1. Presented to Bombay Hospital
By Chandra veer singh, 15th
2014
Cochlear Implant
Technology•A cochlear implant is a small, complex electronic device to
restore some hearing in profoundly deaf or severely hard-of
hearing people when organ of corti is not developed or destroyed
by injury to such an extent that no hearing can be obtained by
Hearing Aids.
• In CI bypass damaged hair cells. Convert the acoustic input
signal into electrical impulses to stimulate the auditory nerve
fibers in the cochlea.
• The resulting electrical sound information is sent through the
auditory system to the brain for interpretation.
2. Introduction
• There is an orderly development of auditory
responses in infants between 4 and 16
months
• A normal hearing alert infant will respond in
a predictable manner in accordance to
mental age
• The type of responses obtained are age
specific depending on maturation of the
infant
3. Age 20th
week to at birth
Human cochlea has normal adult function
after 20th
week of gestation
Foetus can hear a mother’s voice, but sound
lacks tone because of attenuated high
frequencies (querleu, Renard, and Crepin, 1981)
At birth, infant have heard sounds for four
months - fluid-borne, but still true hearing.
At birth, infant can discriminate a mother’s
voice and show a preference to that voice
4. Neonatal Hearing
• There is an orderly development of auditory
responses in infants between 4 and 16
months
• A normal hearing alert infant will respond
in a predictable manner in accordance to
mental age
• The type of responses obtained are age
specific depending on maturation of the
infant
7. Cochlear Implants provide auditory
stimulation to children who have hearing
loss
Cochlear Implants take advantage of the
neuroplasticity of the infant brain to “hard
wire” efficient auditory brain pathways
8. Absence of Sound
Neural deficits occur
Brain reorganizes itself to receive input from
other senses, primarily vision
“Cross-modal” reorganization – reduces
auditory neural capacity
9. The Window is Small
Neuroplasticity is greatest in the first 3 ½
years of life…
The goal of early auditory intervention is to
maintain a child’s ability to learn through a
developmental model
“Developmental synchrony”
10. Anatomy of the Ear
• Outer ear
• Middle ear
• Inner ear - cochlea
Normal Inner Ear Damaged Ear
Inner
Hair Cells
Outer
11. Age of implantation
1) Age at implantation is decreasing from 2 to 1year ,
2) children in oral education programs obtain more
benefit from a cochlear implant than children in total
communication programs,
3) Children who undergo implantation before 2 years of
age show greater benefit than children who undergo
implantation between 2 and 3 years of age,
4) More younger children are using oral communication
than older children,
5) More children with good auditory skills before
implantation and more residual hearing are undergoing
implantation.
6) Cochlear implant in elderly increase self confidence
and improved quality of life.
12. Anatomy (lack of calcification, is there an auditory nerve, malformed / no
cochlea)
Perhaps one ear accepts electrical stimulation better than other Leave ear
with better hearing, implant worse ear, then if not successful can revert
back to aiding that ear.
Implant better ear (opposite argument) - It has already benefited from
hearing aid, will more readily acclimate to implant
Facial nerve too close to cochlea-may pick other ear
If no difference may want it on right- as speech and hearing centers of
brain on left
Want on right- later for later when driving. Can hear people in the car
13. What is a Cochlear
Implant ?
•Surgically implanted device.
• Electrode Array and a Receiver-Stimulator
•But it works only if used with:
• External components :Speech Processor,
microphone, transmitter
•To work, it needs:
• Programming with a computer
•To work even more optimally:
• Rehabilitation sessions necessary
14. Type of cochlear implants
• Single vs Multiple channels
• Monopolar vs Bipolar
• Speech processing strategies
– Spectral pea(nucleus)
– Continuous interleaved sampling (nucleus, clarion)
– Advanced combined encoder(nucleus)
– Simultaneous analog strategy (clarion)
15. The speech processor uses a bank of bandpass filters (or a
Fourier analyzer) to analyze the signal before passing it
along to the array of electrodes
17. What does it look like?
Illustration from Advanced Bionics
18. Indication for CI in Adults
• Bilateral severe to profound SNHL 70 db
HINT sentence score <20% -50% in quiet
• Limited benefit from appropriate hearing aids i.e. poor
speech recognition
• Telephone use is difficult, limited or impossible
• Patient relies heavily on speech reading or note writing to
understand speech
• Patient is distressed by the inability to communicate
efficiently on a daily basis
• No medical contraindications
• No anatomic contraindications
19. Indication for CI in
Children• Severe to profound sensorineural hearing loss in both ears
(>90db in better ear)
• Lack of benefit from hearing aids and therapy
• No medical contraindications
• High motivation and expectations for child and family
• Placement in aural educational program that emphasizes
auditory skills
• 12 months and up; may be indicated earlier for special
cases
• No anatomic contraindications
20. Contraindications
• Incomplete hearing loss
• Neurofibromatosis II, mental retardation,
psychosis, organic brain dysfunction,
• Active middle ear disease
• CT finding of cochlear agenesis(Michel deformity)
small IAC ( 8th
cn atresia)
• Labyrinthitis ossificans
• Advanced otosclerosis
• H/o CWD mastoidectomy
21. How does it work?
• Sound Processor
• captures sound from the environment
• processes sound into digital information
• transmits to the implant.
