Cochlear Implants Slides 030205

8/3/2019 Cochlear Implants Slides 030205

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Cochlear ImplantsCochlear Implants

Glen T. Porter, MDGlen T. Porter, MD

ArunArun K.K. GadreGadre, MD, MDDepartment of Otolaryngology, Head & Neck SurgeryDepartment of Otolaryngology, Head & Neck Surgery

Galveston, TXGalveston, TX


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History of Cochlear ImplantsHistory of Cochlear Implants

VoltaVolta

DjournoDjourno andand EyriesEyriesHouse, Doyle,House, Doyle,

SimmonsSimmons

1972 Single1972 Single--channelchannel

implantimplant

1984 FDA approval1984 FDA approval1990s1990s

BeyondBeyond


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AnatomyAnatomyAnatomy


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AnatomyAnatomyScala tympani

Scala vestibuli

Cochlear duct

Basilar membrane

Vestibular membrane

Tectoral membrane

Hair cells (outer/inner)

Cochlear nerve fibers


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AnatomyAnatomy--micromicro


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Physiology of Hearing


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AnatomyAnatomy


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SensorineuralSensorineural Hearing LossHearing Loss

Death of hair cells vs. ganglioncells

Otte, et al estimated we need10,000 ganglion cells with 3,000apically to have good speechdiscrimination

Apical ganglion cells tend tosurvive better (?acoustictrauma)

Central neural system plasticity


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Pathologic AnatomyPathologic Anatomy


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Anatomy of Sound


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Anatomy of SpeechAnatomy of Speech

Mix of frequenciesMix of frequencies

Speech recognition is topSpeech recognition is top--down processdown processFormant frequencies: frequency maximumFormant frequencies: frequency maximumbased on vocal tractbased on vocal tract

F0 is fundamental frequencyF0 is fundamental frequencyF1 & F2F1 & F2contribute to vowel identificationcontribute to vowel identification

F3F3l,r (lateral and retroflex glides)l,r (lateral and retroflex glides)

F4 & F5F4 & F5higher frequency speech soundshigher frequency speech sounds

Some speech based on amplitudeSome speech based on amplitudek, f, l, sk, f, l, s


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Components of Cochlear Implant


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Implant ComponentsImplant Components

MicrophoneMicrophone

!! amplificationamplification

External speechExternal speech

processorprocessor

!! CompressionCompression

!! FilteringFiltering

!! ShapingShaping

Transmitter (outer coil)Transmitter (outer coil)

ReceiverReceiver

Electrode arrayElectrode array

Neural pathwaysNeural pathways


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Types of Cochlear ImplantsTypes of Cochlear Implants

Single vs. Multiple channelsSingle vs. Multiple channels

!!

Audio example of how a cochlear implant sounds withAudio example of how a cochlear implant sounds withvarying number of channelsvarying number of channels

MonopolarMonopolar vs. Bipolarvs. Bipolar

Speech processing strategiesSpeech processing strategies!! Spectral peak (Nucleus)Spectral peak (Nucleus)

!! Continuous interleaved sampling (MedContinuous interleaved sampling (Med--El, Nucleus,El, Nucleus,

Clarion)Clarion)

!! Advanced combined encoder (Nucleus)Advanced combined encoder (Nucleus)

!! Simultaneous analog strategy (Clarion)Simultaneous analog strategy (Clarion)


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Anatomy of a Cochlear ImplantAnatomy of a Cochlear Implant


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Indication for Cochlear ImplantIndication for Cochlear Implant

AdultsAdults

!! 18 years old and older (no limitation by age)18 years old and older (no limitation by age)!! Bilateral severeBilateral severe--toto--profoundprofound sensorineuralsensorineural

hearing loss (70 dB hearing loss or greaterhearing loss (70 dB hearing loss or greater

withwith littlelittle or no benefit from hearing aids for 6or no benefit from hearing aids for 6

months)months)

!!

