A cochlear implant is an electronic device that restores partial hearing to those with hearing loss who no longer get help from their hearing aids. It is surgically implanted in the inner ear and activated by a device worn outside the ear. Unlike a hearing aid, it does not make sound louder or clearer. Instead, the device bypasses damaged parts of the auditory system and directly stimulates the hearing nerve, allowing individuals with severe hearing loss to receive sound.
What Is Normal Hearing?
Your ear consists of three parts that play a vital role in hearing—the external ear, middle ear, and inner ear.
- Conductive hearing: Sound travels along the ear canal of the external ear causing the ear drum to vibrate. Three small bones of the middle ear conduct this vibration from the ear drum to the cochlea (auditory chamber) of the inner ear.
- Sensorineural hearing: When the three small bones move, they start waves of fluid in the cochlea, and these waves stimulate more than 16,000 delicate hearing cells (hair cells). As these hair cells move, they generate an electrical current in the auditory nerve which travels to an area of the brain that recognizes it as sound.
How Is Hearing Impaired?
If you have disease or obstruction in your external or middle ear, your conductive hearing may be impaired. Medical or surgical treatment can probably correct this.
An inner ear problem, however, can result in a 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 can transmit electrical impulses to the brain, these nerve fibers are unresponsive because of hair cell damage. Since severe sensorineural hearing loss cannot be corrected with medicine and hearing aids provide only limited benefit, it can be treated only with a cochlear implant.
How Do Cochlear Implants Work?
Cochlear implants bypass damaged hair cells by converting speech and environmental sounds into electrical signals and send these signals to the hearing nerve, bypassing damaged hair cells.
The implant consists of a small electronic device, which is surgically implanted under the skin behind the ear and an external speech processor, worn behind the ear or on the head. A headpiece is magnetically worn against the head to send signals to the internal device. The speech processor translates the sound into distinctive electrical signals. These signals travel up a thin cable to the headpiece and are transmitted across the skin via radio waves to the internal device, which then sends the signal to the implanted electrodes in the cochlea. The electrodes’ signals stimulate the auditory nerve fibers to send information to the brain where it is interpreted as meaningful sound.
Who Can Benefit from an Implant?
Implants are designed only for individuals who attain limited benefit from a hearing aid. There is a thorough evaluation process to determine if a cochlear implant would be more beneficial than hearing aids.
Otolaryngologists (ear, nose, and throat specialists) perform cochlear implant surgery, though not all otolaryngologists perform this procedure. Otolaryngologists performing the cochlear implant surgery have received extensive training and continuously update their skills.
At Ear, Nose & Throat SpecialtyCare of MN, the cochlear implant evaluation will be performed by an implant team that includes both cochlear implant otolaryngologists and audiologists. You will undergo a series of tests including:
- Ear (otologic) evaluation: The otolaryngologist examines the middle and inner ear to ensure that no active infection or other abnormality precludes the implant surgery. This evaluation will determine if there is good medical candidacy for the cochlear implant. Your otolaryngologist will also give you a physical examination to identify any potential problems with the general anesthesia needed for the implant procedure. Some patients may need a psychological evaluation to learn if they can cope with the implant.
- Hearing (audiologic) evaluation: The audiologist performs an extensive hearing test as well as additional testing to determine how much you can hear with and without a hearing aid.
- X-ray (radiographic) evaluation: Special X-rays are taken, usually computerized tomography (CT) or magnetic resonance imaging (MRI) scans, to evaluate your inner ear bone.
What About Surgery?
Cochlear implant surgery is performed under general anesthesia and lasts from two to three hours. An incision is made behind the ear to open the mastoid bone leading to the middle ear. The procedure may be done as an outpatient, or may require an overnight stay in the hospital.
Is There Care and Training After the Operation?
About two to three weeks after surgery, you will have a post-operative evaluation with your otolaryngologist. Once it is determined that there has been good healing, you will proceed with activation of the cochlear implant.
At activation, the audiologist places the processor and headpiece on your head. There will be extensive testing to ensure that the cochlear implant is working appropriately. The audiologist will teach you how to look after the device and how to listen to sound through the implant. You will need regular appointments to fine-tune the sound from the implant as you adapt to this different type of hearing.
What Can I Expect from an Implant?
Cochlear implants do not restore normal hearing and benefits vary from one individual to another. Initial experiences with the cochlear implant vary greatly, but you can expect the sound to be very different at first. Many people describe the sound to be “beeps”, “Charlie Brown speech” or “Mickey Mouse” at first. This is normal and to be expected. It takes practice for your brain to learn to hear with the cochlear implant to the point where you can recognize these electrical signals as meaningful sound. Most users find that cochlear implants help them communicate better, and many are even able to eventually talk on the phone.
Good results are not guaranteed, and there are a few patients do not benefit from implants. There are many factors that contribute to the degree of benefit a user receives from a cochlear implant, including:
- how long you have had significant hearing loss
- the number of surviving auditory nerve fibers in the inner ear
- motivation to learn to hear
- support team, including family and friends
- the amount of practice and work you put into listening to sound (“aural rehabilitation”)
Your cochlear implant team will explain what you can reasonably expect. It is important to understand clearly how much time you must commit. All cochlear implant manufacturers offer online support and activities to help you succeed. If interested, you can be connected with someone who has a cochlear implant for information and support. In addition, your audiologist may recommend that you meet with a specialized speech language pathologist to help you make more progress.
How Are New Implant Devices Approved?
The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults and children and approves them only after thorough clinical investigation.
Be sure to ask your cochlear implant team for written information, including brochures provided by the implant manufacturers. You need to be fully informed about the benefits and risks of cochlear implants, how often you must come back to the clinic for checkups, and whether your insurance company pays for the procedure.
How Much Does an Implant Cost?
More expensive than a hearing aid, the total cost of a cochlear implant including evaluation, surgery, the device, and rehabilitation is around $50,000. Most insurance companies, including Medicare, provide benefits that cover the cost as long as certain criteria are met.