The document provides an overview of cochlear implants, including their history, components, surgical procedure, candidate selection criteria, and post-operative considerations. It discusses the main components of cochlear implants, how they work to directly stimulate the auditory nerve, and the different implant systems from Cochlear, Advanced Bionics, and Med-El. Important aspects like electrode array design and coding strategies used to transmit sound are also summarized.
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1. COCHLEAR IMPLANT
Dr. Mukesh Kumar Sah
MS (ORL- HNS), 3rd year resident
GMSM Academy of ENT – Head & Neck
Studies
MMC-TUTH, IOM
2. Roadmap
• Background and Introduction
• History of the procedure
• Components, Working Mechanism and Types
• Candidates selection
• Surgical aspect
• Post Operative Issues
• Results
• Bilateral implant
• Recent advances and future development
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
2
3. Background
• Cochlear implantation a routine procedure
worldwide for the management of severe-
to-profound sensorineural hearing loss
• collaboration between engineers,
surgeons, scientists and the medical
community
• more than 5,30,000 recipient till JanuaryDr. Mukesh Kumar Sah, Cochlear
implant/2017
3
4. Introduction
• A cochlear implant is an electronic device,
that bypasses the damaged hair cells of
the cochlea and stimulates the auditory
nerve directly
• Electromechanical transducer
• First true bionic sense organs
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
4
5. Introduction
• Internal device-interfaced with the cochlear
nerve
• External device-uses a specific speech
coding strategy to translate acoustic
information into electric stimulation
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
5
6. History of the procedure
• 1957, Djourno and Eyries -activation of the
auditory nerve with an electrified device
provides auditory stimulation
• 1963, Doyle and Doyle - scala tympani
implantation
• 1972, House- first House/3M single-
channel implant
• 1984- Multichannel devices introduced
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
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7. Pathology
• direct or indirect injury to the organ of Corti
• degeneration or dysfunction of the hair cell
system
• success of cochlear implantation -
surviving spiral ganglion neurons
• number of surviving neurons needed for
successful implantation remains unclear
• 10-70% of the normal 35,000-40,000 cells
(Seyyedi et al., 2014)Dr. Mukesh Kumar Sah, Cochlear
implant/2017
7
8. Pathology
• normally approx 35,000 nerve fibres and
minimum of 10,000 spiral ganglion cells
required for preservation of speech
recognition
(Otte et al., 1978)
• no significant correlation between total
spiral ganglion cells count
(Blamey , 1997)
• no relation with depth of insertion with
performance
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
8
9. Cochlear implant system
1. Cochlear system, --Cochlear Ltd of
Sydney, Australia
2. Med-El system, --Med El of Innsbruck,
Austria
3. Clarion system, --Advanced Bionics of
California, USA
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
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10. Components of Cochlear
Implant
External part
1. Microphone
2. speech Processor
3. Transmitter
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
10
Pic: cochlearworld.com
11. Components of Cochlear
Implant
Internal part
1. Receiver/stimulator
2. Electrode array
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
11
Pic: cochlearworld.com
12. Dr. Mukesh Kumar Sah, Cochlear
implant/2017
12
Pic: cochlearworld.com
13. Types of Cochlear Implants
• Single vs. Multiple channels
- Early implants-one electrode/one channel
- Recent ones-multiple electrodes(22),
multiple channels(4-8)
- Results of multichannel CI better than
single channel
(Waltzman et al.,1993)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
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14. Multichannel cochlear Implants
1. straight,flexible electrode arrays
2. Precoiled
• less traumatic
• focussed
(Gibson et al., 2006)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
14
15. Types of Cochlear Implants
• Monopolar vs. Bipolar
- Monopolar-one ground electrode for all
- Bipolar-ground for each electrode is
adjacent to or few electrode away
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
15
16. Types of array
• Shortened array – deep insertion not
desired/possible e.g. cochlear ossification
• Compressed array- number same,
compact, can be used with cochlear
anomaly
• Split array- 2 separate electrode branches,
different area of cochleaDr. Mukesh Kumar Sah, Cochlear
implant/2017
16
17. Coding Strategy
• Method by which pitch, loudness, timing of
sound are translated into a series of electrical
impulses
Simultaneous
Non-simultaneous
