BME 215 Biomaterials and Artificial Organs

1
Cochlear Implants a tutorial
Hi! Im Marvin and I want to learn more!
Seth Brown Danaan Metge Rae Luan Megan Toney
Click here to begin!
BME 215 Biomaterials and Artificial Organs Class
Project Fall 2008
2
How to navigate the lesson
Use your mouse to navigate through the pages
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Section
gtgt
Sub-section
3
Ear Anatomy and Disease State
Materials and Manufacture
Cochlear Implant Surgery
Post Operation--Rehabilitation
Performance and Failure Modes
Controversy
Acknowledgements References
4
Ear Anatomy and Disease State
Ear Anatomy
Sensorineural Hearing Loss
Materials and Manufacture
Patient Selection
Cochlear Implant Surgery
Section Review
Post Operation--Rehabilitation
Performance and Failure Modes
Controversy
Acknowledgements References
5
Ear Anatomy and Disease State
Materials and Manufacture
External Components
Internal Components
Cochlear Implant Surgery
Implant Sterilization
Section Review
Post Operation--Rehabilitation
Performance and Failure Modes
Controversy
Acknowledgements References
6
Ear Anatomy and Disease State
Materials and Manufacture
Cochlear Implant Surgery
Overview
Procedure
Post Operation--Rehabilitation
Risks
Tools
Performance and Failure Modes
Section Review
Controversy
Acknowledgements References
7
Ear Anatomy and Disease State
Materials and Manufacture
Cochlear Implant Surgery
Post Operation--Rehabilitation
Post Operation
Rehabilitation Therapy
Performance and Failure Modes
Section Review
Controversy
Acknowledgements References
8
Ear Anatomy and Disease State
Materials and Manufacture
Cochlear Implant Surgery
Post Operation--Rehabilitation
How a CI works Overview
Performance and Failure Modes
Performance
Complications and Failure
Controversy
Section Review
Acknowledgements References
9
Ear Anatomy and Disease State
Materials and Manufacture
Cochlear Implant Surgery
Post Operation--Rehabilitation
Performance and Failure Modes
Arguments Against CI
Controversy
Controversy Today
Acknowledgements References
10
Ear Anatomy and Disease State
Materials and Manufacture
Cochlear Implant Surgery
Post Operation--Rehabilitation
Performance and Failure Modes
Controversy
Acknowledgements References
11
Ear Anatomy and Disease State
Ear Anatomy and Function
Sensoineural Hearing Loss
Click on a section or click Begin Lesson!
Patient Selection
Begin Lesson
Ear Anatomy and Disease State
Lesson Review
12
Human ear slide 1
The human ear consists of three major sections

• outer ear
• middle ear
• inner ear

http//www.apps.hearingworld.co.uk/learn_about_hea
ring_loss.html
Ear Anatomy and Disease State
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Ear Anatomy
13
Human ear slide 2
The outer ear consists of

• the pinna, or
• external ear lobe
• the ear canal

http//www.apps.hearingworld.co.uk/learn_about_hea
ring_loss.html
Ear Anatomy and Disease State
gtgt
Ear Anatomy
Next
14
The middle ear consists of

• the tympanic
• membrane,
• known more
• commonly as
• the eardrum
• the earbones
• (ossicles)
• malleus
• incus
• stapes

http//www.apps.hearingworld.co.uk/learn_about_hea
ring_loss.html
Ear Anatomy and Disease State
gtgt
Ear Anatomy
15
The inner ear consists of

• the cochlea
• the cochlea connects to the auditory nerve

So how do our ears hear?
http//www.apps.hearingworld.co.uk/learn_about_hea
ring_loss.html
Ear Anatomy and Disease State
gtgt
Ear Anatomy
16
What is sound?
Sound is caused by vibrations
pressure
When an object vibrates, it causes movement in
air particles
time
The pressure waves that arise from the movement
of air particles travel through the air and other
fluid mediums so our ears can detect them
Ear Anatomy and Disease State
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What is Sound?
17
Frequency
Frequency is the measure of oscillations per
second and is measured in Hertz (cycles/second)
1 oscillation
Higher frequency signals have more oscillations
that a low frequency signal in the same amount of
time
High frequency
Low frequency
1 second
1 second
Ear Anatomy and Disease State
gtgt
What is Sound?
18
Frequency
Words are characterized by specific frequency
spectra with sounds ranging from 125Hz for a deep
male voice to 7,000 or 8,000 Hz for the hissing
sound of the letter s
So when you listen to someone speaking you decode
their words based on the different frequencies of
each phonetic pronunciation
http//www.daniellongstreet.com/AM_Speech/AMspeech
signal.html2
Ear Anatomy and Disease State
What is Sound?
gtgt
19
Decibels

• Decibels (dB) is a logarithmic measure of the
  power
• For oscillatory sounds
• where A is amplitude
• Prolonged exposure to sounds over 90 decibels can
  lead to eventual hearing loss

OW!
http//www.acme-rents.com/Pages/matrix.html
Ear Anatomy and Disease State
What is Sound?
gtgt
20
The outer ear collects sound in the environment
and guides the pressure waves down the ear canal,
where they cause the eardrum to vibrate.
http//www.apps.hearingworld.co.uk/learn_about_hea
ring_loss.html
Ear Anatomy and Disease State
gtgt
Ear Function
21
Ossicles
The malleus (hammer) is embedded in the eardrum
The end of the stapes inserts into the oval
window of the cochlea
so it can transfer the vibrations in the eardrum
to the incus (anvil)
and passes these vibrations to the inner ear
(specifically the scala vestibuli and the scala
tympani of the cochlea)
which in turn passes the vibrations to the stapes
(stirrup).
http//www.britannica.com/EBchecked/topic/175622/e
ar
Ear Anatomy and Disease State
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Ear Function
22
The Cochlea (cross section)

• Vibrations in the stapes cause pressure waves in
  the interstitial fluid of the scala vestibuli and
  the scala tympani.

