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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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