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Differential diagnosis of Hearing loss 1.Conductive Hearing loss 2.Sensorineural Hearing loss 3.Mixed Hearing loss
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DIAGNOSIS AND Assessment of hearing loss HISTORY Screening test-Behavioural tests Speech test Tuning fork test Pure tone Audiometry Speech audiometry Impedence Audiometry ABLB, SISI, TD Electrocochleography Auditory brain stem response Otoacoustic emissions
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Causes of conductive loss Congenital Meatal Atresia congenital cholesteatoma ossicular discontinuity Fixation of malleus Fixation of stapes
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Acquired Causes of conductive loss Acquired causes EXTERNAL EAR meatal aresia wax foreign body furuncle tumour acquired atresia
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Acquired Causes of conductive loss Middle ear Serous otitis media Otosclerosis Ossicular discontinuity Adhesive otitis media Tympanosclerosis Csom ASOM TUMOUR Trauma
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MANAGEMENT OF CONDUCTIVE LOSS SURGERY Hearing aids
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HEARING AIDS 1.Microphone 2.Amplifier 3.Receiver
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Hearing aids Sounds-----microphone volume control battery amplifier receiver amplified sounds
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TYPES OF HEARING AIDS BODY WORN AID
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bte
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In the canal
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Completely in the canal
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Electroacoustic properties of the hearing aid Acoustic gain Frequency response Maximum output Distortion
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ASISTED LEARNING DEVICE FM Hard wire system, class room amplification Telecommunication device for the deaf Alerting device for the deaf
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Cochlear implants Electronic devices designed to detect mechanical sounds and convert it into electrical signals that can be delivered to cochlear nerve and interpreted by the patients to provide useful hearing.
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level History of Cochlear Implants Volta Djourno and Eyries House, Doyle, Simmons 1972 Single-channel implant 1984 FDA approval 1990’s Beyond
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Anatomy
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Sevent h Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Anatomy Scala tympani Scala vestibuli Cochlear duct Basilar membrane Vestibular membrane Tectoral membrane Hair cells (outer/inner) Cochlear nerve fibers
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Anatomy-micro
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Physiology of Hearing
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Sevent h Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Anatomy
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Sevent h Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Pathologic Anatomy
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Components of Cochlear Implant
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Implant Components Microphone amplification External speech processor Compression Filtering Shaping Transmitter (outer coil) Receiver Electrode array Neural pathways
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Types of Cochlear Implants Single vs. Multiple channels Audio example of how a cochlear implant sounds with varying number of channels Monopolar vs. Bipolar Speech processing strategies Spectral peak (Nucleus) Continuous interleaved sampling (Med-El, Nucleus, Clarion) Advanced combined encoder (Nucleus) Simultaneous analog strategy (Clarion)
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Sevent h Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Anatomy of a Cochlear Implant
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Indication for Cochlear Implant Adults 18 years old and older (no limitation by age) Bilateral severe-to-profound sensorineural hearing loss (70 dB hearing loss or greater with little or no benefit from hearing aids for 6 months) Psychologically suitable No anatomic contraindications Medically not contraindicated
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Indications for Cochlear Implantation -- Children 12 months or older Bilateral severe-to-profound sensorineural hearing loss with PTA of 90 dB or greater in better ear No appreciable benefit with hearing aids (parent survey when 5 yo) Must be able to tolerate wearing hearing aids and show some aided ability Enrolled in aural/oral education program No medical or anatomic contraindications Motivated parents
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Contraindications Incomplete hearing loss Neurofibromatosis II, mental retardation, psychosis, organic brain dysfunction, unrealistic expectations Active middle ear disease CT findings of cochlear agenesis (Michel deformity) or small IAC (CN8 atresia) Dysplasia not necessarily a contraindication, but informed consent is a must H/O CWD mastoidectomy Labyrinthitis ossificans—follow scans Advanced otosclerosis
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General Workup Audiologic exam with binaural amplification CT scan/MRI of temporal bones Trial of high-powered hearing aids Psychological evaluation Medical evaluation Any necessary tests to discover etiology of hearing loss
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Surgical technique
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Surgical Technique
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Sevent h Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level Surgical Technique
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Postoperative Management Complication rate only 5% Wound infection/breakdown Yu, et al showed good response to Abx, I&D Facial nerve injury/stimulation, CSF leak, Meningitis CDC recommendations Vertigo (Steenerson reported 75%) Device failure—re-implantation usually successful Avoid MRI
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Postoperative Rehabilitation Necessary part of implantation Different focus depends on patient’s previous experience with sound Goal is to enable children to be able to learn passively from the environment Program addresses receptive as well as expressive language skills Multidisciplinary, dedicated group necessary
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Results of Implantation Wide range of outcomes Improvement is long-term (Waltzman, et al. 5-15 yr f/u) Implantation is cost effective—even in the elderly (Francis, et al) Research indicates recipe for success includes: Short length of time from deafness to implantation (Sharma showed <3.5 years regain normal latencies within 6 mos. After 7 years, little plasticity remains) Experience with language before onset of deafness Implantation before age six for prelingually deafened children (Govaerts, et al showed 90% of children implanted <2yo were integrated into mainstream vs. only 20-30% if implanted after age 4) Aural/oral education Highly motivated patients/parents
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Click to edit the outline text format Second Outline Level Third Outline Level Fourth Outline Level Fifth Outline Level Sixth Outline Level Seventh Outline Level Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Second level Third level Fourth level Fifth level A Look to the Future Partial implants with hearing aid Those with residual low-frequency hearing Intraoperative mapping Bilateral implantation One vs. two speech processors Implantation for asymmetric SNHL “Softip” array Minimally invasive implantation
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THANK YOU
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