• Fluctuations in this fluid cause the Reissners
  and basilar membranes to vibrate and force
  pressure waves in the cochlear duct.

• The resulting motion of the tectorial membrane
  against the organ of Corti cause displacement of
  the stereocilia.

Visit this website for a detailed animation of
cochlear movement
http//www.britannica.com/EBchecked/topic/175622/e
ar
Ear Anatomy and Disease State
gtgt
Ear Function
23
The Cochlea

• Because the base of the cochlea is stiffer than
  the apex, different positions along the length of
  the cochlea respond differently to a particular
  stimuli
• The bends in the cochlea are tuned to different
  frequencies and generate different electrical
  responses, allowing us to differentiate between
  varying frequencies and sounds.
• This spatial coding of frequency is called
  tonotophy

http//www.britannica.com/EBchecked/topic/175622/e
ar
Ear Anatomy and Disease State
gtgt
Ear Function
24
Hair Cells

• Stereocilia are the hair of the hair cells.
• Movement of the tectorial membrane against the
  basilar membrane causes motion in the
  stereocilia.
• The physical displacement of the stereocilia
  triggers an action potential in the auditory
  nerve.

http//www.britannica.com/EBchecked/topic/175622/e
ar
http//www.britannica.com/EBchecked/topic/175622/e
ar
Visit this website for a detailed animation of
hair cell activation
Ear Anatomy and Disease State
gtgt
Ear Function
25
Auditory Nerve
Movement of the stereocilia trigger action
potentials in the auditory nerve
which transports these electrical impulses to the
brain
where they are processed and interpreted as sound!
http//www.crh.noaa.gov/lmk/?nlightning_safety
This interface between auditory nerve fibers and
each individual hair cell must be intact for a
cochlear implant to be an effective form of
treatment
So what can go wrong?
Ear Anatomy and Disease State
gtgt
Ear Function
26
Sensorineural Hearing Loss
What is it?
Genetic Causes
Aging
Noise and Traumatic Injury
Ototoxicity
Disease
http//www.hearinglife.com.au/about_loss.cfm
Disease is an important causal factor in children
Begin Section
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
27
What is Sensorineural Hearing Loss?

• Occurs in the inner ear when the hair cells
  within the cochlea are damaged but other auditory
  structures remain functional.
• The potential for hearing remains because the
  auditory nerve is still intact and able to
  transmit electrical impulses to the brain if
  properly stimulated.

?
?
?
?
?
How does this type of hearing loss occur?
Sensorineural Hearing Loss
What is Sensorineural Hearing Loss?
Ear Anatomy and Disease State
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28
Genetic Causes

• More than 24,000 children are born with
  congenital hearing loss in the US each year1
• Mistakes in the genetic code can result in ear
  anatomy that is not formed correctly and as a
  result does not collect and interpret sound
  normally

While some are born with hearing loss, it can
occur at any time of life
http//www.frequencyawareness.com/dna_activation.h
tml
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Genetic Causes
29
Aging (Presbycusis)

• At birth, a normal human ear contains about
  15,000 hair cells that degenerate steadily
  throughout life
• 4 basic types
• Sensory hair cells of organ of Corti degenerate
  first
• Neural cochlear neurons degenerate first
• Strial/metabolic atrophy of the stria vascularis
• Mechanical/inner ear conductive thickening of
  basilar membrane
• Older individuals are often favorable candidates
  for cochlear implant selection because they have
  preexisting speech abilities

http//www.offthemark.com/search-results/key/heari
ngloss/
http//news.softpedia.com/news/Vision-and-Hearing-
Loss-Linked-in-Old-Age-37611.shtml
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Aging
30
Aging (Presbycusis)

• Older individuals can be favorable candidates for
  cochlear implant selection because they have
  preexisting speech abilities
• learning to use the implant after surgery can be
  much easier and can lead to a huge improvement in
  quality of life
• However, degeneration of the auditory nerve can
  undermine the effectiveness of a cochlear implant

http//www.offthemark.com/search-results/key/heari
ngloss/
http//news.softpedia.com/news/Vision-and-Hearing-
Loss-Linked-in-Old-Age-37611.shtml
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Aging
31
Noise and Traumatic Injury

• Exposure to noise is the second most common cause
  of all levels of hearing impairment
• The level of hearing loss is dependent on the
  duration and intensity of the sound causing the
  loss
• Can be bilateral (in both ears) or unilateral (in
  one ear) depending on the type of exposure

Traffic could cause hearing loss due to prolonged
exposure
While hearing loss associated with firearm use is
often unilateral and from one time exposure
http//www.orlandhearingaids.com/hearing_info/?iP
rotecting20Your20Hearing
http//www.bowhunting.net/artman/publish/HUNT_DOCT
ORS_81/Hearing_Loss.shtml
Noise and Traumatic Injury
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
32
Noise and Traumatic Injury

