Cochlear Implants

Cochlear implants

A cochlear implant is the only medical device that can actually replace a human sense. In a nutshell, it bypasses the non-functioning parts of the inner ear, directly stimulating the auditory (hearing) nerve that sends information to the brain, where it’s interpreted as sound.

How does a cochlear implant work?

The cochlear implant system consists of external and internal parts. A small device called an audio processor is worn behind the ear. It is connected by a cable to the transmitter coil, which sits on the outside of the head, directly over the surgically placed implant. The coil stays in place with the help of magnets. During the operation, a long electrode is inserted into the cochlea in the inner ear. Here’s how it works:

Source: MED-EL

  1. A microphone inside the audio processor picks up sound.
  2. The audio processor digitally analyses and codes sound into a special pattern of coded electrical signals.
  3. These signals are sent to the coil and transmitted through the skin to the implant. The implant creates electrical pulses from the coded signals.
  4. These pulses are relayed via the electrode contacts to the different parts of the cochlea.
  5. The hearing nerve receives these pulses and transfers them to the auditory cortex, the hearing part of the brain, where they are perceived as sound.

NICE guidelines for cochlear implants

A cochlear implant in one ear is recommended for people who have a severe to profound hearing loss and don’t get enough benefit from hearing aids after three months. An assessment needs to be carried out first by a cochlear implant team. Read more about what assessments involve here.

Who is a cochlear implant suitable for?

  • People with severe to profound sensorineural hearing loss.
  • Candidates must have a functioning auditory nerve.
  • Implantation can take place from a few months old and there is no upper age limit.
  • Candidates must be able and willing to follow a rehabilitation programme, consisting of regular sessions with an audiologist and practice at home. This  may take six to 12 months in adults and several years in children.

Two implants are recommended for:

  • Children who have a severe to  profound hearing loss and don’t get enough benefit from hearing aids after three  months.
  • Adults who have a severe to profound hearing  loss and don’t get enough benefit from hearing aids after three months and who  are also blind or have certain other disabilities

The implants must be fitted in the same operation. However, if someone in these  categories already had one implant when the current guidance was issued, they can  have a second implant fitted on the NHS.

cochlear implant pros and cons

Here are some of the benefits of cochlear implants:

  • Better understanding of speech, even in challenging situations – As a result recipients  are more able to participate in school, work, and their community.
  • Improved speech – Being able to hear their own voice, as well as others’  voices, helps users to improve their own speech.
  • Using the telephone – Improved speech understanding without lip reading makes this easier.
  • Greater independence – Being able to hear the doorbell, telephone and traffic, and join group conversations gives users more independence and confidence.
  • Research shows that children with cochlear implants perform better at school, are more  likely to attend mainstream schools and have better career prospects than their hearing-impaired peers who don’t have implants[1].
  • Many children with cochlear implants go on to enjoy the same  level of employment opportunities as those with no hearing impairment[2].
  • Improved quality of life – Being able to socialise more easily alleviates loneliness and isolation, reducing the risk of depression.  Improved mental health can boost immunity, improving physical health, too.
  • Music appreciation – Because a cochlear implant  enables users to  distinguish a wide range of sounds, they are more likely to be able to appreciate music more fully.

Things to consider

  • Cochlear implant surgery  involves a general anaesthetic. A large 2013 UK study shows that the risk of major complications is small – around 1.6% – and most complications are minor and temporary. For a better insight, ask your doctor  to explain the risks and how they relate to you.
  • The benefits aren’t instant – you need to follow a rehabilitation programme afterwards  to teach your brain to hear again, using the CI. It can take from several  months for most adults to several years for most children before the full  benefits are experienced. Again, ask your doctor for more details.
  • Success varies between individuals,  so ask your doctor to explain more.
Information about cochlear implant risks

What to look for in a cochlear implant?

  • Battery life – How often you need  to recharge or change batteries varies between devices and according to certain  factors.
  • Backwards compatibility – If an audio processor is ‘backwards compatible’, that means it  will be compatible with an implant that you may have had for several years.
  • Compatibility with future sound-coding strategies – This means it’s possible to upgrade your internal implant without surgery as future advances in  technology are made.
  • Electrode array design – The softer and more flexible the electrode, the better protection there will be for the delicate structures of  your inner ear. Also the greater the coverage of your cochlea with the electrode contacts, the better the sound quality will be.
  • MRI compatibility – It’s important to know whether your device is compatible with  MRI scanners used for diagnostic medical tests, and to what degree.
  • Automatic sound  adjustment – The processor adapts to changing listening environments  automatically, so you don’t need to keep adjusting the volume or program settings manually when you go from quiet to noisy surroundings.
  • Audio processor design – Processors come in different sizes and weights. You can choose  from the classic behind-the-ear design or a cable-free, single-unit processor that sits off the ear.
  • Integrated telecoil –  This gives wireless access to assistive listening devices such as induction  loops, mp3 players and laptops
  • Tamper-proof design – This is important if the device is for a young child.
  • Water-resistance – This means it’s splash-proof but not fully waterproof.
  • Waterproof – You  can swim and shower in it.

Connect with a HearPeers mentor

to discuss the design features of cochlear implants in more detail.

Reference:

[1]Bond M, Mealing S, Anderson R, Elston J, Weiner G, Taylor  RS, et al. 2009. The effectiveness and cost-effectiveness of cochlear implants  for severe to profound deafness in children and adults: a systematic review and  economic model. Health Technol Assess13(44):1-330.

[2] Venail F, Vieu A, Artieres F, Mondain M, Uziel A. 2010. Educational  and Employment Achievements in Prelingually Deaf Children Who Receive Cochlear  Implants. Arch Otolaryngol Head Neck Surg 136(4):366-72.

Disclaimer

The contents of this website are for informational and educational purposes only and do not constitute medical advice. This website should not be used to diagnose or treat health conditions. You should contact a healthcare provider if you have healthcare related questions.