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Theses, Dissertations, Professional Papers
Graduate School
1986
Cochlear implants| The audiologist's role
Jill E. King
The University of Montana
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King, Jill E., "Cochlear implants| The audiologist's role" (1986). Theses, Dissertations, Professional Papers. Paper 1815.
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MANSFIELD LIBRARY
UNIVERSITY OF MONTANA
DATE :
1 988
COCHLEAR IMPLANTS:
THE AUDIOLOGIST'S ROLE
by
Jill
E. King
B.A., University of Montana, 1984
A Professional Paper Presented in Partial Fu11fi11ment of the
Degree of MCSD
UNIVERSITY OF MONTANA
1986
Approved by:
Chairman, Board of Examiners
Dean, Graduate School
if
Date
Q
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TABLE OF CONTENTS
LIST OF FIGURES AND TABLES
ii
I.
1
1
4
6
6
6
7
7
8
13
15
15
INTRODUCTION
Introduct i on
Cochlear Implant vs Hearing Aid
Implant Components
Neural Interface
External (Speech) Processor
Signal Transfer Hardware
Perceptual Mechanism
Single vs Mu 1 t i-e 1 ectrode Arrays
Digital vs Analog Coding Schemes
Intra- vs Extra-coch 1 ear Devices
Summary
II.
THREE COMMON TYPES OF DEVICES
3M/House
3M/V ienna
Nuc 1 eus
III.
IV.
V.
VI.
VII.
PATIENT SELECTION - ADULTS
General Considerations
Age
Et l o 1 ogy
Hearing Acuity
Congenital vs Acquired Loss
Additional Factors
Medical Assessment
Psychological Assessment
Audiological Assessment
REHABILITATION - ADULTS
Summary-Patient Reactions
PATIENT SELECTION - CHILDREN
Medical Assessment
Psychological Assessment
Audiological Assessment
Speech and Language Assessment
Post-Implant Results
Summary
REHABILITATION - CHILDREN
Summary
CONCLUSION
17
17
18
19
22
22
22
22
24
25
26
27
30
31
36
44
46
48
48
49
50
50
52
54
55
57
APPENDIX A
64
BIBLIOGRAPHY
65
l
LIST OF TABLES. FIGURES AND APPENDIX
Figure 1 = Cochlear Implant vs Hearing Aids
Page
5
Table 1 = Number of Children Implanted with the
3/M House Device
52
Appendix A = Summary of the 8 Most Common Types
of Implant Hardware
64
ii
INTRODUCTION
A
life,
hearing
impairment
regardless
of
hearing-impaired
language
affects
1982).
in
The
styles,
personal
child
a natural
future
experiences
when
in
minimize
profoundly deaf
Advocates of
a
an
is
developing
adversely
development
(Sanders,
hearing
loss
established
life
preserving
Walter,
much
social
and
Rehabilitation must
as
The
turn
acquired
and
effects
aspects of
acquired.
in
maintaining
Jobs,
these
many
difficulties
relationships (Sims,
cochlear implant
is
faces
with
1982; Alpiner, 1978).
to
loss
cognitive
problems
retaining
the
affect
manner, which
verbal
adult
may
as
and
Whitehead,
be
designed
possible.
A
is a medical device that can help some
individuals perceive acoustic stimuli.
the cochlear
technological
implant
breakthrough
increased enrichment of daily
believe
that
the
can
implant
provide
an
life for hearing impaired
persons (Mecklenburg, 1985a).
The cochlear
to
restore
individuals
implant
hearing
by
a
cochlear
auditory
perception
noise,
in
prothesis
of
for
electrical
elements
goals of
traffic
perception
direct
remaining neuronal
is a device that
profoundly
stimulation
the cochlea.
include
environmental
telephones ringing) and
ability to detect
is designed
deaf
of
the
The main
obtaining
sounds
some
(e.g.,
ultimately
the
and discriminate speech to a greater
1
2
degree
than
that
which
is
obtained
by
conventional
amp 1i f i cat i on.
The basic premise underlying any type of
cochlear
prothesis was summarized by Keidel (1979, p.163).
"Auditory processing is not the exclusive domain
of the central auditory system. The nerve signals
that leave the cochlea via the cochlear nerve are
the
end
products
of
a
series
of
complex,
interlinked processes that take place partially in
the
mechanical
domain
and
partially
in
the
sensorineural one. Two main events stand out:
1)
There is a systematic space/time distribution of
signal components into a number of parallel nerve
fibre channels, of which a maximum of about 30,000
are available; and 2) Each component that travels
in a single given nerve fibre is encoded in the
only form nerve fibres are equipped to handle
(i.e., action potentials).
In the two underlying
processes
of
conversion,
attributes
of
the
original signals are accurately preserved.
A
reasonable degree of speech intelligibility, the
ultimate aim of cochlear protheses, can only be
restored if and when the prothesis is capable of
handling these two tasks in a fair manner."
The
makes
it
stimulate
deaf
ear
complexity
unlikely
nerve
is
of
coding
that
fibers
achieved.
a
so
in
the
auditory
prothesis
normal
However,
can
nerve
exactly
functioning
in
implants can
the
provide
some information regarding intensity and duration which
should aid in
sounds
without
Seligman,
some
lipreading and allow recognition of some
1980).
frequency
stimulation,
and/or
as
place
visual
cues.
(Tong,
Attempts have
information
used
of
with
been
as
stimulation,
mu 11i-e1ectrode devices.
made
well
single
Clark,
to
via
electrode
as
and
provide
rate
of
devices,
used
with
3
Clark,
Shepherd, Patrick,
Black
p.191) stated that any electrical
arid T o n g ( 1 9 8 3 ,
array must meet
these
certain design requirements:
"1) it must be atraumatic in insertion; 2 ) it must
be
biologically inert (i.e., biocompatible with
the tissues); 3) current must be localized (i.e.,
should
not
predispose
the
patient
to
local
infection); 4) only minimal damage should occur
with
chronic
stimulation);
5)
it
must
have
mechanical stability (i.e., not prone to break as
a result of repeated stress); and 6) fabrication
must be practical (i.e., simple and inexpensive)."
There
implant
are
currently
protheses
Appendix
A.
in
The
manufacturers of
several
use.
These
basic
cochlear
types
are
cochlear
summarized
philosophies
implants
of
of
vary
in
different
in
terms
of:
number of electrodes used for stimulation (i.e., single
versus
mu1ti-e1ectrode
(i.e., monopolar:
remote
ground
remaining
versus
bipolar:
spaced
current
which
neurons
electrodes
systems);
stimulation
flows between
stimulates a
and
generates
current
which
site of
stimulation);
versus
digital);
large
wide
flows
for
site
of
of
speech
science,
electrical
of
professions
otopatho1ogy,
an
implant
a
two
more
including
rheology,
engineering
and
of
spread;
closely
localized
analog
(i.e.,
(Staller, 1985)
system
involves a
otology,
audiology,
psychoacoustics,
polymer
current
stimulation
intracoch1 ear versus extracoch1 ear).
variety
population
between
allows
active
coding strategies (i.e.,
and
The development
an
regime
and
(Radcliffe,
e1ectrophysiology,
biomechanical
1984).
and
Other
4
professionals become involved in the rehabilitation and
counseling
of
cochlear
pre-operative1y
speech/1anguage
and
implant
patients
post-operatively
pathologists,
deaf
both
(e.g.,
educators,
pyscho1ogi sts).
Cochlear Implant Versus Hearing Aids
Hearing
amplifiers.
aids
and
vibrotactile
devices
are
A hearing aid has the capability of making
sound louder and possibly clearer due to an increase in
loudness.
acoustical
attempts
A
vibrotactile
information
to
increase
device
through
is
used
tactile
auditory
to
convey
stimulation
awareness.
A
in
cochlear
implant system is also an amplifying device in that the
electrical
signal
his/her most
is
delivered
comfortable
to
loudness
the
level,
patient
at
however,
the
system possesses a speech processor which also selects
key acoustical
and
information (i.e.,
frequency)
(Mecklenburg,
to translate
to
be
1985a).
this
delivered
In
intensity, duration,
to
the
addition, the
information
into
implant
implant
works
electrically
coded
signals that stimulate nerve fibers within the
(Staller,
1985).
Typical
user
implant
cochlea
recipients
have
coh1 ear pathologies which allows for the stimulation of
nerve
fibers
and
makes
use
functioning auditory system.
of
the
otherwise
normal
5
A cochlear
the
input stage
into
electrical
processed
by
compression
implant
is similar to a hearing aid
in that acoustical
current
an
by
to
perceptual characteristics.
aid transduces the
energy,
through
the
microphone
amplifier,
circuit
two devices is in
a
energy
filter
accommodate
electrical
a stimulating
is converted
and
is
then
network,
and
the
patient's
The difference between the
the output stage.
implant
in
signal
delivers
an
Whereas a hearing
back
to
acoustic
electrical
signal
electrode array (Staller,
1985,
see Figure 1).
Figure 1
Hearing Aid Versus Coch1 ear Implant
(Sta11er,1985) Presented at the Denver Ear Institute
Cochlear Implant Symposium, Denver, CO.
COCHLEAR IMPLANT
VS
HEARING AID
INPUT STAGE
ACOUSTIC ENERGY
ELECTRICAL ANALOG
OUTPUT STAGE
modified electrical analog
cochlear stimulation
electrical distribution
acoustic energy
cochlear stimulation
mechanical distribution
6
Implant Components
The goal of any
implant system
patterns of neural
activity that
understand
(Miller,
Most
speech
implant
systems
components.
Miller
can
et
al.
those
the brain requires to
Tong,
be
is to elicit
and
divided
Clark,
into
1984).
four
<1984) described
major
these
as
including the following.
A.
Neural
Interface:
this
component
generates
controlled electrical currents which stimulate auditory
nerve fibers.
B.
processor
External
is needed
(speech)
to
Processor:
transform
incoming acoustic speech signal
the
information
speech
from
into an electrical
the
form
which retains the important speech components but which
can
also
neural
be
presented
at
a
crude
level
through
the
interface of the prothesis.
The signal
processing strategy utilized depends on
which research center is developing and programming the
device.
which
Mu1ti-e1ectrode
extracts
duration,
information
and
electrode/channel
devices
and
frequency
information.
duration
transmitted
to
percutaneous
plug (i.e.,
internal
utilize
the
are
capable
of
direct
single
processing
and
external
electrode(s)
strategy
intensity,
whereas,
information
The
a
regarding
frequency,
intensity
to the
devices
either
electrical
limited
signal
through
is
a
connection
receiver) or a transcutaneous receiver
7
(i.e., data inductively transmitted to a receiver under
the skin via a radio frequency carrier).
