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129 Cards in this Set

  • Front
  • Back
Compression
All 3 companies use AGC
AB and MED-EL: clinician can adjust
Cochlear uses “autosensitivity”: Can be turned on/off by clinician. Like a slow acting compressor for moderate to high level inputs.
Channel Gain
Like sensitivity only on a channel by channel basis. Prior to signal processing. Used to increase the salience of signals in specific frequency ranges without needing to increase upper stimulation levels. Useful if already at max comfort levels. If getting facial stimulation, discomfort.
Volume Control
Changes upper stimulation level. Clinical can restrict amount of VC change by patient.
Electrode Channel vs. Contact
Channel: discrete frequency range over which sound is analyzed for eventual delivery to electrode contact.
Usually direct relationship: Channel 1 to electrode 1 etc…
Clinician can assign channels to different electrodes to restore tonotopicity.
Virtual Electrodes (Current Steering)
AB and MED-EL can do this
Attempts to increase the spectral fidelity of the signal delivered to the nerve.
HiRes120
Frequency Allocation
How Frequencies are allocated to active channels.
Bio mechanical issues/goals of MEI
Should maintain normal function of the ME air system.
Should not alter AC threshold if device is unsuccessful, added mass should not affect structures ability to vibrate.
Secure anchoring of device to ossicles, long term stability of connection.
Mechanical forces on the connection should not affect the life expectancy of the device.
Direction of the transducer's vibration must be coincident with the axis of normal sound transmission through the ossicular chain. In effect, the device must be attached to the TM, he long process of the incus, or the head of the stapes.
Battery life mud be sufficient to avoid frequent replacements requiring reoperation.
Piezoelectric devices
Piezoelectricity: ability of crystals and ceramics to be ate voltage in response to applied mechanical stress and vice versa. Electric current passed into a piezoceramic crystal which changes its volume and thereby produce a vibratory signal. Must have a direct contact between piezoelectric unit and ossicles.
Disadvantage: power output is directly related toy he size of the crystal.
Piezoelectric crystals are MRI compatible.
TICA
Piezoelectric: Tubigen Implantable Communication Assistant
The mic subcutaneously in EAC near TM. A digitally programmable processor located subcutaneously on the mastoid bone brocades the signal. A piezoelectric transducer is coupled to the body of the incus and drives the ossicular chain by vibratory actions.
Not FDA approved.
Rion
Piezoelectric
Partially implanted ear level mic/amplifier, internal coil and piezoelectric vibrator attached to stapes. Incus, malleus, TM removed. Lateralized middle ear canal wall is made of a cartilage graft. MHL and SNHL. PTA <_ 50 dBHL
Benefit decreasing over time: possible aging and tissue reaction around vibrator element.
Envoy Esteem
Piezoelectric
Uses the ear drum as the mic. +EAC acoustics. Mechanical signal is detected from a piezoelectric transducer at the head of the incus (sensor) and converted to an electrical. The electrical signal is amplified, filtered, and converted back to a vibratory signal. The processed vibratory signal is then delivered by means of a piezoelectric transducer (driver) attached to the stapes capitulum/head.
Disadvantage: the incus lenticular process is removed to prevent feedback to the sensor.
Output up to 110 dB SPL.
Features: maintains natural spectral shape + localization cues from Pinna and EAC. No feedback or occlusion. Remote control. Greater power and less distortion than electromagnetic.
Esteem candidacy
Stable bilateral mod to severe SNHL. 18+. Healthy ME, EU tube function and space for device. Normal tymps, unaided WRS >_ 40%. Minimum 30 day trial with hearing aids.
Not MRI safe.
Expected audiologic outcome for esteem
Poorer unaided thresholds.
Functional gain similar to HAs.
Hearing in noise better than with HAs.
Possible side effects of esteem
Taste alteration and facial paralysis.
Permanent CHL due to partial removal of incus.
Lifespan of esteem
Battery requires surgical replacement every 5-8 years
Contraindication for esteem
Hx post adolescent chronic OM, inner ear disorders requiring Tx, episodic vertigo, mastoiditis, MD/hydrops
Hx fluctuating HL in past year of 15 dB at 2 or more frequencies.
Hx OE.
Clesteatoma.
Hypersensitivity to materials in implant.
Pregnant.
Electromagnetic MEI
Pass an electric current into a coil which crates a magnetic flux that drives an adjacent magnet. EM transducers (coil) don't need to touch the ossicles, but need to be near, which have a magnet out on them. Anatomy restricts the size of magnets/ coils than can be used.