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
17
18. Coding Strategy
Simultaneous
• activation of more than one electrode at
the same time
• Improved speech outcomes, a more
natural quality of sound
• Potential “channel interaction”
• Clarion® (Advanced Bionics Corporation,
Sylmar, Calif.)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
18
19. Coding Strategy
Non-simultaneous
• continuous interleaved sampling (CIS)
strategies stimulate each active electrode
serially
• each electrode stimulates a different
frequency within the cochlea, the cochlea
receives complete information about the
frequency composition of the incoming
signal
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
19
20. Nucleus 24 Cochlear Implant
System
• First to receive FDA approval
• Manufactured by Cochlear Ltd. Australia
• Most widely used
• Implant casing- Titanium
• 24 electrodes(2 ground electrodes)
• 3 speech-processing strategies
• Nucleus Contour electrode array- more
closely approximate the modiolus
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
20
21. Clarion Cochlear Implant
System
• Advanced Bionics, California
• FDA approval for use in adults and children in
1996 and 1997
• Newest version- Hi Resolution (HiRes) Bionic
Ear
• 16 channels of frequency/16 electrodes
• Speech Processing Strategy(CIS, SAS, MPS)
• Only CI capable of simultaneous stimulation of
multiple electrodes within the cochlea
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
21
23. Med-El Combi 40+ Cochlear
Implant System
• FDA approval for use in adults and
children in 2001
• Has longest electrode array
• 24+1 additional ground electrode
• Ceramic casing
• Speech Processing Strategy(CIS, n-of-m)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
23
24. Similarities between the three
CI Systems
• Multichannel stimulation
• Transcutaneous communication
• Integrity of intracochlear electrodes
monitored by telemetry
• Range of speech processsing strategy
• Programming of speech processor
• Cost
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
24
25. Candidate selection
• Initially- Postlingually deaf adults with no
improvement with hearing aids
• Neural plasticity- main factor to influence
candidacy
• Neural plasticity- ability of CNS to be
programmed to learn a task
• For auditory function neural plasticity:6-8
years
• For speech articulation: 2-3 yearsDr. Mukesh Kumar Sah, Cochlear
implant/2017
25
26. Candidacy categories
• Postlingual : acquired speech before becoming
complete deaf
• Prelingual : become complete deaf before
acquiring speech
Primary: No other form of language acquired
Secondary: signs to communicate
Change over candidate: auditory skills using
hearing aid
• Perilingual : deafness acquired during speech
development
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
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27. Post lingual candidates
• Post pubertal groups: excellent candidate
– No gross articulation changes even over prolonged
periods of deafness
– Errors: Inappropriate loudness, pitch changes, and
loss of intonation
• Prepubertal groups
– Articulations errors
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
27
28. Peri-lingual candidates
• Deafness at 2-4 years, lose memory of speech
within few months of deafness
• Difficulties similar to pre-lingual
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
28
29. Pre-lingual
• Primary Candidate: As early as possible,
teach the child to hear and speak( auditory
verbal techniques )
• Secondary candidate: Unlikely to get any
significant improvement in speech
intelligibility
• Change over candidate:
Excellent implantees
Auditory system primed
Neural plasticity remainsDr. Mukesh Kumar Sah, Cochlear
implant/2017
29
30. Adult selection criteria
• B/L severe or profound SNHL with PTA
>70dB HL
• Use of appropriately fitting hearing aids
• Aided scores on open-set sentence tests
of <50%
• < 50% correct responses to HINT
sentences in quiet
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
30
31. Adult selection criteria contd…
• No evidence of central auditory lesions or
lack of an auditory nerve
• Psychologically suitable
• No anatomic contraindications
• Medically not contraindicated
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
31
32. Paediatric selection criteria
• 12 months or older
• Bilateral severe-to-profound SNHL with
PTA of 90 dB or greater in better ear
• No appreciable benefit with hearing aids
(parent survey when <5 yr or 30% or less
on sentence recognition when >5 yr)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
32
33. Paediatric selection criteria
contd…
• Must be able to tolerate wearing hearing
aids and show some aided ability
• Enrolled in aural/oral education program
• No medical or anatomic contraindications
• Motivated parents
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