C. Signal Transfer Hardware: this consists of the
internal
receiver,
external
transmitter/connector.
microphone,
These
and
components
external
interact
to
produce electrical
representations of acoustic stimuli
and
this
electrical
radio
frequency
deliver
tissue.
A
transmit
this
internal
The
information
receiver
radio
or
stimuli
carrier
across
a direct
frequency
to
carrier
the
may
the
be
skin
neural
used
to
to
an
percutaneous
connector.
is
such
designed
that
correct data obtained from a custom integrated circuit
is required before any stimulation occurs.
the
Implant
will
be unable
response to any external
Therefore,
to generate stimulation
radio frequencies outside
in
its
acceptance band.
D.
capabilities
will
Perceptual
of
integrate
define
and
his/her
minimal
adult
each
may
auditory
have
patient
to
cues.
to
learn
experiences
and
the
(i.e.,
utilize acoustic
ability
auditory
Mechanism:
make
The
to
how
perceptual
the
patient
information) will
meaningful
post 1ingua11y
analyze
integrate
a
of
deafened
new
these
use
set
with
of
past
speech processing experiences.
The
system
most
fundamental
is to generate neural
auditory
nerve
which
may
function
of
the
implant
discharge patterns to the
be
modulated
by
external
s
signals.
speech
These
signals are
signal
by
a
derived
speech
from
an
processor
acoustic
and
then
transferred to an electrode or electrodes at the neural
Interface.
This results
in
a perceptual
sensation
of
" s o u n d " ( M i l l e r e t a l ., 1 9 8 4 ) .
Single Versus Mu1ti-e1ectrode Arrays
There are a variety
with
a
cochlear
of electrode arrays utilized
prothesis.
Information
may
be
transmitted through a single active electrode as a one
dimensional
active
time
varying
electrodes
as
a
( M i l l e r e t a l ., 1 9 8 4 ) .
extra-coch1 ear
or
on
the
pattern
or
through
several
mu1ti-dimensiona1
pattern
An active electrode can have an
placement
promontory
adjacent
to the
(Hochmair-Desoyer
1983) or the electrode(s) can be
through the round window
round
and
window
Hochmair,
intracoch1 ear, placed
into the sea la tympani (House
and Urban, 1973; Mecklenburg, 1985a; Rebscher, Kessler,
and Calvert, 1985; Dankowske, 1985; Ferreira, 1985).
The
two
perception,
place
controversy
over
mu1ti-e1ectrode
regarding
pitch
theory
the
systems.
delivery
electrode(s)
which
primary
within
the
of
the
theories
and
rate
pitch,
selection
of
Therefore,
frequency
cochlea
implant
regarding
often
single
the
pitch
cause
versus
philosophies
information
differ
according
manufacturer
to
to
maintains.
According to the place pitch theory, the perception of
pitch depends on which auditory nerve fibers are firing
9
Impulses.
Mu 11i-e1ectrode systems are designed around
this theory.
of
pitch
depends
impulses.
through
Rate pitch
on
Implants
one
theorists maintain perception
how
that
electrode
rapidly
deliver
are
and place are
pitch in the normal
the
designed
pitch theory (Kriewel1, 1985).
both rate
the
fibers
entire
around
fire
signal
the
rate
The probability is that
involved
in
the perception
of
auditory system.
In simple terms, a single electrode/single channel
system
consists
information
to
a
of
a
device
is coded into an
single
electrode.
stimulation within
where
all
electrical
Such
acoustical
signal
applied
could
involve
a system
the cochlea or outside the cochlea.
There are single electrode, mu1ti-channe1 devices which
extract
certain
attempt
to
single
acoustical
deliver
electrode
this
features
processed
(Hochmair,
of
speech
information
1983).
In
and
to
a
contrast,
a
mu1ti-e1ectrode system contains a number of stimulation
sites
within
the
cochlea.
The
coding
of
acoustic
information into electrical stimulation takes advantage
of
the
nerve
naturally
fibers
essence,
frequency
become
in
apical
energy
active
in
occurring
the
cochlea
electrodes
is
tonotopic
response
(Hirshorn,
are
dominant
to
organization
1985).
stimulated
and
high
The amount of stimulation received
basal
when
of
In
low
electrodes
frequency
energy.
is dependent on the
10
neural
population
reserve
along
the
cochlea
(Meek 1enburg, 1985b).
Mu1ti-channe1
processing
channel
Theoretically,
for
each
mu1ti-channe1
divide
the speech
allow
subjects
frequency
systems
spectrum
to
employ
a
customized
stimulating
electrode.
speech
in
that
contiguous bands should
discriminate
spectral
processors
components
location of basal electrodes.
between
of
the
speech
higher
due
to
the
Therefore, mu1t1-channe1
stimulation as compared with single channel stimulation
is believed to more accurately
reflect normal
auditory
nerve excitation patterns (White, Merzenick, and Gardi,
1984).).
when
However, White
two
strong
or
more
et
electrode
Interactions
between
al.(1984) discovered
channels
the
are
and
quality
of
the
stimulated,
channels
Those interactions can then greatly alter
sensation
that
can
occur.
the
loudness
evoked
during
mu1ti-channe1 stimulation.
Clark, Black, Dewhurst, Forster, Patrick, and Tong
(1977) stated
evoke
that
temporal
mu1ti-e1ectrode systems
patterns
populations of
auditory
current
must
flow
stimulating
different
attempted
electrodes
highly
at
to
using
either
closely
an
array
1978).
In such cases,
so
sites
active
that
produces
This
positioned
of
to
separate
localized
different
sensations (Chouard,
by
partially
nerve fibers.
be
electrodes
in
attempt
has
been
bipolar
electrodes
11
Interwoven
Patrick,
with
and
a
common
Bailey,
electrode array
using a
cochlea (Berliner
and
ground
electrode
1979)
or
remote
ground
Eisenberg,
with
a
(Clark,
monopolar
external
1985a).
to the
Danley
and
Fretz (1982) concluded that common-ground and monopolar
electrode
arrays
however, this
the
value
of
provide
poorer
current
is sometimes offset
the
lower
current
by
localization,
an
adjustment
threshold
obtained
of
by
these arrays.
Psychophysical
(1983)
indicated
loudness
and
affected
by
channel
that
behavioral
threshold
changing
when
stimulated
experiments described by Eddington
one
or
responses
measures)
the
more
are
stimulus
than
one
simultaneously.
(i.e.,
substantially
polarity
channel
Since
of
are
one
being
interactions
generated during simultaneous stimulation can occur, it
might
be
channel
useful
to
avoid
separately
them
in
by
time
stimulating
(i.e.,
temporally
interlacing the stimuli across the channels).
al.
(1984)
declined
found
with
Interactions
simultaneous
interchannel
were
channel
distance
decreased
with
each
White et
Interactions
and
bipolar
the
channel
rather
than
monopolar stimulation.
Having a choice of stimulation sites is important
for
the
perception
selectivity
fibers
of
(Farrer,
of
pitch
different
Mangham,
due
groups
and
to
of
the
frequency
auditory
nerve
Kuprenas,1984).
The
12
damaged
cochlea
stimulation
Seligman,
some
at
is
different
1980).
there
frequencies
For others,
frequency
discrimination
population
in
electrodes
stimulation
its
response
<Tong,
Clark,
<1980) stated
orderly
along
the
will
be
allow
amplitude
for
at
for
of
on
Therefore,
individual
different
from
the
as clear as
dependent
cochlea.
that
length
to
and
progression
the response is not
the
would
al .
is
cochlea.
in
locations
Tong et
patients,
high-to-low
unpredictable
neural
multiple
adjustments
electrode
of
sites.
Because of greater number of stimulation sites and thus
increased information delivered to the brain, advocates
of
the
mu1ti-channe1/mu1ti-e1ectrode
systems
suggest
that patients do better with speech discrimination even
on
open-set
discrimination
tests
without
lipreading
(Mecklenburg, 1985a, Mecklenburg and Brimacombe, 1985b)
single
Another
argument
supporting
channel
systems was
mu1ti-channe1
provided
by
Farrer
over
et
al.
<1984, p.75):
"In
general,
the
mu1ti-channe1
device
allows
recognition
of
more speech
elements than
the
single
device
through
a
unique
method
of
extracting and recording the important resonances
of the voice and presenting them to the auditory
nerve.
It offers a choice of stimulation sites in
the cochlea as well as several variable dimensions
with which to code incoming acoustic signals."
Single
their
device
clinical
channel/single electrode
is
trials
a
and
proven
one
with
examinations
Implant system has built-in potential
advocates argue
more
and
the
years
of
present
for upgrading as
13
new
devices
are
developed
(Berliner,
1985).
The
3M/House single channel/single electrode unit
also has
the
from
advantage
of
having
received
approval
the
Food and Drug Administration (FDA) for use with adults
and
children
NUCLEUS
(Berliner
and
mu1ti-e1ectrode
Eisenberg,
device
also
1985b).
has
FDA
The
approval
for use with adults and they have recently received FDA
approval
to
use
their
device
on
children
ages
10-18
years.
Comparisons
systems
have
superior
between
shown
in
of
Eddington
recognition results for
two-syllable
words
and
mu1ti-e1ectrode
terms
discrimination.
single
(1983)
devices
better
found
for
single channel
to
recognition
that
open-set, unpracticed
were
systems than the best
speech
mu1ti-e1ectrode
be
and
speech
lists of
mu1ti-channe1
results reported.
However, Eddington (1983) also pointed out that because
the processing schemes used by single channel
are different,
drawing
any
firm
the
merits
of
the
relative
patients
conclusions regarding
single
channel
and
mu1ti-channe1 stimulation scheme is difficult.
Digital
Versus Analog Coding Schemes
There are two major coding strategies utilized in
the
different
the market:
implant
speech
processors
analog versus digital coding.
currently
on
1A
A.
signal
Ana Ioa:
which
Acoustic
This system
is
energy
comparable
filtered
to
The
more
analog
compensate
characteristics.
or
to
is converted
representation.
the
an
electrical
sound
stimulus.
into a direct
signal
for
the
This signal
electrodes
utilizes
is
compressed
patients
is then
CHochmair,
electrical
and
perceptual
delivered to one
1983).
This
type
of
system may introduce added noise but improves precision
of timing and current
B.
Digital:
series of
the
charge
speech
level (Miller et al., 1984).
