Arguments for Bilateral Implantation

1. A spare ear
The value of a spare ear is immeasurable, from the day-to-day advantages to the more catastrophic. When batteries die, it no longer means no hearing. Classes don’t have pause buttons, nor do meetings at work or most of life. If a student with a CI is in class, he/she can keep listening with one ear while changing the batteries in the processor for the other ear. When one CI fails completely, as they eventually will all do, the benefit of a second ear is invaluable. Not only does it mean that the user does not have to endure any time of total deafness, but also, because the readjustment period for a reimplanted ear can vary from a few months to a couple of years, the user has the benefit of one good, continuously working ear and so suffers less disruption in life.

2. Better hearing in background noise
Improved hearing with two ears in background noise is well documented. The measured benefit is as high as a 30% improvement.

3. Ability to localize sound
The ability to localize sound is important for safety and in school — to hear where warning sounds are coming from as a young child playing outside, to hear warning sounds while driving, such as horns, sirens, or someone shouting “Stop!,” to hear which elevator dings in a crowded lobby – All of these require the ability to localize sound. In school, especially in the middle and upper school grades, class discussions become an integral part of the curriculum. In order to better follow the discussion, students need to be able to know who is talking and turn quickly to focus on that person.

4. Neural Plasticity
Research has shown that a child’s brain starts to lose its plasticity at age 7, and by age 12 it is equivalent to an adult’s ear. Thus, in order to take advantage of that window of opportunity for the brain to fully utilize hearing from a second ear, children should receive bilateral implants by age 7.

5. Nerve fiber atrophy
We now know that, left unstimulated, the auditory nerve fibers begin to atrophy. Thus, the earlier argument to implant only one ear and save the other for future technology no longer holds true. To save an ear that receives no benefit from hearing aids instead means that the ear is being wasted. Even if new technology comes along when the child is an adult, he/she will never realize the full benefit of that technology because the nerve fibers in the unstimulated ear will atrophy. To implant that ear while the child is still young and so to stimulate those nerve fibers means that the auditory nerve and the rest of the auditory pathway will be preserved for future technology.

Here are examples of results from two cochlear implant recipients, Rachel, the founder of Cochlear Implant Online, and her sister, Jessica:

Rachel

1 Nucleus 22 CI
Single syllable word test
Hearing in quiet: 90%
Hearing in 10 db signal-to-noise ratio, noise to unimplanted ear: 30%
Hearing in 5 db signal-to-noise ratio, noise to implanted ear: 0%

Bilateral Nucleus 24C CIs
Single syllable word test
Hearing in quiet: 88%
Hearing in 5 db signal-to-noise ratio: 64%

H.I.N.T. (Hearing In Noise Test) sentences
Hearing in quiet: 100%
Hearing in 5 db signal to noise ratio: 91%

Jessica

1 Nucleus 22 CI
Single syllable word test
Hearing in quiet: 90%
Hearing in 10 db signal-to-noise ratio, noise to unimplanted ear: 84%
Hearing in 5 db signal-to-noise ratio, noise to implanted ear: 60%

Bilateral CIs, N22 in left ear, N24 in right ear
Single syllable word test
Hearing in quiet: 96%
Hearing in 5 db signal-to-noise ratio: 84%

H.I.N.T. (Hearing In Noise Test) sentences
Hearing in quiet: 98%
Hearing in 5 db signal to noise ratio: 92%

Click on the titles below for pdf files of research articles supporting bilateral implantation:

Rational for Bilateral Cochlear Implantation in Children and Adults

Sequential Bilateral Cochlear Implantation in Children

Click Here to read about Jessica’s personal experience.

Click Here to read about Rachel’s personal experience.

Reasons, Research, and Support by Jace Wolfe

MED-EL’s Brochure on Bilateral Implantation - This brochure provides great thorough explanation for everyone who is interested in bilateral implantation regardless of brands.