Chapter 3 - Cochlear Implants
What is the average cost of a cochlear implant?
$60,000-$80,000
CI can help an estimated ____ children in the US who do not benefit from haids
200,000
What are the primary functions of the LED?
has three primary functions: battery charge status, lock status, and microphone/system status.
What is RF level and what is its purpose?
- The radio frequency power level required to maintain the proper communication between the internal and external components. - set during programming to prevent any interruptions or breaks in sound transmission.
What skills did the 87% of the auditory/verbal communicators adopt after the surgery?
- awareness of sound - association of sound with events - single word use with understanding - emerging phrases - use of spoken intelligible language to express needs and feelings
How does a cochlear implant work?
- bypasses middle ear, traveling fluid wave in the scala media of the cochlea and sensory cells on the basilar membrane. - It transforms sound energy into electrical energy that will initiate impulses to stimulate the auditory nerve.
How do you know if the battery needs to be replaced?
1 blink
Who is on the cochlear implant team?
1) SLP 2) Psychologist 3) Teachers 4) Parents 5) Social workers
What are some variables that may affect the success of a cochlear implant?
1) age of onset 2) length of deafness 3) age of implantation 4) length of implant use 5) etiology of hearing loss 6) nerve survival 7) technology 8) surgical issues 9) re/hab methods 10) motivation
What are the benefits of CIs in children?
1) implant children as young as possible for language acquisition 2) Older children will also benefit if they use oral communication. Their benefit is limited if they have been deaf for a long time or they use total communication.
Who is a candidate for cochlear implant?
1) must have a moderate to profound sensorineural hearing loss bilaterally 2) Less than 50% speech recognition in the ear to be implanted when listening at normal conversational levels (70dB SPL) 3) Opposite ear must have scores less than 60% 4) Medicare requires speech recognition scores be 40% or less
What are the benefits of CIs?
1) post-lingual adults achieve 80% correct on high context open set sentence materials 2) people with more residual hearing have better results 3) better to put a CI in when person's hearing is not that bad
What does having more electrode sites do?
1) provides better frequency resolution 2) if there are any region on the cochlea that respond poorly, they can be avoided
How does spacing of electrodes affect sound?
1) spacing them too closely could cause serious sound distortions due to channel interaction 2) may affect poor loudness growth
What does the cochlear implant surgery consist of?
1-3 hours outpatient after the receiver and electrode array are placed in the head, the external headset and speech processor are fitted 3-6 weeks later
How many recipients of CI are children?
1/2
How many people world-wide have cochlear implants?
100,000
What is the earliest age for implantation?
12 months
When was the first electrode placed on a person's auditory nerve?
1957 by French surgeons
When was the first cochlear implant implanted?
1972 in an adult
When were CI available for children over age 2?
1980
When was the first CI placed in a child?
1990
What is bipolar mode?
2 adjacent electrodes are paired as active and return 2 electrodes provide only one channel between them i.e. 24 electrodes would deliver 12 channels
How do you know if the battery has sufficient charge?
2 blinks
The demand for CI is increasing annually by
20%
How long is the human cochlea?
20-30mm
Optimally, the cochlea should not be stimulated past ____mm, because
25mm bc it may cause poor pitch discrimination
How many cochlear implant companies in the US are approved by the FDA?
3 companies 1) Cochlear Corporation- Nucleus Freedom System 2) Advanced Bionics- Bionic Ear System 3) Med El Pulsar
How do you know if the CI battery is charged?
3-4 quick blinks
How long has there been research and development of CIs?
30 years
How many hospitals across the US perform CI surgery?
350
In the study for cochlear implant candidacy, 46% of children ages 2-5 years were predicted to have an outcome of an auditory/verbal communicator with visual assist Group B, what percentage of this group performed at this level and how long did it take?
85% performed at this level
In the study for cochlear implant candidacy, 25% of children ages 2-5 years were predicted to have an outcome of an auditory/verbal communicator Group A, what percentage of this group performed at this level and how long did it take?
87% after 3 years post surgery
What is LOCK status?
After the fast blinking battery test sequence, the red LED will continue to flash approximately once per second until the headpiece is properly positioned over the implant and successful communication is established
What is a cochlear implant?
An implantable device designed to substitute for the function of the middle ear, cochlear mechanical motion, and sensory cells (inner ear).
What is the electrical threshold?
C-level AKA M-level maximal level that is COMFORTABLY loud
What is the most used speech coding strategy by manufacturers?
