Value of Head CT in Minor Closed Head Injury
ABSTRACT & COMMENTARY
Source: Holmes JF, et al. Failure of the Miller criteria to predict significant intracranial injury in patients with a Glasgow coma scale score of 14 after minor head trauma. Acad Emerg Med 1997;4:788-792.
Closed head injury is a frequent presentation in the ED, yet the majority of patients who present awake and alert have no abnormalities on computed tomography (CT) of the head.1 Miller and colleagues have previously reported that head CT was unnecessary in minor head injury victims with Glasgow coma scores (GCS) of 15 and a history of loss of consciousness (LOC) or amnesia unless there were signs or symptoms of intracranial injury.2 Evidence of depressed skull fracture was considered a sign of significant injury, while headache, nausea, and vomiting were found to be predictive symptoms.
The present observational study seeks to extend the authors’ findings to head injury victims with GCS of 14 and a history of LOC or amnesia. Two hundred sixty-four subjects met these criteria; all underwent CT of the head. Thirty-five patients (13%) had abnormal studies. Had the criteria from the Miller study been applied to these subjects, only 51% of patients with intracranial injury would have undergone CT imaging (i.e., the sensitivity of the criteria was only 49%). Miller et al conclude that signs or symptoms of intracranial injury are of little value in detecting intracranial injury in patients with a GCS of 14.
COMMENT BY DAVID KARRAS, MD
Most authorities recommend routinely obtaining a CT of the head for every victim of mild head injury with a history of LOC or amnesia. However, the high cost and low yield of this practice has prompted investigation into criteria for selecting which alert head injury victims can safely forgo this study. Last year, Miller et al published a well-received study examining the yield of routine head CT in victims of minor head trauma with normal mental status. The subjects in that study had experienced LOC or amnesia but had GCS of 15 on presentation. Miller et al found that CT revealed no significant intracranial injury unless the patient had evidence of a depressed skull fracture, headache, nausea, or vomiting. They concluded that routine head CT is unwarranted in patients with intact mental status and no signs or symptoms of intracranial injury.
The present study provides importantalthough not unexpectedinformation about the use of clinical predictors in patients with less-than-perfect GCS. In general, the difference between a GCS of 15 and one of 14 is not subtle, and most of us would not feel comfortable withholding a CT of the head in a head trauma victim with an abnormal mental status. One feature of this study that I found confusingand which may weaken its conclusionis the inclusion of patients who were intoxicated and "found down," even if no clear history of head injury was available. Despite this possible limitation, this study confirms our present practice of obtaining a head CT in patients without a completely normal mental status following closed head injury, particularly when LOC or amnesia are reported.
References
1. Dunham CM, et al. Compelling evidence for discretionary brain CT imaging in patients with mild cognitive impairment after blunt trauma. J Trauma 1996;41:679-686.
2. Miller EC, et al. Minor head trauma: Is computed tomography always necessary? Ann Emerg Med 1996; 27:290-294.
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