2. Implant
• converts transmitted information into
electrical signals
• delivers signals to the electrodes for
stimulating the hearing nerve.
3. Hearing Nerve
• carries the sound information to the brain,
where it is interpreted.
22. Evaluation Process
• Audiological
• Medical
• Psychological & Social Worker (children)
• Auditory-Verbal Therapy (children)
• Speech Language Pathology (for adults,
when required)
23. Audiological Assessment
• Diagnostic testing:
– Audiogram >50 db
– Tympanometry & Acoustic Reflexes
– Auditory Brainstem Response
– Otoacoustic Emissions
• Speech perception tests with appropriate
amplification <60
• Hearing in noise test (HINT) <60 % in quiet
• Consonant nucleus consonant word testing
(CNC) <30 %
24. Medical Assessment
• Otologic history & examination
• General medical health
• Pneumococcal meningitis vaccine:
Pneumovax
• Diagnostic Imaging
• Computed Tomography (CAT)
• Magnetic Resonance Imaging(MRI)*
• Electronystagmography ENG(Adult only)
Electronystagmography (ENG) is a diagnostic test to record involuntary movements of the eye
caused by a condition known as nystagmus. It can also be used to diagnose the cause of
vertigo, dizziness or balance dysfunction by testing the vestibular system.
25. Diagnostic Assessment
CT MRI
Morphology of cochlea and semicircular canals ++ +++
Potency of cochlear duct + ++
Status of cochlear nerve - +++
Anatomy of facial nerve and fallopian canal ++ +
Defect of the modiolar + +++
Defect of cribiform area +++ ++
Enlarged vestibular aqueduct ++ +++
Enlarged cochlear aqueduct +++ +
Presence of round or oval window +++ -
CNS abnormalities +++
26. 1. Primary means of determining suitability for cochlear
implantation.
2. The patients to undergo implantation were postlingually
deafened adults with no hearing and who received no
benefit from conventional amplification. Many or all
aspects of spoken language had developed before the onset
of their deafness. There was no likelihood that their
hearing could worsen with cochlear implantation.
Knowledge gained from these patients and with improved
technology, candidacy criteria have broadened to include
prelingually deafened children and patients with some
minimal residual hearing.
Audiologic Assessment
27. 3. Patients who become deaf at or after age 5 are classified
as postlingually deafened.
4. Once access to auditory input and feedback is lost,
rapid deterioration of speech intelligibility often occurs.
Implantation soon after the onset of deafness potentially
can ameliorate this rapid deterioration.
5. Cochlear implantation may be less successful in
postlingually deafened patients if there is a long delay
between the onset of deafness and implantation.
6. A postlingual onset of deafness is an infrequent
occurrence in the pediatric population
28. Psychological Assessment
• 1. Performed to identify subjects who have organic
brain dysfunction,mental retardation, undetected
psychosis, or unrealistic expectations.
• 2. Valuable information related to the family
dynamics and other factors in the patient’s
milieu that may affect implant acceptance and
performance are assessed.
29. Method of hearing assessment:in
infants and children
• Neonatal screening procedures
• Arousal test: high frequency narrow band noise stimuli
3time for 2 sec >aroused twice
• Auditory response cradle: trunk, limb movement ,head jerk
and respiration seen on auditory stimuli
• Otoacoustic emissions:+nt in healthy outer hair cell
– Absent in damaged outer hair cell
– transient evoked emission are absent in ear where hearing loss>30
dB
» Evoked by click
– Distortion product emissions are absent in ear where hearing
loss>50 dB
» 2 tone are simultaneously present to cochlea to produce
distorsion
30. ABR
• screening test and definitive hearing assessment
– Elicit brainstem responses to auditory stimulation of clicks
40nHL or less is criteria of passing in screening test
– Find hearing threshold in infant ,1st
at higher stimulus then
lowered till wave V is just identifiable and repeatable.
– Identifiable waveform are present 10-20 dB above behavioral
threshold.
– done under sedation
– Find integrity of central auditory pathway (EE COLI)
– In normal child 7 waves are produced in 1st
ten millisecond
– 1st
3rd
5th
waves are stable n used in measurement.
– Waves are studied for absolute latency , inter-wave latency
and amplitude.