Vibrant sound bridge
Electromagnetic
Partially implanted system
External audio processor, help by a magnet behind the ear, processes acoustic signal.
VORP: vibrating ossicular prosthesis
Internal receiver sends the processed signal via a wire a floating mass transducer (FMT) attached to the transducer.
Candidacy >50% WRS
Vibrant candidacy
Mild to severe SNHL or mixed or conductive, must be 18+, good for pts who can't wear HAs (chronic otistis externa, microtia, atresia)
Vibrant expected audiologic outcomes
**
Vibrant side effects
Taste alteration, aural fullness
Vibrant expected lifespan
**
Soundtec
Electromagnetic
Semi implanted
Magnet attached to ossicles
**
Residual hearing not affected
Average 4.2 dB poorer thresholds across
**
Ototronix
**
Otologics MET and Carina
Middle Ear Transducer: first offered in clinical trials in semi-implantable style. Magnet held-button like processor in places. Partially implanted. Transducer mounted to incus. Coupled to externally worn button processor.
Carina: fully implantable MET.
General indication for all MEI
Trial with conventional aids with limited success. Mild to severe SNHL. No middle ear disease or infection. Hearing loss should be stable. WRS should be sufficient to allow adequate discrim of sounds. Reasonable expectations. 18+.
**
General challenges of MEI
Limitation in capacity and recharging cycles of available batteries necessitate transducer energy efficiently. Strict ions due to the size of timidly ear challenge the devices to deliver enough gain to aid more sever hearing loss. Cost of surgery. Technical difficulty in implanting some of these devices
**
Current MEI FDA approval
**
Vestibular implants for bilateral vestibular disorders
Built much like a CI.
External part registers head movements is secured to the head, contains gyroscopes and accelerometers, internal part that connects electrodes to the nerve ends.
MedEl: two teams working: one device attaches to the SSC, other device attaches outside the vestibular system. Implant is being developed primarily for patients with bilateral vestibular dysfunction,attempts to restore the VOR.
Vestibular implants for MD
Rubenstein of UW
Cochlear: three shorter arrays to stimulate the vestibular nerve, supplying bursts of electricity to the vestibular nerve to make up for the temporarily disabled hair cells during a Meniere's attach, the device should bring the perceived spinning to a stop. User activated external processor that sits behind the earl just like a CI. Patient controls the activity of the electrical stimulation remotely with a hand held control device. Can turn a dial to regulate how much stimulation his being sent to the semicircular canals and can find a "sweet spot" that helps override the dizzy attacks.
Single channel implant House 3M
Info below 1kHz
Discriminate between voiced and voiceless, different F1 and sometimes F2.
Time envelope info and some frequency info below 1kHz.
Vienna 3M CI
Preserved fine temporal variations in the speech signal. Some patients could recognize speech (15-86% WRS)
Multiple channel implants
1st done in '78
FDA approved for adults in '85 and children in '90.
Graeme Clark made the first implant and implanted Rod Saunders in '78.
How many people have CIs?
As of dec 2010 219,000 people worldwide.
In the US 42,600 adults and 28,400 children.
Electrode array implantation
Implanted in the ST through the round window or a chochleosteomy. Wire made out of platinum-iridium alloy and covered in a silicon rubber.
Hard CI failures
Sudden loss of all device function. Gradual over days weeks. Published clinic-specific reported rates 2.9% -11%, and 15% of peds. Rates going down. Company reported rates lower than clinic specific rates….why would this be?
Cause of failures? Trauma around implant site? Specific event usually denied by patients.
Soft CI failures
Unexplained decrease in clinical benefit, even though manufacturer conducted integrity testing indicates good function. More difficult to identify, may take up to months to diagnose.
Signs of hard failures
Inability to “maintain lock” with external speech processor. Complete loss of connectivity between the receiver and electrode array. Gradual disconnection or short circuiting of one or more electrodes from the receiver.
Early signs: Frequent/intermittent “popping” sounds. Intermittent surges in loudness that exceed the LDL. Intermittent or consistent decreases in speech quality.
What to do when a failure is suspected
Manufacturer is contacted for device integrity testing (within a few days if possible). When documented, surgery ASAP. Same ear usually reimplanted.
CI warranty
10 yr warranty on hard failures on internal device. Replace at no charge. Surgical costs need preauthorization, often covered, if not company often pays.
3 yr External warranty. Upgrades need preauth too, can be covered. Need letter of medical necessity saying that processor no longer has medical usefulness.
