Overview

A cochlear implant is an electronic device that partially restores hearing. It can be an option for people who have severe hearing loss from inner-ear damage who are no longer helped by using hearing aids.

Unlike hearing aids, which amplify sound, a cochlear implant bypasses damaged portions of the ear to deliver sound signals to the hearing (auditory) nerve.

Cochlear implants use a sound processor that fits behind the ear. The processor captures sound signals and sends them to a receiver implanted under the skin behind the ear. The receiver sends the signals to electrodes implanted in the snail-shaped inner ear (cochlea).

The signals stimulate the auditory nerve, which then directs them to the brain. The brain interprets those signals as sounds, though these sounds won't be just like normal hearing.

It takes time and training to learn to interpret the signals received from a cochlear implant. Within a year of use, most people with cochlear implants make considerable gains in understanding speech.

Mayo Clinic Minute: The road to hearing for baby Aida

Vivien Williams: The happy sounds of childhood, a brother's giggle, a mother's loving coo or the joy of your own calls of contentment.

Matt Little: Very happy.

Melinda Little: She loves her daddy.

Vivien Williams: Baby Aida can't hear any of it. She was born deaf.

Melinda Little: When you first hear it, you kind of say, "That's not true,' or, 'What can we do to help it?"

Vivien Williams: Aida's mom and dad, Melinda and Matt Little, took her to Mayo Clinic, where a team of experts diagnosed Aida with a rare genetic condition.

Lisa Schimmenti, M.D.: Aida has a condition called Waardenburg syndrome.

Vivien Williams: Geneticist Dr. Lisa Schimmenti says Waardenburg syndrome is a collection of symptoms caused by a change in a gene.

Dr. Schimmenti: If you went and Googled this disorder, you'll see pictures of people who may have a white streak of hair, or they may have one blue eye and one brown eye…well, this the fish lab.

Vivien Williams: Some of the tools Dr. Schimmenti uses to learn about deafness similar to Aida's are tanks full of zebra fish.

Dr. Schimmenti: We share 70 percent of our genome with zebrafish, and the same genes that cause conditions in us, cause the same condition in fish.

Vivien Williams: But, unlike these fish, Aida may benefit from technology to help her hear.

Matthew Carlson, M.D.: Cochlear implant surgery and cochlear implant technology has evolved very significantly over the last several decades.

Vivien Williams: Surgeon Dr. Matthew Carlson is also on Aida's care team.

Dr. Carlson: There's a lot of different changes that happen in the inner ear that result in this hearing loss, but the end result is loss of inner ear hair cells for almost all these different conditions.

Vivien Williams: Here are the basics on how hearing works. The outer ear collects sound, which travels down the ear canal to the ear drum. The soundwaves cause the ear drum and middle ear bones to vibrate. The sound waves then move into the inner ear, or cochlea, where tiny hair cells turn them into electrical signals that are transmitted to the brain. A cochlear implant bypasses the missing hair cells. Baby Aida, like all patients who get cochlear implants, went through two steps. First was surgery. Through a small incision, Dr. Carlson and his team...

Dr. Carlson: …slip a small group of electrodes or wires that are all kind of bundled together, and they follow the natural curvature of the cochlea. And the electrodes are connected to a device that's underneath the skin in the scalp.

Vivien Williams: The device sends a tiny current via the electrodes to the cochlea and then to the brain.

Matt Little: ...to activate it, they'll just have the outer piece attached, and then it's just like, basically, from what I understand, like a Bluetooth headset, pretty much.

Vivien Williams: Cochlear implants work for most people who have them, but there's always the chance they won't. Aida's brother, parents, grandparents and cousins were all there the day audiologists at Mayo Clinic attached the outside piece behind Aida's ear and turned it on for the first time.

Matt Little: "Hi, beautiful. Can you hear me? It's Daddy."

Matt and Melinda Little: "Hi …Hi, Aida. Hi, Aida. Hi, big girl. Hello. Hi."

Vivien Williams: To people in that room, witnessing Aida hear for the first time was to witness a miracle.

Melissa DeJong, Au.D.: For me, it's what brings me to work every day.

Matt Little: Just to be able to hear, — hear the sounds around her — that's what I'm looking forward to.

Vivien Williams: For Aida to be able to hear the happy sounds of childhood. For the Mayo Clinic News Network, I'm Vivien Williams.

Mayo Clinic Minute: New technology for cochlear implants

Vivien Williams: If hearing aids don't work for you, cochlear implants might. New technology is helping to make cochlear implants even better.

Colin Driscoll, M.D., Otolaryngology - Head and Neck Surgery, Mayo Clinic: "One of the more exciting things that's been developed in the last number of years is surrounding the concept of preserving the hearing that people currently have."

Vivien Williams: Dr. Colin Driscoll says some people who choose cochlear implants do have some level of hearing. It's just not good. Before the new technology was available, any residual hearing that did exist was lost during surgery to implant the device.

Colin Driscoll, M.D.: "The idea now is, can we preserve that functional, mildly useful hearing and then augment it with the cochlear implant?"