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34. Ear selection
• In earliest days of CI, worse ear chosen -
implantation destroys residual hearing
• Currently, better hearing ear (High residual
neural elements)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
34
35. Ear selection contd…
• Duration of deafness
• Previous procedure
• Vestibular function
• Hearing aid beneficial on the contralateral
ear:
If neither ear can continue to use a hearing aid,
then better ear or the ear recently deafened is
chosen
If either ear can continue to use a hearing aid
equally well, we choose the ear to implant on the
basis of handedness, patient preference, orDr. Mukesh Kumar Sah, Cochlear
implant/2017
35
36. Ear selection contd…
• CNS activation: functional MRI, and
refined cortical auditory electrophysiology
(Roland et al.,2001)
• Physical Characteristics: cochlea and the
auditory nerve, prior surgical procedures
(e.g., canal-wall-down mastoidectomy),
facial nerve anomalies, and chronic otitis
media
• All things being equal -right ear: possible
advantage of contralateral left-hemisphere
specialization for speech recognition
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
36
38. COM and Cochlear implant
• dry tympanic membrane perforation: first
stage myringoplasty followed by
implantation in 3 months
• cholesteatoma or an unstable mastoid
cavity: radical mastoidectomy and
obliteration followed months later by a
second-stage cochlear implantation
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
38
39. Pre-operative evaluations
• Clinical otological evaluation
• Audiologic exam with binaural
amplification
• CT scan/MRI of temporal bones
• Trial of high-powered hearing aids
• Psychological evaluation
• Blood tests and medical evaluation
• Any necessary tests to discover etiology of
hearing loss Dr. Mukesh Kumar Sah, Cochlear
implant/2017
39
40. Pre-operative preparation at our
centre
• Pre-op investigations
PTA
Tympanometry
OAE
ABR
Aided threshold
HRCT of temporal bone (cochlea, facial
recess)
MRI inner ear (IAM, auditory nerve, facialDr. Mukesh Kumar Sah, Cochlear
implant/2017
40
41. Pre-operative preparation at our
centre contd…
• Hearing aid/ Speech Therapy- Better
started 2 months prior to surgery
• Vaccinations- Pneumococcus,
Haemophilus, Meningococcus, Hepatitis B
• Admission 1 day prior
• Antibiotics
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
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43. Surgical procedure
• Prophylactic antibiotics, about 1.5-3 hours
• GA, supine with head turned to opposite
side
• Procedure
– Incision and skin flap
– Bony seat for receiver/stimulator
- Mastoidectomy(Drill facial recess)
– Cochleostomy for electrode insertion
- Secure receiver/stimulator with sutures
– Pack with fascia and close incision
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
43
48. Middle cranial fossa approach
• Colletti and colleagues
• Alternative to the transmastoid approach
• Deeper penetration with more extended
coverage of the length of the cochlear duct
• Avoid ossification limited to the basal turn of
the cochlea, the most common area of
ossification
• More risk associated, needs further study
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
48
49. Special Surgical Considerations
Cochlear dysplasia
• Less severe form- results excellent
• Michel’s deformity- contraindicated
• Possibility of facial nerve anomaly
• CSF gusher esp. with Large vestibular
aqueduct syndrome
• Tightly pack the electrode at the
cochleostomy with fascia.
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
49
50. Special Surgical Considerations
Cochlear ossification
• Split electrode arrays (Bredberg et al.,1997)
• Extensive drill-out procedure to gain
access to the upper basal turn (Gantz et al.,
1988)
• Insertion of the active electrode into the
scala vestibule (Steenerson et al.,1990)
• Compressed array ; double array can be
used
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
50
51. Early post operative
complications
• Wound infection- 3%
• Wound dehiscence esp. in children
• Postoperative bleeding or hematoma
• Flap necrosis – thin flap, wound infection
• CSF leak – Cochlear dysplasia
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
51
52. Early post operative
complications contd…
• Facial nerve paresis: 1 to 2%, anomalies
common with cochlear dysplasia
• Facial nerve stimulation (7-25%)
• Early Device Failure
• Balance disturbances: <10% patients
resolves within few weeks
• Meningitis: young age, cochlear dysplasia,
temporal bone abnormalities
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
52
53. Late post operative
complications
• Extrusion or exposure of the device:
suture lines as far as possible from the
edge of the implant
• Pain: periosteitis
• Displacement: physical injury
• Non users: secondary prelingual
candidate.