Digital
balanced
signal.
coding schemes utilize
electrical
The
pulses to
incoming signal
is
a
encode
processed
and selected electrodes are stimulated corresponding to
various
formats
generate
from a
a
of
pulse
speech.
each
time
the
positive to negative
characteristics
intensity)
signal.
by
This
extraction
of
the
certain
has
Digital
either
signal
crosses
input
voltage or
pulses
key
also
systems
(Mecklenburg,
(i.e.,
features
been
determines the
of
referred
1985a,
to
rate
and
the
speech
as
feature
Mecklenberg
and
Brimacombe, 1985a).
The digital processing scheme has been reported to
decrease
also
transmission
limits the
noise
precision
(Miller et al., 1984).
of
problems
but
timing and
this
current
scheme
level
15
Intra-coch1 ear Versus Extra-coch1 ear Devices
Extra-coch1 ear devices, those which are placed on
the
promontory,
the
internal
device may
have
the
auditory
cochlea.
delivered
to
more advantageous than
more
and,
sensitive
being safer
However,
frequency and
nerve
devices
such
a
intensity
fibers within
are
to
believed
to
the
be
extra-coch1 ear devices as seal a
require
electrophysiological
electrodes
of
the
Intra-coch1 ear
electrodes
of
structures.
limit the amount
information
tympani
advantage
less
responses
thus,
current
than
do
intra-coch1 ear
thresholds
than
to
evoke
round
window
devices
reveal
extra-coch1 ear
(Simmons,Lusted, Meyers, and Shelton, 1984).
devices
However,
the placement of intra-coch1 ear devices do increase the
risk of damaging the scala tympani.
Summary
The optimum coding scheme remains controversial at
this
time.
strategies
Clearly,
the
are
difficult
in
assessment
differences
investigators
and
to
the
merits
to
of
assess
tests
used
differences
populations (Hochmai r-Desoyer,
1984).
it
that,
might
amount
eventually
of
stimulation
nerve
turn
out
survival,
scheme
will
the
be
different
due
by
depending
chosen
the
different
the
complexity
Hochmair-Desoyer, and Hochmair, 1985).
to
between
In
coding
patient
future,
on
of
the
the
(Wallenberg,
16
Children and prelingually deafened adults are not
considered good candidates for
due to their
Their
lack
to
because
the
necessary
adequate
lack of experience with acoustic stimuli.
of
trying
experience
adequately
patients
feedback
fitting
stated
current
amount
of
the
mu 11i-e1ectrode devices
to
would
adjust
would
be
the
unable
to
processor
the
to
ensure
Kriewell
(1985)
systems
utilized
when
provide
used
delivered to the
currently
problems
speech
1985).
mu1ti-e1ectrode
strategies
the
clinician
(Kriewell,
information
create
may
limit
the
cochlea due
in
to
mu1ti-channe1
speech processors.
Such strategies focus primarily on
processing
information
speech
appropriately
process
and
environmental
thus
sound
result, could be confusing to the patient.
might
and,
not
as
a
THREE COMMON TYPES OF DEVICES
3M/House
The
3M/House
electrode/single-channel
processor,
and
House,
1985).
which
electrical
current
processor.
a
A
which
then
coil
and
to a
is
this
to a
ground
of sound.
of
a
internal
Eisenberg,
an
electret
energy
into
current
signal
is
to
a
directed
e1ectromagnetica 1 1 y
transcutaneous
flow stimulates auditory neural
perception
has
is then transmitted to an
flows
single
consists
acoustic
electrical
skin
a
transmitter,
transmits
modulated
induced across the
which
system
converts
and
is
system (Berliner,
The
transmitter
The current
external
a magnetic
microphone
to
system
microphone,
receiver, and
system
receiver.
active electrode
electrode.
The
current
tissue and produces the
(Berliner and
Eisenberg,
1985a;
Berliner et al., 1985; Berliner, 1985)
The electrodes are pure platinum and are used in a
monopolar
configuration
with
implanted approximately 6mm
the ground electrode
in
the
active
electrode
into the scala tympani
the
temporalis muscle
and
region.
The speech processor uses a bandpass filter from 340 to
2700 Hz.
to
The signal
amplitude
waveform.
from the
modulate
a
The modulator
16k
bandpass filter
Hz
is highly
sinusoidal
nonlinear
is used
carrier
in
terms
of stimulation voltage at the electrode of the internal
17
18
receiver
in
relation
to
sound
pressure
level
at
the
microphone <Fretz and Fravel, 1985).
3M/V i enna
There are two types of Vienna cochlear protheses:
1) a
four-electrode
bipolar
electrode
intra-coch1 ear
channels;
and
implant
with a single active
use
analog
an
sound
implant
four
an
extracoch1 ear
electrode.
Both systems
processing
2)
with
scheme
that
has
the
capability to cover a frequency range from 30 to 10k Hz
(Hochmair-Desoyer, 1984).
With the extra-coch1 ear device,
placed on,
biggest
not
through, the round window.
advantages of
such
a system
very little risk of mechanical
structures
(Hochmair,
mu 11i-channe1
in
that
device
various
differs
rationale
frequencies
different
is that
The
from
frequency
The
One
damage to the
1983).
individually.
by
the electrode
the
there
is
inner ear
intra-coch1 ear,
the
3M/House
bands
for
of
is
are
amplified
amplifying
amounts stems
device
different
from
the
fact
that high frequency speech signals are relatively weak.
Therefore,
high
amplification
to stimulate
nerve
high
adequately
frequency
frequencies
the
(Kriewel1,
energy
require
fibers of
1985).
is a critical
greater
the
auditory
Transmission
factor
of
for speech
discrimination as most of the consonant phonemes in the
19
English
language consist
of high frequency,
low energy
i nformati on.
A
microcomputer
processor.
The
input
is
used
signal
to
to
adjust
the
the
stimulator
continuous sine wave which varies in frequency
increments
from
100
to
4k
Hz
sweep
<FSS)
is
used
in
patient's feedback to determine
for
sound
constant amplitude and small
increment
levels
equally
loud
at
<Hochmair-Desoyer,
<1984) stated that
most
in small
with
the frequency
During
heard
a
A frequency
conjunction
processor.
be
the
is
CHochmair-Desoyer,
Hochmair, Buriank and Stiglbrunner, 1983).
stepped
speech
the
response
stimulation,
in frequency can
comfortable
1984).
a
loudness
Hochmair-Desoyer
the FSS method has the advantage of
being quicker and easier for the patient.
NUCLEUS
The NUCLEUS mu 11i-e1ectrode/mu1ti-channe 1
utilizes 32 bands
of
pure
which
are
10
of
stiff
support)
The
active,
acoustic
current
and
arranged
signal
is
carrier of 2.5k
is
platinum
which
on
are
a
used
25mm
converted
transmitted
electrodes
via
to
a
an
a
carrier.
electrical
radio
Hz to a tuned external
<22 of
provide
silastic
into
system
frequency
induction coil.
The system utilizes an electromagnetic induction system
between
the
external
coil
and
the
internal
<Mecklenburg and Brimacombe, 1985a, 1985b).
receiver
20
The
strategy
(Fo),
design
which
first
uses
allows
formant
a
feature
estimates
(Fl),
extracting
of
second
the
the patient (Mecklenburg,
results from
an
estimate of
dominant spectral
(Mecklenburg,
peak
is
to
stimulation
at
the rate
Conversely,
a
low
(Mecklenburg,
information
of
a
the
led
peak
and
basal
is
nasality
due
to
by
frequency
electrode
selected
will
for
frequency.
stimulate
an
in the cochlea
the addition
increased
to identify
to
280-4k Hz
high
fundamental
Reportedly,
to
and
to be sent
the range of
frequency
frequency
1985b).
has
and
that
(F2),
represented
is more apically placed
implant recipient
voicing
and F2
detected,
pitch
Electrode selection
Therefore, when
corresponding
electrode which
F1
energy within
1985a).
energy
1985b).
voice
formant
signal amplitude to determine the signal
coding
ability
of
for
F1
the
the acoustic features of
transmission
of
the
low
is
the
pitched F1 component (NUCLEUS Training Manual).
One
microcomputer
of
the
which
variable across the
Interface
systems
allows
major
stimulating
different
levels
electrodes.
provides communication
and the speech processor.
components
There
to
be
A
computer
the
computer
is a special
erasable
between
programmable read-only memory chip (EPROM) which allows
the speech processor to be "mapped".
Mapping Involves
identifying the threshold and maximum comfortable level
(i.e.,
dynamic
range)
for
each
electrode.
This
21
procedure requires approximately three hours to program
and all
of
the electrodes can
patient's perceptions
change
be reprogrammed
due
to
increased
as
the
implant
usage and auditory experience (Mecklenburg, 1985a).
PATIENT SELECTION-ADULTS
General Considerations
A.
Age:
selection, only
In
the
beginning
years
of
those subjects who ranged
patient
in
age
from
18 to 65 years were considered as potential
candidates
(Maddox
House
and
Institute
years
of
Porter,
began
age
1983)-
implanting
with
NUCLEUS system has just
implant
approval
While,
children
to
there
are
from
the
young
Food
The
has
the
Drug
approval
received
(Mecklenburg,
on
two
mu1ti-channe 1
previously
devices
Ear
as
and
recently obtained FDA
adults
other
the
as
1985).
and
implant
1980,
children
approval
Administration (Berliner,
to
In
market
FDA
1985b).
(e.g.,
Storz and Symbion) which have FDA approval for clinical
use, these devices are still under investigation.
B.
Etiology
etiologies
cochlear
among
of
adult
protheses
and meningitis.
malformations of
factors
which
hearing
loss.
single
cochlear
Other
disease,
patients who
(both
systems) include:
Menieres
Hearing Loss;
the
cause
1985; Campos, 1985)
ear),
permanent
(Maddox
and
and
a
mu1ti-e1ectrode
ototoxicity,
loss
include
syndromes (e.g.,
trauma,
profound
Porter,
common
received
hearing
congenital
inner
have
otosclerosis,
causes of
various
The most
and
unknown
sensorineural
1983;
Eisenberg,
23
Information on the etiology of the hearing loss is
important
for
assessing
the
condition
(e.g., ganglion cell population).
by
Goin,
1985)
ganglion
concluded
cells
are
discrimination
and
must
the
be
in
Therefore,
that
certain
implantation.
implantation
is
chances
greater
in
used
to
however,
help
this
assess
3,000
of
assessment
those
cells.
speech
of
the
preclude
success
with
pathologies
which
Promontory
population
procedure
these
cochlea.
may
for
neural
10,000
successful
region
preserve dendrites/ganglion
is
for
etiologies
The
cochlea
approximately
approximately
apical
the
Schuknecht (as cited
that
needed
of
has
testing
reserve,
questionable
success.
