An auditory brainstem implant provides hearing to people with hearing loss who can't benefit from a hearing aid or cochlear implant. This is most commonly due to a missing or very small hearing nerve or severely abnormal inner ear (cochlea). The auditory brainstem implant directly stimulates the hearing pathways in the brainstem, bypassing the inner ear and hearing nerve.
Auditory brainstem implant was originally developed for adults diagnosed with neurofibromatosis type 2 — a rare genetic condition that causes tumors to grow on nerves. The surgery is now considered for adults and children with other nerve and inner ear abnormalities.
Why it's done
The goal of the surgery is to restore hearing in people with hearing loss. An auditory brainstem implant can be alternative approach for people who can't have a cochlear implant. A cochlear implant is an electronic device that bypasses damaged or nonworking parts of the inner ear (cochlea) and directly stimulates the hearing (auditory) nerve. A cochlear implant generally provides better quality sound, but it can't be used in all situations.
You may not be able to receive a cochlear implant if you have:
- A small or missing auditory nerve
- An unusually shaped inner ear
- Scarring of the inner ear caused by infection, such as meningitis
- Damage from a skull fracture
An auditory brainstem implant bypasses the damaged auditory nerves and connects directly to the brainstem to help you detect sounds.
Rare complications following auditory brainstem implants may include meningitis, leaks of fluid found in the brain and spine, facial nerve weakness, pain and dizziness. Despite appropriate device placement, some people don't experience any hearing benefit.
What you can expect
During the procedure
Auditory brainstem implants have three main parts:
- A microphone and sound processor positioned behind the ear to pick up sounds
- A decoding chip placed under the skin to transmit information picked up by the microphone
- Electrodes connected directly to the brainstem that, when stimulated, alert you to sound
If you have neurofibromatosis type 2, the surgery is often performed at the same time tumors are removed from the hearing (auditory) nerves.
After the procedure
After surgery, you'll need many sessions with an audiologist to adjust the sound processor and learn how to use and interpret the signals. This process can take many months. You'll generally see an audiologist every two to four months the first year and annually after the first year.
An auditory brainstem implant doesn't restore normal hearing. But it helps most people distinguish sounds such as telephone rings and car horns. Some people have good word recognition, while others get more general sound cues. Combined with lip reading, the cues can improve your communication with others.