Question 1 · Medium
MRI of the internal acoustic canals in a child with profound congenital deafness, who has gained nothing from hearing aids, shows normal cochleae on both sides but absent cochlear nerves within narrow canals. Which device can give this child hearing sensation?
- ACochlear implant
- BBone-anchored hearing aid
- CAuditory brainstem implant
- DMiddle ear implant
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Answer: C · Auditory brainstem implant
A cochlear implant stimulates the spiral ganglion and cochlear nerve, so it cannot work if the nerve is absent. An auditory brainstem implant places electrodes on the cochlear nucleus in the lateral recess of the fourth ventricle, bypassing the cochlea and the nerve. It is also used in neurofibromatosis type 2 after removal of bilateral vestibular schwannomas. Key point: Absent cochlear nerves: auditory brainstem implant, not a cochlear implant.
- A: A cochlear implant needs an intact cochlear nerve.
- B: Bone conduction still needs a working cochlea and nerve.
- D: A middle ear implant amplifies sound but still needs the nerve.