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Welcome You All: BY:lokendra Yadav

Cochlear implants are electronic devices that bypass damaged parts of the inner ear to provide a sense of sound to those with severe-to-profound hearing loss. They work by directly stimulating the auditory nerve with electrical pulses. Cochlear implants have evolved greatly since the first human implantation in the 1950s and FDA approval in the 1980s. Today's implants can help many recipients reconnect with communication by processing sound into electrical signals mapped to different regions of the cochlea. The surgery to implant the device requires skill to preserve structures like the facial nerve while inserting the electrode array. Post-operative rehabilitation is also important for learning to interpret the new sounds.

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73 views32 pages

Welcome You All: BY:lokendra Yadav

Cochlear implants are electronic devices that bypass damaged parts of the inner ear to provide a sense of sound to those with severe-to-profound hearing loss. They work by directly stimulating the auditory nerve with electrical pulses. Cochlear implants have evolved greatly since the first human implantation in the 1950s and FDA approval in the 1980s. Today's implants can help many recipients reconnect with communication by processing sound into electrical signals mapped to different regions of the cochlea. The surgery to implant the device requires skill to preserve structures like the facial nerve while inserting the electrode array. Post-operative rehabilitation is also important for learning to interpret the new sounds.

Uploaded by

Lokender Yadav
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Welcome you all

BY:lokendra yadav

Cochlear implant A REVOLUTION IN The world of implant & hearing

cochlear

WHAT IS cochlear implant?

Volta: 18th century

Djourno and Eyries: 1950 & 1957(head)


House, Doyle, Simmons(six channel implant) 1972 Single-channel implant

1984 FDA approval


1990s Beyond

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.

Cochlear implant
Cochlear implant

Engg. Approach

Medical Approach

Engineering approach

Components of Cochlear Implant

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)

Basal coochlea High frequencies

Cochlear stimulation

Apical cochlea Low frequencies

Monopolar electrode

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

Bipolar electrode

Horizontal axis = time relative to stimulus onset Blue Yellow Red Low FR high FR (where FR = firing rate in action potentials/second)

Tripolar electrode

= FR weighted centroid of activity

Strategy Signal Representation CA CA Bandpassed Waveforms Bandpassed Waveforms Envelope signals Envelope signals Second formant, Voicing features

Stimulation Channels Rate per channel Analog Analog 4 8 Continuous Waveform 13,000 samples/sec 833 pps 1,515 pps F0 or random rate F0 or random rate

Device Ineraid Clarion1.0

CIS CIS F0/F2

Pulsatile Pulsatile Pulsatile

8 8 1

Clarion1.0 Med-El Nucleus

F0/F1/F2 First and second Pulsatile formant, Voicing features

Nucleus

Simulation of cochlear implant.

Cochlear-implant simulation

8 6 4

Waveform of Original Sound

2 1.5

x 10

Simulated waveform

Amplitude

2 0 TextEnd -2 -4 -6 0 0.5 1 1.5 2 2.5 Time (sec) 3 3.5 4 4.5 5

Amplitude

1 0.5 0 -0.5 -1 0 0.5 1 1.5 2 2.5 Time (sec) 3 3.5 4 4.5 TextEnd

Spectrogram of Original Sound 8000

8000

Spectrogram of simulated waveform

6000

6000

Frequency

4000 TextEnd 2000

Frequency

4000 TextEnd 2000

0 0 0.5 1 1.5 2 2.5 Time 3 3.5 4 4.5

0.5

1.5

2.5 Time

3.5

4.5

From Lokendra:_maulana azad medical college best 6 of 16 channels, 250 Hz pulserate, 16 kHz sampling H/U filterbank

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

MEDICAL APPROACH

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

C.I.

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

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

1st Landmark incus stapes

Incision in round window

insertion of electrode

Cochlear receiver setting Bed arrangement Screw arrangement

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 failurere-implantation usually successful

Avoid MRI

Necessary part of implantation Different focus depends on patients 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

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

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