• Hearing loss due to noise can be temporary or
  permanent
• Cochlear implants are applicable for permanent
  loss presenting as a threshold shift
• Hearing loss due to noise exposure is usually
  characterized by a loss of the sensitive hair
  cells followed by degeneration of the auditory
  nerve
• Workplace guidelines have been established to
  protect workers constantly exposed to high
  decibel noises7

http//www.orlandhearingaids.com/hearing_info/?iP
rotecting20Your20Hearing
http//www.bowhunting.net/artman/publish/HUNT_DOCT
ORS_81/Hearing_Loss.shtml
Ear Anatomy and Disease State
Sensorineural Hearing Loss
Noise and Traumatic Injury
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33
Ototoxicity

• Hearing loss can be the result of adverse
  interaction between the body and certain drugs
• Areas for detecting high frequencies are usually
  affected first (cochlear base)
• Deafness resulting from ototoxicity is correlated
  to the dose, treatment duration, and combined use
  of other drugs
• Neuronal survival is highest for this cause of
  deafness, theoretically making it a candidate for
  good results with a cochlear implant

http//www.buckeyeinstitute.org/article/935
What kinds of drugs can cause this type of
hearing loss?
http//www.nbhope.org/blogs/under_the_microscope/a
rchive/2008/01/29/17441.aspx
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Ototoxicity
34
Ototoxicity

• Aminoglycoside antibiotics
• Cause sensory and supporting hair cells
  degenerate and disappear
• Begins affecting the cochlear base and then
  progresses towards the apex
• Most studies show that hair cells are affected
  and damages to the neural system (ganglion) also
  often occur, but this connection is not well
  understood.
• Survival of the ganglion (nerve) makes cochlear
  implant a potentially good therapy

http//www.buckeyeinstitute.org/article/935
http//www.nbhope.org/blogs/under_the_microscope/a
rchive/2008/01/29/17441.aspx
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Ototoxicity
35
Ototoxicity

• Loop Diuretics
• Most often used to treat heart conditions like
  hypertension and edema resulting from heart
  failure
• Affect the ion transport system of the stria
  vascularis
• Usually only result in short term deafness
• Cisplatin
• Chemotherapy drug used to treat cancer
• Hair cell loss begins in lower basal turn with
  changes occurring in the stria vascularis
• Causes symptoms similar to aminoglycosides

http//www.buckeyeinstitute.org/article/935
http//www.nbhope.org/blogs/under_the_microscope/a
rchive/2008/01/29/17441.aspx
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Ototoxicity
36
Infectious Diseases

• Important cause of deafness in children
• Can be contracted in utero, prenatally, or
  postnatally
• Some diseases that can cause hearing loss
  include
• Bacterial Meningitis
• Measles
• Mumps
• Maternal Rubella
• Syphilis

http//www.metrohealth.org/body.cfm?id1570oTopID
1570
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Disease
37
Infectious Diseases

• Bacterial Meningitis
• Causes hearing loss in about 20 of infected
  individuals
• The cause of hearing loss from meningitis is not
  well understood but is thought to be worsened by
  inflammation and blockage of blood supply to the
  inner ear
• Shows no preference for hearing loss at high or
  low frequencies
• Usually severe and permanent but can be bi- or
  unilateral
• Severe neural damage from infection and bony
  occlusion (labyrinthine ossificans) are known to
  occur

http//www.co.monroe.mi.us/Monroe/uploadedImages/b
acterial20meningitis(1).gif
Unfortunately, if the auditory nerve or the
cochlea are seriously damaged, a cochlear implant
may no longer be an effective treatment
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Disease
38
Infectious Diseases

• Measles
• Common cause of acquired profound hearing loss in
  children
• Lower cochlear turns affected and there is often
  a slightly reduced ganglion presence
• Mumps
• Most often results in unilateral deafness
• Hair cell loss observed in basal and lower middle
  cochlear turn
• Changes are mainly restricted to the cochlear
  duct with mild to moderate secondary
  degenerations of cochlear neurons

www.wikipedia.org
http//www.wales.nhs.uk/sites3/page.cfm?orgId719
pid23312
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Disease
39
Infectious Diseases

• In utero from maternal rubella
• Ear most susceptible in the first trimester
  (especially during the 8th and 9th week)
• There are generally varying degrees of hair cell
  loss but little effect on the neural components
• Primarily affects the Stria vascularis and can
  cause secondary effects in the cochlea
• Deafness occurring with congenital cataracts and
  congenital heart defects are known as the rubella
  triad.

http//www.lib.uiowa.edu/Hardin/md/pictures22/cdc/
269_B82-0203_lores.jpg
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Disease
40
Other Causes

• Other causes for sensorineural hearing loss
  include
• Any stimulus for new bone growth or the
  development of bony abnormalities within the
  cochlea (trauma, otosclerosis2)
• Menieres Disease3
• Autoimmune Inner Ear Disease4
• Hematologic (blood) Disorders
• Can cause thrombosis in the cochlear blood supply
  which can cause cell death and result in
  permanent hearing loss
• Lyme Disease
• Syphilis
• Idiopathic sudden sensorineural hearing loss
• Hearing loss with no apparent cause

http//www.principalhealthnews.com/topic/adam10033
40
Ear Anatomy and Disease State
Sensorineural Hearing Loss
gtgt
gtgt
Disease
41
Patient Selection
Eligibility
Other Solutions
Hearing Aids
Osseo Integrated Hearing Aid
Brain Stem Stimulation
Ear Anatomy and Disease State
Begin Section
gtgt
Patient Selection
42
Eligibility

