Cochlear Implants Flashcards
Cochlear Implants
When hearing aids are not successful
Unilateral vs bilateral
Usually due to damage in the cochlea
CI bypasses damaged hair cells and directly stimulated auditory nerve
Tonotopic organization of cochlea
DO NOT restore hearing to normal
History of CI’s
Started in 1950’s and 60’s in Europe with designs of electrical stimulation devices
FDA improved first CI in 1984 for adults only
Children approved years later
Criteria has changed immensely over the years
CI: Internal component procedure
Implanted in skull
Internal receiver/stimulator placed on mastoid bone
Electrode array which is inserted into cochlea
Not visible after operation
CI: Internal Components
1 Electrode Array
Designed for a gentle cochlear insertion. The electrodes deliver spectral bands of sound.
2 Electronics Package
Advanced technology designed to support current and future generations of sound processors and features.
3 Communication Link
Receives digital representations of sound from the external sound processor and sends information about the status of the implant system and the hearing nerve back to the processor.
4 Magnet
Provides a reliable connection to the externa headpiece.
CI: External Components
Batteries
Microphone
Cables
Speech processor
Transmitter magnetic coil sitting on skull
Speech processor: looks similar to BTE and worn behind the ear
Neptune – recent body worn style (waterproof)
Microphone picks up sound and converts it to electrical sound
Speech processor uses a strategy (algorithm) for determining how it’s processed
Digitized, filtered, segmented so that it can go to different electrodes
Multidisciplinary assessment team
Audiologic evaluation
Medical examination including otology
Auditory skills assessment
Language assessment
Psychological assessment
Educational placement evaluation
Ophthalmologic evaluation
Occupational therapy
Developmental pediatric and neurologic assessment
CI: how it works
After speech is processed it travels to stimulator (Receiver/Stimulator)
Internal and external piece communicate via electromagnetic induction or radio frequency transmission
Sent down electrode array to individual electrodes
Acoustic radio frequency electric pulse
Processing
Interleaved pulsatile stimulation algorithm
Each electrode pair in the electrode array is designated to represent different frequency bands
A CI can have 12, 16, 22 or 24 channels (for basic speech perception about 8 are necessary).
Audio signal is processed then delivered to electrode array by spreading impulses in a non simultaneous manner
Electrode array
Small wire inserted into cochlea through round window or hole drilled called cochleostomy
Electrode pairs with positive and negative contacts which pass current
Current stimulates fibers of auditory nerve
Cochlear Implants
Multichannel
Multichannel
Different information sent to different parts of cochlea
In normal ear, different frequencies stimulate different portions of the cochlea (tonotopic organization)
In the ear there are thousands of hair cells- but only a limited number of electrodes in the array.
Candidacy
Criteria have changed over the years
Bilateral moderate to profound hearing loss
Trial period with HA
Good general health
Residual hearing actually makes for better performance with CI
Commitment to auditory rehabilitation
Future: unilateral hearing losses
Criteria by age and manufactures- page 271
See examples pages 275-278
Hybrid implant
Just FDA approved in 2014
Uses acoustic stimulation for low frequencies
Electrical stimulation for high frequencies
Used for steeply sloping hearing losses
Hybrid Implant
Electrical Auditory Stimulation (EAS)
Shorter array than traditional CI’s
Preserve hearing is goal
Music benefits
Improvements in noise
Good perception of speech prosody
Bilateral CI’s
Increasing number of bilateral patients
Simultaneous vs. one at a time
Some people use HA in contra ear – Bimodal hearing
Some don’t like HA + CI
Factors that affect outcomes of CI
Duration of deafness
Residual hearing
Rehabilitation
Pre-op scores
Success/Outcomes
Postlingual onset of hearing loss
Shorter duration of severe snhl
Style of electrode array (perimodiolar style with better outcomes)
More pre-op residual hearing (better WR scores)
Age
Perimodiolar-positioned cochlear implant electrodes have been developed in order to bring the electrode contacts as close as possible to the spiral ganglion cells, which are the target of electrostimulation.
CI process
CI evaluation
Medical evaluation
Psychological evaluation
If no hearing aids, trial with amplification
Once patient deemed a CI candidate
Surgery to implant internal components
3-4 weeks later, fitting (mapping) of external programs called initial stimulation or activation then…..
Aural rehab & CI
CIs make sound accessible, but in order to give the new sounds meaning a long-term comprehensive aural rehab program to is necessary in order to maximize individual auditory potential.
Research studies demonstrate that patients adjust more quickly and achieve greater overall success when they actively participate in a rehabilitation program.
Child (Re)Habilitation
Most children who receive a cochlear implant are hearing for the very first time.Intervention services aredesigned to support both the child and the family to maximize auditory, speech, and language development. Services may include:
Speech-language evaluations
Regular speech-language-listening therapy
Distance speech-language-listening therapy
Adult Rehabilitation
Adult Rehabilitation
Most notice an immediate improvement in their hearing and listening skills. The therapy program is customized to support each patient’s communication and hearing goals. Services may include:
Aural rehabilitation (therapy services to develop listening skills)
Distance aural rehabilitation
Education for recipients and their families about communication strategies to enhance their interactions
Expectations
Performance improved with technological advancement.
Depends on age at cochlear implantation, onset of HL (pre vs postlingual), time since HL and more…
Children:
School-age children with CI preform relatively similar to their peers on language comprehension, reading, and writing accuracy, but poorer on sentence formulation.
Over 50% of college-eligibility.
Can enjoy music with the latest CIs.
Adults:
Detection of soft spoken speech
Some vowels and consonants discrimination (close set).
Better lipreading
Monaural vs. Binaural Fitting
Binaural Benefits:
Elimination of head-shadow effect
Loudness summation up to 3dB
Binaural squelch improvement of 2-3dB
Localization
binaural squelch effect (BSE) refers to the capacity of the central auditory system to process the stimuli received from each ear and to reproduce it with a higher signal-to-noise ratio (SNR) by comparing interaural time and intensity differences.
Brainstem implants
There are some cases where cochlear implantation is not possible.
Electrical pulses are directly delivered to the cochlear nuclei.
Assist users with sound awareness and communication.
Suitable for patients whose auditory nerves have been irreversibly damaged.
Solution for patients who are at least 15 years of age and who have been diagnosed with Neurofibromatosis Type 2.
Ci and deaf culture
HL is a biological difference not an abnormality.
View CI as an attempt to ethnocide deaf culture.
CI surgery is abusive.
NAD, 2010a (see page 303).
