Cochlear Implants

1
Cochlear Implants

• Shawn Sweeney

2
What is a cochlear implant?

• Surgically implanted device
• Electronically stimulates the cochlea
• External and internal components
• Bypasses the entire outer and middle ear system
• Performs the task of damaged or missing hair
  cells in the cochlea
• IS NOT A HEARING AID!

3
Cochlear Implant vs. Hearing Aid

• Hearing Aid
• External device
• Amplifies sound
• Usually little or no help to a person with a
  profound (90 dBHL) sensorineural hearing loss

4
Cochlear Implant vs. Hearing Aid

• Cochlear Implant
• Directly stimulates surviving auditory nerve
  fibers in the cochlea
• Can be very beneficial for someone with a severe
  to profound sensorineural hearing loss
• Permanently destroys any functioning hair cells
  and therefore, destroys any residual hearing

5
Who is a candidate? A person with

• Profound BILATERAL sensorineural hearing loss
  (PTA greater than 95dBHL)
• which can be documented behaviorally
• 12 months of age or older
• No medical contraindications
• (i.e. ossification of cochlea, damage to VIII
  cranial nerve, as well as cognitive limitations
  and other disabilities)
• High motivation and appropriate expectations

6
Appropriate expectations

• Cochlear implants DO NOT restore natural hearing
  ability
• When implant is off, the person is DEAF
• Years of therapy are necessary to get maximum
  benefit from implant

7
The Surgery

• 2-3 hours under general anesthesia
• Hospitalization for 1-5 nights (depending on
  patient and insurance company)
• Post surgical problems may include soreness
  around the ear, tinnitus, nausea, and slight
  vertigo

8
Cochlear Implant Team

• Surgeon - surgically implants device
• Audiologist - performs pre/post implant testing,
  turns on the implant and adjusts settings as
  necessary
• Speech Pathologist - provides crucial therapy
  needed to gain maximum benefit
• Psychologist - evaluates patient and/or family
  regarding expectations and overall stability
• Educator - interacts with implant user on day to
  day basis and is key in gaining maximum benefit

9
External Components

1. Microphone - picks up sound at ear level
2. Speech processor - filters, analyzes digitizes
   sound into coded signals
3. Transmission Wire - transmits coded signals to
   transmitting coil
4. Transmitting coil - sends coded signals as FM
   radio signals to cochlear implant under the skin

1. Microphone
2. Speech Processor
4. Transmitting Coil
3. Transmission Wire
10
Internal Components

• 5. Internal Receiver - receives code from
  external transmitting coil
• 6. Converter - converts code into electrical
  signals
• 7. Electrodes - stimulate nerve fibers

5. Internal Receiver
6. Converter
7. Electrodes
11
More on electrodes

• Electrical stimulation of the nerve fibers
  through the electrodes produces hearing sensation
• Quality of hearing sensation depends on number of
  electrodes
• The more electrodes stimulated, the more natural
  the sound quality

12
Even more on electrodes

• An electrode stimulates a certain spot within the
  cochlea
• Stimulation at the basal (lower) end results in
  the perception of a high frequency sound
• Stimulation at the apical (higher) end results in
  the perception of a low frequency sound
• Simultaneous stimulation of different areas
  allows for the perception of speech and other
  environmental noises

13
Cochlear Implant Simulation

• Again, more electrodes results in better sound
  quality
• Therefore, a 22 electrode cochlear implant is
  preferred over a 1 electrode cochlear implant

14
FM Systems

• Most current cochlear implants are compatible
• Studies have not yet proven efficacy
• FM boots onto cochlear implant like it does a
  hearing aid

15
MRI Safety

• MRIs use magnets
• Cochlear implants have a magnet in them
• Most people who have cochlear implants cannot
  receive an MRI
• However, current implants made by Cochlear Corp.
  have removable magnets making MRI testing safe

16
In Summary

• Cochlear implants are surgically implanted
  devices which allow for the perception of sound
• They are not for everyone
• Strict candidacy requirements need to be met
• Can provide those with a bilateral profound
  sensorineural hearing loss with the ability to
  perceive sound

17
Resources

• Cochlear Corporation
• www.cochlearamericas.com
• Advanced Bionics
• www.cochlearimplant.com
• Med-El
• www.medel.com