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Otology & Neurotology > Amplification & Implant Otology > Flashcards

Amplification & Implant Otology Flashcards

1
Q

Label the parts of a traditional hearing aid

A
  1. Microphone
  2. Computer processor
  3. Amplifier
  4. Speaker/receiver
  5. Battery

https://www.theeardepot.com/wp-content/uploads/2021/02/HA-Parts.jpg

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2
Q

List all the different types of wearable hearing aids and label them

A
  1. Body aid (obsolete)
  2. Eyeglass aid (obsolete)
  3. Behind the Ear (BTE)
  4. Receiver in the Canal
  5. In-the-ear
  6. In-the-canal
  7. Completely-in-canal
  8. Invisible-in-canal
  9. CROS (Contralateral routing of signal)
  10. BiCROS
  11. Trans-cranial CROS
  12. Bone conduction headband
  13. VORP (Vibrating ossicular replacement prosthesis)

Vancouver 260

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3
Q

Discuss the difference between Behind the Ear (BTE) hearing aids and Receiver in-the-canal Hearing aids.

How are they different?
What are the different types of each?

A

BEHIND THE EAR (BTE):
- Microphone and the receiver/speaker are both in the body of the hearing aid sitting behind the ear.
- The receiver is connected to the ear canal through one of the two options:
1. Occluded fitting: Tubing connects receiver to a mold sitting in the ear canal
2. Open fitting: Tubing alone (without mold occluding the canal

RECEIVER IN THE CANAL
- Microphone is separated from the receiver/speaker which sits in the canal
- Options:
1. In the Ear
2. In the Canal
3. Complete in the canal
4. Invisible in the canal

Vancouver 260

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4
Q

Differentiate CROS, BiCROS, Transcranial CROS

A

CROS: Contralateral routing of signal
- Microphone on deaf side routes signal to contralateral good side, which has normal hearing
- No amplification function

BiCROS: Bilateral CROS
- Used for asymmetric bilateral hearing loss present with an unaidable side
- Good side has an amplifier which will amplify signals from the unaidable side (different than CROS because there is no amplifier for CROS)

Transcranial CROS
- High output in-the-ear or behind-the-ear device on unaidable side with a deep fit in bony EAC to allow for mechanical coupling and transmission through bone to the other side

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5
Q

How does a VORP (Vibrating ossicular replacement prosthesis) work?

A
  • Middle ear implant fixed to the ossicular chain or round window

Indications:
1. CHL/SNHL/Mixed hearing loss with SDS > 50% and < 65dB HL at 500Hz
2. Mild to severe SNHL

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6
Q

What is feedback in the context of hearing aids? Which type of hearing aid does this occur with more?

A
  • Feedback is a function of any sound system
  • Occurs when sound that travels through a microphone to speakers is continuously picked up by the microphone and re-amplified
  • In hearing aids: sound leaks from the receiver back to the microphone, the microphone will continuously re-amplify the sound –> creates a feedback loop and leads to hearing aid feedback problems
  • Manifests as a high-pitched, unwanted squeal or whistle
  • In smaller hearing aids, the microphone and receiver are much closer to each other compared to larger aids, therefore more feedback
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7
Q

Describe the Occlusion effect of hearing aids.
What frequency is more troublesome?
How can this effect be mitigated?

A
  • Occlusion effect = sensation of increased loudness (sound pressure level), especially in low frequencies that a person experiences to self-generated sounds (talking, chewing, swallowing, walking, etc) when their ears are covered/occluded.
  • Theory is that transmission of the signal goes through the middle ear and to the cochlea (effect does not occur with middle ear pathology) - whereas normally sound escapes
  • Occurs with larger hearing aids that block the EAC

Results:
- Shifts the resonance frequency lower, which increases low frequency gain
- Troublesome in people with normal low frequency hearing

Improved with:
- Smaller hearing aids
- Venting (a bore made in an earmold or in-the-ear. Hearing aid that permits the passage of sound and air into otherwise blocked ear canal)

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8
Q

What are the advantages and disadvantages of open fit hearing aids? 4 each

A

ADVANTAGES:
1. Reduced occlusion effect
2. Improved own-voice perception and sound quality
3. Better localization of sound
4. Less otitis externa or cerumen impaction

DISADVANTAGES:
1. Increased feedback
2. Reduced benefits of directional microphones
3. Less noise reduction by hearing aid
4. Less sound compression by hearing aid

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9
Q

What are 5 advantages of larger hearing aids?

