Hearing Implants

Last Updated: 02/24/17

Index

  1. Cochlear Devices
    • CI - Cochlear Implant
    • ABI - Auditory Brainstem Implant
    • Differences of ABI from Typical CI
    • Important CI and ABI Information
  2. Baha
  3. Nerve Damage and Hearing Loss

Also See:

Damage to the Vestibulocochlear Nerve is typically amongst the first issue before an individual is finally diagnosed with Neurofibromatosis Type II (NF2) , even if other tumors may have started to grow first without detection. Tumor growth of Vestibular Schwannoma affects approximately 98% of people with NF2. Rate of growth varies from person and tumor growth rate is based on NF2 mutation type. Rate of growth varies from person and tumor growth rate is based on NF2 mutation type.

NF2 hearing loss is a result of damage the Cochlear Nerve, the connection of the nerve between the Cochlea and the brainstem. Traditional hearing aids that amplify sound, might offer help while the nerve starts to become damaged until a Cochlear Implant might help. With medical advancements many people with NF2 do well with a CI for many years. After the nerve is completely broken which can be easily determined by an ABR (Auditory Brainstem Response) test, sometimes also called BERA (Brainstem Evoked Response Audiometry), only an ABI (Auditory Brainstem Implant) would offer any sound.


1. Cochlear Devices

CI - Cochlear Implant
Cochlear - System Components

A Cochlear Implant (CI) will work if; the CN8 (the Vestibulocochlear Nerve), the Vestibular Nerves, the Cochlear Nerve and the Cochlea itself are intact.

Continued growth of a tumor on any of these nerves, can result in not just damage to the nerve for the connection of the implant, but is can also damage either the Facial Nerve, Brain Matter, or the Brainstem, any of which might require either the removal of a CI, or discontinuation of function of a CI. Because of this, the CI might only work for a short time if tumors are present. However, chemo therapies like Avastin have started to allow for an increased period of effectiveness with CI.

In recent years CI's for people with tumor development for conditions as NF2, have started to become a longer term hearing option, before more dramatic hearing options would need to be considered for sound.


ABI - Auditory Brainstem Implant

When most people lose hearing, sound amplification, is all that is needed to regain missing sound. The Cochlear Implant was designed to direct sound to the Cochlea when bones in the ear or other internal parts of the Middle Ear are broken. But if damage occurs to the Vestibulocochlear Nerve or the Cochlear Nerve, an ABI (Auditory Brainstem Implant) is the only option to regain hearing. ABIs direct sound straight to the brainstem, bypassing the ear components completely.

The brain will need time to adjust and adapt or relearn the new form of hearing and improves over the course of the first year.

ABI and CI

The ABI's quality of sound is different than natural hearing. But with an ABI speech reading (lip-reading) is often easier. Effectiveness of use of an ABI and lip-reading may vary from person to person and can become easier to use to understand speech better over time.

Nucleus 6 (N6)

The Current Sound Processor model for devices of Cochlear Implant (CI) and Auditory Brainstem Implant (ABI) os the Nucleus 6 (N6).

When Cochlear releases a new processor, it does not always work for individuals with ABI. The N6 is the current latest processor for both.


Differences of ABI from Typical CI

Assuming an understanding of basic typical CI, these are the differences for the ABI systems:

  1. Internal Receiver: Internal Receiver components are the same as a CI, the only difference is the sensors and their location in the brain.
  2. Magnet Removal: Due to need for MRIs individuals with NF2 have the internal magnet removed. CI's can have the magnet removed as well but is not typically done.
  3. Possible Side Effects of some Electrodes: Each electrode tested can result in stimulating parts of the brain that could be dangerous.
  4. Poor Pitch Reception: Quality of final sound is not the same level as CI's.
  5. Competing Tinnitus: During tests sounds might be competing with Subjective/Objective/GET Tinnitus
  6. Switching on and Tune Ups: Longer session time than typical CI Sassoon's.

Things to know about Switching on and Mapping ABI's:

  1. Activation can be done six weeks after ABI is implanted and takes two days
  2. Twenty-one Electrodes = Twenty-one Channels of Sound
  3. Channel Deactivation: Due to side effects of some electrodes some will need to be turned off
  4. ECG: Heart Monitor for safety due to potential problematic Electrodes
  5. Mapping:
    • Individual Electrode Test
    • Range For Each Electrode - Increasing Increase Levels Gradually
    • Pitch Comparison
    • Loudness Balancing
    • Testing Live:
  6. During Live Test
    • Side Effects: Side Effects to electrodes can show up.
    • Volume: Overall or individual volume levels might need to needs to be reduced or raised.
    • Speech Readers: Good Speech Readers might think the Volume is good but it is actually too low.

CI and ABI Important Information

Medical Treatment Warnings

In their information packets Cochlear issued a warning certain medical treatments done too close to the implant can break the implant. These treatments include:

  • Electrosurgery
  • Diathermy
  • Neurostimulation
  • Electroconvulsive Therapy
  • Ionizing Radiation Therapy
Additional warnings on damage were included on the following:
  • MRIs
    • MRIs Strength Over 1.5 Teslas
    • Remove Magnet

  • Electrostatic Discharge (ESD) - Static Electricity
  • ESD is the sudden discharge of static electricity. Electronic devices, including cochlear implants (both the internal and external devices), are susceptible to damage from ESD. This could be program issues, processor damage or even receiver failure. [Journal of Educational Audiology, 2002]

    • Low Humidity - Hot or Cold Dry Conditions
    • Removing Clothes over the Head
    • Playing on Plastic Slides
    • Walking Across a Carpet
    • Handling Polyethylene Bags
    • Pouring Polyurethane Foam into a Box
    • Latex balloon coming in contact with Hair
    • CRT's - Computer Monitors and TV's

Radio Frequency Interference

There is interference with Cochlear Implants and RF(Radio Frequency) Technology:

  • Mobile Phones
  • Electronic Article Surveillance (EAS) Systems
  • Metal Detection Systems

2. Baha
Baha

A Baha (Bone-anchored hearing aid), is a solution for people who have unilateral hearing loss (single sided deafness), hearing loss on one ear. It allows for hearing introduced on both sides of the head to be heard.

On the side of the deaf ear, a small hole is drilled into the skull that the processor can be attached to. When attached the sound picked up by the processor is echoed through the skull bone to the hearing ear. This might be only a temporary hearing solution for best hearing for a few years depending on changes in tumors.

For use of a Baha a titanium piece is surgically attached to the skull and the processor is a removable piece that can be attached or disconnected as needed.

Baha piece in skull - MRI Safe

Titanium is not a metal that is an issue or dangerous in MRI scans. The device itself needs to be removed for the scan, but the piece in the skull is MRI safe.


3. Nerve Damage and Hearing Loss

The Vestibulocochlear Nerve affects both the Vestibular Nerve and the Cochlear Nerve. The Vestibular Nerve effects balance, while the Cochlear Nerve affects hearing. When this happens, a Cochlear Implant will not replace hearing lost, but leaves Auditory Brainstem Implants as an option. Learn more about Vestibulocochlear Nerve Damage

4. Reference Sources

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