Floating petrous bone fracture.

Floating petrous bone fracture appears to occur when the elastic pediatric skull is subjected to large compressive forces. Unlike a longitudinal fracture, a floating petrous bone fracture does not involve the ear canal and squamous cortex. Rather, the fracture line runs through the middle ear, separating the petrous apex from its lateral and inferior bony attachments. Characteristic clinical findings include immediate onset of conductive hearing loss, with ipsilateral sixth and seventh cranial nerve paralysis. This article details the third known occurrence of this type of fracture, and includes a discussion of the pathophysiologic mechanism and treatment rationale.