• Late device failure
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
53
54. Postoperative considerations
Device Activation/Hook up
• 2-4 weeks post operatively, when edema
subside
• The implant is connected to the external
component and tuned up
• Determine the stimulation mode: Monopolar,
Bipolar
• Initial programming: threshold level, most
comfortable loudness level, and uncomfortable
loudness level
• Objective methods to assess threshold – NRT,
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
54
55. Postoperative considerations
Switch on
• Switch on is generally done by an
audiologist
• If can hear nothing:
Electrode array is misplaced
No spiral ganglion cell surviving
Young Children recognoizing the response
may be difficult
Device not functioningDr. Mukesh Kumar Sah, Cochlear
implant/2017
55
56. Postoperative considerations
MAPPING
• After switch on
• The map is stimulation threshold and the
maximum comfort level of each electrode
• Can take several months before a stable
map is obtained
• Implant Evoked ABER: can be done prior
to switch on in very young children
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
56
57. Rehabilitation
• Necessary part of implantation
• Multidisciplinary, dedicated group necessary
• Needs differ depending on auditory experience
before deafness
• Prelingual - auditory and speech training
• Postlingual - auditory for complex skills
• Parents play critical role for paediatric patients
• Develop receptive and expressive language
skills
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
57
58. Results of Implantation
• Variability in outcomes primarily due to
patient factors
• Primary goal is improved speech
perception
• Measurement of hearing levels, speech
perception (Open or Closed –set test)
• Postlingual- achieve open-set
discrimination earlier
• Prelingual children continue to improve
over 2-5 yearsDr. Mukesh Kumar Sah, Cochlear
implant/2017
58
59. Factors that affect performance
• Hearing experience (e.g., amount of
residual hearing, length of profound
hearing loss, hearing history for each ear)
• Age at onset of profound hearing loss
(particularly if before the age 3 years)
• Experience with language before onset of
deafness
• Age at implant (particularly if 75 years old
or older)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
59
60. Factors that affect performance
• Status of cochlea
• Cognitive/central abilities
• Motivation to hear
• Communication mode
• Length of cochlear implant use
• Aural/oral education
• Highly motivated patients/parents
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
60
61. Age factor
• <3.5 years regain normal latencies within 6
month. After 7 years, little plasticity
remains
(Sharma et al.,
2002)
• 90% of children implanted <2yr were
integrated into mainstream vs. only 20-
30% if implanted after age 4
(Govaerts et
al.,2002)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
61
62. Age factor
• 54 children <4 years, 82% open-set
discrimination
(Gantz et al., 2002)
• 14 children implanted prior to age 3, followed for
2-5 years, all aspects of hearing improved, oral
language, attended regular school, open-set
discrimination
(Waltzmann et al.,
2002)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
62
63. Device failure
• Causes:
fractures or deformation of the ceramic or
titanium receiver/stimulator cases
failure of the integrated circuit
electrode breakage or short circuiting
• Manifestations:
shocks
intermittency of function
the onset of unusual sounds.
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
63
64. Revision surgery
1. Device failure.
2. Technologically outdated device
3. The device becomes extruded or
exposed. Revision operation may or may not
require
4. The skin flap must be revised, usually
because it is too thick.
5. An additional procedure is being
performed in the area of the implant, for
example, auricular reconstruction
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
64
65. Cost
• In United States, cost range from
US$45,000 to US$125,000 (evaluation,
surgery, device, hospitalization and
rehabilitation)
• Warranty – Implanted components 10yr
and external components 3yr
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
65
66. Bilateral Cochlear Implants
• 1992: 0-1% and 2007: 14-15%
• 70% of bilateral CI usage is among 18
years and under age group
(Source: Cochlear Americas
estimates,2009)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
66
67. Bilateral Cochlear Implants
• Advantages:
Improved hearing in quiet
Improved hearing in noise
Improved sound lateralization
Improved sound localization
Assurance that the “better hearing ear” is
implanted
Qualitative listening improvement (more
“balanced”; “richer quality”; more “confident”
feeling and less fatigued)Dr. Mukesh Kumar Sah, Cochlear
implant/2017
67
68. Bilateral Cochlear Implants
• Disdvantages:
Increased costs (2 devices, batteries, etc.)