Some
implantation
of
the
are
etiologies
temporal
bone
which
von
malformations
(e.g.,
with
as
other
or
severe
congenital
of
membranous
labyrinths
the
bony
and
syndrome);
and
in
which
neurological
or
physical
head
acoustic neuromas
disease);
syndromes
retinitis
in
Recklinghausen's
Mondini's
processes
preclude
fractures resulting
extensive cochlear damage; bilateral
(e.g.,
may
pigmentosa
trauma,
with
certain
deafness
is
disease
present
disabilities such
associated
cerebrovascular
blindness,
accident
and
degenerative neurological disorders (Maddox and Porter,
1983).
unfeasible
These
or
etiologies
make
the
could
make
rehabilitation
implantation
process
too
24
complex
and
lengthy.
Promontory
testing,
X-Rays and CT scans may be used to
of
the
seali
tympani
(e.g., internal
C.
the
and
inability
to
performance
and
Patients
or
amplification
inner
ear
structures
Patients need to demonstrate
receive
cues.
questionable
assess the patency
auditory meatus, transtympanic recess).
Hearing Acui tv:
auditory
other
polytome
limited
often
with
utilize
initially
receive
who
benefits
demonstrate
such
effectively
from
conventional
substantial
devices
after
gains
a
in
period
of
training (Fourcin, Rosen, Moore, Douek, Clarke, Dodson,
and
Bannister,
where
1979).
conventional
assistance.
aid
whether
these
1976).
there
amplification
will
be
gives
cases
little
In such cases, the problem of selection of
hearing
responses
However,
versus
with
cochlear
patients
implant
show
conventional
centers
minimal
but
amplification
around
definite
(Brackmann,
The selection of the best device would then be
focused
on
amplification
whether
are
at
responses
or
lower
with
than
conventional
those
found
with
implant patients.
The use of residual
hearing as the main selection
criteria may be complicated in cases where benefit from
conventional
no benefit
amplification
by
is received by the opposite ear.
Porter (1983) stated there
cochlear
is received
implant
was used
have been
cases
successfully
in
one ear
and
Maddox and
in
which
a
conjunction
25
with conventional
that
the
ability
additional
implant
to
benefits
However, they
pre-operative1y
will
be
gained
stated
predict
by
the
what
cochlear
is difficult, if even possible.
D.
the
amplification.
Congenital
House
Ear
Versus Acquired Hearing Loss;
Institute
(single
NUCLEUS (mu1ti-e1ectrode)
congenital
and
acquired
have
electrode)
reported
hearing
Both
and
success
losses
the
with
(Mecklenburg,
1985a; Berliner, 1985; Eisenberg, Berliner, Theilemeir,
Kirk
and
Tiber,
However,
a
1983;
higher
Eisenberg
incidence
and
of
House,
1982).
failures
(i.e.,
nonusers) exists among patients with congenital
losses
(Ber1i ner, 1985).
Maddox
and
Porter
(1983)
post-implant
patients who do not
not
more
perform
audiological
testing,
subjectively
be
poorly
on
use
that
their
their
use
of
Therefore,
patients with an
recognize
would
and
it
ability
auditory
assumed
with
utilize
congenital
losses
auditory experiences have been severely
The seemingly
predicted
persons
success
with
that
acoustic
important
or
congenital
of
losses
an
their
those
likely to
cues
than
whose
past
limited.
variables which
failure
to
cues may
acquired loss would be more
effectively
patients
has been
do
objective
inferior to patients who successfully utilize
implants.
those
Implant
pre-operative
however,
make meaningful
stated
indicate
implant
include:
among
age
of
26
identification; previous experience with amplification;
and type of communication used (i.e., oral
communication
versus
manual).
versus total
Patients
with
a
congenital hearing loss who were identified at an early
age,
exposed
to
in
an
oral
or total
communication program have been shown
to
have
a higher
(Maddox
alone
and
do
auditory
success
Porter,
not
stimuli,
rate
with
1983).
guarantee
and
a cochlear
However,
success
trained
or
prothesis
these
failure
criteria
with
an
imp 1 ant.
E.
factors
Additional
may
make
Several
post-imp 1 antation
exceedingly complex.
solely on manual
Factors:
additional
rehabilitation
Patients who are nonoral and rely
communication, those who exhibit
poor
language skills and/or minimal or unintelligible speech
skills,
likely
and
to
Children
involve
those
be
patients
additional
in
geographical
cases,
have
considered
and
considered
such
who
mu 11 i-handi caps
for
with
the
patient
cochlear
congenital
rehabilitation
selection.
implant.
losses
needs
that
less
would
must
Financial
considerations must also be assessed.
the
responsibility
rehabilitation staff
of
each
be
and
In
institute's
is to determine whether the staff
are adequately prepared and trained to deal
additional
are
with these
factors (Maddox and Porter, 1983).
27
Medical Assessment
A
major
factor
surgeon's beliefs the
implantation
and
rehabilitation
in
patient
patient
the patient
program
selection
is
the
is a good candidate
will
with
reliably
full
for
complete
cooperation.
a
The
physician's pre-operative assessment typically includes
the following (Goin, 1985):
A.
Routine Physical
Examination
B. Transtympanic e1ectrophonic stimulation of the
cochlea (i.e., promontory testing) in attempt to
demonstrate intact neural function (i.e., ganglion
cell population) within the cochlea and along the
nerve VIII pathway (House and Edgerton, 1982).
C.
Polytome x-rays of the inner ear to determine
if fibrosis or calcification of the cochlea is
present (utilized to evaluate the patency of the
coch1ea)D.
Evaluation of the middle ear
effusion,
recurrent
otitis
round-window obliteration.
to rule
media,
E.
Cranioaxia 1 tomography (CT) scan
evaluate status of the cochlea and
structures.
Although promontory
standardized
estimate
electrical
nerve
critical
system.
in
stimulation
survival
Mathews and Walder,
is
testing is
the
Simmons
et
1979).
does
not
However,
selection
of
a
out
and
to further
surrounding
often utilized,
test
designed
exist
this
to
(Simmons,
information
cochlear
al . (1979) stated
a
that
implant
it
makes
little sense to place a complex mu 11i-e1ectrode system
in
a
cochlea
with
a sparse
nerve population
expect to obtain better results than that
electrode system.
and
then
from a single
28
Post-operative
further x-rays of the
active
electrode
assessment
involves
obtaining
inner ear to check the ground and
placement
and
to
determine
if
the
with
the
electrodes are intact.
The
physician
histopathology
well
as
from
from
is
an
the
also
concerned
implanted
electrode
surgical
risks.
Berliner
Eisenberg, (1985b) discussed the potential
may
occur
as
the
result
of
system
surgical
damage
as
and
that
implantation.
Mastoid surgery may result in infection, meningitis, or
facial
paralysis.
and enter
To transverse
the cochlea
may
the
middle
ear space
provide a potential
pathway
for the spread of otitis media to the inner ear system.
Insertion of
to
trauma
may
be
electrodes into the cochlea also may
of
the
inner
associated
ear
with
structures.
mechanical
lead
Osteogenisis
damage
or
the
presence of the electrode in the seala tympani.
The scala tympani begins to curve at approximately
10mm
at
which
possibly
point
pierce
the
resulting
in
membrane,
Reissner's
spiral
will
a
lamina.
membranes
of
rupture
membrane,
result
and
fluid
in
electrode
the
of
and/or
The rupture of any of
perilymphatic
could
implanted
mechanical
subsequently
perilymphatic
the
the
significantly
toxic
to
the
basilar
the
osseous
diffusion
the
of
fluids.
hair/nerve
increase
ear
these structures
endolymphatic
is
inner
can
cells
amount
the
The
and
of
29
sensorineural degeneration (Otte, Schuknecht, and Kerr,
1978; Burgio, 1985).
The possible long term damage
be
considered
particularly
The coch1 ear nuclei
after birth.
at
implanting
children.
are not completely developed until
Therefore,
the cochlea
when
to the coch1ea must
if
too early
the prothesis
an
age,
it
is placed
could affect
maturity of the cochlear nuclei CGoin, 1985).
auditory
deprivation
revealed that
an
maturation
and,
because
post-nata11y,
require
of
the
early
of
lower
this
cells
and
auditory
in
the
cochlear
takes
is
place
thought
in
order
to
Webster,
1977,
1979).
auditory
system may
to
develop
actually
stimulation.
implantation of children may
have
sound can cause
nucleus
stimulation
the
However,
mammals
development
cochlear
(Webster
enhancement
with
the
auditory
completely
in
the early deprivation of
incomplete
nucleus
studies
in
An
occur
Thus,
the
enhance the maturation
of
the cochlear nucleus.
The possibility of mechanical
taken
into
consideration
when
rupture must also be
implanting
the
NUCLEUS
mu1ti-e1ectrode system which extends approximately 22mm
into the cochlea.
1985)
stated
related
to
deprivation
Brand (as cited in Fretz and Fravel,
tissue
any
of
damage
mechanical
blood
supply
tends
not
to
damage
but
and
tissue
be
directly
rather
fluids
to
the
which
30
subsequently
results
in
deprivation
of
oxygen
and
nutr i ents.
Current
studies
have
found
the
following
histopathologic results from an implanted temporal
(implanted with
the
3M/House single
electrode
bone
device)
(Burgio, 1985):
1) Typical foreign
possible infection)
body
response
2) No significant tissue growth
(e.g.,
edema,
in the middle ear
3) Round window well sealed by fibrous tissue thus
providing a natural barrier between the middle and
inner ear.
4) New bone growth was localized to the round
window and lower basal turn at or near the opening
made
into
the
seal a
tympani
for
electrode
insertion.
The new bone was not along the length
of the electrode and did not appear to adversely
affect the nerve cell populations.
5) The 15mm electrode, which is inserted 6mm into
the seal i tympani, caused mechanical damage to
cochlear tissues.
As the electrode extended past
the first turn of the cochlea, the amount of
tissue damage increased as a result of damage to
the
cochlear
duct
which
in
turn
results
in
degeneration of nerve fibers.
6) Large nerve cell survival
7) In 100% of the cases studied, insertions were
safe to the basilar membrane and approximately 96%
of electrode insertions were safe to the osseous
spiral lamina (Radcliffe, 1984).
Psychological
Any
cochlear
implant
Assessment-Adults
candidate,
both
child, must meet the following psychological
adult
and
criteria:
"1) no evidence of severe organic brain damage; 2)
no evidence of psychosis; 3) no evidence of mental
31
retardation; 4) no behaviora1/persona 1 ity traits
that would make completion of the rehabilitation
program
unlikely;
and
5)
no
unremitting,
unrealistic expectations about the implant on the
part of the patient or the family" (Tiber, 1985,
p-48).
