver operating characteristic curves of Glasgow Coma Scale scores, and findings on head CT. Setting: Urban trauma center. Patients: All trauma patients treated between September 1995 and June 2002 with seizure-related illness. Results: The diagnosis of seizure identified 356 patients. Most (62%) had preexisting seizure disorder. Of the 101 who had antiepileptic drug levels drawn, 75% of these patients were noncompliant. The negative predictive value of a Glasgow Coma Scale score of 15 for intracranial abnormalities on CT scans was 90%. Receiver operating characteristic curve analyses of Glasgow Coma Scale score vs head CT abnormalities for all patients with seizure activity showed the area under the curve was 0.53, indicating poor discriminating ability. Intracranial abnormality was identified in 27% if the seizure resulted from injury and in 11% if the seizure preceded injury (P=.001). Conclusions: Neurologic examination is an unreliable predictor of intracranial injury in patients with seizure disorder. In trauma patients with seizure activity, the yield of CT scans in finding unsuspected intracranial abnormalities justifies its routine use regardless of prior history.