What is a cochlear implant?
In a normally functioning ear the inner ear's hair cells convert the energy of sound into nerve energy, which is then transmitted as information to the brain.
In most cases, people with severe or profound deafness lack the hair cells in the inner ear to convert the sound energy to nerve energy. The exception to this is auditory neuropathy, where hair cells may be present but other impedance stops the transmission of signals from the inner ear to the brain. In both cases, cochlear implants can bypass these impedances by electrically stimulating the nerve endings directly.
Is a cochlear implant an option for your patient?
Cochlear implants may provide a life-changing option for some patients with severe or profound hearing loss but they are not an option for everyone. In most cases cochlear implants are suitable for:
- Young children born with a severe or profound hearing loss, providing the hearing loss is detected by the age of about two years of age - after this age the opportunity to benefit starts to deteriorate rapidly so early detection is essential
- Older infants or children who have had an acquired severe or profound hearing loss, such as following meningitis or trauma
- Older infants or children who have had some level of hearing but a progressive hearing loss has resulted in severe or profound hearing loss
- Adults who have had hearing but now experience severe or profound hearing loss
- Cochlear implants are not suitable for older children and adults who have never experienced sound as the brain's hearing pathways atrophy without sound stimulation .
Is a cochlear implant just a surgical intervention?
Cochlear implants are more than a surgical intervention and require a multi-disciplinary team environment to support their use. Audiology plays a key role in both diagnosis and intervention including providing ongoing maintenance. ENT surgeons are also involved in diagnosis and assessment of suitability, surgical intervention and ongoing review. A cochlear implant does not produce 'hearing' overnight. Intensive rehabilitation is required, especially with infants who have never experienced sound, for the first year following implantation. However, it is not unusual for older people who have experienced sound to very rapidly interpret the signals they receive as sound.
What are the benefits of cochlear implants?
Once a patient has been assessed as appropriate for, and received a cochlear implant the results can be, in many cases, life-changing. About 70 percent of cochlear implant users are able to understand speech using hearing alone, even over the phone. For an infant born deaf, this opens a communication gateway, allowing them to participate appropriately for their age in learning and social situations. For adults, this can make the difference between participating in their usual work and relationships or unemployment and relationship failures.
How can my patient access a cochlear implant?In New Zealand a unilateral cochlear implant is funded through the public health system but volumes are limited. Many adults currently experience long delays due to waiting list and funding constraints. An increasing number of families are also choosing bilateral implants. The second (bi-lateral) implant is not publicly funded.
If you think your patient may benefit from a cochlear implant, you should refer them to either an audiologist or ENT surgeon familiar with cochlear implants. There are two Cochlear Implant Programmes in New Zealand, one in Auckland, the other in Christchurch. The audiologist or ENT surgeon may refer your patient to one of these programmes after diagnostic assessments have been conducted.
Dilworth Hearing provides a comprehensive cochlear implant audiology service in association with specialist ENT cochlear implant surgeons.