Multiple pieces of equipment to manage
Surgical and medical risks
Future developments
No or limited “natural” hearing remaining
Challenge – Different processing strategies &
speech processors (with sequential bilateral CIs)
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
68
69. Follow up
• For Adults:
weekly adjustments of the MAP and
communication therapy for the first month
auditory training, speech, reading, music,
telephone use & communication strategies
• For children:
after the initial 3 month intensive period, every 3
months for the first year and every 6 months for
the second and third years; thereafter, annually
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
69
70. MRI after Cochlear Implantation
• contraindicated -potential for interaction between
the two magnets
• Four possible interactions:
1. movement of the stimulator/receiver or
electrode array,
2. generation of noxious or even injurious auditory
stimuli
3. generation of heat
4. demagnetization
• Nucleus device with a removable magnet
• MED-EL – MRI safe upto 1.5 TDr. Mukesh Kumar Sah, Cochlear
implant/2017
70
71. Recent advances
Combined Electrical and Acoustic
stimulation(EAS)
• patients with more residual hearing
• performance is expected to be better
• Basal end of the cochlea receives electric
signals complemented by acoustic signals
received at the apical portion of the cochlea
• Partial insertion of cochlear implants
• Intraoperative mapping
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
71
72. Combined Electrical and
Acoustic stimulation contd…
• shortened electrode arrays (24 mm for the
MED-EL device, 10 mm for the Nucleus
Hybrid device)
• electrode insertion as atraumatic as
possible
• “Softip” electrode array (Cochlear
Company)
• improved word understanding in noise and
better music appreciation
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
72
73. Future development
• Totally implantable devices
• Remote re-programming
• Delivering drugs or neurotrophic factors to
the cochlea and auditory system through
the intracochlear electrode
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
73
74. Auditory Brainstem Implant
• Deaf patients with damaged or missing
auditory nerve (cochlear nerve agenesis or
excessive ossification)
• ABI has an electrode carrier with 20 small
disc electrodes
• Inserted on to the surface of the cochlear
nucleus in the lateral recess of the fourth
ventricle, accessed through the foramen of
Luschka
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
74
75. Auditory Brainstem Implant
• Correct position of the implant verified by
eliciting EABR
• Outcomes with the ABI are not as good as
typical cochlear implant results
• Awareness of environmental sounds and
enhanced lip reading scores
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
75
76. Issues of deaf culture
Two camps with very different opinions:
There are those who see the CI as a gift and a
miracle that will enhance the quality of life
There are those who see the CI as a threat to
Deaf Culture and as a tool that considers
Deafness as a disability.
Being Deaf is a birth right and not a disability.
A large portion of the Deaf Community sees the
CI as a threat to its very identity.
The implant perpetuates the idea that Deafness
is a disability that should be remediated
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
76
77. Conclusion
Cochlear implants are not experimental
Rehabilitation for severe to profoundly
deaf who doesn’t benefit from
conventional hearing aids
Provide high quality of sensation of
hearing
Further research improves implant
components and implant results
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
77
78. References
• Scott-Brown’s Otolaryngology, Head and Neck Surgery, 7th edition.
2008.
• Glasscock-Shambaugh Surgery of the Ear, 6th edition.2012
• Ear Surgery, W.B. Saunders Co., Philadelphia, 2000.