31. Behaviour observation audiometry
– Moro’s reflex-sudden movement of limb and
extension of head in response to sound of 90dB
– Cochleopalpebral reflex : blink to loud sound
– Cessation reflex:
• starts crying in response to sound of 90 dB
• Or stop activity
32. Distraction techniques
– Used in 6- 7 month child
– Child turn his head to locate source of sound-
when assistant distracts child attention.
– High frequency sound – 8 kH rattle
– Low frequency sound – hum
– Narrow band sound- whispered sound
33. Conditioning techniques
• Play audiometry-
– used in child 2-5 years
– each time after hear a sound signal child perform an act
• Speech audiometry:
– Child is asked to repeat the names of object
– Voice can be gradually lowered
– Hearing level and speech discrimination can be tested
• visual reinforcement audiometry
• Child is trained to look for an auditory stimulus by turning
his head
34. Objective test
– ABR
– Otoacoustic emission
– Impedance audiometry:
• stapedius ms contracts in response to sound of 70-100
dB and this reflex can be recorded.
• Middle ear disorder,retrocochlear hearing loss profound
HL-absence of acoustic reflex
• Absent of acoustic reflex +(n)tympanometry=SNHL
• Absent of acoustic reflex +(abn)tympanometry=CHL
35. Surgery
• Pre operative procedure Intravenous
antibiotics should be given at least 20 minutes
before the incision is made. Antibiotics should be
continued for the first 24 hours postoperatively and
then discontinued
•Requires general anesthesia
•Duration ~ 3-4 hours
36. Behind-The-Ear/Device Marking Template
The Behind-the-Ear/Device
Marking Template is used to allow
adequate clearance between the
pinna, the speech processor and the
head piece.
From Advanced Bionics
37. Device Coil Gauge
After placing the Device Coil
Gauge, an outline is drawn
around the template.
From Advanced Bionics
38. Incision Line
The surgeon will determine the length
of the incision line.
A conventional postauricular-scalp
incision approximately 5.0-6.0cm in
length for children may be used.
The incision may be longer in adults
if the scalp needs to be thinned.
incision-
U shaped incision
Cshaped incision
J shaped incision
From Advanced Bionics
39. Incision and Skin Flap
• Flap can be elevated either as a single layer or in two layers.
If two layers are separately elevated, the superficial layer
should be elevated first and then deep tissues, which include
the periosteum of the mastoid, temporalis fascia, and
temporalis muscle, should be left intact.
•The periosteum of the mastoid should be elevated as an
anteriorly based Palva flap, which can be sutured back into
position at the end of the case to protect the electrode array in
the mastoid cavity.
• The Palva flap should be as large as possible and, will cover
the take off point of the electrodes for the Nucleus and
Advanced Bionics devices
40. • Stimulator/receiver should be placed 2.5 cm posterior
to the posterior border of the external auditory canal.
surgical drill is used to create a defect in the skull
contoured to exactly fit the implanted device exactly.
• The skull of small children, between 1 and 2 years of
age, may be only 2 and 3 mm in thickness. For these
children, the implant often rests on exposed dura.
• Some surgeons seek to leave an "island" of bone in the
center of the area of exposed dura, whereas other
removing all the bone from the dura.
The Well
41. Recess Marking Template
The Recess Marking
Template is used to
determine the location of
the recess bed and
channel for the electrode
lead.
From Advanced Bionics
42. • Incision and skin flap
• Mastoidectomy-not sauceried
• Exposing incus, LSC ,facial reces
• Posterior tympanotomy done through facial
recess
• The facial recess is a triangular area bound by (1)
the fossa incudis superiorly, (2) the chorda
tympani nerve laterally and anteriorly (3) facial
nerve medially and posteriorly
• Round window niche, incudostapedial joint
,pyramid exposed
• Cochleostomy made and widen (0.8-2mm)
• implant-receiver well/recess bed and electrode
lead channel are drilled .
• Fixing of implant into bed after electrode fixed
• Neutral electrode placed under temporalis ms
• Insertion of cochlear electrode into cochlea
• Withdraw of stilete to hug modiolar.
• Palva flap closed
• Skin closer
43. Mastoidectomy
The mastoidectomy cavity should not be
saucerized. The edges should be left as acute.
These edges will help retain the electrode leads
within the confines of the mastoid cavity.
After mastoidectomy is complete, LSC,incus is
identified then facial recess is identified and
widely opened. The most inferior portion of the
facial recess is of greatest importance for
visualization of the round window niche.
44. Some bone medial to the facial nerve must be
removed to see even the anterior boundary of the
round window niche.
Almost all anomalous facial nerves are displaced
anteriorly and medially. Just distal to the oval
window, they turn directly into the hypotympanum
and run just inferior to or directly over the round
window area
45. Mastoidectomy-Facial Recess Approach
After completion of a
mastoidectomy-facial recess
approach, the implant-receiver
well/recess bed and electrode
lead channel are drilled.