A
  1. Better power for amplifying severe hearing losses
  2. Larger battery means better power supply
  3. Better for people with lower dexterity
  4. Less feedback - mic further from speaker
  5. Allow placement of directional microphone
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10
Q

What are 2 disadvantages of larger hearing aids?

A
  1. Poor cosmesis
  2. Occlusion effect
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11
Q

What are 4 advantages of smaller hearing aids?

A
  1. Better cosmesis
  2. Better for less severe hearing losses
  3. Uses pinna anatomy for natural amplification (high frequencies)
  4. Reduced occlusion effect
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12
Q

What are 4 disadvantages of smaller hearing aids?

A
  1. Limited amplification, so for less severe hearing losses
  2. Increased feedback (mic and speaker closer)
  3. Requires better dexterity
  4. More fragile and expensive
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13
Q

Five reasons for feedback in hearing aids

A
  1. Wax
  2. High gain/over amplification
  3. Internal malfunction (e.g. cracked tubing)
  4. Poor fit/leak - large vent
  5. Small hearing aids (mic too close to the speaker

WHIPS

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14
Q

Things to do to a hearing aid mold to decrease low frequency gain in patients with high frequency SNHL 2

A
  1. Open venting - allow low frequency sounds to escape
  2. Enlarge the sound bore
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15
Q

What are the advantages of binaural hearing aid use? List 5

A
  1. Improved sound localization (microphone placed closely to each middle ear)
  2. Elimination of head shadow effect (which normally reduces high-frequency cues necessary for hearing consonants)
  3. Increased loudness (binaural summation)
  4. Release of masking (binaural squelch) - helps tune out unwanted noise, improves speech intelligibility in noise due to phase differences of signal and noise
  5. Avoidance of sensory deprivation in children
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16
Q

What is the definition of functional or serviceable hearing?

A

Definition: Hearing “worthy of preservation”, or hearing that can still be “amplified” and functional. Unserviceable hearing can’t really use hearing aid because can’t really amplify since it’s not really functional at all (would just be amplifying un-functional-ness.

ie. if they don’t meet criteria then its “unserviceable”

SERVICEABLE “50-50 rule”:
1. Speech Recognition Threshold (SRT) or PTA < 50dB
2. Speech Discrimination Score (SDS) > 50%

Alternative uses better hearing cut-offs “70-30 rule”:
1. SRT or PTA < 30dB
2. SDS > 70%

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17
Q

What is the WHO (2006), AAO-HNS (1995), Gardner-Robertson (1988) Hearing classification scales?

A

WHO (2006):
I. SDS 70-100%
II: SDS 50-69%
III: SDS 1-49%
IV: None

AAO-HNSF Scale:
1. Class A: Discrimination 70-100%; PTA < 30dB
2. Class B: Discrimination 50-69%; PTA 31-50dB
3. Class C: Discrimination 50-69%; PTA >50dB (serviceable hearing)
4. Class D: Discrimination < 50%; any PTA
5. Most clinicians consider Class A and B/C to be useable or serviceable hearing; Class D not considered serviceable hearing.

Gardner-Robertson:
1. Class I (good): Discrimination 70-100%, PTA < 30dB
2. Class II (serviceable): Discrimination > 50-69%; PTA 31-50dB
3. Class III (non-serviceable): Discrimination 5-49%, PTA 51-90dB
4. Class IV (poor): Discrimination 1-4%, PTA > 91dB
5. Class V (none): Discrimination 0%, PTA None

Note: Serviceable hearing is really only used to describe VS or Menieres, in order to determine whether a hearing preservation approach should be used (if serviceable) or not

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18
Q

What hearing aids allows use of concha bowl and pinna?

