Lecture- Cochlear Implantation

8/13/2019 Lecture- Cochlear Implantation

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All Hair Cells Have Two FunctionsMechano-Electrical Transduction

Neurotransmission

Outer Hair Cells Carry Out

Electro-Mechanical TransductionPassive Cochlear Model

Mass

Stiffness

Damping

Mechanical

models

Filtering

Passive

Frequency

ActiveSensorineural Hearing Loss

Mechanisms of sensorineural hearing loss

Congenital malformations (otic capsulemay or may not be involved)

Stria vascularisSpiral ganglion cells

Organ of Corti / hair cells

Presbyacusis (age- related hearing loss)

Noise- induced hearing loss

Loss of OHCs

(12,000 max)


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Normal Cochlea

Auditory

Nerve

Hair

Cells

Hearing-Impaired Apex

Scala Vestibuli

Spiral Ganglion

Organ of

Corti

(Hair Cells)

Bipolar Contacts

Audi tor y

Nerve

Oval Window

Round Window

Electrode

Central

Rib

BaseCochleostomy

(scala tympani)

ClarionTM

Cochlear

Implant

Common Components of all CochlearImplant Systems

Microphone & Cable

Speech Processor

Antenna/Transmitter

Receiver/Stimulator

Electrode Array

Nucleus 3 system

1

Sound entersmicrophone onheadpiece

2

Sound travelsdown cable toprocessor


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3

Processed soundtravels back up

cable toheadpiece

4

Processed soundis transmitted to

implant throughskin

5

Implant sendssound to cochleathroughelectrode

6

Electrode incochleastimulatesauditory nerve

Advances in ImplantTechnology

Technological advances have resulted inimprovements in patient performance

In turn, improvements in patientperformance have resulted in expandedaudiological criteria!

Optimal Electrode Placementat Medial Wall

LATERAL MEDIAL


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Advances in Electrode Design

Spiral Electrode

(1990)

Spiral Electrodewith PositioningSystem (EPS)

(1998)

HiFocus Electrodewith PositioningSystem (EPS)

(1999)

CLARION & POSITIONER17 mm insertion 630

CLARION ELECTRODE

24 mm insertion 500

Design changes implemented so that

the electrode closely hug the modiolus

Positioner

Mean Most Comfortable LevelsThree Electrode ConfigurationsMonopolar Pulsatile Stimulation

100

150

200

250

300

350

400

1 2 3 4 5 6 7 8Channel Number

ClinicalUnits

Spiral alone at3 months(n=51)

Spiral + EPS at1 month (n=20)

HiFocus+EPSat 1 month(n=34)

Nucleus Contour Electrode

Stylet in place

Stylet removed

K117L, 12.5 mm el. #1

Insertion tr auma: K117L, 11.5 mm el. #2Insertion trauma: K117L, 11.5 mm el. #2

SGSG

SGSGOSLOSL

Slide from Pat L eake, UCSF

SpLSpL

RMRM

ContourContourTM

ElectrodeElectrodeSpGSpG

OSLOSL

OticOtic

capsulecapsule


SpGSpG

OSLOSL

ElectrodeElectrode

ScSc TymTym

Sc VestSc Vest



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SpLSpL

RMRM

ElectrodeElectrode

PositionerPositioner

OSLOSL

SpGSpG

HiFocusHiFocus

OticOtic

CapsuleCapsule


External Equipment

Speech Processors Automatic, Continuous

Functionality Check of AllExternal and InternalComponents

Multiple Indicator Lights

Programmable Acoustic Alarm

ESD Resistant

Easy to Adjust Controls

> Built-in microphone tester

> Multiple Signal-to-Noise ratiooptions for FM/Accessories

mini-computer

BTE Sound Processor

8 Runs all processingstrategies plus new onesunder development

8 Rechargeable batteries forlow operating cost

8 Compatible with allCLARION internal implants

8 Same functionality as Bodyworn PSP, except nowarning lights/alarms

8 Check functionality withSensor

Clarion

Nucleus

CLARION Sound Processor Development

13

100

S-Series Platinum Series & BTE

Million Instructions Per Second (MIPS)

Continuous Two-Way Telemetry

Ongoing monitoringachieved with twodistinct carrierfrequencies

Normal concurrentsignal operation

Benefit forchildren who areunable tocommunicate

Power

& Data

Back

Telemetry

Headpiece ICS

SP Status Indicator


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Input Dynamic Range (IDR)

The normal earcaptures widelyfluctuating speech

intensities rangingover 50 dB as wellas speech fromtalkers when theyare far away orspeaking softlyCLARION capturesthe widest range ofincoming soundsthrough itselectronics andsoftware

CLARION

60 dB IDR

Industrynorm

30 dBIDRNormal

Hearing120 dB

50 dBPeaks

& Valleysof Speech

30

90

70

50

Narrowed IDR (30 dB)Narrowed IDR (30 dB)

Per

ceptualDR

(

PerceptualDR

(uAuA))

