What is a cochlear implant?

by | October 1, 2021

If you have severe to profound sensorineural hearing loss and have tried conventional hearing aids with little success, this may be an option.

A 2017 study estimated that 422,000 older adults in Singapore suffer from hearing loss, and over 100,000 may have a disabling hearing impairment. Ageless Online finds out more from Dr Barrie Tan of Barrie Tan ENT Head & Neck Surgery at Gleneagles Hospital, and why a cochlear implant may help:


Can you share what and why there is misunderstanding on hearing loss?

There are several commonly held misconceptions about hearing loss, particularly among the seniors:

  • “Hearing loss is a natural part of ageing and therefore there is no need to resist the natural order of things and use hearing devices to help. We should therefore learn to accept the hearing loss.” Whilst it is true that hearing loss is commonly seen in many seniors, it is not true that it is an inevitable part of growing old. There are also many seniors with good hearing who enjoy fully active lives. With hearing devices, those with hearing loss are also able to lead equally active lifestyles.
  • “Hearing loss only affects me, and is my problem; it should not be other people’s problem.” Hearing loss leads to problems with communication which therefore leads to a problem for the other persons who are trying to communicate with the individual with hearing loss. It inadvertently leads to misunderstandings and sometimes strained relationships as others have to shout at the affected individual to be heard, creating a problematic situation. These misunderstandings may arise out of stereotypes and over simplistic analysis of the problem of hearing loss.


What happens when one loses his or hearing?

Hearing is one of the most critical senses that we have and with the elderly, they tend to lose it progressively. This then affects their lifestyle such as losing engagement in the environment since they can’t hear. Also, moderate hearing loss can increase one’s dementia risk and this could lead to further social connections.


Who can benefit from a cochlear implant?

It is suitable for patients of all ages with severe to profound sensorineural hearing loss and who have tried conventional hearing aids but have insufficient benefit with these hearing aids. The oldest patient that I have operated on and implanted was an 86-year-old lady. Those who have mild to moderate sensorineural hearing loss would find hearing aids more suitable. Cochlear implants are suitable for patients who have severe to profound sensorineural hearing loss in one ear only, or in both ears. So long as they have an intact hearing nerve (cochlear nerve) and a cochlea (inner ear hearing organ), they would be suitable candidates for cochlear implantation.


Can those who were born with hearing loss have an implant?

Yes definitely. In fact, it is now the standard of care and the medical recommendation for most children born with congenital deafness, to be offered cochlear implantation. Their hearing loss should be in the severe to profound hearing loss range. Prior to cochlear implantation, these children would usually have a trial with conventional hearing aids to determine if there is sufficient benefit with these hearing aids. If they have insufficient benefit, they would then have a series of radiology scans to look at their inner ear anatomy. The large number of such children would have suitable anatomy to undergo cochlear implantation. The hearing loss may very well be an isolated condition and the child is otherwise healthy and normal, and this happens to be the case in the large majority of cochlear implanted children.

For such children, the hearing outcomes with cochlear implantation generally are excellent and most develop normal speech and language abilities. There is a smaller proportion of children where the hearing loss is part of a disease syndrome, where there are other medical problems and also possible neurological problems. In such cases, the hearing outcomes, speech and language development may not be as excellent due to the other concomitant medical issues. Nonetheless for this group of children, hearing awareness and environmental safety are key benefits afforded by the cochlear implants.


What is a cochlear implant and how does it work?

A cochlear implant is made up of two parts – an implanted device under the skin behind the ear and a removable external sound processor. The implanted device contains electrodes that are threaded through the cochlea.

External sounds received will be converted into electrical signals that are sent to the cochlear through the implanted coil under the skin. The implant’s electrodes stimulate the nerve endings of the cochlear nerve in the cochlea. The impulses are then carried by the cochlear nerve, which carries these signals to the brain, where they can be interpreted as sound.


How is an implant different from a hearing aid?

