Hybrid Cochlear Implant

Hybrid Cochlear Implant Overview

Hybrid cochlear implant is a type of cochlear implant which is used treat certain typed hearing losses (deafness) caused by an inadequate functioning of inner ear. It will help restore high frequency hearing along with amplifying low hearing frequency with one device.

It assists the patient to hear in two ways: Electrically (like cochlear implants) for severely hard of hearing or completely or profoundly deaf at mid and high frequencies, and acoustically (like hearing aids) for mild to moderate hearing loss at low frequencies.

Hybrid cochlear implant is made up of:

  • receiver/stimulator and an intracochlear electrode array
  • Sound processor (worn externally) which can be fit with an acoustic component
  • Programming software/instruments
  • Remote control with various options.

Hybrid Cochlear Implants (CI) are prudent for people who experience with low frequency residual hearing coupled with severe high frequency hearing loss. They function by channelling up sound and conducting the low frequencies to hearing aid, which in turn amplifies sound while relaying the high frequency component to a cochlear implant. The high frequencies then converted into a series of electrical impulses which stimulate the auditory nerve directly.

Working Principle

How Hybrid Cochlear Implant (CI) Works
Fig 1: How Hybrid Cochlear Implant Works

Hybrid cochlear implants works on the principle of differentiating groups of sounds by frequency (low and high pitch sound). The sound processor in the microphone picks up the sound from the environment and distributes it into distinct groups of sounds by frequency. The higher frequency sound is then relayed to receiver/stimulator and the intra-cochlear electrode array of the implanted section of the device that compiles the electrical impulses and sends them to different regions of the auditory nerve, which in turn relay it to brain, allowing the patient to hear. The lower frequency sound is amplified and send to ear directly like hearing aids. For detailed working of cochlear implants or hearing aids please see the dedicated sections on them.

Who will benefit from middle ear implant?

The hybrid cochlear implants are intended for use in one ear by adults above 18 years of age who do not benefit appropriately with the hearing aids in both ears. The patients must meet the following criteria:

  • Patient's hearing range from normal to moderate hearing loss in the low frequencies, with severe to profound loss in the mid to high frequencies.
  • Patient’s consonant nucleus consonant (CNC) word recognition score should be in between 10%-60% in the ear the implant is to be done. The other ear should be equal or better, but no more than 80% correct.
  • If the patient is not already appropriately fit with hearing aids they should have undergone a suitable hearing aid test.

Getting a Hybrid Cochlear Implant

Process of getting a hybrid cochlear implant is same as of cochlear implant. The process involved in getting a cochlear implant involve 3 key steps:

1. Assessment

A cochlear implant candidate need to go through a number of tests to make sure a cochlear implant is the right solution. These steps include:

  • Audiology tests such as hearing levels with and without hearing aids, speech understanding, and auditory nerve function.
  • Medical tests and MRI scans to determine general health, evaluate the cause of the hearing loss and assess the hearing anatomy.
  • Psychological tests to confirm your ability to cope with surgery and participate in follow-up.
  • Speech and language testing, as a benchmark for ongoing assessment of speech and language development.

2. Surgery

The cochlear implant procedure is considered to be a low risk surgery and usually takes between 1 and 3 hours. Thousands of cochlear implant surgeries are performed each year. Your surgeon can give you more information about the surgery.

3. Activation

Within a few weeks of surgery, audiologists activate the cochlear implant for the patient. They program the device to suit the unique hearing needs and hearing loss of patient. They also fine tune the settings over a few follow-up sessions.

Related Articles