A cochlear implant is an electronic device that restores partial hearing to individuals with severe to profound hearing loss who do not benefit from a conventional hearing aid. It is surgically implanted in the inner ear and activated by a device worn outside the ear.
In most cases, the hair cells are damaged and do not function. Although many auditory nerve fibres may be intact and can transmit electrical impulses to the brain, these nerve fibres are unresponsive because of hair cell damage. Since severe sensorineural hearing loss cannot be corrected with medicine, it can be treated only with a cochlear implant. Cochlear implants bypass damaged hair cells and convert speech and environmental sounds into electrical signals and send these signals to the hearing nerve.
The microphone captures sound, allowing the speech processor to translate it into distinctive electrical signals. These signals or “codes” travel up a thin cable to the headpiece and are transmitted across the skin via radio waves to the implanted electrodes in the cochlea. The electrodes’ signals stimulate the auditory nerve fibres to send information to the brain, where it is interpreted as meaningful sound.
The implant team (otolaryngologist, audiologist, nurse, and others) will determine your candidacy for a cochlear implant and review what you may expect as a result of the cochlear implant.
Cochlear implant surgery
Cochlear implant surgery is usually performed under general anaesthesia. An incision is made behind the ear to open the mastoid bone leading to the middle ear space. Once the middle ear space is exposed, an opening is made in the cochlea and the implant electrodes are inserted. The electronic device at the base of the electrode array is then placed under the skin behind the ear.
Three to Four weeks after surgery, cochlear implant team places the signal processor, microphone, and implant transmitter outside your ear and adjusts them. They teach you how to look after the system and how to listen to sound through the implant. There are many causes of hearing loss and some patients may take longer to fit and require more training due to individual differences. Your team will ask you to come back to the clinic for regular checkups and readjustment of the speech processor as needed. While cochlear implants do not restore normal hearing, and benefits vary from one individual to another, most users find that cochlear implants help them communicate better through improved lip-reading.