An
indepth interview is often included to measure
motivation
levels.
Many
patients
request
information
on cochlear implants because of pressure placed on them
by their significant others (Campos, 1985).
Therefore,
these
concerning
the
interviews
patient's
also provide
expectations
of
information
the
both its benefits and limitations.
also
must
be
acceptance
of
support,
and
considered
his/her
regarding
Other factors which
include
deafness,
the
implant
the
the
commitment
amount
to
patient's
of
family
post-implant
rehabi1i tat i on.
Adverse
psychological
long-term stimulation
have
not
yet
been
and use
reported
effects
of
the cochlear
(Miller,
1979).
(1979) concluded that any psychological
occur
are
Implant
generally
has often
positive.
been
shown
secondary
The
to
implant
Miller
changes that do
use
to enhance
of
a cochlear
communication
skills, promote confidence
in social
settings,
promote
independence
provide
positive
feelings
towards
of
(Miller,
1979;
improved
and
quality
Ber1i ner, 1982)
life
House
and
32
Audiological
The
deaf
audiological
adult
is
tests.
unable to adequately
(Edgerton,
Therefore,
assessment
difficult
suprathresho1d
patient
Assessment-Adu1ts
the
to
for
perform
These
the
with
protocols
assessment
and
of
a
conventional
are
assess the residual
Eisenburg,
profoundly
typically
skills of the
Thielemeir,
patient's
1983).
ability
to
receive and utilize auditory cues should not consist of
conventional measurements alone.
Qne critical
patient
will
implant or
implant
clear
a
audiometric question
likely
benefit
from a hearing
cochlear
benefits
aid.
prothesis
from
more
is whether the
from
a
cochlear
Most clinics will
in
patients who
amplification.
This
is
not
receive
based
on
the belief that frequency discrimination will be better
with
an
implant
appropriately
due
generated by
naturally
to
the
hearing aid
unnatural
the electrical
occuring
Mecklenburg, 1985a;
Berliner,
1985;
audiologist
must
sensory
fit
action
method
current
a cochlear
of
stimulation
versus that by the
potentials
Mecklenburg and
than
(Luetje,
1981;
Brimacombe,
1985b;
Hochmair-Desoyer,
also
aid (e.g.,
decide
whether
vibrotactile
1985).
another
with
established for
on
an
implant.
cochlear
environmental
Some
implant
sound
type
device) would
the added cues and increase performance equal
obtained
The
norms
of
provide
to those
have
been
patient's performance
tests
and
the,
33
Monosyllable-Trochee-Spondee
a l .,
1983).
Clinicians
information
to
performance
with
are
compare
the
Implant patients.
(MTS)
test
(Edgerton
encouraged
the
to
patient's
range
obtained
use
best
from
et
this
aided
cochlear
In general, patients wearing hearing
aids who perform
at
or above
the
average
for
cochlear
implant users may not be considered good candidates for
an
any
implant.
Such
further
patients may
benefits
Conversely,
patients
poorly
be
can
be
from
a
to
receive
cochlear
performing
considered
unlikely
marginally
potential
implant.
or
candidates
more
for
cochlear implantation.
Audiometric Evaluation
Audiometric assessment for adults usually includes
the following measures (Edgerton et
a l ., 1 9 8 3 ;
Luetje,
1981; Mecklenburg, 1985a):
UNAIDED EARPHONE
A. Pure-tone thresholds
B. Pure-tone uncomfortable loudness levels (UCL)
C. Speech detection threshold
D. Most comfortable level
for speech
E. Monosyllable-Trochee-Spondee test (MTS)
F. Environmental Sounds test
G.
Test
for
CHABA-Everyday
speechreadi ng
speech
ability
sentences
Hirsh, 1955; Sims, 1975)
such
as
(Silverman
the
and
34
AIDED SOUNDFIELD
A. Warbled tone thresholds
B. Speech detection thresholds
C. Environmental sounds test
D. Minimal
Auditory Capabilities battery (MAC)
The criteria utilized by
when
assessing
aided
performance
obtaining an earmold prior
that maximum
benefit
the House Ear
from
Institute
includes:
to the evaluation
the aid may
1)
to ensure
be obtained; 2)
output of the hearing aid is set at 130 dB SPL or less;
3) at
least two sensory aids are evaluated (including a
vibro-tacti1e
aid);
and
4)
speech
and
environmental
sound stimuli are presented at 70 dB SPL (Eisenberg and
Berliner, 1983; Berliner, 1985).
The
provides
Mononsy11ab1e-Trochee-Spondee
data
on
two
discrimination and
a
forced-choice
The
word
format
Environmental
five-alternative
1983).
levels
of
(MTS)
perception:
test
stress
identification while utilizing
(Erber
Sounds
forced-choice
and
Allencewicz,
test
test
is
a
1976).
20-item
(Edgerton
et
al .,
Patients are required to circle the sound they
hear from the five answer choices on a response sheet.
The
Minimal
Auditory
Capabilities (MAC) battery
was designed by Owens, Kessler, and Schubert (1982) and
is
used
to
obtain
interim
audiometric
indices
on
the
relative benefits of cochlear implants and hearing aids
for
patients
with
profound
postlingual
sensorineural
35
hearing
losses.
The
MAC
battery
consists
auditory tests and one 1ipreading test.
are
designed
prosodic
to
test
features,
environmental
sounds,
the
patient's
phonemes,
sentence
13
These subtests
ability
noise
of
to
versus
recognition,
hear
voice,
and
one-
and two-syllable word recognition.
Usually,
implantation
the
because
worse
if
ear
the
will
be
implant
selected
were
to
for
be
unsuccessful, the patient would have his/her better ear
left unharmed.
If there
is not an ear difference, the
patient's prefered ear is selected.
no preference,
a decision
and the patient.
If the patient has
is reached
by
the
physician
REHABILITATION-ADULTS
Rehabilitation typically
after
surgery
surgical
to
allow
wound.
The
involve
the
fitting
speech
processor)
(Mecklenburg,
Adjusting
the
level
each
for
and
procedure
always
amplification
the
may
of
take
the
(i.e.,
stimulation
to
several
the
current
discomfort
an
weeks as the
likely
to
to
change
The
setting
flow)
1984).
appropriate
prothesis.
includes
(i.e.,
patient's
initial
stimulator
the
rehabilitation
equipment
preferences are
usage
of
Hochmair-Desoyer ,
external
patient
external
the
two months
healing
phases of
the
1985b;
increased
complete
initial
of
patient's perceptual
with
for
begins about
fitting
of
some
guarantee
threshold
level
that
is
not
exceeded (Hochmair-Desoyer, 1984).
The
fitting of
quite complex.
be
"mapped"
comfortable
each
The
which
continued use
processor can
NUCLEUS mu1ti-channe1
includes
loudness
electrode.
a mu1ti-channe1
finding
levels (i.e.,
This
and thus,
range
tends
system
must
thresholds
dynamic
to
new "maps" have
be
and
range) for
increase
with
to be made
as
the rehabilitation progresses.
The cochlear
implant produces electrical
signals
which the patient may perceive as a crackling, humming,
or buzzing noise.
the
parameters
of
This signal may have only a few of
the
sound
36
stimulus
the
patient
may
37
recall
only
as being characteristic
hold
true
(Campos,
for
of speech.
post 1ingua11y
1981,1985;
Maddox
and
This would
deafened
adults.
Porter,
1983).
Therefore, the therapy program must provide the patient
with strategies to re-learn how to make meaningful
of acoustic stimuli.
The patient with an
need to be reminded of
the
impact of
use
implant will
long-term hearing
loss as well as the probability of needing to reprogram
the
auditory
processing
system,
if
this
is
indeed
possible (Campos,1985).
Most
minimum
clinics require
of
30-40
hours
(Mecklenburg,
1985a;
1985).
amount
The
needed for
need
each
instrumentation
effective
use
of
of
and
a
and
therapy
the
basic
minimal
language
speechreading
postoperative
is variableuse
1984;
Berliner,
rehabilitation
Some may
of
the
introduction
auditory
require extensive therapy
training,
attend a
post-surgical
regarding
of
patients to
Hochmair-Desoyer,
patient
instructions
their
cues.
simply
external
to
Others
the
may
in auditory training, speech
therapy,
voice
environmental
monitoring,
manipulation
(Maddox
and Porter, 1983).
The philosophies underlying therapy
institution
cochlear
programs,
providing
implant
a
the
patients.
controversy
should be implemented.
aural
As
exists
vary for each
rehabilitation
with
as
many
to
for
therapeutic
which
method
The issues of unisensory versus
38
mu1tisensory;
(synthetic)
centered
top-down
approaches;
programs;
approaches
(analytic)
must
home
and
be
centered
unstructured
resolved
therapeutic approach
versus
versus
versus
(Eisenberg,
utilized must
bottom-up
clinic
structured
1985).
Any
recognize the
major
levels of auditory processing and work toward obtaining
skills at each
These
levels
sound,
level (Eisenberg, 1985; NUCLEUS manual).
include:
attention,
(same-different);
l)
detection
arousal);
3)
2)
(presence
of
discrimination
identification
or
recognition
(repeating, imitating); and 4) comprehension (Erber and
Allencwicz, 1982).
At
the
detection
most
of
awareness
sound.
of
both
level,
After
sound,
discrimination
using
basic
and
training may
the
patient
activities
identification
linguistic
and
can
focus
on
demonstrates
focusing
be
on
introduced
non1inguistic
stimuli
(Eisenberg, 1985).
The
initial
stimulation
training in critical
techniques,
barriers.
and
The
speechreading
in
is followed by
listening tasks, voice monitoring
reduction
latter
a
of
is
number
known
performed
of
different
situations, varying from the optimal
patient
is
encouraged
to
barriers in ways that will
to
be
achieved
intensive
(Campos,
deal
communication
by
practicing
communication
to the poor.
with
The
communication
allow maximum communication
1981).
Critical
listening
39
tasks for speech
suprasegmental
cues
aspects
differentiation
progresses
to
sentences
medial
in
of
usually
begins
the
final
hierarchy
speech.
polysyllabic
which
and
involve a
with
words,
stress
positions
of
the many
Varied
syllable
word
stimuli
phrases
varies
in
(Campos,
and
and
short
the
initial,
1981;
NUCLEUS
training manual).
A
wide
patients'
variation
ability
to
auditory
sensations.
able
to
integrate
this
information
patients
may
information
in
a
factors which may
Some
unable
this
neural
understand
to
integrate
and
and
manner.
