Cochlear Implant

What is cochlear implant?

A cochlear implant is a medical electronic device designed to bypass damaged parts of the inner ear by directly stimulating the auditory nerve fibres.

Cochlear implants consist of two components – an internal receiver-stimulator implant and an external speech processor. The internal implant is positioned under the skin, secured in the bone behind the ear via a surgical procedure. The external component is worn behind the ear via a magnet.

How does a cochlear implant work?

• Sounds enter the system through a small microphone (external speech processor) attached behind the ear
• The sound is processed and transmitted to the internal component
• The receiver in the internal component receives the signals
• The receiver then sends electronic signals via the electrodes that are in the cochlea (hearing organ) to stimulate the auditory nerve which sends messages to the brain

Who will benefit from having a cochlear implant?

Cochlear implants may be implanted in one ear or both ears in patients not benefiting from appropriately fitted hearing aids, depending on each patient’s needs.

This includes patients:

• With bilateral severe to profound hearing loss
• Who have unilateral severe to profound hearing loss
• Who still struggle with understanding speech and communicating despite assistance with hearing aids

What are the benefits from having a cochlear implant?

• Restoring hearing for severe to profound hearing loss: Provides speech and sound perception for adults and children with a severe-to-profound hearing loss in both ears, who have limited benefit from hearing aids. This will allow themto communicate more normally.  This is also important for safety as users are able to hear the sound of an alarm, car horns and people shouting to alert them. 
• Supporting language development in children: Enables children with hearing impairment to acquire language skills during critical developmental periods. Children as young as one year of age may be implanted. It is usually said that the earlier the implantation, the better the outcome will be.
• Enhancing sound localisation: Assists users in identifying the direction of sounds, improving awareness of their surroundings. This is particularly relevant in patients with single-sided deafness.
• Improving quality of life: When users can understand what is being said to them, they are kept engaged with their family, friends and society. This helps prevent social isolation, depression and the progression of cognitive impairment.

How can you prepare for a cochlear implant?

Preparing for a cochlear implant involves several steps to ensure the procedure's success and a smooth recovery.

• Undergo a comprehensive evaluation: Your doctor and audiologist will review you and determine if you are suitable for a cochlear implant depending on your history and physical examination. You may need to undergo further hearing tests, speech tests and imaging such as a CT or MRI scan.
• Learn about the procedure: Your doctor will brief you on the surgical process, potential risks and expected outcomes.
• Familiarise yourself with post-implant care: Learn about the rehabilitation process, including follow-up appointments, device activation and auditory therapy. It would be helpful if you have a family member or close friend who is able to practise the rehabilitation with you.
   

During the Cochlear Implant 

What can you expect during a cochlear implant?

Surgery is performed under general anaesthesia and takes between two to four hours.

The doctor will make an incision in the skin behind your ear where the implant will be placed. He or she will create a space in the bone behind your ear (the mastoid) and create a tunnel into the hearing organ (the cochlea).

The electrode will be inserted into the cochlea, and the doctor will then close the incision and apply a head bandage.

Patients typically stay overnight in the hospital and the head bandage is removed before the patient returns home the next day.

What can you expect after the cochlear implant procedure?

The cochlear implant will be switched on about 2 to 4 weeks after the surgery. It has to be programmed by the audiologist before it can work. The implant needs to be programmed periodically to maximise the speech sounds that can be heard by the individual (e.g., how loud or how natural the sounds are perceived).

A period of rehabilitation is also required, especially in children, to gain the maximum benefits from listening through the implant. Users will undergo sessions where they are taught exercises to practice with their implant to ensure a better hearing experience.

Cochlear Implant – Limitations

What are the limitations of cochlear implants?

Cochlear implants offer significant benefits, but they also have certain limitations that users should consider.

• Variable outcomes: The level of hearing improvement can differ among individuals, depending on factors like age, duration of hearing loss and prior hearing experience.
• Limited sound quality: Cochlear implants may not replicate natural hearing and can make recognising music or complex sounds challenging.
• Patient suitability: Some people with certain medical conditions or minimal hearing loss may not be candidates for cochlear implants.

Speak to your doctor to understand more.

Cochlear Implant – Risks

What are the risks of cochlear implant surgery?

While cochlear implants are generally safe, they come with certain risks and safety concerns. Although these risks are extremely rare, potential users should be aware of:

• Surgical risks: Possible complications include infection, bleeding or adverse reactions to anaesthesia during the implant procedure.
• Facial nerve damage: The surgery carries a small risk of temporary or permanent facial nerve weakness or paralysis.
• Device failure or malfunction: The internal or external components may fail, requiring repair or replacement through additional surgery.
• Increased risk of meningitis: Cochlear implant users may have a slightly higher risk of meningitis, particularly if they have inner ear abnormalities. Patients will need pneumococcal vaccination prior to this procedure to reduce the risk of meningitis.
• Electromagnetic interference: Precautions are required for future magnetic resonance imaging scans, and you will be given an implant card for travel.
• Skin irritation or discomfort: The external processor can cause irritation or pressure sores at the point of contact with the skin.
• Limited benefit for some users: Some individuals may not achieve the desired level of hearing improvement, especially if the auditory nerve is damaged.

For more information, consult with our doctor for a personal recommendation.

References

Cochlear implants. (n.d.). https://www.asha.org/public/hearing/cochlear-implant/  

U.S. National Library of Medicine. (n.d.). Cochlear Implant: Medlineplus medical encyclopedia. MedlinePlus. https://medlineplus.gov/ency/article/007203.htm

Cochlear Implant Surgery and rehabilitation. Johns Hopkins Medicine. (2024, August 13). https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/cochlear-implant-surgery

U.S. Department of Health and Human Services. (n.d.). Cochlear implants. National Institute of Deafness and Other Communication Disorders. https://www.nidcd.nih.gov/health/cochlear-implants