New brain implant may restore hearing

From WJRT-TV in Michigan:

A new implant may help people who can't have success with other devices finally hear again.

HealthFirst reporter Leslie Toldo tells us about this new technology for a specific type of deafness.

We are talking about people who can't be helped by cochlear and other implants. This new device retrains the brain to hear.

Danny Sanborn wishes he could go back to a time before his world went silent. He suffers from a disease that causes brain tumors. In order to get the tumors out, doctors had to sacrifice his auditory nerve.

"Before I had the tumors, I had hearing. But as soon as they took the tumors out, I didn't have any."

A cochlear implant wasn't an option, so surgeons put in an auditory brainstem implant or ABI to restore certain sounds.

"We are bypassing the auditory nerve to directly stimulate the next level of sound processing in the brain," explained Dr. Daniel Lee.

Lee says surgeons place 21 electrodes on the bundle of nerves that sit on the brain stem, the lower part of the brain. "The electrodes provide electrical current. It stimulates those nerves that are responsible for continuing a signal of sound to the rest of the brain."

A tiny microphone is positioned by the ear. It picks up sounds from the environment and digitally transmits them to a decoding chip placed under the skin. The chip stimulates the electrodes, allowing the patient to hear sounds.

It doesn't restore complete hearing, but Sanborn is now able to hear the phone, an alarm clock and even his best friend.

While the device can restore some hearing, it can't restore a patient's balance that is damaged by the tumors.

Up to one-in-25,000 Americans suffers from the condition that causes hearing loss like Sanborn's, called NF2.

BACKGROUND: An auditory brainstem implant (ABI) is a device that is surgically implanted into the brain of a deaf person who lacks auditory nerves or with a damaged auditory nerve. The auditory nerve is responsible for sending signals from the ear to the brain. The implant consists of a small electrode or multiple electrodes applied to the brainstem where it stimulates sound-producing nerves with electrical signals. The device also includes a small microphone in the outer ear to pick up sounds from the environment and a decoding chip placed under the skin. A wire connects the decoding chip to the electrode at the brainstem. While an ABI doesn't restore a full hearing sense, it enables a deaf person to hear some sounds like sirens and alarms and makes it easier to lip read (Source: hear-it.org). An ABI is different from a cochlear implant, which is implanted in the inner ear, converts speech and other sounds into electrical signals, and sends these signals to the hearing nerve.

According to the Mayo Clinic, the placement of an ABI is only the first step in restoring partial hearing. After the surgery, a patient visits an audiologist for several sessions to test and adjust the sound processor and learn new sounds. While some patients implanted with an ABI develop word recognition, others combine general sound cues with lip reading to improve conversation skills.