What are cochlear implants?
Cochlear implants are the latest advanced devices which convert sound into electrical energy and directly stimulate the cochlear nerve. Thus, they are extremely useful in persons who have lost the cochlear function but the retrocochlear pathway (cochlear nerve) is normal.
What are the parts of a cochlear implant?
The parts of a cochlear implant are as follows:
1) Microphone: This picks up the sound
2) Speech processor: It transfers sound from the microphone into electrical energy
3) Transmitter coil: It is transcutaneous and transmits signals into the implanted receiver coil without need of any wires
4) Receiver coil: It is an implanted coil into the bone of the skull behind the ear. The signals from the transmitter are decoded and relayed to the electrodes. The electrodes are placed in the cochlea to stimulate the VIIIth nerve
What are the types of cochlear implants?
The different types of cochlear implants are as given below.
Based on number of electrodes:
1) Single channel implants: It comprises of a single electrode implanted 6 mm into the scala tympani which stimulates the VIIIth nerve
2) Multi channel implants: They consist of upto 22 electrodes inserted into the scala tympani
Based on position of the electrodes:
1) Extra-cochlear: They are placed in the round window near the basal turn of the cochlea
2) Intra-cochlear: Placed into the scala tympani, they stimulate one or multiple areas of the cochlear nerve
Single channel implants:
1) William House model
2) Vienna Hochnan model
1) Clark Nucleus Model
2) Utch Eddington
What are the indications for cochlear implants?
Indications for cochlear implants are as follows:
1) Profound sensorineural loss with no cochlear function
2) Post lingual deafness
What are the possible complications of surgery?
Possible complications of surgery:
1) Facial nerve weakness
3) Cerebrospinal fluid leak
5) Failure of device
6) Most patients of cochlear implant require prolonged speech therapy.