A
  1. In-the-canal (ITC)
  2. Completely in canal (CIC)
  3. Open fit BTE
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19
Q

What are the options for management of single sided deafness?

A
  1. CROS or BiCROS
  2. Technologies that offer bone stimulation without surgery
    - Trans-ear hearing aid (HA that sits inside the bony ear canal and vibrates the skull - investigational)
    - Head band
    - ADHEAR Bone anchored hearing system (adhesive tape)
  3. Bone anchored technology (e.g. BAHA)
  4. Cochlear implant
  5. Patient education
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20
Q

What does a CROS hearing aid stand for? When is it used?

A

CROS: Contralateral routing of sound

Indications for use:
- Unilateral un-aidable hearing loss, with the other ear having normal or nearly normal hearing that does not require amplification
- The sound from non-aidable ear is routed to the normal side

Gives some similarities in binaural hearing (can’t locate sound, but less head shadow effect)

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21
Q

What does a BiCROS hearing aid stand for? When is it used?

A

BiCROS = Bilateral Contralateral Routing of sound

Indications for use:
- Asymmetric bilateral hearing loss, such that one ear has no functional hearing or loss too great to benefit from amplification (unaidable), and the other ear is aidable (better hearing ear)
- The sound from the un-aided ear is routed to the better ear, which the sounds on that ear are all amplified

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22
Q

Define sound attenuation

A

Loss of auditory sensitivity

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23
Q

Define sound distortion

A

Sound is heard sufficiently loud, but is of poor quality

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24
Q

Define Peak Clipping for hearing aids

A

Output was limited at a predetermined level (in a linear amplification system)

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25
Q

What are 4 circuitry options for hearing aids?

A

Ways to program hearing aids to meet the needs of each user

  1. Compression Circuitry: Limits output within the dynamic range of the user in a non-linear fashion - Boosts the gain of low-intensity sounds so they are audible, but limits the gain of high-intensity sounds so they are not uncomfortable
  2. Linear amplification: Ratio of input to output (ie. gain) always remains one - same amount of gain added regardless of sound intensity; uses peak clipping; distortion is a problem at higher frequencies
  3. Noise-reduction circuitry - available in most modern hearing aids to reduce unwanted background noise in an effort to improve patient comfort and speech recognition.
  4. Feedback suppression Circuitry - the hearing aid recognizes the occurrence of feedback based on frequency, intensity, and temporal characteristics. It then reduces amplification in the offending frequency range to reduce feedback, uses phase cancellation of the feedback signal, or shifts frequency slightly to de-correlate the input and output of the device to eliminate audible feedback
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26
Q

What does Dynamic Range mean in Audiology?

A

Dynamic range is a term used to describe the decibel (dB) difference between the level of a person’s threshold of hearing sensitivity and the level that causes discomfort.

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27
Q

What are the different types of hearing aid technology?

A
  1. Analog: acoustic signal converted by microphone into electric energy
    - Disadvantages: Large, required higher powered batteries
  2. Digital Signal Processing: acoustic signal converted to electrical energy and back to acoustic signal
    - Modern, better shaping, sophisticated compression algorithms, feedback reductions, and noise-reduction algorithms
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28
Q

What are 6 advantages of modern digital hearing aids?