Psychologically suitablePsychologically suitable!! No anatomic contraindicationsNo anatomic contraindications

!! Medically not contraindicatedMedically not contraindicated


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Indications for CochlearIndications for Cochlear

ImplantationImplantation ---- ChildrenChildren12 months or older12 months or older

Bilateral severeBilateral severe--toto--profoundprofound sensorineuralsensorineural hearing losshearing loss

with PTA of 90 dB or greater in better earwith PTA of 90 dB or greater in better ear

No appreciable benefit with hearing aids (parent surveyNo appreciable benefit with hearing aids (parent survey

when 5 yoyo))

Must be able to tolerate wearing hearing aids and showMust be able to tolerate wearing hearing aids and show

some aided abilitysome aided ability

Enrolled in aural/oral education programEnrolled in aural/oral education program

No medical or anatomic contraindicationsNo medical or anatomic contraindications

Motivated parentsMotivated parents


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ContraindicationsContraindications

Incomplete hearing lossIncomplete hearing loss

Neurofibromatosis II, mental retardation, psychosis,Neurofibromatosis II, mental retardation, psychosis,

organic brain dysfunction, unrealistic expectationsorganic brain dysfunction, unrealistic expectationsActive middle ear diseaseActive middle ear disease

CT findings of cochlear agenesis (Michel deformity) orCT findings of cochlear agenesis (Michel deformity) or

small IAC (CN8small IAC (CN8 atresiaatresia))DysplasiaDysplasia not necessarily a contraindication, butnot necessarily a contraindication, butinformed consent is a mustinformed consent is a must

H/O CWDH/O CWD mastoidectomymastoidectomyLabyrinthitisLabyrinthitis ossificansossificansfollow scansfollow scans

AdvancedAdvanced otosclerosisotosclerosis


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CT FindingsCT Findings


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General WorkupGeneral Workup

AudiologicAudiologic exam with binauralexam with binaural

amplificationamplificationCT scan/MRI of temporal bonesCT scan/MRI of temporal bones

Trial of highTrial of high--powered hearing aidspowered hearing aidsPsychological evaluationPsychological evaluation

Medical evaluationMedical evaluationAny necessary tests to discover etiology ofAny necessary tests to discover etiology of

hearing losshearing loss


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Surgical techniqueSurgical technique


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Surgical TechniqueSurgical Technique


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Surgical TechniqueSurgical Technique


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Postoperative ManagementPostoperative Management

Complication rate only 5%Complication rate only 5%

Wound infection/breakdownWound infection/breakdown!! Yu, et al showed good response toYu, et al showed good response to AbxAbx, I&D, I&D

Facial nerve injury/stimulation, CSF leak,Facial nerve injury/stimulation, CSF leak,

MeningitisMeningitis!! CDC recommendationsCDC recommendations

Vertigo (Vertigo (SteenersonSteenerson reported 75%)reported 75%)

Device failureDevice failurerere--implantation usuallyimplantation usuallysuccessfulsuccessful

Avoid MRIAvoid MRI


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Postoperative RehabilitationPostoperative Rehabilitation

Necessary part of implantationNecessary part of implantation

Different focus depends on patientsDifferent focus depends on patientsprevious experience with soundprevious experience with sound

Goal is to enable children to be able toGoal is to enable children to be able tolearn passively from the environmentlearn passively from the environment

Program addresses receptive as well asProgram addresses receptive as well as

expressive language skillsexpressive language skillsMultidisciplinary, dedicated groupMultidisciplinary, dedicated groupnecessarynecessary


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Results of ImplantationResults of Implantation

Wide range of outcomesWide range of outcomes

Improvement is longImprovement is long--term (term (WaltzmanWaltzman, et al. 5, et al. 5--15 yr f/u)15 yr f/u)

Implantation is cost effectiveImplantation is cost effectiveeven in the elderlyeven in the elderly(Francis, et al)(Francis, et al)

Research indicates recipe for success includes:Research indicates recipe for success includes:!! Short length of time from deafness to implantationShort length of time from deafness to implantation (Sharma(Sharma

showed


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A Look to the FutureA Look to the Future

Partial implants with hearing aidPartial implants with hearing aid

!!

Those with residual lowThose with residual low--frequency hearingfrequency hearingIntraoperativeIntraoperative mappingmapping

Bilateral implantationBilateral implantation

!! One vs. two speech processorsOne vs. two speech processors

Implantation for asymmetric SNHLImplantation for asymmetric SNHL

SoftipSoftip array arrayMinimally invasive implantationMinimally invasive implantation


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Cochlear Implants Slides 030205

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