Clinical significance of scalp abnormalities in asymptomatic head-injured infants

OBJECTIVES: 1) To identify clinical features indicating a high risk of skull fracture (SF) and associated intracranial injury (ICI) in asymptomatic head-injured infants. 2) To develop a clinical decision rule to determine which asymptomatic head-injured infants require head imaging. METHODS: We performed a prospective cohort study of all asymptomatic head-injured infants 0-24 months of age presenting to the emergency department of an urban children's hospital. Infants were considered asymptomatic if they had no clinical signs of brain injury, or of basilar or depressed SF. Among subjects who had head imaging, we assessed the utility of age, scalp hematoma size, and scalp hematoma location for predicting SF and ICI. RESULTS: Of 422 study patients, 45 (11 %) were diagnosed with SF and 13 (3%) with ICI. In the 172 subjects who had head imaging, there was a stepwise relationship between hematoma size and likelihood of SF. Parietal and temporal hematomas were highly associated with SF; frontal hematomas were not. There was a trend toward higher rates of SF in younger patients. Both large scalp hematoma and parietal hematoma were associated with ICI. Using these data, we developed a clinical decision rule to determine which asymptomatic infants need head imaging. In our study population, this rule has a sensitivity of 0.98 and specificity of 0.49 for SF, and it detects all 13 cases of ICI. The clinical rule calls for imaging in 146/422 (35%) study subjects. CONCLUSIONS: Among asymptomatic head-injured infants, the risk of SF and associated ICI is correlated with scalp hematoma size, hematoma location, and weakly with patient age. We propose a clinical decision rule that could identify most cases of SF and ICI while not requiring head imaging for most patients. This decision rule should be validated in other study populations.