A
  1. More flexible programming strategies
  2. Multiple programs for different listening environments
  3. Useful for unusual hearing loss configurations
  4. Anti-feedback mechanisms
  5. Improved sound quality
  6. Higher fidelity (no internal noise for circuitry)
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29
Q

What are typical problems with standard hearing aids overall? 6

A

“Hearing Aid FORD”
- Hearing level (not enough amplification)
- Appearance
- Feedback
- Occlusion
- Range
- Distortion

  1. Insufficient gain (amplification)
    - Hard to get the adequate level of gain/amplification needed for severe to profound HL
    - Smaller traditional hearing aids usually means less gain
  2. Poor appearance
  3. Acoustic feedback (which can limit the large amount of gain needed!)… may not be able to get to max gain due to feedback
    - Worse when microphone is closer to speaker (CIC aids)
    - Bad with mastoid cavities
  4. Occlusion effects
    - Most HA’s fitted as tightly in canal as possible to reduce feedback (so speaker is isolated in canal)
    - But there are problems with occluding canal (ie. Pressure discomfort, OE, blocks out normal sounds) - “occlusion effect”
  5. Distortion of spectral shape and phase shifts
    - Most HAs are limited to a certain frequency range (500-2000 hz)
    - Lacks treble and bass, so things sound artificial
    - Because of this, not great for certain types of HL (ie. Presbycusis or ototoxicity.. high freq… or Menieres.. low freq) –> may end up over amplifying the middle normal hearing range in a patient
  6. Non-linear distortion (loud sounds often causes distortion)
  7. Poor transduction efficiency
30
Q

What are microphone options for hearing aids?

A
  1. Directional
    - MIcrophone that picks up sound more from one direction more than others
    - Better in environments with greater background noise
  2. Omnidirectional
    - Microphone that picks up sound from all directions
    - Better in quiet environments

In some instruments, the directionality feature is activated manually by the patient. In most instruments, it can be activated automatically and adaptively, so that the directionality is activated when the hearing aid senses background noise, and the amount of directionality changes based on the extent of the noise.

31
Q

What are some considerations for fitting kids with hearing aids? 3

A
  1. Continued ear growth, altering the gain and output (resonance changes)
  2. Correction factor for SLP for the smaller canal (15-20dB higher in kids)
  3. Resonant frequency of infant canals is much higher (7200 vs. 2700 Hz)
  4. Pinna and canal reach adult size at 9 years
32
Q

What are 3 ANSI (American national Standards Institute) measures in the electroacoustic assessment of hearing aids?

A

Definition: GAIN
- Gain is the amount of energy added to the input signal (Difference in output of a hearing aid relative to its input, measured in decibels)
- Amount of gain varies as a function of frequency to accommodate varying hearing loss configurations.
- Gain = output SPL - input SPL
- Linear amplification = same gain throughout; non-linear amplification = different gain depending on sound intensity level

MEASURES:
1. Full-on gain (maximum volume)
- Amount of amplification when volume is in the maximum position
- Can be measured in/based on the high frequencies average of gain (1K, 1600, 2500 Hz) –> “High frequency full on gain” or “high frequency average”

  1. Reference test gain (HFA = OSPL90 - 17dB)
    - Amount of amplification when the volume is adjusted such that the average gain at 1K, 1600, and 2500 Hz is 17dB below the OSPL90
    - OSPL90: Maximum amount of amplification of a hearing aid with an input of 90dB
  2. Use Gain
    - Gain measured when volume is in its normal use position
  3. Frequency response
    - Gain of a hearing aid at a given frequency
    - Range of frequencies intersected by a line drawn at 20dB below the HFA calculated in the reference test gain
33
Q

Discuss the signal to noise ratio in audiology and hearing amplification

A

SNR

  • Sound intensity in relation to background noise
  • Estimation of operating gain needed for appropriate aid
  • Usually ~1/2 gain rule (gain needed = 1/2 threshold loss at that frequency)
34
Q

What are the clinical indication for a bone-anchored-hearing-aid? 7

A
  1. Intolerance to wearing convenital hearing aids (e.g. chronic dermatitis of EAC, chronic otorrhea from COM or chronic mastoiditis, mastoid cavity (feedback) )
  2. Inability to wear conventional hearing aids (e.g. Congenital malformations of the external and middle ear - microtia/atresia/syndromic/sporadic
  3. T21, Treacher collins, Goldenhar
  4. Unilateral dead ear ± CHL in only hearing ear
  5. Fourth option in otosclerosis
  6. Age > 4
  7. Tolerated a trial of softband (pediatrics)
35
Q

What are the 3 general types of bone-anchored hearing aids currently available (2019) and what are the exampels of each?