Other
use
The
age,
reserve)
been
be
utilize
this
various
individual's ability
(e.g.,
population
stimulated
speech.
stimulation have
paper
implant
recipients may
stimulation
influence an
earlier
cochlear
electrically
meaningful
electrical
onset,
among
implant
better
make use of
in
use
electrical
to
be
exists
to
discussed
etiology,
age
of
(Hochmair-Desoyer,
et.al., 1983).
The
mu1ti-channe1
single
channel
sensations
system
rehabilitation
implants will
systems
available
(Mecklenburg,
device,
each
due
for
program
differ
to
those
1985b).
electrode
is
to
balance
the
the
for
that
for
wider
incoming
used
variety
of
with
a
mu1ti-channe1
With
a
mu1ti-channe1
potentially
producing different sensations.
need
from
designed
capable
Therefore, there
signal
so
that
of
is a
the
40
perceived
sound
transmission
is
of
pleasant
the
most
and
the
information
successful
is
obtained
(NUCLEUS training manual).
The goal
develop
for mu1ti-channe1
two abilities:
information;
and
2)
recognition
for
information
derived
training
NUCLEUS device
formant.
the
from
The
two
the
new
of
of
prosodic
pitch
speech,
is to
pattern
which
requires
second
formant
(NUCLEUS
coding
strategy
information
categories
are
on
of
the
the
first
divided
into
levels of performance which require different
training activities.
may
perception
also provides
These
different
1) the perception
understanding
manual).
implant patients
utilize
features
For example, the easier
materials
of
stressing
speech
information,
such
using
as
word
the
simpler
fundamental
length
male/female speaker discrimination.
sessions
prosodic
frequency
differences
and
The more difficult
tasks may include question/statement discrimination.
Those
materials
which
use
visual
(i.e.,
speechreading) cues are also arranged from easy to most
difficult.
(e.g.,
They
everyday
may
include:
situations),
familiar
contextual
sentences
categories
of
phrases and words (e.g., farming, school, etc.), voiced
versus
numbers
non-voiced
of
(CVs
words
in
rehabilitation
program
format:
length
word
and
words),
sentences.
uses
the
and
segmenting
The
NUCLEUS
following
training
discrimination;
sentence
length
41
differences;
male/female
noise
and
speaker
voice
discrimination;
identification;
vowel
closed-set sentences; closed-set words;
( s t r e s s
manner
accented words
i d e n t i f i c a t i o n ) ;
(question/statement);
vowel
discrimination;
consonant
voicing
i n t o n a t i o n
identification;
clue
length;
sentence
discrimination;
consonant
identification;
consonant
place
discrimination; open-set sentence recognition; open-set
word
recognition;
speech
tracking;
telephone
identification of simple words/phrases with a
speaker;
and telephone
use
with
familiar
an unfamiliar
speaker
(NUCLEUS training manual).
Most
rehabilitation
developed
by
clinics
utilize
success
(Berliner,
1985;
method
the
with
involves
an
tracking
open-set
speech
1985a;
reading
of
minutes
session
and
their
correctly
compared
of
scores
intense
are
identified per minute.
for
stimulation
speechreading
and
and
This
appropriately
The patient must
repeat each sentence or phrase verbatim.
ten
a
materials
1985).
an
selected story, sentence by sentence.
allowed
procedure
Mecklenburg
Hochmair-Desoyer,
oral
implant
Scott (1978) to evaluate
Mecklenburg,
1985b;
cochlear
speech
DeFi1ippo and
patient's
Brimacombe,
offering
Patients are
speechreading
recorded
as
per
words
The results are then
alone,
speechreading,
and
electrical
electrical
42
stimulation alone (DeFilippo and Scott, 1978; Berliner,
1985; Mecklenburg, 1985a).
DeFi1ippo and Scott's (1978) goal
tracking
procedure
situational
is
to
conversational
speechreading
procedures
procedure
differs
from
procedures
in
it
opposed
to
procedure
develope
that
where
relevant
The
tracking
speechreading
connected
of
speech
sentences.
a measure
of
to
conventional
conventional
lists
provides
skills
failed.
utilizes
unrelated
also
use
for the speech
correct
as
This
message
reception as opposed to a two choice method.
The developers speculated that
"tracking with ongoing speech would require
a
wider range of perceptual and linguistic skills
that can be applied, more or less efficiently,
dependent on the display characteristics of the
aid being used (p. 1186)."
After
basic rehabilitation
goals have
been
met,
open-set speech discrimination and training on the use
of
the
telephone
may
begin.
The
more
successful
implant patient may learn to recognize and discriminate
between a dial-tone, a busy signal, and ringing as well
as be
able
speaker on
variety
of
to
carry
the other
effective
on
a
limited
end could be
common
conversation.
taught
strategies
The
to utilize
such
as
a
the
syllabic responses of "no", and "yes-yes" (Mecklenburg,
1985b; NUCLEUS training manual).
The
environmental
training
sounds
is
for
critical
carried
out
listening
mainly
in
for
the
43
patient's home.
to
The patient
increase an
is given home assignments
awareness of
surrounding sounds and
become familiar with the implant system
range
of
operation
for a personal
and
its
in terms of
to
its
limitations.
This allows
insight into the potential
problems with
the prothesis and allows the patient to monitor his/her
own progress with sound detection and recognition.
Each patient
all
their
is requested to keep a daily diary of
auditory
experiences
including the number of hours the
day
and
the
novel
auditory
with
therapy
is
sensations
terminated,
assignments
provided
in
patients
usually
the
experienced.
in-clinic therapy,
staff determines whether
warranted.
When
are
in-clinic
given
consisting
clinical
implant
implant was used per
Following the initial 30-40 hours of
the rehabilitation
the
a
of
setting.
additional
therapy
series
training
The
of
is
home
materials
patient
is
encouraged to maintain contact with the
rehabilitation
staff
their progress
via monthly reports
in order that
can be monitored and any medical
which
may
asked
to
arise
return
can
be
to
the
following the initial
progress
Brimacombe, 1985a)
corrected.
institution
Most
every
problems
patients
are
6-12 months
rehabilitation for re-evaluation,
evaluations,
(Ber1iner,1985;
or equipment
and
equipment
Campos,1981;
adjustments.
Mecklenburg
and
44
Patient Reactions
Adult cochlear implant
timing and intensity
not
significantly
normal
users may
learn to utilize
discrimination abilities that
different
from
the
abilities
hearing subjects (Helmerich and Edgerton,
Bilger, 1977; Wallenberg et al., 1985).
most
post lingual
signal's
deaf
amplitude
predictor
of
implantation
and
their
and
electrode
frequency
pitch
Bilger
speech
information.
single
Dent
electrode
to
this
first
formant
the
reduced
limit
information
limited frequency
information
may
place
of
position
He
or
to
frequency
high
that
information
fundamental
only.
single
of
energy
frequency
of
a
ability
the
the
after
pitch
lack
as
key
Edgerton
that
to
decreases
secondary to the transmission
and
due
<1982) supported
devices
the
and
reduces
Furthermore,
secondary
frequencies.
stated
the
Buriank, and
Helmerich
perhaps
frequencies
is
Hochmair,
significantly
1982;
discriminate
features
have
of
The ability of
understanding
However,
perception,
increases,
temporal
<1977)
device
discriminate
to
<Hochmair-Desoyer,
Stiglbrunner,1983).
<1982)
adults
are
frequency
stated
that
allow for
some
basic differentiations of speech prosody and manner of
articulation
but
restricts a
person's ability
for
the
differentiation of the place of articulation.
Although cochlear
implant users possess intensity
discrimination abilities, most
implant patients exhibit
45
an extremely
limited electrical
(Pfingst, 1984).
25 dB below
less at
1984).
The dynamic range
250 Hz
higher
intensity dynamic range
and can
be as
is often
little
frequencies (Michelson,
less than
as
1971;
10
dB
or
Pfingst,
Therefore, the patient may be unable to tolerat
stimulation
i nformati on.
at
levels
needed
to
transmit
the
desired
PATIENT SELECTION-CHILDREN
The House Ear
in
1980
as
House,
an
experimental
1982).
electrode
States
Institute began to implant
To
cochlear
Food
Drug
the
ear,
causes are
children
who
maternal
some of
have
by
rubella,
United
(FDA)
Bacterial
and
single
the
younger than
1985).
toxemia,
just
3M/House
is approved
device for children
ototoxicity,
inner
the
(Eisenberg
Administration
of age (Berliner et.al.,
trauma,
only
implant
and
experimental
date
program
children
as
10
years
meningitis,
deformities
cytomegalovirus,
and
the
deafness
been
etologies of
selected
an
for
of
unknown
in
implantation
(Luxford and House, 1985).
The
child's
primary
consideration
potential
for
when
implantation
assessing
is
the
the
valid
confirmation of audiometric results which demonstrate a
profound
sensorineural
particularly
responses
true
are
for
hearing
loss.
young children
often
whose
inconsistent
and
This
is
behavioral
inaccurate.
Auditory brainstem evoked potentials are often utilized
with
these
children
to
confirm
the
presence
of
a
profound loss (Berliner, 1985).
The
assessment
gained
of
from
second
major
children
is
conventional
unaided audiometric
consideration
how
much
actual
amplification.
results
46
are
not
always
during
benefit
Aided
the
is
and
predictive
47
of
the
aspect
success
is
or
failure
difficult
limitations
of
the
to
with
assess
hearing
because
protocols,
aids.
of
cognitive
This
age-related
factors,
and
l a c k o f e x p e r i e n c e w i t h s o u n d ( E d g e r t o n e t a l ., 1 9 8 3 ) .
Berliner
and
following selection
be at
least
criteria
(1985b)
for
Test
children.
hearing
of
loss.
Auditory
implantation
average
test
cochlear
of
an
They
the
must
The aided performance
Comprehension
Discrimination After Training test
for
provided
two-years of age with a profound bilateral
sensorineural
the
Eisenberg
must
results
implant.
If
amplification
poorer
obtained
in the ear
than
from
The child must
appropriate
training.
be
no
hearing-aid
progress
(i.e.,
no
is
or
children
also have
seen
awareness
to
to
the
using
a
a history
and
with
the
selected
equal
trial
speech development), a cochlear
and
on
auditory
conventional
sound
and
implant should then
no
be
considered (Edgerton et.al., 1983).
The
(Trammel 1,
of
Test
1985b).
developed
Auditory
1976) evaluates
environmental
hierarchy
of
of
sounds
and
difficulty
specifically
the
for
House
auditory
speech
(Berliner
The Discrimination
by
the
Comprehension
comprehension
in
a
and
Institute,
to
assess
the
Eisenberg,
profoundly
was
designed
deaf
children
and adults (Berliner and Eisenberg, 1985b).
used
sequenced
After Training (DAT) test,
Ear
prellngual
(TAC)
subject's
ability
The DAT is
to
utilize
48
auditory cues to make discriminations of speech or some
of the nonsegmental aspects of speech.
test materials are
incorporated as part of the test
an attempt to control, or at
past
auditory
The training of
experience
in
least minimize, the effect
may
play
on
test
results
(Thielemeir, Tonodawa, Peterson, and Eisenberg, 1985).
