Final Exam Study Flashcards
(188 cards)
1
Q
Traditional CI indications
A
9 months +
* 9 mos Cochlear
* 12 mos MED-EL
Moderate-profound SNHL, bilaterally. 70 db or greater
* HA Trial with limited benefit
* scoring < 50% on CNC and AzBio
CNC 60% or less → AzBio Score of 60% or less.
2
Q
EAS/Hybrid CI Indications
A
- 18 years+
- Normal to Moderate → Low Frequency & Severe to Profound → Mids & High Frequencies
- SNHL - No ABG greater than 15db
(60 dB HL or better up to 500 Hz and 70db or worse for 2000 Hz+) - 60% or less one CNC = next test → 60% or less using AzBio at 10 dB SNR = Candidate
Children (9-24 Months)
* Bilateral profound SNHL
* Limited benefit from binaural amplification
3
Q
SSD CI Indications
A
- 5 years+
- Better ear: Normal or nearly normal hearing sensitivity in the better ear
- Poor Ear: severe to profound SNHL
- 5% or less using CNC; additional recommendations based on MSTB3 you could AzBio 0 SNR.
4
Q
AHL CI Indications
A
- 5 years+
- Poor Ear: profound SNHL
- Better Ear: mild to moderately severe SNHL
- Difference of 15 db between ears
Thresholds 90 dB HL or greater in the ear to be implanted and mild to moderately severe SNHL in the better with a difference of 15 dB HL or more between ears.
5
Q
List the CMS criteria for Medicare coverage of CIs in adults
A
- Diagnosis of bilateral moderate-to-profound SNHL with limited benefit from appropriate HAs.
- ≤60% (or less) correct scores in the best-aided listening condition on open-set sentence cognition tests. (CNC & AzBio)
- No ME infection, normal inner ear and auditory nerve.
- No contraindications to surgery.
6
Q
Absolute contraindications for cochlear implantation
A
Anatomic
* Absent cochlea/cochlear nerve
* Neurological damage impeding auditory processing
* Damaged auditory cortex
Medical
* Medical condition(s) preventing surgery
* Medical risks of surgery exceed expected benefits
Not a CI candidate
* A child w/significant residual hearing levels and receives good benefit from HAs
* Absence of the VIIIth cranial nerve
* Absence of the labyrinth (Michel’s Aplasia)
* > 20 yrs patient with prelingual deafness who has never acquired speech
* Cognitive impairment that would prevent adequate rehabilitation (dementia)
* Lack of adequate support to ensure attendance at activation and programming sessions
* Active external or middle ear infections
* Known allergy and/or intolerance of device materials
7
Q
Key factors in deciding which ear to implant
A
- Anatomy abnormality; nerve or cochlea related)
- one ear accepts electrical stimulation better
- Implant the worse hearing ear OR Implant better ear (opposite argument)- It has already benefited from hearing aid, will more readily acclimate to implant
- Implant by the patients dominate hand
- Facial nerve too close to cochlea- may pick other ear
- If no difference may want it on right (speech and hearing centers of brain on left)
8
Q
Factors that affect CI outcomes in adults
A
- Duration of hearing loss and deafness: Longer durationof deafness = worse CI outcomes
- Age at implantation: Poorer outcomes in elderly Pt’s ↑Age = ↓Outcome Success
- Preoperative hearing status FDA Indicated PTA does not implant performance
-
Etiology: Pt’s w/ Sudden Idiopathic HL, MD, genetic → better outcome
TBI,ANSD, acoustic neuroma → poorer outcomes
9
Q
60/60 guideline
when a patient should be referred for a CI candidacy evaluation
A
referred for CI eval if…
* Better hearing ear → 60% of less on WRS
* HL PTA in Better Ear → 60 db HL or worse (unaided)
10
Q
Purpose of preoperative vs. postoperative assessments, and what each is meant to determine
A
- Preoperative: goal is to find out if the patient is a candidate
- Postoperative: goal is to determine the outcome or the success of the implantation
11
Q
How to set realistic expectations for CI outcomes during preoperative counseling
A
Detailed counseling is vital before cochlear implant activation.
* establish a relatively conservative and realistic expectation
* review typical performance at activation
* Strike a balance between conservative outlook and understanding the value of cochlear implantation.
* discuss the schedule (audiological, medical, & rehab appt pre and post implantation,)
* familiarize patient/ family with the implant hardware
* provide written materials
12
Q
During CI pro operative counceling you want to strike a balance between ___ outlook and ____ __ ___ of cochlear implantation.
A
Strike a balance between conservative outlook and understanding the value of cochlear implantation.
13
Q
What is the most important objective prior to activation or implantation?
A
Helping the patient and family to establish realistic expectations is one of the most important objectives prior to activation.
* Unfortunately, no matter how thoroughly expectations are discussed, patients and families often are discouraged with performance during the first few days of even weeks of use.
14
Q
hint - 4
What are the key steps in the candidacy process?
A
- Comprehensive Audiological Evaluation
- Hearing Aid Verification
- Aided Speech Recognition Testing
- Outcome Measures
15
Q
Purpose of speech coding strategies and why they are necessary
A
Speech coding strategies condense the incoming signal into a form suitable for transmission while maintaining the important info
16
Q
What is the Importance of verifying hearing aid output using real-ear or simulated coupler measurements
A
- Hearing aids should be fit appropriately to maximize aided speech performance.