• Determining whether a patient is eligible for a
  cochlear implant an assessment of responsiveness
  of auditory nerve is required
• Adults
• Must have at least 6 months experience with
  high-powered binaural (two ears) amplification
  AND undergo aided speech audiometry (established
  by FDA guidelines)
• Individuals with some remaining speech
  comprehension tend to have more success with a
  cochlear implant
• PTA gt 90dB or word understanding up to 30
• Children
• PTAs of at least 90dB
• Evaluation of child ability to acquire speech and
  language
• For infants, threshold testing is used to asses
  degree of hearing loss

Ear Anatomy and Disease State
gtgt
gtgt
Patient Selection
Eligibility
43
Success of Implantation

• While many factors impact how successful a
  particular implantation will be, the most
  successful patients generally17
• Have been hearing impaired for only a short time
• Are younger
• Have some level of retained speech abilities
• Patients who learned to speak before losing their
  ability to hear tend to regain speaking abilities
  faster than individuals who never acquired
  speaking skills
• Able and willing to learn quickly
• Have strong support networks for learning to use
  their new implant
• Retain more nerve (spiral ganglion cells) for the
  cochlear implant to stimulate

What happens if a cochlear implant is not an
effective treatment?
Ear Anatomy and Disease State
gtgt
gtgt
Patient Selection
Eligibility
44
When a cochlear implant is not effective

• Sometimes a cochlear implant is not the best
  treatment option and other restorative procedures
  must be considered and may include
• Hearing Aids
• Osseo-integrated Hearing Aids
• Brain Stem Stimulation

http//jamescartermd.com/the-hearing-aids.htm
http//www.earcentergreensboro.com/baha_device.htm

http//www.wiredtowinthemovie.com/mindtrip_xml.htm
l
Ear Anatomy and Disease State
gtgt
gtgt
Other Solutions
Patient Selection
45
Hearing Aids

• Amplify existing sound (increase dB) but do not
  help the ear to distinguish between different
  frequencies
• Many individuals who use hearing aids do not
  qualify for cochlear implantation because their
  hair cells are mostly intact and require only
  amplification in order to detect sounds and
  discriminate between frequencies18
• Often employed for older patients with functional
  but desensitized inner ear structures (including
  the cochlea and hair cells)

http//www.nidcd.nih.gov/health/hearing/hearingaid
.asp
Ear Anatomy and Disease State
gtgt
gtgt
Other Solutions
Patient Selection
46
Osseo-Integrated Hearing Aids

• Used to bypass the outer and middle ear if they
  are damaged
• A sound processor is anchored in the temporal
  bone of the skull and translates sound waves into
  structural vibrations in the skull that stimulate
  the cochlea and trigger the signal cascade to the
  auditory nerve
• This implant is a good option for individuals who
  retain normal cochlear function19

http//www.cochlearamericas.com/Products/2127.asp
Ear Anatomy and Disease State
gtgt
gtgt
Other Solutions
Patient Selection
47
Brain Stem Stimulation

• ABI (auditory brainstem implant) is a relatively
  new technology that bypasses all periphery
  auditory structures (outer, middle, and inner
  ear) to directly stimulate the cochlear nucleus
  in the brainstem
• ABIs are often used to treat neurofibromatosis
  type 2 (NF2) in which noncancerous tumors develop
  in the peripheral auditory structures

Tonotopic mapping of the cochlear nucleus is
required at the time of implantation
Ear Anatomy and Disease State
gtgt
gtgt
Other Solutions
Patient Selection
48
Ear Anatomy and Disease State Review
What part of the inner ear is damaged with
sensorineural hearing loss?
a. pinna
b. ossicles
d. ear canal
c. cochlea
What is an important causal factor in hearing
loss in children?
a. noise
b. disease
d. ototoxicity
c. age
Ear Anatomy and Disease State
Next Lesson
Repeat Lesson
gtgt
REVIEW
49
Cochlear Implant Surgery
Overview
Procedure
Risks
Click on a section or click Begin Lesson!
Tools
Cochlear Implant Surgery
Begin Lesson
Lesson Review
50
Cochlear Implant Surgery Overview
Minor operation - General Anesthesia - Time
1.5 - 5 hours 1. Emplacement of Receiver 2.
Insertion of electrode array into cochlear 3.
Suture and Clean up Some patients can go home
immediately afterwards
Cochlear Implant Surgery
gtgt
Overview
51
Surgery Procedure
Last Chance to look AWAY!!
1. Minimally shave the location of surgery
2. Incision into skin
3. Mastoidectomy
4. Cochlear implant Receiver/tie down
Cochlear Implant Surgery
gtgt
Procedure
52
Surgery Procedure
5.Cochleostomy
6. Electrode Insertion
7. Telemetry, closure, Radiography
Click for Detailed Step-by-Step Procedure
Cochlear Implant Surgery
gtgt
Procedure
53
Surgery Risks

• Any remaining hearing will be permanently lost
• Slight Risk of
• Facial paralysis
• Meningitis
• Metallic taste disturbance
• Infection
• Extreme Pain

http//innovativeproperty.net/Adoption20Pictures/
Peter20CI/Web20CIMG0048.jpg
Dont worry these guys are GOOD!!
Cochlear Implant Surgery
gtgt
Risks
54
Surgery Tools