Medical
Typically, the
Assessment
same assessment
protocol
used
for
adults is also used for children (e.g., polytomes etc.
to
observe
turn
of
the
status
the cochlea
of
the
round
in search
of
window
and
congenital
basal
anamolies
of the inner ear or labyrinthine ossification).
Psychological
A.
Assessment
Interviews: A
to
obtain
(Tiber, 1985; Selmi, 1985)
variety
of
information
developmental
regarding
history,
method
and emotional
adjustments,
potential
also
provide
used
problem
by
of
the
what
is
history,
social
expectations,
These
regarding
given
child's
family,
parental
areas.
information
understanding
the
educational
communication
and
interviews are
interviews
the
involved
parents'
and
the
potential benefits and limitations of the cochlear
implant.
Child
Implant
Specific
Behavior
tools
Rating
Questionaire.
utilized
Scale
A
and
pattern
of
include
the
the
Cochlear
parent-child
49
interaction must emerge which indicates the family
will
be
able
to
effectively
follow
through
with
the post-implant rehabilitation program.
B.
Intel 1iaence Tests:
1.Stanford-Binet Forms L-M-for children 2-4
years
2.Wechsler Pre-School and Primary Scale of
Intel 1iaence-for children 4-6 1/2 years
3.Wechsler Intelligence Scale for ChildrenRev ised-for children 6 1/2-16 1/2 years
4.Wechsler Adult Intelligence Scale-Revisedfor children 16 1/2-18 years
C.
Neuropsychological Tests:
1.Hal stead-Rei tan Test of Lateral
2.Bender-Gesta1t
3.Wide-Range Achievement Test
Dominance
Audiologic Assessment
The
following
audiometric
results
should
be
obtained when possible (Berliner and Eisenburg, 1985b):
A. Tympanometry and otoscopy (rule out middle
ear
pathology)
B. Acoustic reflex at
500, lk, and 2k Hz measured
with a maximum stimulation output of 110 dB SPL
C. Warbled tone thresholds 250-4000 Hz
D. Speech detection thresholds
E. Speech uncomfortable loudness levels
F.
Brainstem
appropriate
under)
Evoked
(used
for
Responses
all
children
(BSER)
6
years
when
and
50
Warbled tone thresholds and uncomfortable loudness
levels (UCL) are obtained
of
the
appropriate
to select
hearing
soundfield evaluation.
the gain
aids
used
and SSPL
during
The SSPL of the hearing aid
the
is
not to exceed 132 dB SPL.
Soundfield testing includes:
A. Warbled tone thresholds
B. Speech detection thresholds
C. Speech UCL's
D.
Speech
discrimination:
performed with
best
aided
the hearing
warble-tone
These
aid
that
tests
provided
thresholds, with
each
are
the
ear
being tested separately.
1. Discrimination After Training (DAT)
2. Test of Auditory Comprehension (TAC)
Finally,
provided
to
speech
evaluate
and
the
language
child's
assessment
receptive
is
language,
expressive language, and phonology/articulation.
Post-implant Results
Most
3M/House
children who
implant
system
have
had
been
no
implanted
measurable
250, 500, lk, 2k, 3k, and 4k Hz.
Once
these
SPL
frequencies
ranged
tested
from
(Berliner
hearing
the
at
The aided soundfield
thresholds rarely exceeded 80 dB SPL.
thresholds
with
59-64
and
dB
implanted,
across
Eisenberg,
the
1985a;
51
1985b). The goal
to
obtain
for setting the gain of the implant
warble-tone
thresholds
45-60 dB HL across the frequency
(Thielemeir
et
al.,
1985;
on
the
range
average
of
Eisenberg
is
of
250-4000 Hz
and
Berliner,
1983).
Additional
implant
in
following
benefits
derived
children have been
(Berliner,
1985;
from
reported
Tiber,
a
to
cochlear
include the
1985;
Kirk
and
Hi 11-Brown, 1985):
A. Simple auditory discrimination
B. Detection of environmental sounds
C. Increased speech production skills
1.increased vocalization
2.improved voice quality (i.e., monitoring of
intensity
and
pitch,
and
decreased
vocal
strain)
3.improved speech rhythm (e.g., speech
rate,
stress, syllabification)
4.improved
imitative
and
spontaneous
production of vowels and simple consonants
Based on
follow-up.
a six
the
month, post-implant
data
have
psychological
effects
Tiber
found
(1985)
implanted
a
children's
short-attention
spans.
not
indicated
(Tiber,
1985).
significant
level
psychological
of
These
any
adverse
Behaviora11y,
reduction
in
the
distractabi1ity
and
children
are
also
52
reported
on
to
have
certain
demonstrated an
psychological
and WISC-R).
However,
tests
improved
(i.e.,
maturation
may
performance
Bender-Gesta1t
have
influenced
these improved scores.
The House Ear Institute have reported that of
205 children
implanted, only
Eight
of
these
refuse
to
utilize
and/or
peer
10
are
the
10 do not use the device.
teenagers and
device
pressure
the
due
to
(Berliner,
they
reportedly
cosmetic
1985).
reasons
Table
1
presents a summary of data from the House Ear Institute
as of
September
3M/House
at
single
the
15,
1985
electrode
Denver
Ear
regarding
cochlear
children
implant
Institute's
with
the
(Presented
Cochlear
Implant
Symposium, Denver, Colorado, 1985).
TABLE 1: Cochlear Implantation of Children
AGE AT TIME
OF SURGERY
2-5 YEARS
USERS
NONUSERS
DEVELOPMENTAL
FAILURE
NONSTIMULABLE
IN PROCESS
DECEASED
(unrelated to
the implant)
6-12 YEARS
13-17 YEARS
63
2
83
0
29
8
1
0
3
0
2
1
8
1
2
1
1
0
Summary
In
proven
auditory
summary,
to
be
the
effective
thresholds
can
3M/House
for
be
cochlear
some
implant
children,
obtained
at
in
levels
has
that
which
53
allow
profoundly
deaf
children
to
detect
speech
and
environmental sounds as well as to make simple auditory
discriminations (Thielemeir et al., 1985).
At
minimum,
profoundly
deaf
information
speech
implant
as
well
(Kirk
of
as
the
limited
speech
pitch
Hill-Brown,
of
voice
perform
timing
allow
at
a
auditory
patterns
and
in
intensity
information
1985).
age
by
a
of
the
Thielemeir
auditory performance
time and that
two-years
may
This may be due to the provision
al., (1985) reported that
after
implant
detect
and
different
regarding
and
to improve over
to
level
structured situation.
of
cochlear
children
conversational
discriminations
the
et
appears
children who become deaf
and
utilized
an
oral
communication method tended to also perform better than
average with
Hi 11-Brown
the cochlear
(1985)
found
implant.
improved
However,
speech
and
production
skills in children who were trained in both an
a total communication program.
Kirk
oral
or
REHABILITATIQN-CHILDREN
The initial
with
children
considered
phases of
focus
to
be
on
an
the rehabilitation
parent
counseling
integral
part
of
program
which
the
is
program.
Decisions also must be made regarding internal settings
of
the
implant
threshold
and
patients.
signal
comfort
A
on
The
important
ability
speech
to
level,
rehabilitation
dependent
most
processor
not
be
is
While
achieved,
language
child
may
also
pragmatic
variety
skills
of
enable
cochlear
errors (Howarth
of
listener
and
that
may
deaf
in
Smith
his/her
1985).
A
training
the
improve
speech
1965;
may
sounds and the
the
and,
to compensate
John,
implant
Hill-Brown,
shown
child's
intelligible
improvement
speech
patterns
the
an
and
have
aspects of
intonation
might
(Kirk
studies
nonsegmental
and
demonstrate
is
ability.
the
obtaining
enable the child to detect environmental
adult
children
improve
the
electrical
with
for
and
to
on
done
program
is
communicate.
may
as
the child's speech
goal
based
foe
1975;
stress
in
turn,
segmental
Osberger
and Levitt, 1979).
Following
hours),
House
basic
therapy
the child returns
therapeutic
contact
the
settings.
with
Ear
Institute
to his regular
The
teachers,
period (i.e.,
implant
parents,
has
54
and
initiated
academic and
staff
maintain
therapists.
a
30-40
School
The
Contact
55
Program
in
personnel
(1985)
order
to
maintain
in the schools of
described
program:
the
1)
to
provide
regarding
benefits
limitations;
personnel
in
educational
available materials
school
cochlear
3)
2)
to
that
auditory skills in the
objectives
information
with
assist
to
will
this
school
including
the
realistic
provide
Selmi
of
implants
to
establishing
goals;
contact
implanted children.
following
professionals
and
regular
school
long-term
information
maximize
development
on
of
implanted child as well as guide
professionals
in
choosing
and
evaluating
auditory objectives; and 4) to develop a system whereby
the
House
schools
Ear
on
a
Institute
regular
receives
basis
information
(e.g.,
from
summaries
of
the
the
child's progress, child's responses to classroom sounds
etc.>.
Summary
Initial
implanted
auditory
children
skills
(Selmi, 1985).
the ages 13-18
in
the
results
Hill-Brown,
are
over
able
time
in
Currently, only
years have
production
segmental
from
skills
1985).
of
program
indicate
to
increase
certain
a
classroom
setting
those children
demonstrated any
several
following
This
this
is
decrements
non-segmenta1
implantation
probably
between
and/or
(Kirk
related
reported unwillingness of some of the patients
to
and
the
in this
56
age
group
to
fully
utilize
their
devices
due
to
cosmetic reasons and peer pressure.
Although early
the
number
Because
of
most
research results seem encouraging,
subjects
of
the
actually
implanted
assessment
tools
is
small.
utilized
are
age-dependent, gathering long-term data is difficult as
the
implantation
concept.
already
Additional
implanted
limitations
fully
of
of
and
is
experience
is required
cochlear
defined
Professionals
children
with
before
implants
(Kirk
others
a
and
in
relatively
those
the
children
benefits
children
can
Hill-Brown,
working
new
with
and
be
1985).
implanted
children must also consider the fact that cognitive and
speech/1anguage skills develop
drastically change
over
time
and will
in short-time periods as will
not
other
measures (e.g., audiological) regardless of whether the
prothesis is on or off.
