A 29-year-old man is brought to the emergency department following a high-speed motorcycle accident. He was wearing a helmet but experienced a brief loss of consciousness. On arrival, he is awake but disoriented. Physical examination reveals clear fluid leaking from the right ear and a large area of ecchymosis behind the right ear. There is no evidence of facial nerve asymmetry. A non-contrast CT scan of the head shows a fracture line running parallel to the long axis of the petrous temporal bone, sparing the cochlea and semicircular canals.
Which of the following is the most likely additional finding in this patient?
The correct answer is:
A) Conductive hearing loss
This patient has a longitudinal temporal bone fracture, which is the most common type (roughly 80% of cases). These fractures typically result from lateral blows to the skull. Because the fracture line often involves the external auditory canal and the middle ear space, it frequently causes conductive hearing loss due to ossicular chain disruption or hemotympanum (blood behind the eardrum).
Answer choice B: Immediate-onset facial paralysis, is incorrect. Facial nerve injury occurs in about 20% of longitudinal fractures and is often delayed due to edema. Immediate-onset complete paralysis is much more characteristic of transverse fractures, where the nerve is often physically transected.
Answer choice C and D: Sensorineural hearing loss and vertigo, are incorrect. Sensorineural hearing loss (SNHL) and vertigo are hallmarks of otic capsule-violating fractures (classically transverse fractures). Since the question specifies the fracture spares the cochlea and semicircular canals, SNHL and vestibular symptoms are unlikely.
Answer choice E: Tinnitus and dizziness, is incorrect. While these are common in many head injuries, they are non-specific and do not point to the structural consequences of a longitudinal fracture as accurately as conductive hearing loss.
Key Learning Point
Longitudinal temporal bone fractures (otic capsule-sparing) are common and typically present with conductive hearing loss and a lower risk of facial nerve injury. Transverse fractures (otic capsule-violating) are less common but much more severe, often resulting in sensorineural hearing loss, permanent vertigo, and immediate facial nerve paralysis.