- properly fit and programmed to ensure accurate aided results can be obtained
17
Q
What is the importance in input/output calibration?
A
Calibration ensures speech stimuli are presented at consistent, clinically relevant levels.
* Inaccurate presentation levels may lead to inappropriate CI referrals - either under qualifying or over qualified patients.
* Enables reliable tracking of patient progress
* Outcome measures remain valid and comparable
18
Q
How to perform input/output calibration
A
Input- CD, calibration tone Dial on Audio
Output - CD, Calibration speech signal, UV meter, Adjust dial until Uv meter read desired db – used adjusted dbA value for test
19
Q
Why is input calibration important?
A
Input calibration – prevents distortion or clipping of the input signal.
20
Q
Why is output calibration important?
A
Output calibration – ensures that speech materials are presented in the SF at the intended level.
21
Q
Importance of testing 125 Hz in patients who meet CI candidacy
A
Testing at 125 Hz should be included to …
* To assess hearing preservation and guide post-op amplification strategy
* To support counseling by setting expectations about potential hearing loss
22
Q
Basic operation of a CI from sound input to auditory nerve stimulation technical terms
A
Microphone picks up & amplifies sound → converts to electrical signal → to speech processor, SP analyzes & converts to digital info → external transmitting coil → Power & Digital info through RF link→ internal receiver/stimulator, decodes digital signal → electrical stimulation to electrode array (cochlea) → Stimulates Auditory Nerve w/ biphasic current pulses → amplitude, duration, and rate of these pulses are controlled by the speech processor.
23
Q
What is speech coding strategy?
A
speech coding strategy determines how the auditory signal is processed and delivered to the auditory nerve.
* Takes the acoustic signal and transfers it to an electric signal
* condense the incoming signal into a form suitable for transmission while maintaining the important info
24
Q
Why speech is hard to code?
A
- Speech is “complex” signal
- Coarticulation (phonemes influence each other in connected speech)
- Talker variability
25
two main types of information in a speech signal.
**Spectral** information which frequencies are present, and at what intensity.
**Temporal** information how the pattern of speech changes over time.
* Envelope cues: slow fluctuations in amplitude
* Fine structure cues: rapid changes in waveform
26
What two major categories of speech processing strategies emerged:
* Feature-extraction strategies
* Waveform strategies (taking the red line (envelope))
27
What do Feature-extraction strategies do?
Extract spectral information (formants), and uses it to generate the stimulus to the electrodes.
* Limitation: no significant improvements on consonant recognition scores
28
Types of Feature-extraction strategies
and what they do
F0/F2 Strategy: Only Extract fomant frequency and F2
F0/F1/F2 Strategy: More successful than F0/F2 based off WRS scores
29
what is MPEAK (Mulitpeak) & limitation
Extracts formants (F0/F1/F2), but also HF information (800 - 4000 Hz) - showed some improvement but not enough.
* Limitation: it tends to make errors in formant extraction, especially in noise
30
HiResolution sound processing is available in what two commercial forms?
**HiResS and HiResP**
* Clinical trials showed HiRes led to better speech recognition
| Variants of CIS
31
Channel interaction and its effect on spectral resolution and speech perception
In the map, you specify channels, there is frequency range (bands), ex: 100-300 which is transferred to the more apical threshold.
* If the contact is stimulating that frequency region and another, it leads to distortion.
* More channels/electrodes, better spectral resolution. You are getting more frequency specific.
* **improving channel interaction = improving speech quality**
* Decreasing channel interaction = increases quality
* Less electrodes = less channel interaction
32
33
Differences between CIS-based and n-of-m coding strategies in terms of electrode stimulation pattern
* CIS-based strategy, known as Fine structure Processing (FSP). -- Extracts spectral, envelope, and fine temporal structure information from the input signal.
* N-of-m strategies are more spectral and amplitude based.
34
How HiRes Fidelity 120 and HDCIS strategies create virtual channels and the mechanisms used to improve frequency resolution
* **HiRes** creates virtual channels by steering current between electrodes, resulting in a physical virtual stimulation site between electrodes.
**“Physical”**
* **HDCIS** creates virtual spectral channels by using overlapping frequency filters during signal processing. This results in closely timed, sequential stimulation of adjacent electrodes, which the brain interprets as an intermediate pitch between the two.
**“Perceptual”**
35
Monopolar stimulation
* The ground electrode is placed under the temporalis muscle (outside the cochlea).
* When current is sent to an electrode inside the cochlea, it flows through all tissue between it and the ground electrode. What it flows through determines impedance, due to attenuation from body tissues.
* Result: Wide spread of current → less focused stimulation.
36
Bipolar stimulation
* The ground electrode is an electrode on the electrode array (inside cochlea)
* Uses two electrodes within the cochlea—one as active and one as ground.
* Current flows only between these two electrodes, stimulating a smaller area and allow for more selective stimulation
* has not proven useful and is rarely employed.
* Result: More focused, selective stimulation → but not commonly used due to poor outcomes.
37
Differences between monopolar and bipolar stimulation
Monopolar (MP):
* Ground Outside cochlea
* Broad (through many tissues)
* Selectivity Less selective
* Commonly used
Bipolar (BP):
* Ground Inside cochlea (another electrode)
* Narrow (limited between two electrodes)
* More selective
* Rarely used (not very effective)
38
What Influence does middle ear status have on implant function?