• SINCE THE IMPLANT CONTAINS A STRONG
  MAGNET---NEVER USE MAGNETIC SURGERY TOOLS

Cochlear Implant Surgery
gtgt
Surgery Tools
55
Surgery Review

• Minor Surgery
• - Risks low
• Steps
• Implant receiver stimulator
• Insert electrode array into cochlear
• Tie down
• Close incision
• Hospitalization is usually not required

Boston Scientific
Next Lesson
Repeat Lesson
Cochlear Implant Surgery
gtgt
REVIEW
56
Post Operation and Rehabilitation
Post Operation
Limitations
Click on a section of click begin lesson!
Auditory Rehabilitation Therapy
Auditory Training
Training for Adults
Training for Children
Post Operation and Rehabilitation
Begin Lesson
Lesson Review
57
Post Operation

• 7 days of oral antibiotic and pain medication
• After 2-3 days remove the mastoid dressing
• Visit 2 weeks after operation
• Visit for Device Stimulation and Receiver fitting
  a month after surgery

http//www.my-potpourri.com/Cochlear_Implant_1
Post Operation and Rehabilitation
gtgt
Post Operation
58
Limitations

• Do not fly for 1 week
• Avoid Heavy Lifting for 6 weeks
• No vigorous activity of exercising
• Abstain from school or work for at least a week
• Keep area dry for 2 weeks
• Do not blow nose for 10 days
• No ibuprofen or aspirin for 10 days after

http//www.fnal.gov/pub/today/archive_2005/today05
-05-02.html
http//en.wikipedia.org/wiki/ImageShowerhead.JPG
http//www.flickr.com/photos/naser/298443329/
Post Operation and Rehabilitation
gtgt
gtgt
Post Op
Limitations
59
Auditory Rehabilitation Therapy

• External transmitter and sound processor given 1
  month after surgery
• Rapid improvement over first 3 months to
  recognize sounds and
• Lifelong Commitment- Annual checkups
• Audiologists
• adjusts sound processor to fit implanted patient
• Tests the patient for sounds he can hear

http//www.ntid.rit.edu/current/has_ci_program.php
Post Operation and Rehabilitation
gtgt
Rehabilitation
60
Auditory Training

• Awareness of sound
• Presence, absence
• Identification of sound
• Discrimination of speech sound
• Recognizing syllables
• Comprehension of speech discourse
• understanding

http//www.audiologyonline.com/articles/article_de
tail.asp?article_id332
http//cdswebserver.med.buffalo.edu/drupal/files/c
linic-kristen2.jpg
Break the Lip reading habit!!
http//buytaert.net/tag/photography?page8
http//www.mccullagh.org/image/1ds2-2/ear-closeup.
html
Post Operation and Rehabilitation
gtgt
Training
61
Training for Adults

• Use implant as much as possible
• Read aloud to friends and family
• Listen to books on tape while reading along
• Listening to radio
• Auditory Development Program
• Recognizing speech and environmental sounds
• Develop hearing techniques
• Develop communication techniques with loved ones

http//www.hearinglosseducation.com/Implants/132.a
sprehab
Post Operation and Rehabilitation
gtgt
gtgt
Training
Adults
62
Training for Children

• Wear the processor whenever awake
• Providing teachers, therapists, and family with
  plan to improve listening and communication
• Make Hearing and listening as fun as possible
• Talk about actions as they are executed
• Encourage child to make noises
• Motivational support

http//www.healthsystem.virginia.edu/internet/otol
aryngology/patient_cochlear.cfm
http//www.fda.gov/cdrh/cochlear/beforeduringafter
surgery.html
Post Operation and Rehabilitation
gtgt
gtgt
Training
Children
63
Psychological Recovery

• Good

• Bad

• Decline in loneliness, depression, social
  isolation
• Increase self-esteem

• Unreasonable Expectations
• Difficulty hearing with background noise

Documentary Hear and Now Sally and David Taylor
get implanted at same time. The Husband has a
more successful recovery with his implant
http//www.amfest.ru/files/Hearandnow_filmstill5.j
pg
Post Operation and Rehabilitation
gtgt
gtgt
Training
Psychological Problems
64
Post Operation and Rehabilitation Review

• Implant is turned on 1 month after surgery
• Appropriate expectations are key!
• Implant receivers will not be able to hear
  perfectly right away
• Hearing will improve, but a lot of practice is
  necessary
• It is important to wear the implant as much as
  possible

Next Lesson
Repeat Lesson
Post Operation and Rehabilitation
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REVIEW
65
Materials and Manufacture
Overview
Click on a section or click Begin Lesson!
External Components
Internal Components
Implant Sterilization
Materials and Manufacture
Begin Lesson
Lesson Review
66
Overview

• The purpose of the cochlear implant is to
  convert sounds from the environment into
  electronic signals, and to transmit these signals
  into the brain of an implantee, where the signals
  may be interpreted by the brain as sound.