A conventional hearing aid provides acoustic amplification whereas a cochlear implant provides electrical stimulation to the inner ear for hearing. This means that the conventional hearing aid serves to amplify the environmental sounds that it collects. Cochlear implants are more sophisticated technologies that converts the acoustic sounds that it collects from the environment into specialised electrical current discharges at different contact points located on the electrode tip that will directly stimulate the cochlear nerve endings in the cochlear. This generates a different type of hearing stimulus, an electrical hearing stimulus as opposed to the acoustic hearing stimulus that the conventional hearing aid provides.

Also, a cochlear implant will require surgery to implant the internal component of the device, whereas a hearing aid does not require any surgery and the users put them on only when they choose to use them.


Can you explain the implant surgery?

The cochlear implant surgery is typically performed under general anaesthesia. The ENT surgeon will make a small incision behind the ear and sometimes a small area of hair may be shaved away from the incision site. The implant is then placed under the skin and the electrode is inserted into the inner ear.

The surgery usually takes about three hours to perform for one side. If both sides are implanted, the surgery takes about six hours. The usual hospitalisation stay is between one to two nights and there will be a bandage around the head applied after the surgery and applied overnight. This bandage will be removed on the day after the surgery. An X-ray will be done to confirm the position of the electrode and the cochlear implant.


What are the risks of surgery?

The risks may include major wound infections, meningitis (brain lining infection) and damage to the balance function. However, these complications very rarely occur.


What happens after the surgery?
After discharge, the patient returns one week after surgery to have the stitches removed. Thereafter, three weeks after surgery, the patient will undergo the “switch-on” process of the cochlear implant. This is a process of activating the implant and testing the responses received by the patient. There will be the need then to program the cochlear implant according to the hearing needs of the patient. This process of tuning the program of the implant will take several months and is called “mapping” of the implant. As the patient uses the cochlear implant, the hearing gets more and more natural sounding. The initial hearing after the surgery has been described as being rather robotic sounding but this changes into a very natural sounding hearing usually within six months or so.


There are a number of cochlear implant brands in the market. How do I go about choosing the right one for me?

In choosing a cochlear implant brand, there are several issues I would recommend to pay attention to. The first is the reliability of the company brand and its products. The company should be able to clearly show its statistics. Also, patients should also pay attention to the warranty periods for the implant device and the various components. They should find out what sort of after-sales support is available for them here in Singapore, both from the clinic and hospital that performed the surgery as well as the vendor brand that has an office and support staff stationed here in Singapore. The next thing to pay attention to would be the technologies that the different brands focus on for their products and whether these special technologies like wireless compatibility with smartphones and with other hearing aids are present. These are important not just from a lifestyle perspective but also from a very functional perspective of maximising the capabilities of the cochlear implants chosen.


How much is the cost of an implant?

It costs over S$40,000 for an implant (which does not include the sound processor). There is a national subsidy programme for all Singaporeans and PRs for cochlear implantation done in the public hospitals. Many private integrated shield plan insurance also cover the last majority cost of the cochlear implant surgery and the cochlear implant in the private hospitals as well. Therefore, depending on your candidacy and suitability, if you are a Singaporean or PR, most of the cost of the surgery and cochlear implant will be covered.


What is the occurrence of an implant failing?
This would be an extremely rare occurrence. The overall reliability of cochlear implants nowadays is in the region of 99.5-percent reliability.


What changes does one have to make after having an implant? Can one swim with the implant?
Once implanted, it would be highly encouraged for the patient to wear the external component of the implant system everyday throughout the waking hours, to get used to hearing with the implant. Once implanted, the patient should avoid contact sports and avoid any possible trauma to the skull as this may cause damage to the implant. Apart from that the patient can resume all other normal activities. If the patient wishes to swim with the implant on, there are various accessories that they can attach to the speech processor to protect it in the water.


(** PHOTO CREDIT: Cochlear)


Submit a Comment

Your email address will not be published. Required fields are marked *