“First Brainstem Implants Aim to Tackle Deafness”
Author: Duncan Graham-Rowe
Publication: New Scientist
Date: January 7, 2004
Cochlear implants help many people who have lost their hearing as a result of problems with their hair cells. However, the implants depend on direct stimulation of an intact auditory nerve. This means that many people cannot be helped by a cochlear implant. However, this article from New Scientist describes a new technique that could potentially restore the hearing of people with a nonfunctioning auditory nerve.
This technique, called the auditory brainstem implant, seems like the natural next step from cochlear implants. Instead of stimulating the auditory nerve, which then sends electrical signals to the brain, auditory brainstem implants directly stimulate the brain by inserting electrodes into the cochlear nucleus in the brainstem. Other than the placement of the electrodes, auditory brainstem implants work in the same way as cochlear implants. As in cochlear implants, an external microphone collects sound waves, which are converted into electrical impulses by a speech processor. The electrodes then use these electrical impulses to stimulate different pitch areas of the brainstem. This hopefully results in the person receiving the implant being able to hear.
There are several problems with the new implants. Current brainstem implants can only stimulate one channel (or frequency), which is enough to improve lip reading by 30 percent but not enough to understand speech. Newer implants will include up to eight electrodes that will stimulate eight different channels. This will be more than enough to understand speech. However, there is also one other problem that is much more significant than the number of channels that are stimulated. Unlike the cochlear implant, the auditory brainstem implant could potentially damage the brainstem. As the article points out, the brainstem carries signals from the entire body to the brain, and thus any damage to the brainstem would have tragic consequences.
The article provides a clear introduction to auditory brainstem implants. It both demonstrates the enormous potential of the implants and points out the problems and dangers inherent in the process. Like the Science article that I wrote on last week, however, the article does not touch upon the deaf community’s reaction to the brainstem implant, and thus completely avoids any mention of the potential controversy. Also, the article does not mention the cost of the brainstem implant, or if insurance will cover the procedure. Nevertheless, the article successfully highlights the fact that this implant could give hope to many who have given up on ever being able to hear.
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