Criteria to be a candidate for a cochlear implant:
- Severe-to-profound hearing loss in both ears caused by sensorineural damage to the inner ear
- Limited benefit from hearing aids as determined by specialized audiologic testing
- No medical or radiologic conditions or factors that increase the risks associated with cochlear implants
- High motivation to participate in rehabilitation sessions and to be part of the hearing world
- Clear understanding of what cochlear implants can and cannot do for hearing
Mayo Clinic has performed cochlear implants in children as young as 1 year of age and adults as old as 96.
You undergo many tests during several outpatient visits, including:
- Hearing test
- Hearing aid evaluation
- Speech understanding with appropriate hearing aids
- Balance assessment
- MRI scan
- Medical evaluation
- Insurance consultation
- Audiologic consultation
- Psychology consultation
- Speech pathology consultation
Surgery is performed while you are under general anesthesia and takes approximately one to three hours. The ear, nose and throat surgeon makes an incision behind the ear and forms a slight depression in the mastoid bone, where the internal device rests. The surgeon then creates a small hole in the cochlea and threads the electrode array of the internal device through this hole. The incision is closed so that the internal device is beneath the skin. Most people feel well enough to return home the day of surgery.
Two to four weeks after surgery, the external components of the device can be programmed and activated. There's no hearing ability from the implant until this is done.
The activation comprises:
- Fitting the headset. An audiologist attaches a headset that consists of a transmitter and a microphone-speech processor. The transmitter sends sound signals across the skin to the internal receiver-stimulator.
- Cochlear implant check. Every component, including each electrode, is checked to make sure it's working properly.
- Programming the speech processor. An audiologist creates a "hearing map," an individually designed set of instructions that tells each electrode how to stimulate the nerve endings in the cochlea.
- Trying it out. The speech processor is turned on, and you hear through the cochlear implant for the first time. On this first day, speech usually sounds garbled or high-pitched. Environmental sounds may be difficult to identify. Over time, speech and environmental sounds become clearer and more natural. The audiologist will verify that you can tolerate a range of sounds, such as soft speech, conversational speech, loud speech, hand clapping, coughing or doors shutting.
- Instruction. The audiologist shows you how to wear and operate the speech processor and its accessories and how to maintain the device.
- Fine-tuning. You will return several times over a year to program the device for optimal performance.
Rehabilitation involves training the brain to understand sounds heard through the cochlear implant. Speech and everyday environmental noises will sound different from what you remember; the 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.
You may be given listening exercises to do at home. The difficulty level of these exercises varies. Some people may need weekly rehabilitation therapy to help retrain the brain to hear. Speech therapy may be recommended for people whose speech has been significantly affected by hearing loss.
Bilateral cochlear implants
Bilateral cochlear implants are increasingly being accepted as standard care for the treatment of severe hearing loss. This is particularly true for infants and children who are acquiring speech and language.
Bilateral cochlear implants have been documented to provide significant hearing benefit for children and adults, related to quiet, noise, reverberation and localization of sounds. There's also evidence that bilateral cochlear implants significantly improve the quality of life in people with severe hearing loss and that the cost of the second implant is offset by its benefits.