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Cochlear Implants

Are electronic devices which convert sound signals into electrical impulses, this in turn stimulates the cochlear nerve directly by pressing the hair cells of cochlea.
  1. Component:
    1. Microphone – picks up acoustic signals
    2. Speech processor – converts sound signals into electrical energy
    3. Electrode – Stimulates the cochlearnerve
  2. Surgery:
    In most cases cortical mastoidectomy is done and through the facial recess, middle ear is accessed, a small whole is made near the round window and the electrodes are passed through it into the scala tympani of cochlea. The microphone and peech processor are attached to skull externally and are connected to the electrodes.
  3. Selection of Candidates for Cochlear Implants
    Implants have been used both for adults and children.
    Criteria for adults
    1. Age: 1 year or more
    2. Bilateral severe to profound hearing loss (> 90 db) >70 decibels
    3. Limited or no benefit from hearing aids
    4. No medical contraindication to undergo surgery.

Post-lingually deafened adults are good candidates. Results are not so good in pre-lingually deaf adults

unless they had been receiving aural-oral training for communication. Rehabilitation is very important

for all the candidates.

  1. Criteria for children. Auditory deprivation, i.e. lack of auditory stimulus in the early developmental period causes degenerative changes in central auditory pathways. An early auditory stimulation by cochlear implants can pre­vent it. Now implants can be used at an age as early as 12 months. Implants can be used in both pre-lingually or post­lingually deafened infants and children. The criteria are:
    1. Bilateral profound or severe to profound hearing loss
    2. Minimal or no benefit from hearing aid
    3. No medical contraindication
    4. Willingness and support of family to enroll the child for post-implant training programme.

Complication of cochlear implants


Early complications

Late complications

1. Facial paralysis

1. Exposure of device and extrusion

2. Wound infection

2. Pain at the site of implant

3. Wound dehiscence

3. Migration/displacement of device

4. Flap necrosis

4. Late device failure

5. Electrode migration.

5. Otitis media

6. Device failure


7. CSF leak


8. Meningitis


9. Post-operative dizziness/vertigo


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