Reasons for soft CI failures
Trauma to device. Usually leak in hermetic seal surrounding device. Bacterial biofilm formation. Unknown causes.
Symptoms of soft failures
Elevated or fluctuating thresholds or C/M levels over time. Facial nerve stim. Decrease loudness growth. Adaptation of sound. Parental or school concern about a drop in performance. Intermittent “popping” sounds. Unexplained fluctuation of soundfield thresholds. Intermittent/permanent changes in speech perception or sound quality.
Diagnosis and troubleshooting for CI
Pt performance data most important tool:
–Annual tests recommended
–Check all external equipment, usually solves it
–Tympanometric /audio done, especially if HA used on contra ear (increased hearing loss?)
–Objective measures:
–NRT, ESRT, electrical ABRs to evaluate device status/verify mapping
–Radiological to r/o ossification, electrode placement
–Try different strategy and electrode configuration
Importance of baseline data
•Radiological
•Psychophysical and objective measures
•Speech perception
•Speech/language tests
When is surgical revision/replacement necessary?
•Mechanical device failure (hard failure)
•Less than optimal electrode placement
•Skin flap complications
•Need for technological upgrade
•Intratemporal pathological conditions
Pre-op assessment outline
1. Medical evaluation and Imaging
2. Audiological evaluation
3. Electrophysiological testing
4. Hearing aid evaluation
5. Speech language evaluation
6. Psychological evaluation
7. Speech perception testing
Who to refer for a CI eval
When a patient is not a successful hearing aid user. E.g. Cannot use telephone, difficulty even one-on-one in quiet.
Referral criteria are based on: degree of hearing loss, low word recognition test scores.
Must suspect peripheral HL, not central.
Factors determining success
Performance depends on factors such as: age at onset of hearing loss, etiology of the loss, duration of loss, previous hearing aid use, cochlear and neural anatomy, motivation, commitment to rehabilitation, medical contraindications.
Private insurance criteria
Adults: Pre-linguistic or post linguistic onset. Moderate-profound SNHL AU. ≤ 50% sentences in quiet on implanted ear. ≤ 60% sentences in quiet contra ear or AU. No medical contraindication. Motivation/commitment.
Medicare criteria
Adults: Pre-linguistic or post linguistic onset. Moderate-profound SNHL AU. ≤ 40% sentence in quiet better ear. No medical contraindication. Motivation/commitment
Children: < 30% on open set speech scores (MLNT or LNT).
Modern day CI performance
Criteria have change as technological advances have improved outcomes.
Tests used to assess candidacy have also become harder.
Candidacy determined by HINT and newer tests: eg CNC, AzBio, BKB-SIN
Current test materials
The 3 companies have agreed: AzBio, CNC, BKB-SIN
At average conversational speech: 60 dB SPL or 45-48 dB HL
Goal of programming
Restore audibility for a range of speech sounds from soft to loud. Optimized for speech. Maintain normal loudness percept, i.e. soft is soft and loud is loud.
Parameters affecting signal coding for intensity
Stimulation levels
Threshold of stimulation
Upper stimulation levels
Current amplitude and pulse width
Mapping acoustical inputs into EDR: IDR, Sensitivity, Compression, Channel gain, Volume control
Parameters affecting signal coding in the frequency domain
Electrode contact vs. channel
Virtual electrodes
Frequency allocation
Parameters affecting signal coding in the time domain
Stimulation rate
The goal of CI mapping is optimized for ________
Speech
Volume control adjust the ___________
Maximum level (the M level)
Stimulation levels
Current levels used to stimulate the ear. Threshold of detection and upper stimulation level are lower and upper boundaries known as Electrical Dynamic Range. Restore audibility for speech for normal loudness perception.
Threshold of Stimulation
AB=50% detection
MED-EL=highest level where no response
Cochlear=lowest level of 100% detection (with counted Ts)
Programming/Measuring Ts only done with Cochlear.
AB and MEDEL use calculated Ts. Research showed audibility and speech recognition similar to measured Ts.
Integration time of the auditory system
1 second
Input Dynamic Range
Sound levels that are captured, processed and delivered to the electrode array.
Default IDR ranges from 40-75 dB. Lower end usually around 20-30 dB SPL. Upper end around 85 dB SPL.
Cochlear has Instantaneous IDR: Range of short term fluctuations that are mapped without compression captures range of ongoing speech amplitude (peaks/valleys) at any one point in time.
Sensitivity
Controls gain of microphone. An input control, interacts with IDR.