Active Middle ear effusion may delay cochlear implant surgery and has been reportedly associtaed with reduced hearing during episodes of Otitis media or negative middle ear pressure.
39
Reasons for Preference for scala tympani as the site for electrode array insertion.
Take advantage of the **place-to-frequency coding mechanism** used by the normal cochlea.
Scala tympani over the scala vestibuli becuase...
* Larger diameter accommodates the electrode array better
* Allows insertion below the fragile cochlear duct and in close proximity to the SG cell bodies
* Closer proximity to the round window during surgical insertion
* Less intracochlear trauma and better preservation of residual hearing
* Leads to better implantation outcomes and reduced postoperative vertigo
40
Why the Scala tympani has been favored over the scala vestibuli to accommodate the intracochlear electrodes?
* **Larger Diameter**
* Allows **insertion below cochlear duct & close to SG Cell Bodies**
* Closer to **Round window** during insertion
* **Less intraccohlear trauma** & better preservation of resiudual hearing
* **better outcomes** & reduced post op vertigo
41
What is the Rationale for using charge-balanced biphasic pulses in CI stimulation?
* Each pulse is equal-sized negative and positive phases, **designed to deliver no net charge through the electrode at the end of the pulse**
* This charge balancing avoids the accumulation of charge that could produce toxic tissue reactions
42
What charge balancing avoids the accumulation of charge that could produce toxic tissue reactions?
**Charge-balanced biphasic pulses** in CI stimulation
* each pulse is equal-sized negative and positive phases designed to deliver no net charge through the electrode at the end of the pulse
* This charge balancing avoids the accumulation of charge that could produce toxic tissue reactions
43
# Limits of CI's
Limitations of cochlear implants in replicating natural hearing
Phase locking & what it does
* Cochlear nerve fibers fire at the same point in each sound wave cycle, but due to their refractory period, individual fibers cannot respond to every cycle, so groups of fibers collectively encode sound frequency and pitch up to about 4000 Hz.
44
what are the Limitations of cochlear implants in replicating natural hearing?
CI's do not replicate
* Spontaneous firing rate:
* Phase Locking
* Stochasticity
45
# Limits of CI's
Limitations of cochlear implants in replicating natural hearing
Spontaneous firing rate & what it does
Spontaneous firing rate
* Spontaneous activity helps **maintain sensitivity and supports coding across a wide dynamic range**. - CIs do not do this
46
# Limits of CI's
Limitations of cochlear implants in replicating natural hearing
Spontaneous firing rate & what it does
Spontaneous firing rate
* Spontaneous activity helps **maintain sensitivity and supports coding across a wide dynamic range**. - CIs do not do this
47
# Limits of CI
Limitations of cochlear implants in replicating natural hearing
Stochasticity & what it does
* Random but phase-related firing of individual cochlear nerve fibers.
* This randomness across fibers allows neighboring groups to collectively encode the temporal structure, frequency, intensity, and duration of sounds through the volley principle, **enhancing the auditory system's ability to represent complex acoustic signals**.
48
# True or false
New CI's are successful because multichannel CIs can replicate the spectral analysis that occurs in the cochlea.
FALSE
Success of CI is surprising because even multichannel CIs cannot replicate the spectral analysis that occurs in the cochlea.
* CIs bypass the frequency selectivity of the basilar membrane and replace it by a more coarse division of the audible spectrum.
* CI do not replicate Spontaneous firing rate, Phase locking and Stochasticity
49
What are the different Surgical approaches used to access the scala tympani?
1. Basal turn cochleostomy
2. Round window membrane
3. Extended Round Window cochleostomy
50
Describe the Cochleostomy surgical approach
| SP to access the scala tympani for CI
* **drilling through the promontory** directly into the basal turn of the scala tympani - avoiding the hook area of the most proximal basal turn
* Correct placement of the cochleostomy is critical for avoiding damage to inner ear structures.
* An attempt should be made to limit the amount of bone dust within the cochlea to prevent new bone formation.
51
Describe the Round Window surgical approach
| SP to access the scala tympani for CI
* RWM is partly hidden behind a ridge from the promontory, which limits visability of RWM during surgery.
* The facial recss is used in posterior tympanotomy to impant array
* major boundaries of the FR are the facial nerve (FN) and chorda tympani (CT)
52
What is the Facial Recess ?
| SP to access the scala tympani for CI
FR is triangular space created by drilling between:
* chorda tympani anteriorly
* facial nerve posteriorly
* incus superiorly
identify the facial nerve but not to expose it.
It is usually possible to spare the chorda tympani.
* used as entrance for RWM electrode insertion
53
Comparison of cochlear arrow trajectory between RW and extended RW approaches
* In the RW approach, the membrane's orientation directs the electrode **upward, inward, and forward**.
* The crista semilunaris further **pushes it toward the osseous spiral** lamina.
* To ensure smooth entry into the scala tympani, surgeons **drill part** of the **posterior round window lip and crista semilunaris.**
54
What is Soft surgery?
Soft surgery refers to cochlear implantation techniques designed to **minimize intracochlear trauma, preserve residual hearing**, and **optimize electrode placement** within the ST relative to SGNs.
55
Goals of soft surgery approach and its role in preserving residual hearing
Goal is to reduce disruption to delicate cochlear structures such as the **basilar membrane, osseous spiral lamina, and modiolar wall**.
