A new hope for the deaf! Let's learn everything about the Auditory Brainstem Implant (ABI)!

Have you ever imagined a world without sound? A loved one's voice, a beautiful song, a baby's laughter... A life without hearing anything. It's hard to imagine, isn't it? But, for some people, this is the truth. When they lose their hearing completely, that is, when they lose their hearing, they lose their connection with the world of sound. However, with the advancement of medical science, there is now a technology that can give hope to such people. That's what we are going to talk about today.

Simply put, what is this Auditory Brainstem Implant (ABI)?

This is also a hearing aid. But it's not like the hearing aid you usually see in the ear. An Auditory Brainstem Implant (ABI) is a device that is surgically implanted inside the body. It is designed to give a person who is completely deaf the sensation of sound .

This is especially important if the cause of hearing loss is either a problem with the cochlea (inner ear) or a problem with the hearing nerve. This means that if the "path" that carries sound signals from the ear to the brain is completely broken, this device bypasses that broken path and sends signals directly to the part of the brain that is responsible for hearing (the brainstem).

The main benefits that one gets from this are:

• Being able to be aware of sounds around you (e.g. someone talking, a car approaching, etc.).
• The ability to understand what someone is saying by watching their lips (lip-reading) increases when they are speaking.
• Sometimes, you can recognize sounds, understand words, and even sentences.

What does this ABI device look like?

This device has two main parts: one that is worn outside the body, and the other that is surgically implanted inside the body.

1. Processor: This is the part that is on the outside of your body. It looks like a small device. It is worn over your ear or on the side of your head. It uses a microphone to pick up the sounds around you. It then converts those sounds into electrical signals and sends them to the other part that is implanted under your skin. You can remove this external part while you sleep.

2. Internal Implant: This is what doctors surgically place inside the body. This also has two parts:

• Receiver-stimulator: This is placed under the skin of your head. It receives signals from the external processor.
• Electrode paddle: The signals from the receiver are delivered directly to the main hearing center of the brain, the cochlear nucleus complex, in the brainstem, through a small electrode pad.

Simply put, it picks up sounds from the outside and sends them to the inside. The inside sends those signals directly to the brain.

Is this ABI the same as the Cochlear Implant we often hear about?

No. Although both are surgically implanted devices that help with hearing, the way they work and the people they are compatible with are different. Think of it this way: the ear is the gate, and the auditory nerve is the road from the gate to the home (the brain).

• A cochlear implant is used for people whose only gate (the `cochlea` inside the ear) is broken, but whose road home (the auditory nerve) is intact. The cochlear implant bypasses the broken gate and sends signals directly to the road (the auditory nerve).
• An ABI is only used by people who have both the gate (cochlea) and the road (auditory nerve) damaged, or who have no road at all. In that case, there is no point in sending signals to the road. What the ABI does is bypass both the gate and the road and send signals directly to the house (the brainstem).

This difference will become clearer to you when you look at the table below.

Who is this ABI surgery suitable for?

This technology was first developed for people with a rare genetic condition called `Neurofibromatosis 2 (NF2).` In this disease, tumors develop along the auditory nerve. Surgery to remove these tumors can damage the auditory nerve. Then they lose hearing in both ears. In such a case, neither a hearing aid nor a cochlear implant will help. That is why ABI mainly helps such people.

But now, not only those with NF2, but also those whose auditory nerve or inner ear has malfunctioned for many other reasons can benefit from this technology. For example:

• Young children who are born with an auditory nerve that is absent (`aplasia`) or not fully developed (`hypoplasia`).
• People who have lost hearing due to causes such as deformities in the shape of the inner ear (cochlea), incomplete development (cochlear hypoplasia), lack of formation of parts (cochlea aplasia), or bone growth (cochlear otosclerosis or cochlear ossification).
• Those who have damage to the auditory nerve due to severe head injuries (e.g. temporal bone fractures).
• For those who are deaf due to other reasons and cannot be heard with any other device.

What should you do before surgery?

Because this is a major surgery, several tests will be performed to thoroughly study your condition beforehand.

• Behavioral testing: Measures your hearing level.
• Communication evaluation: A speech-language pathologist will examine your language skills and communication style.
• Electrophysiologic testing: Special tests are performed to determine exactly where and to what extent the hearing system is damaged.
• Imaging tests: These include CT scans and MRI scans to examine the inner ear, auditory nerve, and surrounding structures in the brain.
• Medical history: Your doctor will ask about your medical conditions and history of hearing problems.

What are the benefits, risks, and results of this surgery?

When talking about this, we need to understand the real situation.

Advantages:

Although results vary from person to person, in general, things like speech recognition and lip reading improve significantly. In particular, research has shown that children who undergo this surgery at a young age (before their hearing loss has been long) have a better ability to understand words than adults.

Risks and Complications:

This is a very complex brain surgery, so there are some risks. However, when performed by a skilled team of doctors who are experienced in this type of surgery, the chances of complications are very low. Your doctor will explain all this to you before the surgery. Some of the possible complications are:

• Cerebrospinal fluid leaks.
• Implant failure.
• Discomfort caused by stimulation of nerves other than hearing.
• Infections such as meningitis.
• Damage to the facial nerves (`Palsy of your facial nerve`).
• Infection of the surgical wound.

What happens after the surgery?

You will need to stay in the hospital for two to four days after the surgery. If you had this surgery at the same time as the removal of an NF2 tumor, your hospital stay may be longer.

Once the device is fitted, it will take four to six weeks to activate. After that, you will have several appointments with your audiologist. Each time, the device will be programmed to work best for you. This process will continue for about the first year.

When should you see your doctor?

After surgery, if you develop a fever or severe pain, you should notify your doctor immediately. The medical team will also monitor you closely to prevent complications. After surgery, it is also very important to visit your audiologist on the scheduled days to adjust the settings of the device.

An Auditory Brainstem Implant (ABI) is not for everyone. However, for some people who have no other options and are completely deaf, it offers an invaluable opportunity to reconnect with the world of sound. The best way to find out if this is right for you or someone you know is to talk to a specialist.