Vivien Williams: The new technology allows Dr. Driscoll and his team to monitor hearing levels during surgery to make sure implantation does not disrupt existing hearing. It allows patients to…

Colin Driscoll, M.D.: "... get the best of both worlds. Hang on to what you have and then augment what you don't have."

Vivien Williams: For the Mayo Clinic News Network, I'm Vivien Williams.

Why it's done

Cochlear implants can restore hearing in people with severe hearing loss who are no longer helped by using hearing aids. Cochlear implants can improve their communication and quality of life.

Cochlear implants may be placed in one ear (unilateral) or both ears (bilateral). Cochlear implants in both ears have started to be used more often to treat bilateral severe hearing loss — particularly for infants and children who are learning to speak and process language.

Adults and children who are as young as six to 12 months old can benefit from cochlear implants. People who have cochlear implants report improved:

  • Ability to hear speech without needing visual cues such as reading lips
  • Recognition of normal, everyday environmental sounds
  • Ability to listen in a noisy environment
  • Ability to find where sounds are coming from
  • Ability to hear television programs, music and telephone conversations

To be eligible for a cochlear implant, you must have:

  • Hearing loss that is so severe it interrupts spoken communication
  • Limited benefit from hearing aids as determined by specialized hearing tests
  • No medical conditions or factors that increase the risks associated with cochlear implants
  • High motivation to participate in hearing rehabilitation and be part of the hearing world
  • Realistic expectations of what cochlear implants can and can't do for hearing

Risks

Predicted outcomes

Cochlear implant surgery is generally safe. Risks of cochlear implantation can include:

  • Loss of residual hearing. Implantation of the device can cause a loss of any remaining, unclear, natural hearing in the implanted ear in some people.
  • Inflammation of the membranes surrounding the brain and spinal cord (meningitis) after cochlear implant surgery. Vaccinations to reduce the risk of meningitis are generally given to adults and children before implantation.
  • Failure of device. Surgery may sometimes be needed to repair or replace a faulty internal device.

Complications are rare and can include:

  • Bleeding
  • Facial paralysis
  • Infection at the surgery site
  • Device infection
  • Balance problems
  • Dizziness
  • Taste disturbance
  • New or worsened ear noise (tinnitus)
  • Spinal fluid leak

How you prepare

Cochlear implant surgery is done under general anesthesia. This means you or your child will be in a sleep-like state during the procedure. You or your child might need to:

  • Stop taking certain medications or supplements for a certain amount of time
  • Avoid eating or drinking for a certain amount of time

Your doctor will give you specific instructions to help you prepare.

What you can expect

Before the procedure

You or your child will need a detailed medical evaluation to determine if cochlear implants are a good option. A doctor will conduct an evaluation that may include:

  • Ordering tests of hearing, speech and sometimes balance
  • Performing a physical examination to assess your inner ear's health
  • Ordering MRI or CT imaging tests of the skull to assess the condition of the cochlea and inner ear structure
  • Ordering mental health (psychological) testing in select cases to determine your ability to learn to use cochlear implants

During the procedure

Your surgeon will make a cut (incision) behind your ear, and form a small hole in the portion of skull bone (mastoid) where the internal device rests.

Your surgeon will then create a small opening in the cochlea in order to thread the electrode of the internal device. The skin incision is stitched closed so that the internal device is under your skin.

After the procedure

You or your child might experience:

  • Pressure or discomfort over the implanted ear or ears
  • Dizziness or nausea

Most people feel well enough to return home the day of surgery or the next day.

An audiologist won't turn on (activate) the cochlear implants for about two to six weeks after your surgery — to give the surgery site time to heal.

Activation

To activate the cochlear implant, an audiologist will:

  • Adjust the sound processor to fit you or your child
  • Check the components of the cochlear implant to make sure they work
  • Determine what sounds you or your child hears
  • Give you information on the proper care and use of the device
  • Set the device so that you can hear to the best of your ability

Rehabilitation

Rehabilitation involves training your brain to understand sounds heard through the cochlear implant. Speech and everyday environmental noises will sound different from what you remember.

Your brain needs time to recognize what these sounds mean. This process is ongoing and is best achieved by wearing the speech processor continuously during waking hours.

Results

Results of cochlear implant surgery vary from person to person. Factors that can affect the outcomes of cochlear implantation include the age when hearing was lost, and the length of time between hearing loss and the cochlear implant surgery.

For children, the best results generally occur with getting a cochlear implant at a young age.

For adults, the best results are generally associated with a shorter period of profound hearing loss before cochlear implantation. Adults with little or no experience with sound tend to benefit less from cochlear implants.

Some predicted outcomes may include:

  • Clearer hearing. Many people who meet the hearing criteria for cochlear implantation may eventually get clearer hearing with using the device.
  • Improved tinnitus. Although ear noise (tinnitus) isn't a primary reason to receive a cochlear implant, the cochlear implant may partially suppress or improve the severity of tinnitus during use. It can rarely worsen tinnitus severity.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

Cochlear implants care at Mayo Clinic

March 24, 2020
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