It focuses on
* Preventing blood and bone dust entry
* Using steroids
* Careful surgical site selection
* Minimizing perilymph leakage and suctioning
* Controlling insertion depth
56
soft surgery approach It focuses on what?
* Preventing blood and bone dust entry
* Using steroids
* Careful surgical site selection
* Minimizing perilymph leakage and suctioning
* Controlling insertion depth
57
Early complications following CI surgery
* **Facial N Injury**: FN Palsy or paralysis
* **Alteration of Taste**: metallic taste
* **Infection**: Bacterial meningitis
* **Dizziness**: tinnitus or vertigo
* **Wound dehiscence / Flap necrosis** aggressive thinning of flap - Most serious compication & Requires device removal.
* **Early device failure**
* **CSF leak (gusher)**: CSF leak in CI
58
Late Complications
following CI surgery
* Extrusion / Exposure of Device
* Displacement of electrodes
* Late device failure
* Otitis media
* Meningitis
59
# True or false
Cochlear implantation recipients are at high risk of developing Pneumococcal Meningitis.
TRUE
It is can be a late complication post implantation
60
Two types of electrode misplacement
* Lateral Wall Trauma
* Osseous Lamina Fracture
61
Impact of electrode misplacement on implant outcomes
* Lateral Wall Trauma
One of the **most commonly** reported types of insertional damage
.
Lateral wall trauma may occur in several ways
* When the basilar membrane is involved, often torn at lateral wall & can cause **penetration of the electrode into scala media.**
62
Impact of electrode misplacement on implant outcomes
* Osseous Lamina Fracture
* Osseous lamina fracture would sever the dendrites of spiral ganglion cells eventually leading to **ganglion cell degeneration in the affected area.**
63
Soft Failure
* Slow Decline
* Uncommon
* declining performance, aversive symptoms such as a popping or shocking sensation or intermittent function
* only be confirmed by removal,examination & identification
64
Solution for soft failure
Reimplantation with another device
* Relief of symptoms following reimplantation of a new device strongly supports the diagnosis.
65
Hard Failure
* Device Malfunction
* easily confirmed with the available assessment tools
* Symptoms: ↓Hearing performance & integrity testing shows malfunction
66
66
67
68
What impedance is
Electrode impedance is a measure of the **opposition to electrical current flow across an electrode when a certain voltage is applied**
* Opposition to flow
69
clinical purpose of impedance in cochlear implants
* Idenify electrode failure
* Verification of voltage compliance
* Monitor electrode function
* Evaluate intraoperative to post op changes
* Changes across follow ups
70
Definitions, causes, and identification of Open Circuits
**Definition**: incomplete path for current to flow, or a discontinuous circuit.
**Causes**:
* Broken electrode contact
* Broken lead wire
* ossification/buildup
* air bubble
**Impedance**
* HIGH
* 30+ kohms
71
Definitions, causes, and identification or short circuit
**Definition**: low resistance between two points in a circuit that differ in potential which typically are separated by higher resistance → increase in current flow
**Causes**:
* kinked or curled array
* Excessive distortion or tension on the electrode array.
* Electrode lead wires that are touching within the electrode carrier due to damaged insulation.
**Impedance**
* Low
* less than 1 (0 or 0.5)
72
Definitions, causes, and identification
Partial short circuit
**Definition**: relatively low resistance resulting in increased current flow, but still higher impedance for a true short circuit.
**Causes**:
* small tears or fractures in the silicone surrounding the electrode
**Impedance**
* Low
* altering the impedance
* zigzag pattern
73
Impedance of >30 kohms indicates what?
**Open circuit**
* Broken electrode contact
* Broken lead wire
* ossification/buildup
* air bubble
74
Low and alternating impedances indicate what
Partial short circuit
* small tears or fractures in the silicone
75
excessively low impedance; >1 (0 or 0.5)
Short circuit
* kinked or curled array
* Excessive distortion or tension on the electrode array.
* Electrode lead wires that are touching within the electrode carrier due to damaged insulation.
76
Short and Open circuit management
* **disabled** but re-evaluated after a period of implant use.
*
77
# True or false.
Electrode impedances are often high at initial activation but usually decrease with electrical stimulation.
TRUE
Due to accumilation around electrode away
78
Partial short circuit management
may or may not be disabled, depending on the **extent** to which **performance is affected**
79
CIs have constant current determined in the software, and the amount of voltage (coming from the battery) changes based on the ____ what?
CIs have constant current determined in the software, and the amount of voltage (coming from the battery) changes based on the **impedance of the electrode.**
80
What is voltage compliance
The **voltage is limited by the battery** - this is called voltage compliance
* Using a battery with higher voltage capacity can help avoid reaching the compliance limit. 0 once you reach compliance limit - you cannot increase any more.
81
The maximum amount of electrical current available to stimulate an electrode contact is determined by what law:
Ohm’s law
Voltage (V) = Current (I) X Resistance (R)
82
If a recipient uses a map with electrodes that are “out of voltage compliance” what happens?
* Speech recognition and sound quality may be reduced.
* Loudness may be unbalanced across the electrode array.
* The user may experience non-auditory effects, such as facial nerve stimulation, due to maximum current amplitude.