Sound

Pressure

Level(dB

SPL)

Sound

Pressure

Level(dB

SPL)

IDR T

M

AGCAGC

Speech ProcessorSpeech Processor ElectrodeElectrode

30

90

70

50

Widened IDR (60 dB)Widened IDR (60 dB)

PerceptualDR

(

PerceptualDR

(uAuA))

Sound

Pressure

Level(dB

SPL)

Sound

Pressure

Level(dB

SPL)

IDR

T

M

AGCAGC

Speech ProcessorSpeech Processor ElectrodeElectrode

Acoustic Signal

Pass band 1 Envelope Compression Ch 1

Pulse Train Carrier

Pass band 2 Envelope Compression Ch 2

Pass band N Envelope Compression Ch N

AGC & Low Pass

high

low

mid

BTE Decals

Six inter-changeable colorheadpiece caps

Nucleus


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Speech Processing

Speech Spectrum

S e n t e n ce

Spectral Resolution (Number ofChannels)

Most important factor is the number ofspectral channels of information

number of distinct pitch channels

Number of effective channels is not thesame as the number of electrodes


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Spectral Cues in Music

While spectral and temporal fine structure are notnecessary for speech recognition they constitutethe very heart of music, i llustrating the differentdemands of speech and music on peripheralsensory processing

Melody recognition requires many more spectralchannels than speech

The cochlea isnt designed for speech thecochlea is designed for music (Ed Burns)

4 8 16 32 Origi nal

Popular Music with male vocal

Processing Strategy and Stimulation Mode

CIS

MonopolarSAS

Enhanced Bipolar

Ch. 1

Ch. 2

Ch. 3

Ch. 4

Ch. 5

Ch. 7

Ch. 8

Ch. 6

MPSMPSBipolar or MonopolarBipolar or Monopolar

Who is a CI Candidate?


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Who Should Get a Cochlear Implant?Children

Children aged 12 mos-17 years

Profound sensorineural hearing loss of 90 dB or greater

in both ears (No Response ABR) Lack of benefit from high powered hearing aids

3-6 month Required Hearing Aid Trial < 2 on Questions 3, 5, & 6 on the IT-MAIS

Questionnaire

Older child (>6yrs): Some auditory skills 0-20% on tests of open-set word recognition (PB-K or MLNT)

Dont Wait!The Younger the Better!

Who Should Get a Cochlear Implant?Children

Rehabilitative or educational setting wheredevelopment of listening and speakingskills are emphasized

Positive family environment where deviceuse through listening and speaking isencouraged

AdultsWho Should Get a Cochlear Implant?

Healthy adult over 18 years of age, no upper agelimit

Severe-Profound sensorineural hearing loss of 70 dBor greater in both ears

Postlingual onset of deafness (after age 6 yrs)

Prelingual adults that are members of the hearingcommunity (lip readers, verbal intent)

Lack of benefit from hearing aids

HINT Sentence score < 50%

Adult Referral Criteria

PTA of >70dB in Both Ears

Monosyllabic Word score of < 30%in Both Ears

Audiological Measurement:CI Candidate?

250 500 1000750 1500 2000 4000 6000 8000-10

010

2030

40

50

Hz

60

70

80

90

100

110

120

dB

X X

XX

XX

86 Yr. Old Adult

PTA=103dB AS

PTA=105dB AD

CNC Words:

=0% AS =0% AD

O

OO

O

O

O

X

CI CI CI CI CI

YESAudiological Measurement:

CI Candidate?

250 500 1000750 1500 2000 4000 6000 8000-10

010

2030

40

50

Hz

60

70

80

90

100

110

120

dB

X

X

XX

X

X

56 Yr. Old Adult

PTA=83dB AS

PTA=75dB AD

CNC Words

=12% AS =16% AD

O

OO

O

O

O

X

XO

YES


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Evaluation&

Expectations

Adult Evaluation: Pre-Operative

Thorough Audiological assessment to determinedegree and type of hearing loss and amount ofbenefit from acoustic amplification

Include OAEs &/or Acoustic Reflex Testing

Medical work up, including CT scan or MRI

Counseling for realistic expectations

Cochlear Implant Surgery

About 2.5 hours General anesthesia, Outpatient Procedure

Incision Drill facial recess Trough for electrode lead Bony bed for receiver/stimulator Secure receiver/stimulator with sutures Cochleostomy for electrode insertion Pack with fascia and close incision

Covered by InsuranceDont take NO for an answer

Cochlear Implant Surgery72 year old male with progressive sensorineural hearing loss

A Post-Auricular Incis ion


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Exposure of the Mastoid CortexDrilling the Mastoid and

Countersinking the Implant

Securing the Implant The Facial Recess

Stapes

Round

Window

Facial Nerve

Lateral

SCC

Incus

Placement of the ElectrodeComplications

Hearing loss - in everyone New techniques to reduce HL

Variable outcomes Chorda tympani nerve injury

COMMON

Infections - uncommonFlap necrosis - uncommonTinnitus & Imbalance - usually self limitedFacial nerve injury - congenital abnormalityMENINGITIS - a problem of mythic

proportions

UNCOMMON


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Risk factors for meningitis

Inner Ear MalformationsPrior history of meningitis

Young children (esp.< 5 yrs).