A

A. PERCUTANEOUS (Traditional)
- Implant/fixture + abutment + external sound processor (contains microphone, speech processor, vibrating component)
- ACTIVELY vibrates the skull to which it is directly attached
- Options:
(1) Cochlear BAHA connect (± power)
(2) Oticon Ponto (± power)

B. TRANSCUTANEOUS, PASSIVE BONE CONDUCTION
- Transcutaneous = processor is attached to the implant by a magnet that conducts through the skin
- PASSIVE means sound transmitted through bone, but not being actively moved (this does not allow for much amplification)
- Options:
(1) Cochlear BAHA Attract: Implant (osteo-integrated) + magnet + external sound processor
(2) Medtronic Sophono: Implant screwed into skull, not osteointegrated (ie. the implant itself isn’t in the bone, just screwed to the bone with screws)

C. TRANSCUTANEOUS, ACTIVE BONE CONDUCTION
- Active means implant sits within a well, has an integrated vibrator that vibrates the skull directly (can allow for higher amplification)
- Options:
(1) MED EI Bone bridge
(2) BCI (Oticon)
(3) Cochlear Osia

Vancouver Pg 263

36
Q

What is the ideal implant site for BAHAs look like? 3

A
  1. Thin skin (can be thinned, or STSG)
  2. Hairless
  3. Non-modbile (for adhesive-ness)
37
Q

How do you select which type of bone anchored hearing aid to use?

A
  1. Pure conductive loss (ABG should be at least 30dB PTA for patient to benefit)
    - Transcutaneous, passive deices (cochlear BAHA attract, medtronic sophono)
  2. Mixed/SNHL hearing loss with bone conduction < 45 dB
    - Transcutaneous, active devices (MedEI Bone bridge)
    - Percutaneous (Oticon Ponto, BAHA connect)
  3. Mixed/SNHL hearing loss with bone conduction < 55dB
    - Percutaneous powered devices (BAHA connect power, Oticon Pro Power)
38
Q

Is MRI safe with BAHA?

A

Yes, implant is titanium (non-ferrous)
- May create imaging artifact
- External process IS ferrour - REMOVE!

39
Q

What are the audiometry requirements for a BAHA? 4

A
  1. If conductive, ABG ≥ 30dB
  2. If mixed/conductive HL, PTA BC < 45dB (or 55dB for BAHA Power); with SDS > 60%
  3. If singls sided deafness, air conduction PTA < 20dB in good ear
40
Q

What are the contraindications of BAHA?

A
  1. Age < 5 years old
  2. Bone thickness < 4mm
  3. PTA BC thresholds (500-3000Hz) > 45 dB HL (> 55dB if using BAHA power)
  4. HL, SDS < 60%
41
Q

What are the possible complications of a BAHA? 6

A

INTRAOPERATIVE:
1. Bone too thin
2. Sigmoid injury
3. Dura injury

WOUND:
1. Infection/granulation
2. Overgrowth over implant
3. Frostbite
4. STSG failure
5. Failure of osseointegration
6. Keratin build up

POST-OPERATIVE:
1. Extrusion (trauma)

42
Q

Name five assistive listening devices for patients with hearing loss

A

“C FLAT”

C: Closed caption decoder
F: FM Radio
L: Laser/infrared
A: Alarm (visual or vibratory)
T: Telephone amplifer

43
Q

Name the components of a cochlear implant 6

A
  1. Microphone
  2. External processor
  3. External transmitter
  4. Magnet
  5. Internal receiver/stimulator
  6. Electrode array
44
Q

What are the current companies that manufacture cochlear implants?