83
Expected/normal impedance fluctuations
* Impedance lowest at the time of surgery
* After surgery impedance increases due to inflammation
* Steroid use during surgical insertion
reduce fibrous tissue growth and lower impedance.
* Once the implant is stimulated, impedance typically decreases over time.
* Impedances should remain stable one to three months post-activation
84
Impedances should remain stable ___ to ___ months post-activation
Impedances should remain stable **1** to **3** months post-activation
85
Factors affecting impedance measurements...
* **electrode contact**
* **electrode lead that is coupled to the contact**
* **Surrounding medium**, including:
Cochlear fluids
Surrounding tissues
Electrolytes
Macrophages
Proteins
86
Purpose of electrode conditioning
EC is presentation of low-level current to each electrode to remove air bubbles, protein buildup, and so forth.
87
When is electrode conditioning is typically used?
* Prior to testing in the operating room
* At initial activation
* At a programming session preceded by a prolonged period of nonuse
* When activating electrodes were previously disabled and reactivated
87
Names of the clinical programming software used by the three manufacturers
* Cochlear: Custom Sound
* Advanced Bionics: SoundWave
* MED-EL: Maestro
88
programming software for cochlear
Custom Sound
89
programming software for AB
Sound Wave
90
programming software for MED-EL
Maestro
91
What is Input Dynamic Range (IDR)?
range of acoustic inputs that are mapped to the user's electrical Dynamic range
92
Lower IDR is what
Lower IDR → Threshold of electrical stimulation.
93
Upper IDR is what?
Upper IDR → maximum electrical stimulation level
94
the lower end of the IDR usually is set to what?
lower end = 20 to 30 dB SPL
95
upper end of the IDR is set to what?
Upper end = 65 to 85 dB SPL
96
Typical IDR effect of sensitivity settings on soft sound audibility
* Controls the microphone gain in the sound processor.
* Adjusts the input signal level before frequency analysis.
* Works to shape how acoustic signals are mapped into the user’s electrical DR.
* ↑ sensitivity allows softer sounds to be included in the mapped input range, while ↓ sensitivity excludes lower-level sounds.
97
Frequency allocation table controls what?
Frequency allocation table controls **how frequencies are delivered across the active channels**.
98
Frequency allocation tables; how disabling electrodes changes the frequency-to-electrode assignment
* They can also choose from four frequency allocation tables based on different psychoacoustic models.
* Current methods include anatomy-based assignment.
* **If an electrode is turned off, its frequencies are reallocated to remaining active electrodes**.
99
# True or false
Optimal stimulation rate can vary across individuals
TRUE
100
Effect of stimulation rate on temporal resolution
**High stimulation rates improve access to fine temporal details in sound. =** Enhanced temporal resolution
* Better speech understanding in noise
* Improved music perception and appreciation
* Recognition of vocal pitch
* Potential for improved pitch perception
101
Effect of stimulation rate on pitch perception
**Higher rates can result in a higher pitch perception** and increase loudness due to temporal summation.
102
Effect of stimulation rate on loudness,
**Higher rates** can result in a higher pitch percept and **increase loudness due to temporal summation.**
103
Electrode spacing may influence a recipient’s performance with higher stimulation rates at higher rates...
Closer spacing increases the risk of temporal channel interaction, which can degrade performance.
104
# True or false
It most important to select a magnet strength that is sufficient to prevent the transmitting coil from repeatedly falling off of the recipient’s head.
FALSE
* It is important to select a magnet strength so the transmitting coil does not repeatedly falling off of the recipient’s head.
* It is **more important that the magnet strength is not too great because excessive adherence of the coil may compromise circulation to the skin underneath the coil.**
105
Prolonged excessive magnet strength may cause __ ___under the coil, potentially leading to skin flap breakdown and requiring reimplantation.
Prolonged excessive magnet strength may cause **skin necrosis** under the coil, potentially leading to skin flap breakdown and requiring reimplantation.
106
# Determining appropriate magnet strength
Middle-aged males and obese recipients need what magnet strength?
Middle-aged males and obese recipients may require **stronger magnet strength due to thicker skin flaps.**
107
# Determining appropriate magnet strength
Young children and elderly women often need what magnet strength?
Young children and elderly women often need **weaker magnet strength due to thin skin flaps.**
108
How minimum stimulation levels are defined by AB
Advanced Bionics: lowest amount of electrical stimulation a user can detect with 50% accuracy; T levels. Can be locked to 10% of the DR.
* **Threshold → T Level**
109
How minimum stimulation levels are defined by cochlear
Cochlear: the minimum amount of electrical stimulation the recipient can detect 100% of the time; T levels.
* **little Above Threshold → T Level**
110
How minimum stimulation levels are defined by MED-EL
MED-EL: highest level at which a response is not obtained; THR. Can be locked to 10% of the DR.
* **right below Threshold →THR**
111
How upper stimulation levels are defined by AB
Advanced Bionics: most comfortable; M levels
112
How upper stimulation levels are defined by MED-EL
MED-EL: very loud but comfortable; MCL
113
How upper stimulation levels are defined by Cochlear
Cochlear: loud, C levels
114
Setting threshold level
* Start with LF electrode; give them an audible sound and then ascend to find the threshold.
* Used to prevent the t tail
* Use larger steps early on, and smaller steps for fine tuning after a week.
