What is a cochlear implant?

A cochlear implant is an electronic hearing device that is surgically implanted to provide useful hearing sensations to individuals with severe to profound nerve deafness. It works by electrically stimulating the nerves inside the inner ear. The implanted device is managed by an external processor, which is usually worn on the ear. These two components are linked by magnets—one located under the skin and the other above the skin.

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Who is a good candidate for cochlear implants?

Cochlear implants are designed to help adults and children with severe to profound hearing loss, or those who get little or no benefit from hearing aids.

What is normal hearing?

Your ear consists of three essential parts that play a crucial role in hearing: the external ear, middle ear, and inner ear.

  • Conductive hearing: Sound travels through the ear canal in the external ear, causing the eardrum to vibrate. Three small bones in the middle ear conduct this vibration from the eardrum to the cochlea (auditory chamber) in the inner ear.
  • Sensorineural hearing: When the small bones move, they create waves of fluid in the cochlea. These waves stimulate over 16,000 delicate hearing cells (hair cells). As these hair cells move, they generate an electrical current in the auditory nerve. This electrical signal travels through connections in the brain to specific areas that interpret it as sound.

How is hearing impaired?

If there is disease or obstruction in the external or middle ear, conductive hearing may be impaired, which can often be corrected with medical or surgical treatment.

However, an issue in the inner ear can lead to sensorineural impairment, or nerve deafness. In most cases, the hair cells are damaged and do not function. Although many auditory nerve fibers may be intact and capable of transmitting electrical impulses to the brain, they may be unresponsive due to hair cell damage. Since severe sensorineural hearing loss cannot be remedied with medication, it is treated with a cochlear implant.

How do cochlear implants work?

Cochlear implants bypass damaged hair cells and convert speech and environmental sounds into electrical signals that are sent to the hearing nerve.

A cochlear implant has two main components:

  1. Internal component: This consists of a small electronic device that is surgically implanted under the skin behind the ear and is connected to electrodes inserted inside the cochlea.
  2. External component: Usually worn behind the ear, this includes a speech processor, microphone, and battery compartment.

The microphone captures sound, which the speech processor translates into distinctive electrical signals. These signals, or “codes,” travel via a thin cable to the headpiece and are transmitted across the skin using radio waves to the implanted electrodes in the cochlea. The electrodes stimulate the auditory nerve fibers, sending information to the brain, where it is recognized as meaningful sound.

Cochlear implant benefits

Cochlear implants are intended for individuals who receive little to no benefit from hearing aids. Candidates must be 12 months of age or older (unless deafness is due to childhood meningitis).

Otolaryngologists (ear, nose, and throat specialists) perform the implant surgery, although not all are qualified to do so. Your local doctor can refer you to an implant clinic for evaluation. The implant team—comprising an otolaryngologist, audiologist, nurse, and others—will assess your candidacy for a cochlear implant and discuss expectations. They will conduct a series of tests, including:

  • Ear (otologic) evaluation: The otolaryngologist examines the middle and inner ear to ensure no active infection or abnormalities prevent the surgery.
  • Hearing (audiologic) evaluation: The audiologist performs extensive hearing tests to determine how much you can hear with and without a hearing aid.
  • X-ray (radiographic) evaluation: Special X-rays, typically CT or MRI scans, are taken to assess your inner ear anatomy.
  • Physical examination: Your otolaryngologist conducts a physical exam to identify any potential issues with using general anesthesia for the procedure.

Cochlear implant surgery

Cochlear implant surgery is typically performed as an outpatient procedure under general anesthesia. An incision is made behind the ear to access the mastoid bone, which leads to the middle ear space. Once this area is exposed, an opening is created in the cochlea, and the implant electrodes are inserted. The electronic device at the base of the electrode array is then placed under the skin behind the ear.

Is there care and training after the operation?

Several weeks post-surgery, your cochlear implant team will fit the signal processor, microphone, and implant transmitter outside your ear and make adjustments. They will teach you how to care for the system and how to listen through the implant. Due to individual differences, some patients may take longer to adapt and require more training. Your team will schedule regular checkups and readjustments of the speech processor as needed.

What can I expect from an implant?

Most adult cochlear implant users notice immediate improvements in their communication skills. Children, however, may take time to benefit, as the brain needs to learn to interpret the electrical sound input correctly. While cochlear implants do not restore normal hearing and benefits vary, many users find that they improve communication through enhanced lip-reading. Approximately 90% of adult cochlear implant patients can discriminate speech without visual cues. Factors influencing the degree of benefit include:

  • The duration of hearing loss
  • The number of surviving auditory nerve fibers
  • The patient’s motivation to learn to hear

Your team will explain what to reasonably expect. Understanding the time commitment required for optimal results is essential, as it is rare for patients to derive no benefit from a cochlear implant.

FDA approval for implants

The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults and children, granting approval only after thorough clinical investigation.

Be sure to ask your otolaryngologist for written information, including brochures from implant manufacturers. You should be fully informed about the benefits and risks of cochlear implants, including safety, reliability, effectiveness, follow-up checkups, and insurance coverage.

Costs of implants

Cochlear implants are more expensive than hearing aids, with total costs—including evaluation, surgery, the device, and rehabilitation—reaching up to $100,000. Fortunately, most insurance companies and Medicare provide coverage for these costs.