High microphone sensitivity on sounds
Lots of gain for soft sounds.
Low microphone sensitivity effect on sounds
Only captures the loud sounds, does not capture soft sounds.
Compression
All 3 companies use AGC
AB and MED-EL: clinician can adjust
Cochlear uses “autosensitivity”: Can be turned on/off by clinician. Like a slow acting compressor for moderate to high level inputs.
Channel Gain
Like sensitivity only on a channel by channel basis. Prior to signal processing.
Used to increase the salience of signals in specific frequency ranges without needing to increase upper stimulation levels.
Useful if already at max comfort levels. If getting facial stimulation, discomfort.
Volume Control
Changes upper stimulation level.
Clinical can restrict amount of VC change by patient.
Electrode Channel vs. Contact
Channel: discrete frequency range over which sound is analyzed for eventual delivery to electrode contact.
Usually direct relationship: Channel 1 to electrode 1 etc…
Clinician can assign channels to different electrodes to restore tonotopicity.
Virtual Electrodes (Current Steering)
AB and MED-EL can do this.
Attempts to increase the spectral fidelity of the signal delivered to the nerve.
Frequency Allocation
How Frequencies are allocated to active channels.
Stimulation Rate
Number of biphasic pulses delivered to an electrode within one second (pps).
Today’s devices up to 5,000 pps.
Codes temporal cues.
Influences pitch and intensity percepts.
Slow changes (2-50Hz) give envelope of speech.
Faster rates give fine temporal structure important for speech in noise, music, vocal pitch.
While individual nerves cannot keep up with the faster rates, collectively the auditory nerve can use a “volley approach”
Eg. Rates </=2000 pps: nerve fibers very synchronous, but then all in refractory at same time, so more difficult to follow fine temporal information.
Faster rates may force nerve fibers into more of a volley approach and thus collectively may follow fine temporal information better.
Interpolation
Streamlined programming, estimated T and C between channels.
Sweeping
Sequential presentation of stimuli across active electrodes at one stim level.
Loudness Balancing
Similar to sweeping, usually only 2 electrodes.
Radio frequency (RF)
Carrier frequency of the radio signal from coil to receiver/stimulator.
No communication: loss of RF lock.
Telemetry
Transmission of data to and from internal device.
“Lock” successful radio communication between inside and outside parts.
Electrode impedance
Measure of the opposition to current flow.
Low level delivered, measures current that returns to ground electrode etc.
Short: excessively low impedance (electric coupling between two electrodes), Open: excessively high (>30kohm).
Normal to have high at activation due to bubbles and protein buildup, and non use.
Voltage compliance
A limit to the amount of current you can send through an electrode.
Mixing ratio
The ratio between the mic and t-coil (or FM, direct audio) levels
Realistic expectations
General surgical considerations
Appointment schedule
Financial aspects, lifelong
Contra indications after surgery (MRI, contact sports etc)
Warranty policy, reliability of internal/external
Residual hearing
Increased risk of meningitis
Tailor for age, etiology, age of onset: sudden HL best results typically, mondini malformation lower results likely.
Be realistic to lessen the potential for dissatisfaction at activation.
Acclimatization period will be necessary, benefit will take time to manifest
Prepare for limited word understanding or only hearing noise in the beginning.
Kids may show slow progress in spoken –language skills.
Prepare families: sound awareness, anxiety, happiness, fear, indifference, crying, smiling.
Goals of Initial Stimulation
Select proper magnet strength.
Connect processor to computer and patient to assess implant: measure impedances.
Obtain psychophysical measures (Ts and Cs).
Re-introduce patient to sounds.
Don’t worry about perfecting MAP: many physiological and psychological changes over first week especially.
How much information is too much information depends on the patient!
Binaural advantages
Head shadow effect: 3 dB
–Improved s/n
Binaural squelch: 1-2 dB
–binaural redundancy
These translate into:
–Better speech understanding in quiet
–Better speech understanding in noise
–Better localization ability
–Better sound quality perception
–Better enjoyment of music
–Overeall ease of listening
CI + HA benefits
Save other ear for better technology
Risk of bilateral surgery and time under anesthesia
Cost
HA can provide better low frequency information (important for:
–hearing speech in noise
–Music
Complementarity-
–Better voice segregation and perception of voicing and manner cues
Goals of the idea processing strategy
Preserve important information from acoustic stimulus.
Minimize “noise”: Do not stimulate for non-important information, minimize channel interactions (unintentional stimulation).