115
List Setting threshold level Approaches
* Traditional threshold measurement techniques (modified Hughson-Wastlake)
* Count-the-beep method
* Psychophysical loudness scaling
* Threshold estimation
116
Approaches for Setting upper stimulation levels
* Psychophysical loudness scaling
* Global increase in upper stimulation levels while the user listens to speech
117
Setting upper stimulation levels
w/ Psychophysical loudness scaling
* Pt is asked to indicate the loudness percept of the stimulus by pointing to a loudness scale chart.
* Clinicians gradually increase the level of the programming stimulus until the pt reports that it is comfortably loud.
| Like MCL's on Audio
118
Setting upper stimulation levels
w/ Global increase in upper stimulation levels while the user listens to speech
* Upper stimulation levels will be set where speech and environmental sounds are most comfortable.
119
C levels are critically important for what?
* Preventing sounds in the environment from being uncomfortably loud.
* Supporting speech recognition and sound quality
* Enabling prelingually deafened children to monitor their own voice and develop intelligible speech
120
negative consequences to Improperly programmed T levels can lead to
* too low, the recipient will **not have adequate audibility** of low-level or soft sounds.
* too high (i.e., above the real threshold), the recipient may experience **excessive ambient noise** and a reduced electrical dynamic range.
121
negative consequences to Improperly programmed upper stimulation levels
* Discomfort
* Poor speech recognition
* Reduced overall sound quality
* An aversive reaction to CI
* Poor overall outcomes, especially in children relying on auditory feedback for speech development
122
Loudness balancing aims to what?
Loudness balancing aims to ensure **equal loudness at upper-stimulation levels in order to optimize speech recognition and sound quality** by maintaining the typical loudness/intensity relationship that exists for different phonemes.
123
Three objectives are associated with electrode sweeping:
* Measuring sound quality
* Determining appropriate pitch transitions
* Confirming equal loudness across all channels
124
Loudness Balancing Procedure
* upper-stimulation level for two channels at a time.
* begins with the most apical (lows/inside) channel and progresses toward the more basal (high)
* PT attend to loudness and not the pitch
* adjustment to stimu level **always** should be to the **second electrode**
125
If recipients have a difficult time tolerating high-frequency how do you conduct loudness balancing?
For recipients who have a difficult time tolerating high-frequency stimuli, conduct from **high to low frequencies**.
Basal → Apical
126
Sweeping involves the sequential presentation of the programming stimulus across ___ electrode contacts in the array, starting from __ to __
Sweeping involves the sequential presentation of the programming stimulus across **all** electrode contacts in the array, starting from **lows** to **highs**
127
Loudness Balancing Clinical Use
* Sweeping- depends on your purpose
* Loudness balancing, sound quality & speech understanding.
To make sure the frequencies are balanced
Pitch & comfort
128
Name & Goal of the anatomy-based fitting by MED-EL
**Otoplan**
Goal: To **reduce spectral mismatch through imaging.**
* Identify where each electrode contact is
* Use that information to apply a place-specific map with individualized center frequencies for each contact that is a closer match to the natural frequency-place.
129
Approaches used to manage non-auditory stimulation in CI patients
1. Try lowering the amplitude
2. Increase the pulse width
3. Turn off Electrode
* Cochlear → monopolar to bipolar: more focused and reaches less neurons
* MED-EL → triphasic stimulation: disperses the current between two reference electrodes instead of just one.
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Evaluate progress for Optimization Phase
* Up to one month: Informal speech perception measures
* One to three months: CNC words in the implanted ear and in the everyday listening condition.
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Optimizing the map during the Optimization Phase
**Sweeping**
* levels have been set sweep at the upper-stimulation level
* detect any channel-specific undesirable effects such as loudness discomfort or a non-auditory response
**Loudness balancing**
* Loudness balancing should be completed whenever possible after setting upper-stimulation levels in live speech mode.
* loudness balancing around 6 to 7 years - youngest
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Patient should be able to what during the Optimization Phase?
* map allows gives to access quiet spoken language while not exceeding levels of comfort.
* wear consistently min of 10 hours per day.
* hear ≤ 30 dB HL
* hear to at least 30 feet away
* able to tolerate loud sounds
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Child may smile, vocalize, or seem pleased with the sound
Positive response pattern at activation
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How does a patient move from Optimization to the
Maintenance phase
Patients enter the maintenance phase when ...
* SF thresholds better than 30 dB.
* 10 hours +/ day with data logs.
* Post-operative CNC word score in the implanted ear is 56% or better; OR. the patient’s scores in the implanted ear have improved by at least 20% when compared to scores obtained in that ear prior to implantation
If the patient has not yet met these milestones or if other concerns exist, they can remain in the optimization phase for further support.
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What to expect during Maintenance phase
* SF thresholds better than 30 dB.
* 10 hours +/ day with data logs.
* Post-operative CNC word score in the implanted ear is 56% or better; OR. the patient’s scores in the implanted ear have improved by at least 20% when compared to scores obtained in that ear prior to implantation
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List the three typical response patterns children may show at activation
positive, neutral, or distressed
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no visible response, even when sound is clearly audible.
Neutral or non observable reaction response patterns
at activation
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* The child may cry, remove the device, or seek comfort.
* This is often due to sudden exposure to a new sensory input
Negative: Upset or distressed response pattern
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Importance of full time device use in young children and why easing into wear time is not appropriate
* Early auditory input is a neurodevelopmental emergency — the **brain requires consistent sound exposure to develop speech and language pathways**.