Materials and Manufacture
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Overview
67
External Components
Transmitter
Speech Processor
Microphone
https//www.healthbase.com/hb/images/cochlear_impl
ant.jpg
Materials and Manufacture
External Components
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68
Microphone and Speech Processor
http//www.medel.com/US/MAESTRO-Cochlear-Implant-S
ystem/Speech-Processors/index.php
The microphone works with the speech processor to
take sounds from the environment
and convert them into electronic signals.
Microphone and Speech Processor
Materials and Manufacture
External Components
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Transmitter
http//www.medel.at/US/Information-for-Candidates/
Solutions-for-Children/BabyBTE.php
The transmitter attaches to the outside of the
skull with a magnet, and transmits signals
transcutaneously to the receiver.
Materials and Manufacture
External Components
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Transmitter
Next
70
Internal Components
Receiver
Stimulator
Electrode Array
https//www.healthbase.com/hb/images/cochlear_impl
ant.jpg
Internal Components
Materials and Manufacture
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71
Receiver
The receiver consists of a coil of wire, which
functions as an antenna, and receives signals
from the transmitter.
http//www.bcm.edu/oto/jsolab/cochlear_implants/Im
planted-device.gif
To find out what engineers considered when
designing the receiver, click the next button!
Materials and Manufacture
Internal Components
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Receiver
72
What properties are important in the receiver
design?
- Biocompatibility
- Non-Corrosivity
Internal Components
Materials and Manufacture
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Receiver
Properties
73
Receiver - Materials
Silicone
is used to encase the antenna wire. Silicone is
highly biocompatible in a cochlear implant
application, giving manufacturers more freedom
when choosing an antenna material.
http//www.thegolfproducts.com/images/L10798400a.j
pg
The silicone also protects the antenna from
corrosion in the bodys warm, salty interior.
Internal Components
Materials and Manufacture
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Receiver
Materials
74
How is the receiver made?
A straight wire is welded onto a ceramic disk in
the stimulator housing. This wire is then curled
into an antenna.
The coil wire is then encased in silicone in
order to protect the antenna. A small,
disk-shaped magnet is inserted into a pocket in
the silicone. This magnet allows the transmitter
to attach outside the skull.
Internal Components
Materials and Manufacture
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Receiver
Manufacture
75
Stimulator
The stimulator decodes signals from the receiver,
and sends them down a platinum wire to the
electrode array.
To find out what engineers considered when
designing the stimulator, click the next button!
Internal Components
Materials and Manufacture
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Stimulator
76
What properties are important in the stimulator?
- Biocompatibility
- Non-Corrosivity
- Strength
Internal Components
Materials and Manufacture
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Stimulator
Properties
77
Titanium
is used to encase the stimulator in an outer
shell. Titanium offers an excellent combination
of strength, biocompatibility, and
non-reactivity.
Cross Section of Stimulator
Silicone
envelops the simulator circuitry within the
titanium casing, absorbing shocks and insulating
the sensitive electronics.
Internal Components
Materials and Manufacture
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Stimulator
Materials
78
How is the stimulator made?
To manufacture the stimulator unit, the electrode
array and receiver antennae are welded to the
stimulator circuitry. The circuitry is then
encased in silicone to insulate it from
electrical impulses.
A titanium shell is then laser welded over the
silicone. This shell is hermetically sealed at
the entrance holes for the antennae and electrode
array.
Internal Components
Materials and Manufacture
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Stimulator
Manufacture
79
Electrode Array
http//www.cadinfo.net/editorial/cochlear.htm
Electrical signals, transmitted from the speech
processor, are used by the electrode array to
stimulate the auditory nerve at different points
along the cochlea.
Materials and Manufacture
Internal Components
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Electrode Array
80
The electrode array consists of 24 electrodes
imbedded in a flexible carrier.
To find out what engineers considered when
designing the electrode array, click the next
button!
Materials and Manufacture
Internal Components
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Electrode Array
81
What properties are important in the electrode
array?
- Biocompatibility
- Non-Corrosivity
- Conductivity

• Flexibility

Internal Components
Materials and Manufacture
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Electrode Array
Properties
82
Electrode Array - Materials
Platinum
is used in the electrodes. The high conductivity
and near incorruptibility of platinum make it an
excellent choice for delivering electrical
signals in a harsh environment like the human
body.
Silicone
encases the platinum electrodes and their
attached wire. The flexibility of silicone allows
it to be inserted into the cochlea with a minimum
of force.
Internal Components
Materials and Manufacture
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Electrode Array
Materials
83
How is the electrode array made?
To manufacture the electrode array, platinum
electrode wires are welded onto platinum rings.
Each wire is welded at the other end onto a pin
in the stimulator.
The whole assembly is then coated in silicone, to
provide structure and protection.
Internal Components
Materials and Manufacture
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Electrode Array
Manufacture
84
Ethylene Oxide Sterilization Advantages and
Disadvantages

• Advantages

• Disadvantages

• Complex Process
• Long Turnaround
• Carcinogen
• Explosive
• Negative environmental emissions

• Highly effective vs microbes
• Diffusive
• Compatible with Cochlear implant device and
  packing
• Bag flooded with ethylene oxide and other gasses
  which are later aerated
• Takes 2-3 hours
• 120oF

Materials and Manufacture
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Implant Sterilization
85
Cochlear Implant Sterilization and Packaging

• Sterilized by Ethylene Oxide (EO)
• Packaged in Sterile Package
• 2 year shelf life
• Templates are shipped non sterile
• Storing temperature
• 0to 43C
• 32 to 109F

http//www.powerhousemuseum.com/hsc/cochlear/img/P
ro006lr.jpg
Materials and Manufacture
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Implant Sterilization
86
Ethylene Oxide Sterilization Process

• Sterilization

• Post Sterilization Tests

• Conditioning
• Expose to high relative humidity and Temperature
• Sterilization cycle
• Expose to Ethylene Oxide Gas
• Aeration
• Dissipation of remaining gasses