One of
the most
difficult
decisions audiologists
are going to face is a recommendation for or against
cochlear
implant
(Campos,
1985;
Mecklenburg,
a
1985a;
Dankowske, 1985). More than a dozen centers through-out
the world have
involving
systems
the
via
developed
set
of
extent
electrical
cochlear
to
varied
which
in
implants.
for
developing
variability
in
the
reasons
success of
for
goals.
or
The
have
been
procedures
there
is
rehabilitation
success
has
and its own
data
rehabilitation
Therefore,
auditory
center
these
scientific
programs
of
Each
achieving
available
considerably.
the
stimulation
its own goals for rehabilitation
strategies
utilized
and
initiated independent clinical
failure
has
large
programs
are
poorly
understood (Pfingst, 1984).
There
seem
to
implantation than
the
inquiries
relatives
of
fewer
one might
about
deaf
surprising number
never used
be
of
candidates
suspect.
cochlear
implants
individuals
these
who
do
achieve
from
some
are
of
in
to
A
have
limited
Another group
dissatisfied hearing
degree
by
1985).
tried one
them.
1/2 of
made
individuals appear
ways and consequently rejected
inquiries are
cochlear
least
(Campos,
a hearing aid or have
the
At
for
benefit.
aid
Many
of
users
deaf
individuals living in the deaf community express little
interest
in cochlear
implantation.
57
They also have the
58
right
to determine whether
or not
they
wish
to become
part of the "hearing" world.
Unfortunately, the medical, hospital, and product
costs
are
sources.
some
not
always
The
medical
mu1ti-channe1
underwritten
and
units
by
various
hospitalization
may
be
funding
costs
underwritten
for
by
a
research grant, however, these may involve no more than
two
volunteers
insurance
companies
experimental
expense
and
as the
California
position
Approval
the
are
cochlear
the
the
barrier
to
surgical
FDA
more
reimbursement
have
treatment
of
adults
procedure
implants
to
insurance
insurance
for both
in
1985).
remove
the
coverage
of
in
coverage
cochlear
may
(Staller, 1985; Campos,
insurance
the
acceptable
deafness
involved
be
formal
(Simmons,
helped
to
and
the
an
are
medical
appears
taken
are
also
Many
Association
implants
complete
include rehabilitation
many
that
stance
Medical
has
however,
1985).
a reimbursable
This
deafened
from
However,
not
Association
for
implantation,
maintain
1985).
Medical
post 1ingual1y
(Simmons,
still
American
that
procedure
year
thus
(Staller,
changing
major
per
not
1985).
companies
are
now
providing
the surgical
and
rehabilitation
costs.
There
rehabilitation
total
exists
for
communication
a
controversy
deaf
children
versus
manual
over
any
type
of
(i.e.,
oral
versus
versus
acoupedics).
59
This
controversy
extends
implantation in children.
to
the
issue
of
benefit
an
implant
Children need ample time to experiment
with hearing aids before determining that
no
cochlear
Specific problems arise when
trying to assess the success or failure
with children.
of
from
conventional
they
receive
amplification.
This
more difficult to determine for children than it
adults.
to
changes
versus
directly
changes
due
related
to
to
the
cochlear
maturation.
In
cases, each child serves as his/her own control
the
is for
Another problem may be encountered when trying
document
implant
is
lack
of
development
normative
of
data
implanted
(Berliner and Eisenberg,
compare
the
on
profoundly
1985b).
performance
the
of
most
due to
communication
deaf
children
Researchers may also
implanted
children
to
profoundly deaf children without an implant who are the
same age (Eisenberg et al., 1983).
Good cochlear
are
living
in
implant candidates are persons who
the
hearing
world
motivation
to continue to do so.
critical
factor
satisfactorily
living in a
in
adjusted
Those
their
deaf community will
have
media attention
over
the
past
professionals
who
years.
Cochlear
However,
criticize
the
and
a
have
are
typically not be good
al., 1985).
increasing
strong
who
deafness
candidates (Berliner et
gained
have
This seems to be
success.
to
and
and
there
influx
of
implants
popularity
are
also
cochlear
60
implantation.
Despite these criticisms,
of
the cochlear
to
stay
The
implant
(Berliner
implant
has
et
a l .,
1985;
introduced
treatment
of
approach
involves
profound
professionals who
potential
believe that
a
Mecklenburg,
concept
sensorineural
must
benefits
implants are here
unique
teamwork
work
for
the
investigators
1985b).
into
deafness.
the
This
between
a
variety
of
together
to
maximize
the
implant
patient
(Campos,
clinical
programs
1985).
Most of the centers
with
cochlear
system
of
to
the
evaluate
of
devices (Bilger,
provide
the
running
speech
goal
stimulation
has
deaf
been
have
patients
the major
initiated
psychophysical
laboratories
evaluations
One of
have
the
electrical
additional
these
implants
involved in
patient
without
achieved
at
conducted
1977;
least
with
a
the
a
ability
to
most
of
the
patients
understanding has been poor
implanted
In
fact,
extent
even under
circumstances (BuriOn,
1981;
1981;
1983).
Clark
et
al.,
advancements
and
research
implantation
becomes
a
to
in
common
a
few
However,
date,
speech
structured
and
Schindler,
Further
needed
this
very
Michelson
are
is to
understand
patients under certain restricted conditions.
in
of
1984).
implantation
limited
two
variety
Hochmair-Desoyer,
cochlear
of
psychophysical
speechreading.
to
sort
characteristics
and
implanted
goals of
some
technological
before
treatment
of
cochlear
profound
61
sensorineural
are
deafness. Such
presently
being
conducted
implantation
may
become
professions,
particularly
Mecklenburg, 1985a;
an
prepared
refer
to
them
to
evaluations,
services.
cochlear
potential
appropriate
be
able
to
it
implantation
alternative
promote
likely
a
perform
provide
the
will
frequency
which
necessary
rehabilitative
qualifications
as
candidates,
the
become
of
cochlear
current
trend
transpire.
summary,
the
implant
sources,
is
is
this
a
author's
great
hearing health care profession.
meet
many
Therefore, audiologists must
increases,
indicates will
In
audiology
of
1985a;
necessary
implantation
part
Mecklenburg and Brimacombe,
These
increasingly
integral
cochlear
1985;
identify
and
and
(Campos,
Hochmair-Desoyer, 1985).
be
advancements and research
candidacy
treatment
positive
probability
that
have,
their
mental
achievement
that
in
the
Those who are deaf and
criteria
for
opinion
at
handicap.
health
auditory
by
last,
an
This helps
providing
experience
the
will
once
again be a part of these persons' lives.
To date, the reports from
have been optimistic.
of success
the
and/or
new auditory
the
recipients
Implant recipients vary in terms
failure.
Some will
perceptions and
utilize their device.
implant
may
never
rarely,
adjust
if
to
ever,
On the other extreme, there are
recipients wearing their
devices most
of
the
time
and
comprehending open
that
the
obtained
do
with
the
not
implant
than
most
truly
of
implants.
part,
objective
implant
keep
open
represent
recipients
most
improved quality of
day
One must
measures
cochlear
from
performance
For
speech.
objective
discrimination
reports
set
set
subjective
indicate
far
measures
hearing
in
report
a
much
feel
more
a
less
part
be measured
lsloated
of
much
in every
The fact seems to be that
general,
world,
better
demonstrate.
life, qualities that cannot adequately
recipients,
benefits
life based on performance
by objective tests.
mind
speech
the
The
patients
in
implant
from
their
the
everyday
env i ronment.
As research
population
of
successfully
implant
development
deaf
with
patient
candidacy
and
individuals
cochlear
may
criteria
advances,
of
not
may
be
implants.
have
present.
to
a
wider
treated
The
meet
future
the
rigid
Prelingually
deafened
adults have been implanted with single channel
devices.
Paralinguals, those who have acquired language but have
been
deaf
a
implanted.
of
the
majority
The FDA
NUCLEUS
of
their
has now approved
mu 11i-e1ectrode
10-18 years of age-
lives,
the
device
have
been
implantation
for
children
The list should continue to expand
with time and experience in the field.
The
critical.
audio1ogist's
Without
proper
role
in
this
rehabilitation,
process
the
is
patient
63
may never
as,
to
learn to utilize the device to
date,
hearing
no
to
implant
a
system
normal
is
level .
rehabilitation required per
patient
its potential
able
to
The
amount
varies.
restore
of
Some will
require minimal training including simply adjusting and
fitting
more
of
external
intensive
equipment.
therapy
the suprasegmenta1
Others
including
the
and segmental
will
require
training of
both
components of speech.
The program for rehabilitation differs with each device
currently
on
the
market.
However.
establish a common goal:
the patient
speech
than
at
a
higher
level
that
most
shall
which
programs
understand
is obtained
with hearing aids.
The audiologist should maintain knowledge
area as more
on
cochlear
closer
to
anxious
patients may
implants.
the
about
hearing
this
Accurate,
realistic
potential
candidates
impaired population
to all
As
audio1ogists.
seek
a
world,
new
advice and
last
many
help
information
of
clients
treatment
information
and
hope
will
serve
in this
for
help
returning
will
be
deafness.
identify
the
to a greater degree, a goal
hearing
common
APPENDIX A
Sirrmary of the 8 Most Ccxmion Types of Inplant Hardware
(Staller 1985; ASHA, 1986)
1
I TYPE O
j SYSTEM
i
NUCLEUS
Digital
i Feature
:
Extract
COOING
STRATEGY
Dt.> I
in
3M/House
3M/Vienna
BIOSTEM
STORZ
SYMBION
Hurtmarr.
Analog
Filter
Bank
Analog
Filter
Bank
Analog
Digital
Filter
Analog
Filter
Bank
Analog
Filter
Bank
Analog
Filter
Bank
Digital
Feature
Extract
Monopolar
Monopolar
Bipol ar
Monopolar
Monopolar
Monopolar
STIMULATION
REGIME
Bipul ar
Monopolar
NUMBER OF
CHANNELS
22
1
1
1
4
4
1
12
ACTIVE
ELECTRODES
21
1
1
1
4
4
8
12
IntraCochlear
ExtraCochlear
IntraCochlear
IntraCochlear
IntraCochlear
ixtraCochlear
IntraCochlear
Grm
3nni
24nm
22iT5TI
Qiffi
$6,000$9,500
$4,500
$12,000
$11,000
|
.
. .
SITE OF
STIMULATION
IntraCocnl ear
!
ELECTRODE
DEPTH
I
j
2'jfim
ij
APPROXIMATE
COST
!
| $11,000
j
6MTI
i1
Ii
i
|
fj-jin
1
i
$6,500
-uO,'
$9,000
;
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