* Missing input during this critical period can **cause irreversible delays in auditory and spoken language development.**
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Missing input during this childs critical period can cause ___ delays in __ and __ __ development
Missing input during this critical period can cause **irreversible** delays in **auditory** and **spoken language** development
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Techniques used to estimating upper-stimulation levels in young children
* Psychophysical loudness scaling
* Global adjustment in live speech
* Flat MAP
* Flat MAP with fine tuning
* Estimation from objective measures
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Estimation from objective measures
* Using play behavior to guide upper-stimulation level settings
* In live speech it may be helpful for children to play with noise makers.
* **Child Plays with toys = Level too low**
* **Child Stops Playing = uncomfortable level, too loud**
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Flat MAP with fine tuning
* begin with a flat MAP or global increase from T levels and then fine-tune based on the recipient’s feedback.
* Upper-stimulation levels are refined to improve sound quality and comfort based on the user’s feedback.
Advantages: has the advantage of possibly improving sound quality and recipient performance
Limitations: Loudness may still be uneven across electrodes
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Flat MAP
* Start with flat stimulation levels (T + C), initially inaudible to the child.
* live speech mode, gradually increase stimulation
* Identify the level where the child first responds to sound—this is used to set T Levels.
* Continue increasing upper-stimulation levels while observing the child’s responses to sounds until desired loudness is achieved.
* Levels should reflect a typical electrical DR for the implant being used.
* Advantages: Quick and easy to implement during live speech mapping and can serve as a starting point for programming in difficult cases or with limited time.
* Limitations: Using the same intensity across all channels may result in uneven loudness perception.
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Global adjustment in live speech
“Building From the Floor” Approach
* Programming begins by measuring minimal electrical detection levels.
* Upper-stimulation levels are then globally increased from the T Level profile using live speech mode.
* Clinicians observe the child’s behavior for signs of discomfort or overstimulation
* If the child shows signs of distress, programming should be immediately stopped and levels adjusted to ensure comfort.
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Psychophysical loudness scaling
* Used primarily with older children (8–9 years and up) and adults
* Present pulsed electrical signals to individual electrode(s), increasing loudness gradually until patient reports to sound is loud.
* Procedure is repeated across multiple electrodes to determine frequency-specific levels.
* Advantages: help identify if a child is struggling to access sounds in a specific frequency range or finds a certain channel aversive.
* Limitation: Requires consistent reliable responses
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Reasons to avoid routine increases in upper-stimulation levels in children without a clear evidence of under stimulation
* Routine increases can lead to stimulation levels that exceed those used by adults
* Overstimulation could hinder long-term auditory performance
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Recommended follow-up schedule for pediatric CI users
First year of device use:
Initial activation: 1–4 weeks
1 week post initial activation
2 months post initial activation
3 months post initial activation
6 months post initial activation
9 months post initial activation
12 months post initial activation
After the first year
* every 3 mos if not reliable
* Every 6 to 12 mos if reliable
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ESRT: Electrically -Evoked Stapedial Reflex Threshold
* contraction of the stapedial muscle in response to intense electrical stimulation from the cochlear implant.
* Objective and quick to administer
* Preferable methods for setting upper-stimulation levels in children as precise loudness scaling and balancing are often unreliable before age 8.
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ESRT Procedure
* Place an acoustic immittance probe (reader) into contralateral ear to the CI
* Record acoustic admittance while presenting stimulus to the implant in an ascending manner.
* Decrease Stimulation levels to avoid loudness discomfort before activating the sound processor in live speech mode.
* Gradually increase the upper-stimulation levels while monitoring.
Adjust levels until optimal loudness and sound quality are achieved.
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ESRT Clinical Applications
* ESRT for predicting upper-stimulation levels
* ESRT is within an average of 9 clinical units of upper-stimulation levels
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Relation between levels estimated using ESRT procedures and behavioral levels across manufacturers
ESRT is lower than levels set by behavioral measures, making it a safer starting point.
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ESRT limitations
* **middle ear anomalie**s may interfere w/obtaining a measurable response.
* If a contralateral ESRT is not measurable, testing may be attempted in the ipsilateral ear.
* ESRT measurements may be more **problematic** to measure in **bilaterally implanted** recipients because both ears have undergone surgery.
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How ESRT can be used to identify overstimulation in children who are unable to provide reliable feedback
Electrical Stimulation Threshold needs to be **at or below your ESRT but you are never above**
* If they are way above red line = over stimulation
* Below Red line = lots Under stimulation
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What EABR is and how it differs from ECAP and acoustic ABR, and its clinical applications
EABR is a neurophysiological test measuring auditory brainstem activity in response to electrical stimulation from a CI.
* EABR is recorded from scalp electrodes in response to electrical stimulation from the cochlear implant.
* Reflects synchronous firing of neurons in the auditory brainstem.
* Waves III and V are typically present, with wave V being most prominent.
* **No latency shift**
* Waves are generated in the pons and midbrain regions.
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EABR VS ABR
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Why is EABR not as commonly used anymore?
We do not need EABR when **telemetry** is present in CI’s because the function and responsiveness is already determined though impedance or ESRT’s
* Telemetry: communication between the implant and the hardware; radiofrequency
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Clinical use of EABR
* confirm implant function or auditory responsiveness in recipients without telemetry systems.
