cochlear implant

1. Welcome you all



BY:lokendra yadav

2. Cochlear implant
A
REVOLUTION
IN
The world of implant & hearing

3. cochlear

5. WHAT IS cochlear implant?

?

6. Volta: 18
th
century
Djourno and Eyries: 1950 & 1957(head)
House, Doyle, Simmons(six channel implant)
1972 Single-channel implant
1984 FDA approval
1990’s
Beyond

7. A cochlear implant is an electronic device that allows
many people with hearing loss to hear better. Unlike
hearing aids, which amplify sound, cochlear
implants bypass the damaged inner ear and send
sound directly to the brain. Many recipients can
reconnect with loved ones, contribute their talents at
work, and chat comfortably in restaurants.

8. Cochlear implant
Cochlear
implant
Medical
Approach
Engg.
Approach

9. Engineering
approach

10. Components of Cochlear Implant

12. Single vs. Multiple channels
Audio example of how a cochlear implant sounds with
varying number of channels
Monopolar vs. Bipolar
Speech processing strategies
Spectral peak (Nucleus)
Continuous interleaved sampling (Med-El, Nucleus,
Clarion)
Advanced combined encoder (Nucleus)
Simultaneous analog strategy (Clarion)

13. Firing rate responses (color
coded) evoked by various
cochlear-implant stimuli in the
auditory cortex (guinea pig).

Vertical axis = cortical place
• top = caudo-medial
• bottom = rostro-lateral

Horizontal axis = time relative
to stimulus onset

Blue  Yellow  Red
Low FR  high FR
(where “FR” = firing rate in
action potentials/second)

 = FR weighted centroid of
activity
Monopolar electrode
Bipolar electrode
Tripolar electrode
Basal coochlea
High frequencies
Apical cochlea
Low frequencies
Cochlear stimulation

14. Strategy Signal
Representation
Stimulation Channels Rate
per channel
Device
CA Bandpassed
Waveforms
Analog 4 Continuous
Waveform
Ineraid
CA Bandpassed
Waveforms
Analog 8 13,000
samples/sec
Clarion1.0
CIS Envelope signals Pulsatile 8 833 pps Clarion1.0
CIS Envelope signals Pulsatile 8 1,515 pps Med-El
F0/F2 Second formant,
Voicing features
Pulsatile 1 F0 or
random rate
Nucleus
F0/F1/F2 First and second
formant,
Voicing features
Pulsatile 2 F0 or
random rate
Nucleus

15. Simulation of cochlear implant……….

16. Cochlear-implant simulation 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
-6
-4
-2
0
2
4
6
8
Waveform of Original Sound
Time (sec)
Amplitude TextEnd
Time
Frequency TextEnd
Spectrogram of Original Sound
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
0
2000
4000
6000
8000 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
-1
-0.5
0
0.5
1
1.5
2
x 10
4
Simulated waveform
Time (sec)
Amplitude TextEnd
Time
Frequency TextEnd
Spectrogram of simulated waveform
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
0
2000
4000
6000
8000
From Lokendra:_maulana azad medical college
best 6 of 16 channels, 250 Hz pulserate, 16 kHz sampling H/U filterbank

17. General specification of cochlear
implant device:
Length of electrode array:25mm
2 Gnd electrode
No of channels: 20
Electrode impedence:2K
General features
Surgical features
Electrode array features
Stimulation features

18. MEDICAL
APPROACH

19. Adults
18 years old and older (no limitation by age)
Bilateral severe-to-profound sensorineural hearing loss
(70 dB hearing loss or greater with little or no benefit
from hearing aids for 6 months)
Psychologically suitable
No anatomic contraindications
Medically not contraindicated

20. R
C.I.

21. Pre surgical requirement:
Check the impedance of ear it should not be more
CT findings
Check BP
No anatomical disorders in ear
No psychological complain history

23. Surgical steps:
Step 1: provide anesthesia to patient before 10 min (subjected)
Step 2 : marking of area where incision would be given by methyl blue
Step3: surgeon should initiate the process mastoidtomy, posterior
tympanotomy by giving surface incision(temporal fasica graft) by using
surgical blade or electric cut.


Now temporal bone dissection : use drill bit of 1mm at 18000 to 20000 rpm not
above .some time 3mm drill bit is also used.
Facial nerve preservation is crucial part of the surgery

24. 1
st
Landmark incus
stapes
Incision in round
window
insertion of electrode

25. Cochlear receiver setting

Bed arrangement
Screw arrangement

29. Complication rate only 5%
Wound infection/breakdown
Yu, et al showed good response to Abx, I&D
Facial nerve injury/stimulation, CSF leak,
Meningitis
CDC recommendations
Vertigo (Steenerson reported 75%)
Device failure—re-implantation usually successful
Avoid MRI

30. Necessary part of implantation
Different focus depends on patient’s previous
experience with sound
Goal is to enable children to be able to learn passively
from the environment
Program addresses receptive as well as expressive
language skills
Multidisciplinary, dedicated group necessary

31. Partial implants with hearing aid
Those with residual low-frequency hearing
Intraoperative mapping
Bilateral implantation
One vs. two speech processors
Implantation for asymmetric SNHL
“Softip” array
Minimally invasive implantation