• Cochlear Implant: A short hand
• http://emedicine.medscape.com/
• http://www.uptodate.com
• https://en.wikipedia.org/wiki
Dr. Mukesh Kumar Sah, Cochlear
implant/2017
78
patients presenting with severe-to-profound deafness have had a direct or indirect injury to the organ of Corti, leading to degeneration or dysfunction of the hair cell system
number of surviving neuron populations needed for successful implantation remains unclear
success of cochlear implantation depends on stimulation of surviving spiral ganglion neurons
(10-70% of the normal 35,000-40,000 cells)
patients presenting with severe-to-profound deafness have had a direct or indirect injury to the organ of Corti, leading to degeneration or dysfunction of the hair cell system
number of surviving neuron populations needed for successful implantation remains unclear
success of cochlear implantation depends on stimulation of surviving spiral ganglion neurons
(10-70% of the normal 35,000-40,000 cells)
Microphone- receives sound from environment
Speech Processor – selectively filters sound, splits sound into channels and sends the electrical sound signals through a thin cable to the transmitter
Transmitter - coil held in position by a magnet, transmit sound signal to the internal device by electromagnetic induction or radio frequency transmission
Internal part
Receiver/stimulator- secured in bone beneath skin, converts signal to electrical impulses
Electrode array- lies within the cochlea
Multiple channel- better sense of speech
Early multichannel CI used straight,flexible electrode arrays which lay against the lateral wall of the cochlea after insertion.
Current electrode arrays are precoiled, allowing the electrodes to be placed closer to the center of the modiolus where spiral ganglion cells are located
Current arrays are designed to be less traumatic. (Patrick, Busby, & Gibson, 2006).
Arrays are also designed to provide a more focused delivery of electric current than earlier devices (Roland, Huang, & Fishman, 2006).
Shortened arrays - when deep insertion is not desired /not possible due to anatomic restrictions(cochlear ossification or cochlear anomaly).
Compressed arrays - same number of electrodes as a standard array, may also be used with cochlear anomalies.
Split arrays - two separate electrode branches designed for insertion into different areas of the cochlea.(Roland et al.,2006)
Presence of the cochlea and the auditory nerve, the degree of dysplasia, the degree of ossification, prior surgical procedures (e.g., canal-wall-down mastoidectomy), facial nerve anomalies, and chronic otitis media
2 to 6 months after obliteration.(Gray,1995)
C, inverted U and hockey-stick incision
Current devices – Flap thickness less than 10 to 12 mm.
Recommended - Thickness not less than 8 mm.
Excessive thinning – Flap necrosis and device exposure
Mastoid exposure
Seat for receiver- replica
The facial recess is bounded by the fossa incudis superiorly, the chorda tympani nerve laterally and anteriorly, and the facial nerve medially and posteriorly. A cochleostomy is created anterior and inferior to the round window
Cortical mastoidectomy, posterior tympanotomy; cochleostomy held
Avoid saucerization. Edges acute - to retain electrode leads.
Facial recess – widely opened, inferior portion – RW niche
Receiver placed in the seat created earlier and fixed
Cochleostomy/round window exposure
; Cochleostomy – just anterior and inferior to the round window membrane.
Cochleostomy somewhat anterior to the anterior attachment of the round window membrane to avoid the “hook” of the cochlea-allows a straighter, more direct insertion of the electrode array into the scala tympani. Cochlea should not be opened until all the drilling has finished to prevent fluid and bone chips entering the duct.
Monopolar cautery turned off. Jeweler's forceps. Placement of electrode and ground electrode
At the first sensation of resistance, insertion should be stopped to avoid trauma to intracochlear structures.
Earlier generations of Clarion devices required a cochleostomy of 2 mm or more. Most currently available devices can be easily inserted through a cochleostomy of between 1.0 and 1.5 mm in diameter
confirmation with NRT-The electrical integrity of the device can be tested by neural response telemetry.(Whole nerve action potentials are recorded from the auditory nerve in response to stimulation of individual electrodes within the cochlea
closure
Split electrode arrays -One electrode is inserted as above and the other array is placed through a second cochleostomy created just anterior to the oval window (Bredberg et al.,1997)
Gantz and colleagues 1988 described an extensive drill-out procedure to gain access to the upper basal turn
Steenerson and co-workers 1990 described insertion of the active electrode into the scala vestibuli -the scala vestibuli is frequently ossified when the scala tympani is completely obliterated
Compressed array ; double array can be used
Early Device Failure: result of factory defects or a consequence of damage during surgical manipulation(discard the monopolar cautery once the implant is brought into the field; hypotympanic air cells are mistaken for scala tympani; not fixed properly) - 3.7% in 900 CI
Early Device Failure: result of factory defects or a consequence of damage during surgical manipulation(discard the monopolar cautery once the implant is brought into the field; hypotympanic air cells are mistaken for scala tympani; not fixed properly) - 3.7% in 900 CI
Clarion implant positioner- Risk of Pneumococcal meningitis > 30 times greater than general population. CDC recommend use of vaccination prior to surgery
Parkins and colleagues criteria for exposed prosthesis:
