Cochlear implants are bionic devices implanted in the inner ear to bypass damaged auditory cells, providing a sense of sound to individuals with profound hearing loss. The technology has evolved significantly since the first implantation in 1976, with various types available and specific criteria for candidacy in both adults and children. Surgical procedures, postoperative care, and potential complications must be carefully managed to ensure successful outcomes.

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 !!!