• Device functionality
• Package integrity
• Re-sterlizaiton potential

www.pacificbiolabs.com
Materials and Manufacture
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On to Review
Implant Sterilization
87
Materials and Manufacture Review
The internal components of the cochlear implant
are the receiver, the stimulator, and the
electrode array.
In the Implant Titanium is welded around the
stimulator to provide strength Silicone
enshrouds the electrodes in the electrode array
and the circuitry in the stimulator to provide
insulation and protection Platinum is used in
the electrode array to conduct electricity
Next Lesson
Repeat Lesson
Materials and Manufacture
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REVIEW
88
Performance and Failure Modes
How a CI works
Performance
Audiological Performance
Click on a section or click Begin Lesson!
Skills development
Failure Modes
Surgery-related Failure
Device-related Failure
Begin Lesson
Lesson Review
89
How a CI Works

• Microphone detects sounds

Transmitter
Microphone
Performance and Failure modes
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How a CI works
90
How a CI Works
Microphone detects sounds Processor generates
electrical signals corresponding to detected
sound
Transmitter
more info about processor
Performance and Failure modes
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How a CI works
91
How a CI Works
Transmitter
Transmitter transmits signal to implanted
receiver
more info about transmitter
Performance and Failure modes
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How a CI works
92
How a CI Works
Transmitter
Transmitter transmits signal to implanted
receiver Electrode stimulates cochlear nerve
inside cochlea
Performance and Failure modes
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How a CI works
93
Transmission LinkHow external and internal parts
are connected

• Peridermal Coils to transmit and receive RF
  signal (similar to FM radio)
• Attached with magnet
• not safe for MRI
• Transdermal physical connection (a wire)
• higher likelihood of infection
• currently not used

skin
To electrodes
Wire
To electrodes
skin
Performance and Failure modes
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How a CI works
94
Performance
Audiological Performance
Speaking listening skills development
You can skip to the Summary of Results page for a
quick overview of the lesson!
Summary of Results
Performance and Failure modes
Begin Section
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Performance
95
Audiological Performance

• Enables user to perceive sounds
• - ambient sounds help user to orient him/her
  self and become more aware of the surroundings
• - Following successful implantations, many
  patients are able to understand speech
• Patients must adjust to listening electronically
• - voices may sound different than remembered
• - sounds may be squeaky
• - sound quality differs for each implant
  receiver

http//www.earfoundation.org.uk/research/faq_artic
les/3
Sound quality improves with use and practice.
Performance and Failure modes
Audiological Performance
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Performance
96
Factors Affecting Performance
Results vary depending on
Age
Duration of deafness
Device programming
Scroll over a topic to learn more!
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Performance
Factors affecting performance
97
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
In children, devices implanted after the critical
period for auditory input for acquisition of
speech may not produce optimal results.
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
98
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
The longer the duration of deafness the higher
the likelihood of loss of acquired skills and
cochlear nerve atrophy
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
99
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
The etiology or cause of hearing loss does not
directly affect implant performance of success.
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
100
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
Practice around the home with friends and family
is important!
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
101
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
It takes a lot of practice to adapt to hearing
with a CI. Motivation to succeed is a big factor
in achieving good results.
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
102
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
Previous listening experience can help to
interpret new sounds. But results also depend on
duration of deafness.
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
103
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
Cochlear malformations or ossification can hinder
positioning and insertion to hamper performance.
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
104
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
A supportive environment encourages implant
success
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
105
Factors Affecting Performance

• Results vary depending on

Age
Duration of deafness
Device programming
Highly advance signal processors allow tailoring
to each patient. Click here to learn more about
device programming.
Cause of hearing loss
Education environment
Family support
Health of cochlea
Motivation
Previous listening experience
Performance and Failure modes
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Factors affecting performance
Performance
106
Listening Skills Development
Timeline
http//www.healthyhearing.com/management/uploads/a
rticles/cochleararticle82503.gif
Beginning user
Sound awareness
Discriminates sounds can tell that one sound is
different from another
Understands environmental sounds
Understands single words and short phrases
supported by lip-reading
Understands single words and/or phrases (through
listening only)
Understands details in sentences
This process takes time and hard work!
Understands connected conversational speech
Practiced user
Performance and Failure modes
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Skills Development
Performance
107
Speaking Skills Development
Timeline ?
Speech recognition is a highly trained and
well-practiced skill based on auditory pattern
recognition.
Practice! Practice! Practice! And dont be shy.
http//www.healthyhearing.com/management/uploads/a
rticles/cochleararticle82503.gif
Performance and Failure modes
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Skills Development
Performance
108
Summary of Results
Highly successful in patients with intact cochlea
Unsuccessful in patients with abnormalities of
the cochlea and cochlear nerve (CN) or other
forms of auditory disconnection
Children who receive the implant at a young age
can benefit in language and speech development
Remember! Motivation and consistent implant
usage are important in implant success!
Performance and Failure modes
Next Section
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Results
Performance
109
Previous Listening Experience
Previous listening experience is usually found to
be beneficial. The auditory center of the brain
is developed. However, drawbacks are that sounds
do not sound the same when listening with a CI.
This is also closely linked to the duration of
deafness.
Recipients who are pre-lingually deaf
Recipients who are postlingually deaf

• - have no previous listening or speaking
  experience
• mostly children
• the optimum age to implant is before 5 yr
  
• after 5 years old, the brain is no longer able
  to develop listening as easily

• - have previous listening and perhaps speaking
  experience
• mostly adults
• may have forgotten abilities if duration of
  deafness is long
• those who remember hearing need to adjust more
  to CI listening

Performance and Failure modes
Factors affecting performance
Previous Listening Experience
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Performance
110
Duration of Deafness

• Individuals with shorter durations of auditory
  deprivation tend to achieve better auditory
  performance from any type of sensory aid
  (including cochlear implant) than individuals
  with longer durations of auditory deprivation.

