High resolution CT scan of temporal bone fractures: association of facial nerve paralysis with temporal bone fractures.

This radiologic study analyzed high resolution computed tomographic (CT) scans of 22 patients with temporal bone fractures. There were 19 males and three females. Fifteen of 22 had clinical evidence of facial nerve injury ranging from mild paresis to complete paralysis. The high resolution CT scan analysis identified a characteristic fracture of the temporal bone in every patient with facial nerve injury. A high percentage of these fractures (68%) could be classified as mixed and did not fall into a longitudinal or transverse fracture category. The characteristic fracture extends from the petrotympanic fissure at the glenoid fossa to the anterior inferior aspect of the medial bony external auditory canal. It resumes at the superior aspect of the external auditory canal (scutum) extending laterally along the external canal wall. If the vector force of the fracture is projected medially, it will cross the facial nerve in its horizontal portion. Often, the evaluation of trauma patients with routine CT scans for central nervous system (CNS) (brain) evaluation is inadequate for evaluation of temporal bone fractures. A high resolution CT scan should be performed when clinical criteria warrant its use. It is recognized that the incidence of facial nerve injury may be higher in this select population.