* With the development of telemetry and ECAP, the routine clinical use of EABR has declined.
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ECAP: Electrically-Evoked Compound Action Potential
synchronous response from electrically stimulated auditory nerve fibers. (ECochg)
* neural response from the distal cochlear nerve fibers and/or spiral ganglion cell bodies of the cochlear nerve.
* ECAP give you upper and low levels
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ECAP: Electrically-Evoked Compound Action Potential in the manufactures
* ART (MED-EL),
* NRI (AB),
* **NRT (Cochlear)**
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ECAP's origin
* Spiral Ganglion Neurons are the most likely generator of the ECAP.
* A neural response from the distal cochlear nerve fibers and/or spiral ganglion cell bodies of the cochlear nerve.
* (ECochg)
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ECAP's morphology
ECAP is recorded as a negative peak (N1) at about 0.2 - 0.4 ms following stimulus onset, followed by a much smaller positive peak (P2) or plateau occurring at about 0.6 - 0.8 ms.
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ECAP's properties, and the general stimulation and recording setup
ECAP is essentially the electrical version of Wave I of the ABR with
Greater amplitude
Shorter latency
No myogenic artifact
Unaffected by sleep and anesthesia.
No need for sedation when measured in children.
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The three major limitations of ECAP recordings
* **Current source saturation**: greater distance results in lower voltage.
* **Poor reference contact**: Poor contacts = high impedance = recording more difficult andartifacts bigger.
* **Stimulation artifact**
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ECAP threshold is measured on all active intracochlear electrode contacts
Off-set method:
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ECAP threshold is measured for every intracochlear electrode contacts
Live Speech method
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The three different types of measurements that can be obtained using ECAP recording
**Amplitude to growth function**: measuring with ECAP threshold
**Refractory function**
**Spread of excitation**: Overlap between two electrode
* Further = less excitation
* Closer = more excitation
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Auditory Brainstem Implant (ABI):
Surgically implanted device that directly stimulates the cochlear nucleus of the brainstem.
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Two hypotheses for ABI differences in performance:
Difference in speech understanding between CI and ABI is caused by the
* **ABI bypassing or distorting activation of specialized neural circuitry** occurring in the CN.
* ABI does not make selective contact with the tonotopic dimension of the CN which limits the number of independent channels of spectral information.
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# *
Current FDA-approved indications for ABI
Inclusions (must meet both):
1. At least 12 years of age or older who have neurofibromatosis Type II
2. Who are rendered deaf due to bilateral resection of neurofibromas of the auditory nerve
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FDA primary contraindications for ABI
* Children without NF2
* Anatomy Factors
* Physiological factors
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Related risks for ABI
* Standard surgical risk
* Meningitis (risk with all neurosurgery)
* CSF leak
* Unsuccessful hearing enhancement
* Unknown long-term effects of electrical stimulation
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two main surgical approaches used for ABI placement
Translabyrinthine
&
Retrosigmoid approach:
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# ABI surgical approache
Involves removal of the mastoid bone behind the auricle as well as the semicircular canals of the inner ear.
Translabyrinthine approach:
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# ABI surgical approache
Desirable because it provides good visualization of the lateral recess of the fourth ventricle and the facial nerve and does not require retraction of the cerebellum.
Translabyrinthine approach:
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# ABI surgical approache
Eliminates the possibility of preserving residual hearing.
Translabyrinthine approach
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# ABI surgical approache
Requires retraction of the cerebellum and does not provide complete visualization of the facial nerve.
Retrosigmoid approach
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# ABI surgical approache
Less invasive, enables removal of skull-based tumors provide improved visualization of the cochlear nerve.
Retrosigmoid approach
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# ABI surgical approache
Involves an incision made behind the auricle and accessing the brainstem and cerebellum through a small opening that is made near the base of the skull.
Retrosigmoid approach
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Why use EABR during ABI placement?
* Confirms stimulation from the electrode array activates the auditory brainstem pathway, as reflected in the eABR waveforms
* Assists in optimizing electrode placement by confirming effective stimulation of the CN
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Challenges in electrode array placement
* The full surface of the CN is not visible during surgery
* No clear anatomical landmarks
* Anatomical variations between patients
* Removal of large tumor can distort surrounding anatomy
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How non-auditory sensations are managed by the programming audiologist.
If minor, the following adjustments should be considered:
* Reduce current level
* Increase the Pulse Width of the electrical pulse
* Change the electrode coupling mode to avoid the non auditory side effect.
* Reduce pulse rate
* If current level reduction does not help, the affected electrodes should be disabled.
Non-auditory sensations often decrease over time
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Types of non-auditory sensations patients may experience during device programming
* Auditory perception
* Tinnitus or ringing sensation
* Other sensations (e.g., paresthesias, vertigo, dizziness)
* Any combination of auditory and non-auditory effects
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Factors that influence ABI outcome
**Placement of the device & anatomy**
* Motivation to hear - Commitment to rehabilitation
* Psychological readiness
* Acceptance of device limitations
* Anatomical status
* Family and support system
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Persistent inflammation following electrode insertion trauma during cochlear implantation can result in what?
* **Development of fibrosis and calcification**
* Immediate inflammation is normal but if persists the inflammatory response will become subacute and pass into a chronic phase. Development of fibrosis and calcification and even new bone formation.
