Temporal bone fracture
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Temporal bone fracture is usually a sequela of significant blunt head injury. In addition to potential damage to hearing and the facial nerve, associated intracranial injuries, such as extra-axial hemorrhage, diffuse axonal injury and cerebral contusions are common. Early identification of temporal bone trauma is essential to managing the injury and avoiding complications.
Temporal bone fracture is thought to occur in ~20% (range 14-22%) of all calvarial fractures. They have a prevalence of 3% of all trauma patients in one series 6.
Temporal bone fracture is suggested by Battle sign (post-auricular ecchymosis) and bleeding from the external auditory canal. As the fracture can sometimes involve the ossicles, inner ear and facial nerve, symptoms such as hearing loss, vertigo, balance disturbance, or facial paralysis may be present.
Temporal bone fracture is described relative to the long axis of the petrous temporal bone, which runs obliquely from the petrous apex posterolaterally through the mastoid air cells. Using this plane, fractures may be classified as follows:
Otic capsule involvement
Other classifications have been proposed as being more clinically relevant, specifically focusing on whether or not the otic capsule is involved, that is otic capsule-violating (OCV) versus otic capsule-sparing (OCS) injuries 4,5,9. Involvement of the otic capsule is a predictor of several serious complications 5,6:
facial nerve paralysis (2-5x as likely)
cerebrospinal fluid leak (4-8x as likely)
sensorineural hearing loss (7-25x as likely)
Head CT with petrous temporal bone fine slice (≤1 mm) multiplanar bone window reformats is the imaging modality of choice. Aside from the fracture lucency itself, which may be subtle on thicker slices or some planes, there may be secondary imaging features that, while less specific, raise concern in the setting of trauma for temporal bone fracture 7:
air surrounding the temporal bone
fluid opacification within the temporal bone
Treatment and prognosis
Treatment is based on managing facial nerve injury, hearing loss, vestibular dysfunction, and CSF leakage. If immediate facial nerve paralysis occurs with loss of electrical response, surgical exploration should be considered. Delayed-onset or incomplete facial paralysis almost always resolves with conservative management, including the use of tapered-dose corticosteroids.