What is a cochlear implant?
Simply put, a cochlear implant is a hearing prosthesis. It bypasses the non-functioning part of the inner ear, the cochlea, and stimulates the hearing nerve. This is the main difference to a conventional hearing aid. The hearing nerve sends acoustic information to the brain which recognizes them as sound. Surgery is considered low risk and routine. A large UK study shows that the risk of major complications is small – around 1.6%.
What does a cochlear implant consist of?
A cochlear implant system consists of an internal and an external part. The implant (internal part) is placed under the skin. It has an electrode attached which is inserted into the cochlea in the inner ear. This electrode replaces the damaged or missing hair cells in the cochlea. The audio processor (external part) is worn behind the ear. A microphone in the audio processor detects sound signals and sends them to a coil. This coil transmits the sound signals to the internal implant, which then converts them into electrical pulses.
How does a cochlear implant work?
- A microphone inside the audio processor picks sound.
- The audio processor analyses and codes these signals into electrical pulses.
- These signals are sent to the coil and transmitted through the intact skin to the implant. The implant creates pulses from the coded signals.
- These pulses are relayed via the electrode contacts to the different parts of the cochlea.
- 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 (speech,music,…).
Who s a cochlear implant suitable for?
A cochlear implant is suitable for people of any age with a severe to profound sensorineural hearing loss. Both, children who were born deaf as well as individuals who lost their hearing after learning to speak, benefit from a cochlear implant. Implantations in children can already be performed in the first year of life. To receive a cochlear implant, individuals must have a fully functional hearing nerve which can send signals on to the brain.
How does a cochlear implant sound?
This is a question that many cochlear implant candidates ask. There is no uniform answer to it, because every person’s hearing is different. The brain needs to learn to hear (again) with an implant. This learning process varies individually and depends on several factors. Rehabilitation after surgery is essential for the success with a cochlear implant. It consists of sessions with a speech therapist and of listening training that can be done at home. Adults need rehabilitation up to 6-12 months after implantation, children’s rehab may last for several years.
Benefits of cochlear implants
- Better understanding of speech, even in background noise. As a result users are able to better participate in school, work, and their community. Many users even understand speech without lip reading.
- Improved speech – Being able to hear their own voice, as well as others’ voices, helps users to improve their own speech.
- Using the telephone gets easier due to improved speech understanding without lip reading.
- Independence – Being able to hear the doorbell, telephone and traffic, and join group conversations gives users more independence and confidence.
- Research shows that children who received their cochlear implant at an early age perform better at school, are more likely to attend mainstream schools and have better career prospects than their peers with similar degrees of hearing loss who are implanted at a later age .
- Many children with cochlear implants go on to enjoy the same level of education and employment opportunities as those with no hearing impairment .
- Better quality of life – Many users enjoy a more active social life (again). Subjectively, more social connections are linked to a better quality of life. The risks of social isolation and depression decrease.
- 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.
What to look for in a cochlear implant?
Choosing a cochlear implant is a major long-term decision. At best, the implant is for life. The audio processor can easily be exchanged. Therefore, the focus should be put on the internal implant. When deciding for a cochlear implant, we recommend taking the following points into consideration:
- Electrode length: Each cochlea is different in length. Make sure that the electrode covers the whole length of your cochlea. Each frequency matches a certain place in the cochlea, just like the keys of a piano. Only if an electrode covers every part of the cochlea, users can hear both high and low pitches. For maximum benefit the electrode should match your individual cochlear length.
- Flexible electrodes: The cochlea is the size of a pea and has an extremely delicate structure. The electrode needs to be soft and flexible to prevent any damage to the cochlea during insertion. A soft electrode is more likely to protect your residual hearing. Users may benefit from future technological and medical developments.
- MRI Compatibility: agnetic Resonance Imaging (MRI) is frequently used in today’s modern diagnostic medicine to get a clear image of the body. However, not every cochlear implant allows for MRI scans, as the magnet of the implant may be dislocated during the scan. Therefore, the magnet of such devices needs to be surgically removed before any MRI scan. There are some implants that allow MRI scans up to 3 Tesla without the need to remove the internal magnet. It self-aligns to the magnetic field and does not dislocate. Cochlear implant manufacturers offer detailed information on MRI compatibility
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.
 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.