Temporal bone fracture

Head and Neck

Fractures through the mastoid and temporal bone are best described primarily by whether or not the fracture extends to the otic capsule or labyrinth, and by the fracture orientation relative to the axis of the petrous temporal bone. Temporal bone fractures can result in temporary or persistent conductive hearing loss, sensorineural hearing loss (usually permanent), facial paralysis due to peripheral seventh-nerve palsy, bruising about the mastoid eminence (Battle sign), or periorbital ecchymosis (raccoon eyes).

Indirect findings are usually evident on noncontrast head CT and include mastoid air cell opacification, fluid within the external auditory canal and middle ear, air in the temporomandibular fossa, and intracranial air adjacent to the petrous bone.

Longitudinal fractures do not typically involve the otic capsule. Hemorrhage within the mastoid air cells and tympanic cavity results in immediate conductive hearing loss that resolves over time. Some patients will have more complicated injuries with ossicular dislocation and/or tympanic membrane disruption. In the case of ossicular dislocation, conductive hearing loss may not resolve without surgical repair.

Otic capsule–sparing (longitudinal) fracture. This fracture is parallel to the axis of the temporal bone and results in incudomalleolar dislocation (the normal incus and malleolus should look like an ice cream cone on axial epitympanic images; in this case the ice cream and cone are on different slices), as well as intratympanic and mastoid hematoma. The otic capsule is intact.

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In contrast, fractures that disrupt the otic capsule are usually transversely oriented, and are more likely to result in immediate and irreversible sensorineural hearing loss, CSF otorrhea, and facial nerve injury.

Otic capsule–violating (transverse) fracture. The fracture is oriented perpendicular to the axis of the petrous temporal bone and crosses the vestibule, the posterior semicircular canal, and the lateral semicircular canal. The tympanic cavity and epitympanum are completely opacified.