This slide is all about cochlear implantation concisely. I have depicted the surgical steps by pictures. Enjoy guys.

1. Cochlear Implantation
Dr. UtkalMishra
2nd Yr. PG (ENT)

2. INTRODUCTION
Cochlear implants are the 1st true bionic sense organs.
It is surgically implanted in the inner ear and activated by a device
worn behind the ear.
Cochlear Implants are not hearing aids.
The Fundamental Concept of Cochlear Implant is to bypass the
damaged hair cells.
The device bypasses damaged parts of the auditory system and
directly stimulates the nerve of hearing, allowing individuals who are
profoundly deaf to receive sound.

3. HISTORY
1800 – Alexandro Volta - electrical stimulation to metal rods inserted
in his ear canal created an auditory sensation .
1957 – Djourno & Eyeries – stimulated auditory nerve directly with
current & the patient reported a clear auditory percept.
1961 – House & Doyle – put electrodes in scala tympani of 2
profoundly deaf adults & get a clear auditory response
1972 – First single channel cochlear implant developed.
1984 – Cochlear Corporation introduced the first ever Multichannel
Cochlear Implant System called “NUCLEUS 22”
1976 Wednesday 22 September - The first cochlear implant took
place at Saint-Antoine hospital, Paris. It was performed by
CH Chouard & assisted by Bernard Meyer.

4. PARTS OF COCHLEAR IMPLANT
EXTERNAL PART –
1. Microphone
2. Speech processor
3. Transmitter
INTERNAL PART –
1. Receiver – Stimulator
2. Electrode Array

5. EXTERNAL PART
MICROPHONE
SPEECH PROCESSOR
TRANSMITTER

6. INTERNAL PART
MAGNET
ANTENNA
STIMULATOR
ELECTRODE

7. TYPES OF COCHLEAR IMPLANT
3 Types :-
1. NUCLEUS 24 FREEDOM by Cochlear Corporation
2. HI RES 90K by Advanced Bionics
3. PULSAR by Med El

8. NUCLEUS 24 FREEDOM

9. HI RES 90K

10. MED EL PULSAR

11. COCHLEAR IMPLANT CANDIDATES
Each cochlear implant system is shipped with a
“Physician's Package Insert” which specifies the FDA
labeled indications for implantation.
Since the three cochlear implant manufacturers generally
work independently, the labeled indications for cochlear
implant criteria vary across the companies.

12. ADULT
Age – More than 18 yrs
Bilateral severe to profound Sensorineural hearing loss.
Both Advanced Bionics and Med El - severe-to-profound
Cochlear Corporation - moderate-to-profound
Must be Postlingual Deaf
Little or no benefit from hearing aids.
Inner ears must be surgically able to accept the device
Must not have any chronic illness
A deaf adult who never learned to speak does not benefit from a cochlear
implant.

13. AUDIOMETRIC CRITERIA
Gone are the days when cochlear implantation is done only in
hearing loss above 90 dB

14. SPEECH RECOGNITION
Sentence recognition testing is done in best aided condition at 60 dB
SPL
FDA approved sentence lists used are –
1. BKB – SIN sentences in Noise & Quiet
2. Az -Bio sentences
3. CNC monosyllabic words
Maximum score for cochlear implant candidacy varies
Advanced Bionics – 50 %
Cochlear Corporation – 60 %
Med El – 40 %

15. PEDIATRIC
Age – More than 12 months
Bilateral profound sensorineural hearing loss > 90 dB
No benefit at all with the most optimized hearing aid.
Inner Ear surgically accesible in CT scan
Auditory nerve present in MRI
Post lingual profound deafness caused by meningitis is not a good
candidate for cochlear implant. – neoosteogenesis causing cochlear
duct obliteration.

16. AGE 12 – 24 months
Bilateral profound sensorineural hearing loss
Trial of hearing aids for 3 months - should make at least 3 months of
progress in auditory skills and speech/language development.
The evaluation of auditory skills and progress for children aged birth to 2
years is not achieved by simply looking at the audiogram.
Auditory skills are generally assessed via parental history and administration
of validated questionnaires designed to gauge auditory-based responsiveness to
speech and sounds in a child's environment.

17. QUESTIONNAIRE
IT-MAIS – Infant Toddler version of
meaningful Auditory Integration Scale
(Commonest)
FAPCI - 23-item Functioning after Pediatric
Cochlear Implantation
35-item Little Ears auditory questionnaire
PEACH - Parents' Evaluation of
Aural/Oral Performance in Children

18. OLDER CHILDREN
The determination of cochlear implant candidacy for older children
is generally based upon either mono- or multi-syllabic word
recognition by
Early Speech Perception Test
Multisyllabic Lexical Neighbourhood test
HINT Sentences for children < 30 %

19. WHICH EAR TO IMPLANT
Better hearing ear
Most recently deaf ear
Least obstructed labyrinth
In traumatic hearing loss the ear with reduced labyrinth
function chosen

20. Electroacoustic / Hybrid Implant
Combine a cochlear implant with hearing aid.
Indication – Individuals with profound high frequency loss with
retained low frequency hearing
CI – Stimulates basal turn >> High Frequency
Hearing aid amplifies low frequency

21. DEVICE SELECTION
Aesthetic looks
Coding Strategy
Electrode arrays –
1. Compressed array
2. Double array

22. CODING STRATEGY
A speech coding strategy defines the method by which pitch,
loudness & timing of sound is translated into series of impulses.
2 types –
1. Simultaneous (Only AB)
2. Non simultaneous

23. SIMULTANEOUS STRATEGY
Activation of more than one electrode at same time.
Provide a more natural quality of sound
Only Advanced Bionics is capable of SS.
Disadvantage- When 2 electrodes are activated simultaneously there
is chance of signal interference.
So Modiolus Hugging Electrodes are developed – lies close to
spiral ganglion so less intensity sound is required for activation hence
less interference.

