What is cochlear Implant
A cochlear implant is an implanted electronic hearing device, designed to produce useful hearing sensations to a person with severe to profound nerve deafness by electrically stimulating nerves inside the inner ear.
These implants usually consist of 2 main components:
• The externally worn microphone, sound processor and transmitter system.
• The implanted receiver and electrode system, which contains the electronic circuits that receive signals from the external system and send electrical currents to the inner ear.
Currently made devices have a magnet that holds the external system in place next to the implanted internal system. The external system may be worn entirely behind the ear or its parts may be worn in a pocket, belt pouch, or harness.
Who uses cochlear implants
Cochlear implants allow deaf people to receive and process sounds and speech. To a certain degree, they are devices that allow deaf people to “hear.” However, it is important to understand that these devices do not restore normal hearing. They are tools that allow sound and speech to be processed and sent to the brain.
The way candidates are selected for cochlear implants is changing over time as the technology changes, and our understanding of the brain’s hearing (auditory) pathways improves.
Both children and adults can be candidates for cochlear implants. They may have been born deaf or become deaf after learning to speak. Children as young as 1 year old are now candidates for this surgery. Although criteria are slightly different for adults and children, they are based on similar guidelines:
1. The patient should be completely or almost completely deaf in both ears, and get almost no improvement with hearing aids. Anyone who can hear well enough with hearing aids is not a good candidate for cochlear implants.
2. The patient needs to be highly motivated. After the cochlear implant is placed, they must learn how to properly use the device.
3. The patient needs to have reasonable expectations for what will occur after surgery. The device does not restore or create “normal” hearing.
4. Children need to be enrolled in programs that help them learn how to process sound.
5. In order to determine if a patient is a candidate for a cochlear implant, the patient must be examined by an ear, nose, and throat (ENT) doctor (otolaryngologist). Patients will also need specific types of hearing tests performed with their hearing aids on. This may include a CT scan or MRI scan of the brain and the middle and inner ear.
6. Patients (especially children) may need psychological evaluation to determine if they are good candidates.
How does a cochlear implant work
In a normal ear, sounds are transmitted through the air, causing the eardrum and then the middle ear bones to vibrate. This sends a wave of vibrations into the inner ear (cochlea). These waves are then converted by the cochlea into electrical signals, which are sent along the auditory nerve to the brain.
A deaf person does not have a functioning inner ear. A cochlear implant attempts to replace the function of the inner ear by turning sound into electrical energy. This energy can then be used to stimulate the cochlear nerve (the nerve for hearing), sending “sound” signals to the brain.
Most cochlear implants operate using several similar parts. Sound is picked up by a microphone worn near the ear. This sound is sent to a speech processor usually connected to the microphone and worn behind the ear. The sound is analyzed and converted into electrical signals, which are sent to a surgically implanted receiver behind the ear. This receiver sends the signal through a wire into the inner ear. From there the electrical impulses are sent to the brain.
How does someone receive a cochlear implant
Surgery for inserting a cochlear implant is performed while you are fully asleep. A surgical cut is made behind the ear, sometimes after shaving part of the hair behind the ear. A microscope and bone drill are used to open the bone behind the ear (mastoid bone) to allow the inside part of the implant to be inserted.
The electrode array is passed into the inner ear (cochlea). The receiver is placed into a pocket created behind the ear. The pocket helps keep it in place, and makes sure it is close enough to the skin to allow electrical information to be sent from the device. A “well” may be drilled into the bone behind the ear so the implant is less likely to move under the skin.
After surgery, there will be stitches behind the ear. You may be able to feel the receiver as a bump behind the ear. Any shaved hair should grow back. The outside part of the device will be placed 1 – 4 weeks after surgery to give the opening time to heal.