Otitis media

Immune dysfunction

Prior ear surgery

Meningitis in Cochlear Implantation

91 people worldwide (N=60,000) 17 deaths

53 US cases (N= 25,000) Ages 18 mos to 84 yrs; Most under 7 years of

age (n=33) Signs and Sx 6 yrs 50% developed meningitis < 1 year postop

(N=32) 29 Advanced Bionics CLARION (1996;N=7500) 22 Cochlear Nucleus (1985; N=16,500) 2 MED-EL (2001; N=770)

Design Flaws?

Higher incidence with

Clarion positioner

Removed fro m the

market

HF1 electrode now

available without the

positioner

Positioner

Post-Operative Evaluations:Device Fitting and Follow-up

Initial stimulation: 3-6 weeks post surgery

Adjustments maderegularly based onfeedback frompatients, parents,therapists andeducators

Speech perceptionevaluations semi-annually to annually

Evolution of Implant Outcomes

Single-channel implants Sound detection, perception of speech

rhythm, lipreading enhancement

First generation multichannel implants Closed-set word identification, some

open-set sentence recognition; pooropen-set word recognition

Current Expectations

Sound Field thresholds 20-45dB @ 250-6K Hz

Cannot return to Hearing Aid in implanted ear

>80% Postlingual Adults use the telephone

>50% of Postlingual Adults enjoy music

Near peak performance by 3 months!


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Open-Set Speech RecognitionN=56 Postlinguistic Patients

Six-Month Scores

* Note: Only patients who score > 20% on HINT Sentences in quiet are administered

HINT Sentences in n oise.

3%

13%11%

20%

44%

57%

71%

35%

79%

40%

51%

67%

47%

73%

52%

81%

0%

20%

40%

60%

80%

100%

CNC Words CID Sentences HINT in Quiet HINT +10 S/N*

PercentCorrect

Pre

1Month

3Month

6Month

Individual CNC Word Scores at 3 Monthsand Duration of Deafness (n= 67)

High levels of CNC word recognition were achieved bypatients with long as well as short duration ofdeafness.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 0 1 1 1 1 2 2 2 2 2 3 3 3 6 6 7 7 8 1 0 1 2 1 2 1 5 1 7 2 0 20 21 26 26 28 30 38 43 58

Years of Deafness - Implanted Ear

PercentCorrect

0 00

Mean = 40%

Median = 42%

Individual CNC Word Scores at 3 Monthsand Age at Implant (n=67)

31% of the sample was implanted at > 70 years of age. Someof these older patients show high levels of word recognition atthree months. Others may require more implant experiencebefore they demonstrate open-set word recognition abilities.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

22 26 28 33 39 40 43 45 46 49 50 52 53 55 56 59 60 61 62 63 65 68 69 71 73 73 75 75 76 78 80 82 84 88

Age at Imp lant (Years)

PercentCorrect

00 0

Mean = 40%

Median = 42%

SPIRAL GANGLION CELL DEGENERATION

FOLLOWING NEONATAL DEAFNESS

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10 11 12

Duration of Deafness (months or years)

< 1 year n = 56

r2 = 0.83 p 2 years n = 11 (6 cats)

GanglionCellDensity

(%n

ormal)


K117 L, GM1 Stimulated:K117 L, GM1 Stimulated:

5 mm, SG = 80% of normal5 mm, SG = 80% of normalK117R, GM1 Deafened Contr ol:K117R, GM1 Deafened Control :

5 mm, SG = 40% of normal5 mm, SG = 40% of normal


Why Research Cochlear Implant

Alternatives?

Outcomes with a cochlear implant are

good but not as good as normal hearing

Cochlear implants can not be used for

mild or moderate levels of hearing l oss


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Baylor College of MedicineChul-HeeChoi, Ph.D.Gentiana Wenzel, M.D.

Anpi ng Xia, M.D., Ph.D.Nicola Schug, M.S.

William E. Brownell, Ph.D.Ruth Anne Eatock, Ph.D.Fred Pereira, Ph.D.Peter Saggau, Ph.D.

University of California San FranciscoPat A. Leake, Ph.D.Russell Snyder, Ph.D.

New York UniversityAnil K . Lalwan i, M.D.

Stanford UniversityRobert K. Jackler, M.D.

Rice UniversityBahman Anvari, Ph.D.Robert Raphael, Ph.D.

Johns Hopkins UniversityAlex Spec tor, Ph .D

University of Tuebingen, GermanyMarkus Pfister, M.D., Ph.D.Nicola Schug, M.S.

National Institutes of HealthNational Organization for Hearing Research

Acknowledgments

Documents

Lecture- Cochlear Implantation