04 December 2009

How a Cochlear Implant Works?

Knowing what, exactly, the cochlear implant does may help kids better understand their new bionic ear and the cool technology behind it that allows them to hear better.

Here's how the implant works:

  • The microphone picks up sound.
  • Sound is sent to the sound and speech processor.
  • The sound and speech processor analyzes the sound and converts it into an electrical signal. (The signal contains information that determines how much electrical current will be sent to the electrodes.)
  • The transmitter sends the signal to the implant package, where it's decoded.
  • The implant package determines how much electric current should pass to the electrodes and sends the signal. The amount of electrical current will determine loudness, and the position of the electrodes will determine the sound's pitch.
  • The nerve endings in the cochlea (the area where the hair cells are located) are stimulated and the message is sent to the brain along the hearing nerve.
  • The brain interprets the sound and the person hears.

Cochlear Implant Surgery

The actual surgical procedure, which takes 2 to 4 hours and uses general anesthesia, involves securing the implant package under the skin and inside the skull, and then threading the wires containing the electrodes into the spirals of the cochlea.

To secure the implant, the surgeon first drills a 3- to 4-millimeter bed in the temporal bone (the skull bone that contains part of the ear canal, the middle ear, and the inner ear). Next the surgeon opens up the mastoid bone behind the ear to allow access to the middle ear. Then, a small hole is drilled in the cochlea and the wires containing the electrodes are inserted. The implant package is then secured and the incision is closed.

After having cochlear implant surgery, a child:

  • will probably be able to go home the next day
  • will have to wear a dressing over the implant area for 24 hours
  • may be off-balance or dizzy for a few days
  • may experience mild to moderate pain (the doctor may recommend giving pain medications)
  • won't have to have the stitches removed — they're absorbable and dissolve on their own
  • can lie on the side with the cochlear implant in a few days

Two to four weeks after surgery, the sound and speech processor is matched with the implant package and is programmed and fine-tuned to meet the child's individual hearing needs.

From: http://kidshealth.org

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