A
  1. Advanced bionics
  2. Cochlear
  3. MedEI
  4. Oticon
45
Q

What are the important components of consent for a cochlear implantation

A

EARLY POST-OPERATIVE
1. Anesthesia
2. Local injury (sigmoid sinus bleeding, tegmen injury, CSF leak, facial nerve injury, SCC injury/vertigo)

INTERMEDIATE POST-OPERATIVE
1. Infection (e.g. local infection, meningitis)
2. Extrusion of implant

LATE POST-OPERATIVE
1. Extrusion
2. Failure

OTHER:
1. Cost
2. Battery life
3. Device choice
4. Committed to follow up
5. Vaccinations

46
Q

What are the cochlear implantation criteria for adults?

A
  • Implant criteria varies by region (ie. money in each region)
  • Important to remember that most hearing loss is caused by hair cell loss and not complete 8th nerve loss. This means that most ears CAN be stimulated

ADULT CRITERIA IN ONTARIO:
1. 18 years of age or older
2. Moderate to severe/profound hearing loss with limited benefit from optimally fit amplification (BC criteria - Bilateral moderate (> 40dB in low frequencies)
to profound SNHL)
3. Obtain limited or no benefit from well-fitted traditional amplification
4. Spoken language as a primary mode of communication
5. No medical contraindications
6. Strong motivation and commitment
7. Realistic expectations of the cochlear implant
8. BC Criteria additionally: Best aided AzBio Speech perception score - Ear to be implanted ≤50%, Non-implanted ear ≤60%

47
Q

What are the indications for a hearing-in-noise test (HINT)? 4

A
  1. Assessment of CI candidacy
  2. Auditory Neuropathy Spectrum Disorder (ANSD)
  3. Central auditory processing disorder (CAPD)
  4. Hidden hearing loss
48
Q

What are the Cochlear Implantation Criteria for adults according to the AAO-HNS?

A
  1. Age of 18 or older
  2. Bilateral, moderate to profound SNHL (ie. ≥40dB PTA at 500, 1000, and 2000Hz)
  3. Limited benefit from an adequately fitted binaural hearing aid; OR
  4. Best aided HINT or CUNY (City University of New York) tests (speech recognition criteria)
    - ≤ 50% sentences in the ear to be implanted
    - ≤ 60% bilaterally or in opposite ear (contralateral ear, best aided condition)
49
Q

Give expanding indications for adult cochlear implantation 6

A
  1. Bilateral moderate to profound SNHL
  2. Asymmetric HL - Bilateral SNHL who meet traditional criteria for one but not both ears (traditional criteria: bilateral severe to profound SNHL when there is little to no benefit from hearing aids)
  3. Single sided deafness (SSD)
  4. Significant residual hearing (e.g. “Ski slope” SNHL, for electro-acoustic stimulation (EAS))
  5. Tinnitus as a primary symptom in patient with single sided deafness
  6. Geriatric patients, such as above age 80 years
50
Q

What are the factors that affect cochlear implantation success? 4

A
  1. Otologic history (e.g. AOM, COM, cholesteatoma, TM perforation)
  2. Pre-lingual vs. post-lingual deafness (prelingual - earlier the implantation, the better to ensure neural plasticity - smaller window of opportunity)
  3. Amplification status (has the patient worn hearing aids before?)
  4. Length of time single loss of hearing
51
Q

What are 6 patient factors in post-lingual deafness for adults that are predictive of good outcomes post-CI?

A
  1. Short duration since deafness
  2. Use of amplification prior to implant
  3. Motivation to use implant
  4. Uses other forms of communication
  5. Cognitively normal
  6. No comorbidities

“SAMCON”
- Short duration of deafness
- Amplification previously tried
- Motivated
- Cognitively normal
- Other modes of communication used (continues to communicate)
- No comorbidities

52
Q

What are factors to help decide which side to implant in an adult? 3

A
  1. Length of auditory deprivation time
  2. If one ear is still receiving benefit from a hearing aid, implant the unaidable ear
  3. If one ear has never responded to auditory stimuli, implant the opposite ear
53
Q

What are the required immunizations prior to CI?