• As duration of deafness increases
• acquired skills and knowledge decline
• behaviors that work against successful
  adaptation to a sensory device develop

Performance and Failure modes
Factors affecting performance
Previous Listening Experience
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Performance
111
Cause of Hearing Loss

• There is some disagreement regarding whether the
  disease state or condition causing hearing loss
  (etiology) affects auditory performance with CIs.
  
• Etiology of hearing loss correlates with
  performance only in so much as the symptoms
  associated with the disease. The effects of
  etiology can now be distinguished from other
  factors such as the duration of deafness and the
  age of onset.

Example Meningitic deafness does not necessarily
limit the benefit of cochlear implantation in the
absence of central nervous system complications,
cochlear ossification, or cochlear occlusion.
Children with congenital deafness and children
with pre-lingually acquired meningitic deafness,
can achieve similar auditory performance if the
cochlear implant is received before age 5 years.
In general, etiology does not appear to impact
auditory performance in either children or
adults.
Performance and Failure modes
Factors affecting performance
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Cause of Hearing Loss
Performance
112
Health of Cochlea

• Common conditions affecting physiology and health
  of cochlea
• Cochlear ossification Bone growth inside
  cochlea, can be caused by trauma or often by
  bacterial meningitis
• Cochlear malformation usually a congenital
  conditions, but can be caused by physical
  trauma
• Cochlear occlusion any condition or growth
  that blocks the cochlea canals and hinders
  implantation
• These conditions can make it difficult to
  surgically insert the electrode array.

http//universe-review.ca/I10-85-cochlea2.jpg
Performance and Failure modes
Factors affecting performance
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Health of Cochlea
Performance
113
Device Programming

• After activation of device
• Audiologists makes a MAP, which is unique to each
  individual. This MAP indicates the amplitude and
  frequency of stimulation, and also maps
  frequencies ranges onto electrodes. The patient
  must subsequently return for reprogramming
  routinely, as preferences as well as the cochlear
  physiology continues to change.
• Website about CI mapping

Performance and Failure modes
Factors affecting performance
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Device Programming
Performance
114
Processor

• The Med-El processor has the capability of
  generating 12,500 pulses/sec for a high-rate
  implementation. The amplitudes of the pulses are
  derived as follows. The signal is first
  pre-emphasized, and then applied to a bank of
  eight (logarithmically-spaced) bandpass filters
  of Butterworth type and of sixth-order. The
  bandpass filter outputs are full-wave rectified
  and low-pass filtered with a cutoff of 400 Hz.
  The low-pass filter outputs are finally mapped,
  using a logarithmic-type compression function, to
  the patient's dynamic range. Biphasic pulses,
  with amplitudes set to the mapped filter outputs,
  are delivered in an interleaved fashion to eight
  monopolar electrodes at a maximum rate of 1,515
  pulses/sec per channel. The pulses are
  transmitted transcutaneously through a
  radio-frequency link.

Performance and Failure modes
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Processor
How a CI works
115
Implant Complications and Device Failure
Surgery-related Complications
Infection
Incorrect Placement
Click on a topic or click the next arrow to learn
more!
Skin Flap Necrosis
So what can go wrong?
Device-related Failures
Electrode Array
Receiver/Stimulator
Performance and Failure modes
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Failure Modes
Back
116
Surgery-related Complications
Skin flap breakdown
(causing device extrusion)
Infection
Incorrect placement
Device removal and re-implantation
Performance and Failure modes
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Failure Modes
Surgery-related
117
Infection

• In addition to the general risks of surgery,
  cochlear implant patients are at a higher risk of
  bacterial meningitis (inflammation of the
  protective membranes covering the brain).

In 2008, - there has been one reported death of
a CI patient due to bacterial meningitis -
there has been one reported death of a CI patient
due to complications and infection post surgery
Click for more information on risks of CI surgery
Performance and Failure modes
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Surgery-related
Failure Modes
118
Incorrect Placement

• There have been documented cases of mis-insertion
• For example
• Insertion of electrode array into vestibular
  canal
• This is usually detected during surgery through
  monitoring, but can also be found after surgery
  through radiography. Misplaced electrodes are
  sometimes discovered at device activation or
  explantation.
• Trauma during surgery can stimulate ectopic bone
  formation around electrode array. This can
  hinder removal and re-implantation.

Performance and Failure modes
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Surgery-related
Failure Modes
119
Skin Flap Necrosis

• The skin flap is the section of skin under which
  the implanted receiver/stimulator sits
• Complications to healing after surgery can cause
  fluid drainage into the skin flap, abscess
  formation, swelling, and pain.
• This leads to skin flap breakdown or necrosis
  and implant extrusion.

Skin
Implant
Incision
Performance and Failure modes
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Surgery-related
Failure Modes
120
Device-related Failure
Most device failures occur at the two implanted
components Electrode array ? implanted in
cochlea Receiver/ stimulator ?
implanted under skin
www.nidcd.nih.gov
Performance and Failure modes
Material and Mechanical
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Fai