Suture tie-down holes to
stabilize the implant are placed.
A standard cochleostomy is
used.
From Advanced Bionics
46. Cochleostomy
•Once the facial recess has been widely opened, the round window
niche can be clearly seen. It is often useful to remove the anterior lip of
the round window niche so that the anterior attachment of the round
window membrane itself can be visualized.
• Make the cochleostomy inferior to the inferior attachment of the
round window membrane to avoid the "hook" of the cochlea. This
allows a straighter, more direct insertion of the electrode array into
scala tympani. "pure" RW insertion avoids the trauma and bone dust
associated with a classic promontory cochleostomy. Insertion through
the RW ensures entrance into scala tympani.
•The size of the cochleostomy will be of 2 mm or more. Most currently
available devices can be easily inserted through a cochleostomy of
between 0.8 and 1.2 mm in diameter.
47. Electrode Insertion
The insertion tool is used to
insert the electrode array in the
usual fashion.
The Insertion Tube is placed
just inside the cochlea toward
the basal turn of the scala
tympani, with the insertion tube
slot directed toward the
modiolar (or inner) wall.
From Advanced Bionics
50. Audiological testing in the OR
• Impedance
check on all
electrodes
• Neural response
testing to help
estimate
required levels
51. X-Ray to confirm position
of internal device
Courtesy of Cochlear Corporation
52. INITIAL FITTING OF
COCHLEAR IMPLANT
• 1. External processor and transmitter fit
approximately 1 month after surgery.
• 2. Magnet strength for transmitter
determined.
• 3. Electrical threshold and comfort levels
determined.
• 4. Map created
53. After the surgery
•Initial stimulation: 4-6
weeks post surgery
•Adjustments made
regularly based on
feedback from patients,
parents, therapists and
educators
•Rehabilitation to meet
specific patient needs
•Regular follow-up
appointments
54. • Facial nerve injury –intra operative
• Chorda tympani nerve injury- intra operative
• Post operative bleeding and hematoma
• Infection –open wound and tt with antibiotic
• Wound dehiscence-flap necrosis
• Early Device failure-out of box failure
• CSF leak-penetration of dura -presence of modiolar
defect
• Labyrinthisis
• Meningitis
• Balance Disturbance-Dizziness - vertigo
Post operative complication
55. Post operative complication-late
1 Extrusion or exposure of device -used pericranial
flap to fully cover device
2 Displacement- d/t injiry- do CT scan
3 late Device failure-d/t trauma –replacement of
external components-no improvement-CTscan-
no explanation-electrical integrity check-soft
failure-replace device
4 Otitis Media infection – tt with antibiotics
5 Meningitis- d/t Pneumococcal infection-
pneumococcal vaccination
56. Intracochlear ossification
• Ossification at round window common in
post meningitic patients
• In these patients, a cochleostomy is
developed anterior to round window. New
bone is drilled. If an open scala tympani is
entered, a full insertion is performed.
57. • Less frequently, the scala tympani is completely
obliterated by bone. - drill open the basal turn and
create a tunnel approximately 6 mm in depth and
partially inert a straight electrode. This allows
implantation of 10 to 12 active electrodes which has
proven satisfactory.
• Specially designed split electrodes have been
developed One branch of the electrode array is placed
into the tunnel described earlier and the second active
electrode is inserted into a second cochleostomy
developed just anterior to the oval window.
58. Cerebrospinal fluid leak
• Eliminated by drilling shallow well for implant
package not exposing dura and eliminating
control holes for tie-down sutures.
• CSF gushers have occurred in children with a
Mondini deformity and major inner ear
malformations and patients with the large
vestibular aqueduct syndrome.
59. • The flow of CSF has been controlled by entry
into the cochlea through a small fenestra,
allowing the CSF reservoir to drain off, insertion
of the electrode into the cochleostomy, and tight
packing of the electrode with fascia At the
cochleostomy site.
• It is postulated that the source of the leak is
through the lateral end of the internal auditory
canal.
• The eustachian tube is occluded with tissue and
fibrin glue is placed in the middle ear.
61. Negative psychological
& social impacts
• Concerns about the maintenance
and/or malfunctioning of the Cochlear
Implant
• Difficulty in background noise
• Unreasonable expectations of aural-
only benefit on the part of the implant
user or their family and friends
62. Potential Benefits
1. Better speech understanding compared to a
hearing aid
2. Awareness and responsiveness to environmental
sounds
3. Less dependence on family members for day to
day living
4. Reconnection with the world of sound
5. Facilitation of communication with family and loved
ones
6. Ability to talk on the phone
7. Better appreciation of music