24. MODIOLUS HUGGING ELECTRODE
Self coiling electrode array with
memory.
Comes with a stylete which keeps
the electrode straight during insertion
As it uses low intensity signals –
Extended Battery Life

25. Electrode 1 Electrode 2
Channel
interaction
IncreasedDistance

26. Spiral Ganglion cells
Electrode 1 Electrode 2
Activated CellsActivated Cells

27. PRE-OP EVALUATION
1. AUDIOLOGICAL –
PTA
Speech audiometry
Aided audiometry
BERA
Promontory Stimulation Test
OAE
2. RADIOLOGICAL –
HRCT –
Cochlear Hypoplasia
IAC
MRI –
Early Labyrinthitis Ossificans
Postmeningitic Endocochlear
Obstruction
Absent Cochlear Nerve

28. SURGICAL PROCEDURE

29. CONSIDERATIONS
Can be done as outpatient or inpatient.
Can be done under GA or LA.
IV antibiotics should be given at least 20 minutes before skin
incision.
Surgery duration – 3 -5 hrs
Duration of stay in Hospital – 2 days
3 to 4 weeks later – Programming of device

30. INCISION & SKIN FLAP
Inverted – J shaped incision.
Incision should not cross the edges of
device
Flap elevated in 2 layers
Periosteum of mastoid is elevated as
an anteriorly based Palva flap.
Skin thickness over implanted
stimulator should be less than 6.0 mm

31. THE WELL
A portion of skull as flat as possible selected for the placement of
stimulator minm. 15mm postr. to EAC.
Surgical drill used to create a defect in the skull contoured exactly
to fit the stimulator
A channel is also formed for the passage of electrodes to mastoid
cavity.
Tie down holes are drilled around the well. Dangerous !!!
Device is fixed with sutures in the well.

32. MASTOIDECTOMY
The cavity should not be saucerized.
Edges should be left as acute as possible to retain the electrodes
within its confine.
Facial recess identified & posterior tympanotomy done.
If facial recess seems unusually large – Facial N. anomaly suspected –
Be ready for a cochlear anomaly also !!!

33. COCHLEOSTOMY
Remove the anterior lip of round window niche.
Apply Lubricant – “Healon” or “Provisc”
The electrode array is inserted as atraumatically as possible with its
tip directed inferiorly.
Cochleostomy sealed with a small piece of soft tissue.

34. CLOSURE
Three layered wound closure done –
Palva flap closed tightly with interrupted absorbable sutures
Superficial flap closed with burying interrupted sutures
Skin closed with Subcuticular sutures.

67. POST OP COMPLICATIONS

68. EARLY
Facial N. Injury
Alteration of Taste
Infection
Wound dehiscnce / Flap Necrosis
Early Device Failure
CSF Leak

69. WOUND DEHISCENCE / FLAP NECROSIS
Wound dehiscence occurs commonly in an active child.
If small – leave as such to heal by secondary intension
If large – Secondary closure in OT
Flap Necrosis occurs due to aggressive thining of flap – most
serious complication & require device removal.

70. CSF LEAK
Occurs frequently at the time of drilling tie down holes.
Can also occur after opening of scala tympani in case of – modiolar
defect. / Common cavity deformity. GUSHERS
Controlled by packing the common cavity with muscle.
If still not controlled – Ear is closed by plugging the eustachian tube,
filling the middle ear & mastoid with fat and oversewing the Extn.
Auditory canal.

71. LATE
Extrusion / Exposure of Device
Pain
Displacement of Electrodes
Late device failure
Otitis Media
Meningitis

72. MENINGITIS
Cochlear implantation recipients are at high risk of developing
Pneumococcal Meningitis.
Center for Disease Control made it mandatory for pneumococcal vaccination
as follows -
All children < 1 yr. must receive 3 doses of Pneumococcal Conjugate
(PEVNAR) vaccine.
Cochlear implant child > 2 yr who have received PEVNAR should receive
one dose dose of pneumococcal polysacharide vaccine.
Cochlear Implant child > 5yr should receive one dose of pneumococcal
polysaccharide vaccine.

73. DEVICE ACTIVATION

74. PROCESS
After 3 -4 weeks post op when the wound is well healed implantee
returns to clinic to have the external parts of the device fitted called
“HOOK UP”
There are 2 types of device stimulation modes –
BIPOLAR – each active electrode paired with another
intracochlear electrode.
MONOPOLAR – It is most preferred mode. Paired with
extracochlear electrode.

75. PROCESS
Determination of Threshold level – (minimum) & most comfortable
loudness level (maximum) for each electrode
Then frequency bands are assigned to each electrode pair by software
program.
In prelingually deaf child this process is very complicated so recently
some objective methods are devised like –
Neural Response Telemetry
Stapedial reflex estimation
Electrical ABR

76. Now I am ready to answer
your Questions !!!