CIS (Continuous Interleaved Sampling)
What is CIS?
Continuous Interleaved Sampling uses the full spectrum of the incoming waveform
T/F Cochlear implants restore normal hearing
False- may improve, but probably will not be 100%
T/F T level are the same as threshold results on audiogram
False. T level are the softest sounds detected 100%
What is the LED on the cochlear implant?
Light Emitting Diode located on the top of the processor
What is the T-level?
Minimum stimulation level test for softest electrical current felt 100% of the time
What theory is more commonly used among CI manufacturers?
Multichannel -place theory or tonotopic theory
For adults, what is the candidacy?
Must have had 3-6 month trial with amplification with limited benefit
How are C-levels and T-levels tested in young children?
NRT (Neural Response Telemetry) by behavioral observation
Who were the last population CI were made for?
Prelinguistic congenitally deaf children
What is SAS?
Simultaneous Analog Stimulation generates digitally reconstructed analog waveforms and delivers it simultaneously along the electrode sites
What is intensity coding?
achieved by manipulation of electrical current pulse width, height, and by the quantity of auditory nerve fibers stimulated in the cochlea
When does the plasticity of the auditory system tend to decline?
after age 6
What are compressed analog strategies?
all electrodes stimulated simulataneously
Where do maximum sensitivity to low frequencies occur in the cochlea?
apex
For children, what is the candidacy?
at least 6 months trial period of amplification unless there is hearing loss from etiliology
Where do maximum sensitivity to high frequencies occur?
at the base
Why is it argued that multichannel CI devices should not be manufactured?
because people with severe hearing impairment do not have residual neuronal population to use tonotopic electrical stimulation because they have few or no dendrites along the basilar membrane
When does the cochlea fully develop?
by the 8th week of gestation
Stimulating electrodes at different regions along the length of the cochlea produces
different pitches (frequencies)
What is auditory brainstem implant?
for people with (neurofibromatosis) bilateral nerve VIII damage
What does "n of m" strategy provide?
improved consonant recognition performance
The information in the speech signal can be grossly divided into
intensity and frequency
What are the external components of the cochlear implant?
microphone processor transmitter
The number of available electrodes for stimulation depends on the
mode of stimulation
What mode spreads over a wider area stimulating a larger neuronal population?
monopolar
What are the two modes of stimulation employed by the CI?
monopolar bipolar
What do studies indicate regarding conveying adequate speech info?
multichannel CIs are better than single channel
What's better simultaneous or non-simultaneous stimulation?
non-simultaneous
What percentage of 80 children in the study for cochlear implant candidacy were predicted to be Group C- Complimentary, auditory verbal/oral skills assist primary visual communication?
of the 28% predicted 70% maintained performance
What is monopolar stimulation mode?
one active electrode (ground) one return electrode (implant package)
What is sequential stimulation?
only one electrode is stimulated at any time this eliminates channel interaction
What is place theory or tonotopic theory?
place of stimulation along the length of the cochlea
What do multichannel CIs code frequency based on?
place theory
Who were cochlear implants for after post-linguistic adults
post linguistic children
What were cochlear implants originally made for?
post-linguistically deafened adults
What is temporal theory?
rate of firing of electrical pulses
What do single channel CIs code frequency based on?
rate of firing of electrical pulses (temporal theory)
What are the internal components of the cochlear implant?
receiver and electrode array
What is the electrode array threaded through?
scala tympani to get closer to the spiral ganglion
Who uses cochlear implants?
severe to profound hearing loss - Post-linguistically deafened children from mainstreamed, oral, or signing programs, with or without intelligible speech - Post-linguistically deafened adults with short or long-standing deafness - Senior citizens with progressive hearing loss who receive limited benefit from hearing aids. - Infants with SNL in the newborn nursery, toddlers and preschool-aged children with SNL - Elementary school children and teens from mainstreamed, oral, or signing programs, with or without intelligible speech - Young adults and middle-aged adults who have congenital or peri-linguistic deafness:
What do all CI manufacturers strive to stimulate?
spiral ganglion cells in the modiolus
What is an advantage of monopolar mode?
spread of current over a large number of neurons, it can achieve higher loudness levels with lower current
What is the test called to test the hook-up or internal device of the cochlear implant?
telemetry
Frequency coding depends on ??
the rate of nerve firing (temporal theory) the place of stimulation along the length of the cochlea (place theory)