Acute radiographic workup of blunt temporal bone trauma: maxillofacial versus temporal bone CT

To evaluate the radiographic workup of blunt temporal bone trauma and determine the utility of maxillofacial computed tomography (CT) versus temporal bone CT in identifying carotid canal fractures.

Retrospective review.

The charts of 227 patients evaluated at a level I trauma center receiving a temporal bone CT for blunt head trauma within 48 hours of admission were reviewed. Acute evaluation findings and complications were noted. Sensitivity, specificity, positive predictive value, and negative predictive (NPV) value were calculated for maxillofacial CT's ability to identify carotid canal fractures compared to temporal bone CT.

One hundred forty fractures were found. Physical exam findings of blood in the external auditory canal as the sole finding, and blood in the external auditory canal with associated hemotympanum were significantly associated with absence and presence of fracture respectively. The sensitivity and specificity of maxillofacial CT for identifying carotid canal fractures, when compared to temporal bone CT, were 90.3% and 94.4% respectively (NPV > 95%). Only 6% of all patients either did have or should have had their management changed based on the temporal bone CT findings. All of these changes were regarding further workup for blunt carotid artery injury.

A combination of helical computed tomography and physical exam findings can allow for judicious use of temporal bone CTs when no maxillofacial CT is indicated. Temporal bone CTs rarely change acute management. But when they do, it is in regard to the need for further workup of possible vascular injury. Lastly, maxillofacial CTs are adequate for identifying carotid canal fractures.