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Differential diagnosis
of Hearing loss
1.Conductive Hearing
loss
2.Sensorineural
Hearing loss
3.Mixed Hearing loss
DIAGNOSIS AND Assessment of
hearing loss
HISTORY
Screening
test-Behavioural tests
Speech test
Tuning
Pure
fork test
tone Audiometry
Speech
audiometry
Impedence
ABLB,
Audiometry
SISI, TD
Causes of conductive loss
Congenital
Meatal Atresia
congenital cholesteatoma
ossicular discontinuity
Fixation of malleus
Fixation of stapes
Acquired Causes of conductive
loss
Acquired
causes
EXTERNAL EAR
meatal aresia
wax
foreign body
furuncle
tumour
acquired atresia
Acquired Causes of conductive
loss
Middle
ear
Serous otitis media
Otosclerosis
Ossicular discontinuity
Adhesive otitis media
Tympanosclerosis
Csom
ASOM
MANAGEMENT OF CONDUCTIVE
LOSS
SURGERY
Hearing
aids
HEARING AIDS
1.Microphone
2.Amplifier
3.Receiver
Hearing aids
Sounds-----microphone
battery
volume control
amplifier
receiver
amplified sounds
TYPES OF HEARING AIDS
BODY
WORN AID
bte
In the canal
Completely in the canal
Electroacoustic properties of
the hearing aid
Acoustic
gain
Frequency
Maximum
Distortion
response
output
ASISTED LEARNING DEVICE
FM
Hard
wire system, class room amplification
Telecommunication
Alerting
device for the deaf
device for the deaf
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.
History of Cochlear Implants
Volta
Djourno
and Eyries
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House,
Doyle,
Simmons
1972
Single-channel
implant
1984
FDA approval
1990’s
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Anatomy
Anatomy
Scala tympani
Scala vestibuli
Cochlear duct
Basilar membrane
Vestibular membrane
Tectoral membrane
Hair cells
(outer/inner)
Cochlear nerve fibers
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Anatomy-micro
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Physiology of Hearing
Anatomy
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Pathologic Anatomy
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Components of Cochlear Implant
Implant Components
Microphone
amplification
External speech processor
Compression
Filtering
Shaping
Transmitter (outer coil)
Receiver
Electrode array
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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
Speech
vs. Bipolar
processing strategies
Spectral peak (Nucleus)
Continuous interleaved sampling (Med-El,
Nucleus, Clarion)
Advanced combined encoder (Nucleus)
Anatomy of a Cochlear Implant
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Indication for Cochlear Implant
Adults
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18 years old and older (no limitation by age)
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Bilateral severe-to-profound sensorineural hearing loss
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(70 dB hearing loss or greater with little or no benefit
from hearing aids for 6 months)
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Psychologically suitable
No anatomic contraindications
Medically not contraindicated
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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
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No appreciable benefit with hearing aids (parent survey
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when <5 yo or 30% or less on sentence
recognition
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Must be able to tolerate wearing hearing aids and show
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some aided ability
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Enrolled in aural/oral education program
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No medical or anatomic contraindications
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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
General Workup
Audiologic
CT
exam with binaural amplification
scan/MRI of temporal bones
Trial
of high-powered hearing aids
Psychological
Medical
Any
evaluation
evaluation
necessary tests to discover etiology of
hearing loss
Surgical technique
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Surgical Technique
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Surgical Technique
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Postoperative Management
Complication
Wound
rate only 5%
infection/breakdown
Yu, et al showed good response to Abx, I&D
Facial
nerve injury/stimulation, CSF leak,
Meningitis
CDC recommendations
Vertigo
Device
(Steenerson reported 75%)
failure—re-implantation usually
successful
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
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)
A Look to the Future
Partial
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Those with residual low-frequency hearing
Intraoperative
Bilateral
mapping
implantation
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One vs. two speech processors
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Implantation for asymmetric SNHL Outline Level
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“Softip” array
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Minimally
invasive implantation
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