cochlear implant

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cochlear implant

  1. 1. Welcome you allBY:lokendra yadav
  2. 2. Cochlear implant A REVOLUTION INThe world of implant & hearing
  3. 3. cochlear
  4. 4. WHAT IS cochlear implant? ?
  5. 5.  Volta: 18th century Djourno and Eyries: 1950 & 1957(head) House, Doyle, Simmons(six channel implant) 1972 Single-channel implant 1984 FDA approval 1990’s Beyond
  6. 6. A cochlear implant is an electronic device that allowsmany people with hearing loss to hear better. Unlikehearing aids, which amplify sound, cochlearimplants bypass the damaged inner ear and sendsound directly to the brain. Many recipients canreconnect with loved ones, contribute their talents atwork, and chat comfortably in restaurants.
  7. 7. Cochlear implant Cochlear implant Engg. MedicalApproach Approach
  8. 8. Engineering approach
  9. 9. Components of Cochlear Implant
  10. 10.  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)
  11. 11. Basal coochlea Cochlear stimulation Apical cochlea Firing rate responses (colorHigh frequencies Low frequencies coded) evoked by various Monopolar electrode 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
  12. 12. Strategy Signal Stimulation Channels Rate Device Representation per channelCA Bandpassed Analog 4 Continuous Ineraid Waveforms WaveformCA Bandpassed Analog 8 13,000 Clarion1.0 Waveforms samples/secCIS Envelope signals Pulsatile 8 833 pps Clarion1.0CIS Envelope signals Pulsatile 8 1,515 pps Med-ElF0/F2 Second formant, Pulsatile 1 F0 or Nucleus Voicing features random rateF0/F1/F2 First and second Pulsatile 2 F0 or Nucleus formant, random rate Voicing features
  13. 13. Simulation of cochlear implant……….
  14. 14. Cochlear-implant simulation Waveform of Original Sound 4 Simulated waveform x 10 8 2 6 1.5 4 1 Amplitude Amplitude 2 0.5 0 TextEnd 0 TextEnd -2 -4 -0.5 -6 -1 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Time (sec) Time (sec) Spectrogram of Original Sound Spectrogram of simulated waveform 8000 8000 6000 6000 Frequency Frequency 4000 4000 TextEnd TextEnd 2000 2000 0 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Time TimeFrom Lokendra:_maulana azad medical collegebest 6 of 16 channels, 250 Hz pulserate, 16 kHz sampling H/U filterbank
  15. 15. General specification of cochlearimplant 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
  16. 16. MEDICALAPPROACH
  17. 17.  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
  18. 18. RC.I.
  19. 19. 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
  20. 20. Surgical steps:Step 1: provide anesthesia to patient before 10 min (subjected)Step 2 : marking of area where incision would be given by methyl blueStep3: surgeon should initiate the process mastoidtomy, posteriortympanotomy by giving surface incision(temporal fasica graft) by usingsurgical blade or electric cut.Now temporal bone dissection : use drill bit of 1mm at 18000 to 20000 rpm notabove .some time 3mm drill bit is also used.Facial nerve preservation is crucial part of the surgery
  21. 21. 1st Landmark incus stapes Incision in round windowinsertion of electrode
  22. 22. Cochlear receiver settingBed arrangementScrew arrangement
  23. 23.  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
  24. 24.  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
  25. 25.  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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