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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
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 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
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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
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No anatomic contraindications
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Medically not contraindicated
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Indications for Cochlear
Implantation -- Children
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12 months or older
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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
when
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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)
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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

 Click
implants with hearing
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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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