Power efficient: better battery life, smaller processor size.
Test design for comparing CI processing strategies
Subject characteristics: age, hearing loss, how long they have had their implant ect.
Test design: double blind, give everyone all strategies but change up the order.
Assessment: speech perception scores (AzBio: good because there are not ceiling effects).
Special considerations
Filterbanks
The signal is divided into channels, each electrode has its own filterbank (the frequencies it is responsible for).
Current Steering
Two adjacent electrodes fire (simultaneously or quickly sequentially).
Stimulated neural population is between the two electrodes.
Result :“virtual channels” or “intermediate pitch percept”.
Cycle/sweep
The electrodes being stimulated in the cochlea are stimulated over and over again
Stimulation rate
How fast is each cycle?
Ideally: fast enough to maximize temporal cues.
Consideration: limitations of auditory nerve firing rate, neural fatigue.
Lower rates sound lower pitched, higher rates sound higher pitched.
Two primary families of strategies
CIS-like strategies: every electrode stimulated during each cycle.
n-of-m strategies: only channels with highest amplitude selected for stimulation each cycle.
SAS (Simultaneous Analog Stimulation) strategy
Early processing strategy by AB.
All electrodes stimulated simultaneously for each sweep. Preserves almost all cues from acoustic signal. Channel interactions cause distortion. Not power-efficient.
CIS strategy: continuous interleaved sampling
Every electrode is stimulated sequentially during each cycle. Higher amplitude input = higher amplitude stimulation for that electrode.
Rate: 800-1400 pps
8-16 channels
MPS strategy: multiple pulsatile sampler
Variation on CIS by Advanced Bionics.
2 electrodes spaced apart are stimulated at same time during cycle. Allows faster stimulation rate. Spacing minimizes channel interaction compared to SAS. Faster than CIS.
CIS+ strategy
Variation on CIS by MedEl.
Frequency bands expanded. More accurate estimation of the input signal. Uses Hilbert transformation instead of wave rectification & low-pass filtering. The biggest difference is how the signal is devised into filter banks.
HDCIS strategy
Variation on CIS by MedEl.
Like CIS, with the addition of current steering. Sequentially stimulate 2 neighboring electrodes, and attain locus of stimulation between the two electrodes.
FSP strategy: fine structure processing
Variation on CIS by MedEl. Current strategy they use.
Overlapping filterbanks to enable current steering. For low-frequency channels, modulated timing designed to improve temporal structure. Handles low frequencies differently.
HiRes strategy
Variation on CIS by AB. Current strategy they use.
16 active electrodes instead of 8. Faster max stim rate than CIS. Higher cutoff frequency for low-pass filter. More sophisticated AGC.
HiRes S: Sequential
HiRes P: Partial simultaneous stimulation
HiRes 120: Uses current steering (default)
n-of-m strategies
Acoustic energy in m channels determined. Stimulate up to n channels with the highest amplitude input.
CIS vs. n-of-m Strategies
n-of-m: Faster possible stim rate. Less channel interaction and masking. More power-efficient. Improved battery life. Smaller processor size.
HOWEVER… some channels will not get selected, so patient misses that information.
The verdict thus far? No significant performance differences between CIS vs n-of-m strategies.
SPEAK: spectral peak strategy
n-of-m strategy by Cochlear.
Subset of electrodes stimulated on. Up to 10 maxima (n) from 20 total channels (m). Slow rate (250 pps/ch).
ACE strategy: advanced combination encoder
n-of-m by Cochlear.
Like SPEAK, but faster rate (up to 3500 pps/ch). Performance: ACE>SPEAK (Kiefer et al, 2001; Skinner et al 2002).
Pediatric CI team members
•Parents (and older pediatric candidates)
•Surgeon
•Audiologist
•Speech/language pathologist
•Educator
•Educational Audiologist
•Child psychologist
•Early Intervention Provider
•Developmental Pediatrician/Specialist (as indicated)
•Opthamologist
Pediatric candidacy considerations
•Etiology, anatomy & physiology
•Presence of other handicapping conditions
•Age of implantation
•Family commitment, motivation, and expectations
•Access to aural habilitation
•School services
•Experience level of implanting center
Pediatric assessment tools
•OAE
•ABR
•Tympanometry and reflexes
•BOA, VRA, CPA
•Speech perception: interview/questionnaires, closed set tasks, open set tasks.
