Auditory brainstem implant
Encyclopedia
An Auditory Brain Stem Implant (ABI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf, due to sensorineural hearing impairment (due to illness or injury damaging the cochlea
or auditory nerve
, and so precluding the use of a cochlear implant
).
The auditory brain stem implant uses similar technology as the cochlear implant
, but instead of electrical stimulation being used to stimulate the cochlea, it is instead used to stimulate the brain stem of the recipient.
Only about a thousand recipients have been implanted with an auditory brain stem implant, due to the nature of the surgery required to implant the device (as it requires brain surgery
to implant the device) and the reduced effectiveness of the implant (most auditory brain stem implant recipients only have an awareness of sound - recipients won't be able to hear musical melodies, only the beat).
In the United States ABIs are only approved for adults (18 & over) and only for patients with Neurofibromatosis type II
(NF2).
In Europe, ABIs have been used in children and adults, and in patients with NF2 as other auditory complications, such as auditory nerve aplasia and cochlea ossification . Speech perception in non-NF2 patients on average has been reported to be higher than that of NF2 patients.
In the US in 1992 an eight electrode implant developed by Cochlear Limited, the House Ear Institute and Huntington Medical Research Institute . An electrode array with 21 electrodes developed by Cochlear Limited was developed for the European market at the same time . The processor for both the eight and 20 electrode implants used Nucleus 22 ABI (Cochlear Limited) external speech processors. Since 1999 a 21 electrode array implant has been used with the Nucleus 24 ABI (Cochlear Limited) speech processor.
A 12 electrode array implant with a speech processor based on the C40+ cochlear implant (Med-El) and a 16 electrode array implant with the Clarion-1.2 cochlear implant (Advanced Bionics) have also been developed.
Cochlea
The cochlea is the auditory portion of the inner ear. It is a spiral-shaped cavity in the bony labyrinth, making 2.5 turns around its axis, the modiolus....
or auditory nerve
Vestibulocochlear nerve
The vestibulocochlear nerve is the eighth of twelve cranial nerves, and is responsible for transmitting sound and equilibrium information from the inner ear to the brain...
, and so precluding the use of a cochlear implant
Cochlear implant
A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing...
).
The auditory brain stem implant uses similar technology as the cochlear implant
Cochlear implant
A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing...
, but instead of electrical stimulation being used to stimulate the cochlea, it is instead used to stimulate the brain stem of the recipient.
Only about a thousand recipients have been implanted with an auditory brain stem implant, due to the nature of the surgery required to implant the device (as it requires brain surgery
Neurosurgery
Neurosurgery is the medical specialty concerned with the prevention, diagnosis, treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spine, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system.-In the United States:In...
to implant the device) and the reduced effectiveness of the implant (most auditory brain stem implant recipients only have an awareness of sound - recipients won't be able to hear musical melodies, only the beat).
In the United States ABIs are only approved for adults (18 & over) and only for patients with Neurofibromatosis type II
Neurofibromatosis type II
Neurofibromatosis Type II is an inherited disease. The main manifestation of the disease is the development of symmetric, non-malignant brain tumours in the region of the cranial nerve VIII, which is the auditory-vestibular nerve that transmits sensory information from the inner ear to the...
(NF2).
In Europe, ABIs have been used in children and adults, and in patients with NF2 as other auditory complications, such as auditory nerve aplasia and cochlea ossification . Speech perception in non-NF2 patients on average has been reported to be higher than that of NF2 patients.
Implant history
The auditory brainstem was first implanted in humans in 1979 at the House Ear Institute, CA, USA. This original ABI consisted of two ball electrodes which were implanted near the surface of the cochlear nucleus. A change from a percutaneous connection to a wireless transcutaneous connection, and from ball electrodes to flat electrodes were the only changes to the implant until 1991, where 25 people had received the ABI .In the US in 1992 an eight electrode implant developed by Cochlear Limited, the House Ear Institute and Huntington Medical Research Institute . An electrode array with 21 electrodes developed by Cochlear Limited was developed for the European market at the same time . The processor for both the eight and 20 electrode implants used Nucleus 22 ABI (Cochlear Limited) external speech processors. Since 1999 a 21 electrode array implant has been used with the Nucleus 24 ABI (Cochlear Limited) speech processor.
A 12 electrode array implant with a speech processor based on the C40+ cochlear implant (Med-El) and a 16 electrode array implant with the Clarion-1.2 cochlear implant (Advanced Bionics) have also been developed.
External links
- Nucleus ABI24M Brief description of the Nucleus Auditory Brainstem Implant (the Nucleus ABI24M)
- Picture & brief description of the MedEl ABI electrode array