Middle Ear Implants
Middle ear implants, or MEI, are used to treat people with sensorineural hearing loss. These devices are implantable alternatives to hearing aids. In rare circumstances, these implants can be helpful for those with conductive or mixed hearing loss, if conventional hearing aids cannot be used.
With moderately severe to severe hearing loss, traditional hearing aids need to powerfully amplify sound, so that the acoustic signal stimulates the reduced function of the inner ear. This powerful amplification can create some problems with hearing aids that lead to sound distortion, feedback, and an uncomfortable obstruction effect.
Middle ear implants are best for individuals who do not benefit from, or are unable to use, traditional hearing aids.
An MEI is directly attached to a structure in the middle ear. It causes this structure to vibrate in much the same way that sound traveling down the ear and through the ear drum causes middle ear structures to vibrate. These acoustic vibrations are amplified and can be adjusted to optimally compensate for different kinds of hearing losses.
Most middle ear implants are semi-implantable and consist of two parts, an external and an internal component. For semi-implantable MEIs, the external part is an audio processor, which consists of a microphone, speech processor, and radio frequency transmitter. The internal, implanted part consists of a radio frequency receiver, electronic components, and a mechanical vibrator. A fully implantable MEI is also available. All of its components, including the battery and microphone, can be implanted.
Candidates for middle ear implants should be free of significant middle ear disease or infection. Hearing loss should be stable, and word recognition scores should be sufficient to allow adequate discrimination of sounds.