Longitudinal temporal bone fracture with incudo-malleolar disruption

Case contributed by Bruno Di Muzio


Pedestrian hit by a tram.

Patient Data

Age: 20 years
Gender: Male

There is a longitudinal fracture through the left temporal bone extending into the middle ear and associated with incudomalleolar disruption and partial obliteration of the middle ear and mastoid air cells. This fracture extends also through the squamous and lambdoid sutures posteriorly and into the glenoid fossa of the left TMJ, without displacement. No signs of involvement of the carotid canal. No other skull fractures were seen. Left parieto-occipital subgaleal hematoma. A small amount of pneumocephalus noted along the middle and posterior fossa on the left. There are small foci of subarachnoid hemorrhage along the left silvan fissure. Ventricular system and cisternal spaces appear normal. Orbits have normal appearances. The paranasal sinuses are mostly clear and aerated. 

CT Temporal Bones (reconstruction)


Longitudinal comminuted fracture line through the left mastoid bone, associated with ossicular chain disruption with incudomalleolar disruption. Minor pneumocephalus is present. The membranous labyrinth is preserved.

The incus and malleus are normally closely apposed, resembling a scoop of ice cream in a cone (check the normal appearance on the right - orange circle):

  • the head of the malleus represents the ice cream (yellow arrow)
  • the body and short process of the incus represent the cone (blue arrow)

Case Discussion

Note how the temporal bone reconstruction appears blurry when compared to CT acquisitions with a dedicated high-resolution temporal bone algorithm. 

Longitudinal temporal bone fractures normally occur parallel to the long axis of the petrous bone, as shown in this case. A more current classification of the extent of temporal bone fractures describes the integrity of the otic capsule rather than the fracture orientation, as the involvement of the otic capsule is a predictor of more serious complications. Our case has no signs of fracture extension into the otic capsule. 

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