Can a cochlear implant help severe hearing loss?

DEAR DOCTOR K:

I have severe hearing loss that hasn’t been helped by hearing aids. Could I be a candidate for a cochlear implant?

DEAR READER:

You sure could be. Cochlear implants are a relatively new technology; they weren’t available when I graduated from medical school. There often were no effective options for people like you with severe hearing loss. Even the most advanced hearing aids didn’t help. But since then, more than 200,000 people around the world have been helped by this technology.

To understand how a cochlear implant works, you need to understand how we hear. Hearing starts when little hairs inside your ear pick up sound waves. The hairs are in a snail-shaped part of your ear called the cochlea. When sound waves cause the hairs to vibrate, signals are sent up the hearing nerve (called the acoustic nerve) to the brain. The brain then interprets those signals and we hear sound.

Sensorineural hearing loss usually comes on gradually, caused by aging or by an ongoing exposure to loud noise. The hair cells in the cochlea can be damaged beyond repair. One way that happens is being exposed too often to very loud sounds — such as operating a jackhammer, or attending too many rock concerts.

 How a cochlear implant works: When sounds are detected by a microphone in the earpiece (A), the speech processor converts the sound waves into electrical signals. These pass along a wire to a transmitting coil that attaches behind the ear (B). The transmitter relays the signals through the skin to the implanted receiver (C), which sends the electrical current down wires to electrodes (D) in the cochlea. These electrodes stimulate the auditory nerve, which sends the signal to the brain.

 

Cochlear implants are used only when a person has severe hearing loss in both ears, so extreme that even the best hearing aid doesn’t help.

If you are a good candidate for an implant, here is what happens in the procedure: An ear surgeon who specializes in cochlear implants places a wire inside your cochlea. The wire is attached to a tiny receiver, placed just inside your skull. Electrical signals through that wire stimulate the hearing nerve. You are under general anesthesia during the procedure and don’t feel anything.

Outside your ear you wear a little microphone that is attached to a transmitter. When the microphone picks up sound waves, it transmits a wireless signal to the receiver inside your skull. That signal travels down the wire into your cochlea and stimulates your hearing nerve.

Once your implant is in place, you must work with an audiologist to learn how to listen to and interpret sounds through the implant. Speech may sound mechanical, and other sounds may be unrecognizable at first. Just as important, you must be willing to put in the time and effort required to relearn how to hear. Rehabilitation can take up to a year.We have more information on cochlear implants in our Special Health Report, “Hearing Loss.” You can learn more about this report here.

Although it takes work and time to learn how to hear again after a cochlear implant, the rewards can be enormous. You don’t absolutely need to restore hearing to carry on conversations, as people who are deaf can tell you. What my patients who have had cochlear implants talk most about are the sounds — of the wind, the music, their grandchild laughing in the next room. That’s what makes the effort worthwhile.