IT-MAIS
Infant/Toddler Meaningful Auditory Integration Scale
Birth-3 years
10 questions evaluating use of sound
Vocal behavior, attachment to hearing device, alerting to sound, attaching meaning to sound
ESP
Early Speech Perception Test
–3-12 years old
–Low Verbal and Standard Verbal Versions
–Pattern perception: ball, hot dog, ice cream cone
–Spondee identification: airplane, hotdog, popcorn
–Monosyllable identification: book, bird, ball,
NU-CHIPS
•Northwestern University Children’s Perception of Speech
•Auditory language age 2-5 years
•4-alternative picture identification
•Monosyllabic words, words are not similar
WIPI
•Auditory language age 4-6 years
•6-alternative picture identification
•Monosyllabic words, words are very similar
MLNT and LNT
•Lexical neighborhood test
•Multisyllabic lexical neighborhood test
•Auditory language age 3-5 years old
•Open set word test: each list has 25 lexically easy words and 25 lexically hard words
•LNT Easy: brown, old, push, girl
•LNT Hard: tea, dad, cap
•MLNT Easy: children, monkey, apple
•MLNT Hard: bunny, summer, yellow
PBK
•Phonetically Balanced Kindergarten word list
•Auditory language age 5-8 years
•Open set word test
–Tree, night, please, yes, shoe….
HINT
•Hearing In Noise Test
•Open set sentences in quiet or noise
•Auditory language age 5-6 yrs+
•10 sentences per list
–Flowers grow in (a/the) garden.
–Her shoes (are/were) very dirty.
Pediatric CI programming overview
Set levels so soft sounds are audible and loud sounds are comfortable
–AB: Measuring comfort levels
–Cochlear: Measuring threshold and comfort levels
–MedEl: Measuring comfort levels
May use behavioral or objective measures
Behavioral measurement for threshold levels
•Behavioral observation
•Visual reinforcement
•Conditioned play
•Hand-raising
•Count the number of beeps
Behavioral measurement for comfort levels
•Global adjustment when live
•Individual channel measurements
•Behavioral observation
•Point to loudness scale
•Sweeping/balancing
Objective Measurements for pediatric CI appointments
•NRI/NRT/ART
•Stapedial reflexes
•Electrical Auditory Brainstem Response
ECAP
Electrically evoked compound action potential.
Stimulate intracochlear, record intracochlear.
Quick, non-invasive, objective measure of peripheral neural function.
Shows you compound action potentials generated by specific neural populations in the cochlea. Amplitude functions: electrophysiological responsiveness of neural population(s).
Current ECAP applications
Confirmation of Implant Function
Objective Assessment of Changes Over Time
Estimation of C- or M-levels and T-levels (Advanced Bionics and Cochlear only)
ESRT
Electically-evoked stapedial reflex threshold.
Stimulate ear intracochlear, surface recording.
Loud stimulus from CI evokes reflex of stapedial muscle. Highest level where no response or lowest level where there is a response. Measured using CI software and tympanometer. Strongly correlated with comfort levels. Measurable with all three manufacturers.
How is ESRT measured?
Connect processor to programming computer, place processor on recipient’s ear. On contralateral ear, obtain tympanogram. Begin Reflex Decay test on tympanometer. Stimulate one electrode via programming computer. Look for deflection in tympanometer indicating response. Increase/decrease stimulus level until threshold is found. Record stimulus level that elicited ESRT.
Special considerations for ESRT
Recipient must: have Type A tympanogram for contralateral ear, remain still during measurement.
No talking, head movement, minimal swallowing/jaw movement: probe must maintain seal throughout measurement.
EABR
•Electrically-evoked auditory brainstem response
•CI processor and software stimulate pathway
•ABR electrodes and software record response
•Can be used similarly to ECAP response for programming
•Presence of EABR response is good indication that stimulus is reaching brainstem and is likely audible
ABI
Auditory brainstem implant.
Placement on and stimulation of dorsal cochlear nucleus.
Things to ask at a pediatric CI follow-up
What has he been hearing?
What has he been saying?
How are the lings going?
Is the equipment working?
Any concerns?
How often is he wearing it?
Telemetry
Data transmission via radio frequency from a source to a receiving station.
NRT/I
Neural response telemetry/imaging.
Clinical uses for ECAP
Verify auditory nerve function (objectively).
Verify electrode/device function (objectively).
Assist with programming, if reliable responses difficult.
Verify accuracy of questionable behavioral responses.
Very important in pediatric population.
Difficult to separate stimulus and response in ECAP. How do we do this?
Forward masking subtraction method.
Alternating polarity.
MPI
Masker to probe interval