An auditory brainstem implant provides hearing to people with hearing loss who cannot benefit from a hearing aid or cochlear implant. Most commonly this is when there is an absent 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.
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.
Mayo Clinic's approach
Why it's done
The goal of the surgery is to restore hearing. An auditory brainstem implant offers an alternative approach for people who aren't candidates to receive a cochlear implant — an electronic device that bypasses damaged or nonworking parts of the inner ear (cochlea) and directly stimulates the auditory nerve. A cochlear implant typically provides better quality sound but cannot be used in all situations.
Reasons you may not be eligible to receive a cochlear implant include having:
- A small or absent auditory nerve
- An unusually shaped cochlea
- Scarring of the cochlea 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.
Although rare, complications following auditory brainstem implants may include infection (meningitis), cerebrospinal fluid leaks, facial nerve weakness, pain and dizziness. In some cases, despite appropriate device placement, patients do not receive 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 auditory nerves.
After the procedure
After surgery, you will need multiple 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 will typically see an audiologist every two to four months the first year and annually thereafter.
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 get good word recognition, while others get more general sound cues. In combination with lip reading, the cues can improve your communication with others.
Dec. 29, 2017