Which finding is consistent with facial nerve injury?

Which finding is consistent with facial nerve injury?

• A. Loss of taste on the posterior third of the tongue
• B. Hyperacusis on the affected side
• C. Vision loss
• D. Hearing loss unrelated to the facial nerve

Answer: (B)

Hyperacusis on the affected side reflects facial nerve injury because the nerve supplies the stapedius muscle in the middle ear. When stapedius is paralyzed, its normal dampening effect on loud sounds is lost, making sounds seem louder. The posterior third of the tongue’s taste is carried by the glossopharyngeal nerve, not the facial nerve, so that finding isn’t consistent with CN VII injury. Vision loss points to the optic nerve, and hearing loss unrelated to the facial nerve isn’t a typical sign of CN VII damage. So hyperacusis on the affected side is the characteristic clue for facial nerve injury.

Hyperacusis on the affected side reflects facial nerve injury because the nerve supplies the stapedius muscle in the middle ear. When stapedius is paralyzed, its normal dampening effect on loud sounds is lost, making sounds seem louder. The posterior third of the tongue’s taste is carried by the glossopharyngeal nerve, not the facial nerve, so that finding isn’t consistent with CN VII injury. Vision loss points to the optic nerve, and hearing loss unrelated to the facial nerve isn’t a typical sign of CN VII damage. So hyperacusis on the affected side is the characteristic clue for facial nerve injury.