1. Repair must remove enough skin and cicatrix to avoid suture lines that parallel the implant edge closer than 11/2 cm.
2. A paracranial flap should be rotated to fully cover the device with or without a temporoparietal flap as the initial layer of closure
Late device failure- Do replacement of external components- if no improvement, then CT scan: Displacement to be ruled out- if normal then integrity check by company representative
2-4 weeks post operatively, implant is activated, when edema subsides
Also called as hook –up
The implant is connected to the external component and tuned up
First decision that must be made during the hook-up process is to determine the stimulation mode. Every “channel” requires an active electrode paired with a ground electrode- Bipolar stimulation
Monopolar modes of stimulation - each electrode within the cochlea is grounded to an extracochlear electrode, resulting in wide current spread throughout the cochlea with every stimulation.
Initial programming of the device also requires that the threshold level, most comfortable loudness level, and uncomfortable loudness level be determined for each active electrode
Objective methods to assess threshold – NRT, electrical ABR, stapedial reflex
2-4 weeks post operatively, implant is activated, when edema subsides
Also called as hook –up
The implant is connected to the external component and tuned up
First decision that must be made during the hook-up process is to determine the stimulation mode. Every “channel” requires an active electrode paired with a ground electrode- Bipolar stimulation
Monopolar modes of stimulation - each electrode within the cochlea is grounded to an extracochlear electrode, resulting in wide current spread throughout the cochlea with every stimulation.
Initial programming of the device also requires that the threshold level, most comfortable loudness level, and uncomfortable loudness level be determined for each active electrode
Objective methods to assess threshold – NRT, electrical ABR, stapedial reflex
2-4 weeks post operatively, implant is activated, when edema subsides
Also called as hook –up
The implant is connected to the external component and tuned up
First decision that must be made during the hook-up process is to determine the stimulation mode. Every “channel” requires an active electrode paired with a ground electrode- Bipolar stimulation
Monopolar modes of stimulation - each electrode within the cochlea is grounded to an extracochlear electrode, resulting in wide current spread throughout the cochlea with every stimulation.
Initial programming of the device also requires that the threshold level, most comfortable loudness level, and uncomfortable loudness level be determined for each active electrode
Objective methods to assess threshold – NRT, electrical ABR, stapedial reflex
1.There has been device failure.
2. A technologically outdated device needs to be removed and an updated device inserted.
3. The device becomes extruded or exposed. Revision operation may or may not require explantation and/or reimplantation.
4. The skin flap must be revised, usually because it is too thick.
5. An additional procedure is being performed in the area of the implant, for example, auricular reconstruction
Totally implantable devices that use either an intrinsic power source or implanted batteries that can be recharged remotely through intact skin.
Remote re-programming.
Research is also well advanced into mechanisms for delivering drugs or neurotrophic factors to the cochlea and auditory system through the intracochlear electrode.
Deaf patients with damaged or missing auditory nerve (cochlear nerve agenesis or excessive ossification)
The ABI has an electrode carrier with 20 small disc electrodes
Inserted on to the surface of the cochlear nucleus in the lateral recess of the fourth ventricle, accessed through the foramen of Luschka.
Correct position of the implant verified by eliciting EABR.
Outcomes with the ABI are not as good as typical cochlear implant results. Nevertheless, most patients gained an awareness of environmental sounds and found the ABI enhanced their lip reading scores.
Deaf patients with damaged or missing auditory nerve (cochlear nerve agenesis or excessive ossification)
The ABI has an electrode carrier with 20 small disc electrodes
Inserted on to the surface of the cochlear nucleus in the lateral recess of the fourth ventricle, accessed through the foramen of Luschka.
Correct position of the implant verified by eliciting EABR.
Outcomes with the ABI are not as good as typical cochlear implant results. Nevertheless, most patients gained an awareness of environmental sounds and found the ABI enhanced their lip reading scores.