COCHLEAR IMPLANTS
Worldwide, approximately one person in a thousand is born with a hearing loss. Almost an equal number of people born with hearing will develop deafness during their lifetime.
The cochlear implant is an electronic device which restores partial hearing to the severe or profoundly hearing impaired. Part of the cochlear implant is surgically implanted in the ear and part of it is worn externally like a hearing aid. A cochlear implant is not a hearing aid. It is a medical device which bypasses the damaged part of the inner ear and electronically stimulates the nerve of hearing in those patients who get little benefit from hearing aids. Our implant center is currently using the latest Cochlear Americas and Advanced Bionics systems.
Cochlear Americas Nucleus 5
How Cochlear Implants Work
Cochlear implants are electronic devices that bypass the damaged hair cell and stimulate the hearing nerve directly. The cochlear implant system consists of internal and external parts. The microphone and speech processor are worn outside the body, like a hearing aid. A surgically implanted receiver provides a direct connection between the speech processor and electrodes. The electrical signal stimulates the auditory nerve fibers, and the signal is then sent to the brain.
Who is a Cochlear Implant Candidate
The cochlear implant is designed for individuals who have sensorineural hearing loss and receive no significant benefit from hearing aids. Candidates are usually one year of age or older. The criteria for cochlear implant candidacy are as follows:
Children Ages: 12 months to 24 months
- Profound sensorineural hearing loss in both ears
- Lack of progress in the development of auditory skills
- No medical contraindications
- High motivation and appropriate expectations from family
Ages: 25 months to 17 years, 11 months
- Severe-to-profound sensorineural hearing loss in both ears
- Lack of progress in the development of auditory skills
- No medical contraindications
- High motivation and appropriate expectations
(both child when appropriate and family)
Adults Age: 18 years of age or older
- Severe-to-profound sensorineural hearing loss in both ears with poor speech discrimination
- Pre linguistic or post linguistic onset of severe-to-profound hearing loss
- No medical contraindications
- A desire to be part of the hearing world
Becoming a Cochlear Implant Patient
Becoming a cochlear implant patient involves a series of evaluations including otologic, audiologic, radiographic and psychological tests to determine candidacy. An examination must be performed to assure that there is no active infection or other problem with the middle or inner ear that would preclude the surgical placement of the implant. An audiologist performs extensive hearing tests to determine the degree of hearing with and without a hearing aid. Special tests are also performed to evaluate the benefits from hearing aids. Special x-rays, usually computerized tomography (CT) scans or Magnetic Resonance Imaging (MRI), are taken to evaluate the condition of the inner ear bone.
Cochlear Implant Surgery
Cochlear implant surgery is performed under general anesthesia. An incision is made behind the ear. The mastoid bone is opened, leading to the middle ear. The operation takes about 2 to 3 hours and the patient usually goes home the same day.
Postoperative Care and Follow Up
About a month after surgery when the incision is healed, the recipient returns for the first fitting of the external components. The audiologist uses a computer and special software to program the speech processor to the best listening strategy for the recipient. The audiologist along with the recipient’s assistance will determine the appropriate levels of stimulation for each electrode and these levels will be used to make “maps” for the recipient to hear with their implant. The audiologist and recipient together will develop a schedule of follow up visits for fine-tuning of the speech processor. As the recipient becomes more experienced with their cochlear implant, the follow-up visits will become less frequent and the recipient will only need to be seen once or twice a year for adjustments.
What is the Baha system?
The Bone Anchored Hearing Aid, or Baha system, is comprised of a sound processor, an abutment and a small titanium implant that is implanted in the bone behind your ear. The Baha system was originally developed for patients with conductive or mixed hearing loss and was later found to be beneficial for patients with single-sided deafness.
Who is a Baha candidate?
There are several types of hearing loss that can be helped with the Baha System.
Someone with a conductive hearing loss where the outer or middle ear is blocked or a mixed hearing loss where both the middle and inner ear is blocked may be a candidate. Also it has been shown that someone with normal hearing in one ear and total deafness (single-sided deafness) in the other ear may be a candidate.
For someone with a conductive hearing loss the Baha system re-routes the signal through the skull bone to the inner ear bypassing the outer or middle ear.
For someone with a mixed hearing loss the Baha system can bypass the outer or middle ear problems and provides the appropriate amount of amplification to the inner ear.
For someone with single sided deafness the Baha system transfers sound directly to the healthy cochlea so it is possible to hear from both sides.
How does the Baha system work?
Sound waves are first received by the sound processor and then changed into vibrations. The vibrations from the sound processor are transferred from the abutment to the titanium implant. The implant then uses direct bone conduction to transfer the sound vibrations to the functioning cochlea.
For a person with a conductive hearing loss where the outer or middle ear is blocked and a mixed hearing loss where both the middle and inner ear is blocked hearing aids will increase the sound until it is forced through the blockage. This effect will be like turning up the stereo too loud and with higher volume so that the sound becomes distorted and uncomfortable. The Baha system will re-route the signal through the skull bone directly to the inner ear and avoid distortion and feedback.
For single-sided deafness the Baha processor transfers the sound to the healthy cochlea which makes it possible to hear sound from both sides.
How can I find out if I am a candidate for the Baha system?
First you must have a medical evaluation with a physician that is specially trained in the Baha system.
The physician may require audiological testing to help determine your candidacy. If the physician determines you are a candidate for the Baha system he will refer you to the audiologist for a trial with the Baha processor. After this trial with the processor and the evaluation with the physician it will be determined if you are a candidate for the surgery. The surgery is done as an outpatient and after several months of healing you will return for the fitting with the sound processor. The audiologist will demonstrate how to put on the processor and review how the processor works and how to care for it and the abutment site.
Southwest Ohio ENT Specialists presently uses the Cochlear Americas Baha system. They have multiple sound processors available and it is possible to have a trial with them before making a decision on which one works best for your hearing loss.