A
  1. Hemophilus influenza B vaccine
  2. Pneumococcal vaccination series should be completed at least 2 weeks before surgery
    - Age 5 and 64 - PPV 23 (pneumococcal polysaccharide)
54
Q

What are the absolute contraindications for cochlear implantation, based on temporal bone imaging? 4

A
  1. Complete otic capsule aplasia (Michel’s aplasia)
  2. Narrow IAC syndrome (< 3mm wide with normal facial nerve function - suggests that CNVII is the one that is absent since FN normal)
  3. Complete ossification of the cochlea
  4. Absent or surgically resected CNVIII
55
Q

What are the relative contraindications to cochlear implantation in adults? 6

A
  1. TM perforation
  2. Chronic serous otitis media
  3. Mastoid cavity - needs to be obliterated first
  4. Prelingually deaf adults
  5. Deaf ear, never aided
  6. Not medically fit for surgery
56
Q

What are the considerations for a Cochlear implantation in a malformed ear?

A
  1. Acknowledge the risks - increase risk of injury to local structures, adjusted outcomes expectations
  2. Role of imaging
  3. Modified electrode arrays
  4. Extra procedures may be needed (e.g. atresia repair, etc.)

Auricular atresia: expect the normal canal to be more anterior and superior

57
Q

Discuss the concept of “soft surgical technique” for cochlear implantation, and what measures are thought to be important? Name 6

A

Principle of “soft surgery” = limit trauma to the inner ear

SURGICAL APPROACH:
1. Preload with IV steroid
2. RW vs. cochleostomy
3. Minimal drilling, reduce drill speed
4. Avoid unnecessary suction
5. Avoid intracochlear debris, bleeding, or bone dust
6. Intratympanic/intraoperative steroids

ELECTRODE DESIGN:
1. Soft tipped, thin, noodle-like electrodes
2. Increased awareness of the variability in cochlear length and the perils of over-insertion

FUTURE DEVELOPMENTS (intracochlear therapy)
1. Biopolymer electrodes with capacity for drug elution

58
Q

Discuss hearing preservation in cochlear implantation. What are the main goals?
What are 3 main benefits of EAS?

A

Hearing preservation in cochlear insertion = electrodes that preserve low frequency hearing (short electrode)

GOALS: Allows for acoustic and electrical stimulation
- Acoustic amplification of low frequencies (hearing aid)
- Electrical amplification of high frequencies (implant)

BENEFITS:
1. Improved speech perception in noise
2. Improved sound quality (music and pitch discrimination, interval perception, song recognition)
3. Improvement of quality of life

59
Q

Discuss electric acoustic stimulation (Hybrid CI)

A
  • EAS is intended for people with high-frequency hearing loss, who can hear low-pitched sounds but not high-pitched ones
  • Hearing preservation CI allows for EAS (electric acoustic stimulation)

EAS = A type of CI that electrically stimulates mid-high frequencies, while (attached to) a conventional hearing aid acoustically amplifies the residual low frequencies

60
Q

What are the indications for electric acoustic stimulation? 7

A
  1. Severe to profound SNHL bilaterally above 1.5 khz
  2. Normal to moderate SNHL below 1.5 khz
  3. Others:
    - Monosyllabic word score < 60%
    - No ME disease
    - A-B gap < 10-15 dB
    - Less than 20 dB difference between ears
    - Need to prove benefit with HA
    - No evidence of retrocochlear reasons
61
Q

What layer is a cochlear implant typically placed into, and why? 4

A

SCALA TYMPANI:
1. Accessible
2. More robust
3. Closer to nerve cells/basilar membrane
4. Least gtraumatic to residual cochlear structures
5. Less vestibular symptoms

62
Q

What are 4 different routes to insert the electrode into cochlea (insertion techniques)?

A
  1. Round window insertion
  2. Standard cochleostomy (anterior-inferior to round window)
  3. Proximal basal turn drill-out
  4. Scala vestibuli insertion with anterior superior cochleostomy
  5. Middle turn insertion
63
Q

What are 11 complications of cochlear implantation?

A

INTRAOPERATIVE COMPLICATIONS:
1. General Anesthesia
2. Partial implant insertion
3. Perilymph gusher
4. Traumatic implantation
5. Bleeding

EARLY POSTOPERATIVE:
1. Cross stimulation of CNVII
2. Leak (CSF or perilymph)
3. Infection (wound, flap necrosis, or meningitis)
4. Tinnitus/Vertigo

LATE POSTOPERATIVE:
1. Device failure
2. Extrusion

64
Q

What are 7 factors that increase risk of meningitis following cochlear implantation?

A

“HEARS BAD”

H: ‘Hot ear’ - ie. Signs of inflammation at time. of implant
E: ‘Ear infection’ - ie. Otitis media prior to implantation
A: ‘Aplasia’ - ie. Inner ear malformation
R: ‘Recalled’ - ie. Implant positioner (model of implant that was recalled in 2002, which included a space-occupying “positioner” with the electrode)
S: Smoking in the household

B: Brain leak - ie. CSF leak
A: ‘All the way in?’ - ie. Incomplete electrode insertion
D: ‘Drain’ - ie. history of VP shunt

  1. Implant Positioner
  2. History of VP shunt
  3. Incomplete electrode insertion
  4. Smoking in the household
  5. Inner ear malformation or CSF leak
  6. Otitis media prior to implantation
  7. Signs of inflammation at the time of implant
65
Q

What are the indications for CI explantation?

A
  1. Device failure
  2. Migration/extrusion of the electrode
  3. Infection/wound complications, such as:
    - Wound abscess
    - Infected implant
    - Labyrinthine infection
    - Mastoiditis (some can be treated conservatively with antibiotics as the implant forms a fibrous seal around itself that is a barrier to infection even in the presence of mastoiditis)
    - Skin necrosis
  4. Poor outcome:
    - Non-user of device due to lack of benefit
    - Patient’s request for implant removal
    - Progression of pathology that leads to device not being beneficial
66
Q

What is the risk if the electrode of a CI becomes extruded?

A

Given the inflammation, risk that the cochlea ossifies and cannot re-implant.

Therefore when doing an explant if a device is not working or eroded through the skin for example, leave the electrode IN until you are about to re-implant (so not to risk any chance of fibrosis of the cochlea)

67
Q

What should be done for patients with a CI that may need an MRI?

A
  • Recommendation for MRI vary by model
  • Most makers recommend removing the magnet (in the OR) from the implant for MRI scanner with > 1.5 tesla
  • If not removing the magnet, the head has to be wrapped in a tensor
  • New CI’s are compatible with up to 3.5T MRI

Model “6” Cochlear brands usually MRI compatible

68
Q

What are some complications of not removing a CI before a child goes into an MRI machine? 5

A
  1. Device movement (vibration, force or torque - causing skin or tissue trauma)
  2. Implant heating
  3. Damage to device
  4. Weakening of implant magnet
  5. Image artifact (worse with a magnet)

There is a removable magnet inside the implant magnet pocket

Vancouver Pg 267

69
Q

Discuss the management of dealing with cautery and cochlear implants 3

A

NOT OK:
1. DO NOT use monopolar cautery above the clavicles
2. NO bipolar cautery within 1cm of electrodes
3. Contraindications:
- Electroconvulsive therapy
- Diathermy using electromagnetic radiation neurostimulation (for neuropathy) or ionizing radiation therapy over the implant

“OK” ish
- Limited use of monopolar below the clavicle is okay
There are recent animal studies that have shown no adverse effects, however no human studies exist

70
Q

Regarding auditory brainstem implants, discuss:
1. When are they typically used?
2. How are they accessed?
3. Outcome?

A
  • Generally used for NF2 where the 8th nerve has been surgically sectioned
  • Access: foramen of Lushka, lateral recess via 4th ventricle, ventral cochlear nucleus stimulated along its lateral medial axis
  • Tonotopic organization preserved at brain stem level
  • Outcome: 85% perceptable audio

Otology & Neurotology (17 decks)

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