Auditory Brainstem Implant
You may have heard of an auditory brainstem implant (ABI), which is
used for people whose auditory nerves are no not functional. Here's
an introduction to the ABI.
January 2004 - Here's some information on the first
major upgrade we've seen to the ABI.
April 2004 - And here's a followup on the first two
patients implanted with the Penetrating ABI.
May 2006 - ABI Sends Sound Signals Directly to Brain
Most readers are familiar with the cochlear implant (CI), but how
many have heard of a related device called the auditory brainstem
implant (ABI)? The ABI, like the CI, replaces part of the hearing
mechanism that is not working properly. Whereas the CI is implanted in
the cochlea and replaces the function of defective hair cells, the ABI
is implanted in the brainstem, and replaces the function of a defective
auditory nerve.
The ABI may be an appropriate treatment regardless of the cause of
the auditory nerve problem. It may be used most often in patients who
become deaf due to neurofibromatosis Type II (NF2). This disease causes
tumors on the cranial and spinal nerves. Removing those tumors often
requires severing the auditory nerve, which destroys the hearing in the
affected ear. Bilateral surgeries can destroy the hearing in both ears.
Traditional CIs are ineffective in these cases, because they rely on
the auditory nerve to transmit signals from the cochlea to the brain.
But the ABI bypasses the auditory nerve to inject acoustic information
directly into the brain.
The recently approved device is the Nucleus 24 Multichannel Auditory
Brainstem Implant from Cochlear Corporation. It is approved for use in
teens and adults with NF2. An evaluation of the device in 60 patients
revealed that 82 percent were able to detect environmental noise. The
majority of these patients reported that the ABI assisted their
lipreading, and a few were able to use a voice telephone. Eighteen
percent of the patients derived no benefit from the ABI.
For additional information, point your browser to www.cochlear.com.
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January 2004
We recently published an article about auditory brainstem implants (ABIs)
and explained that they are used by people who have had their acoustic
nerve severed, usually as treatment for neurofibromatosis, type 2 (NF2),
a disease which causes tumors on various nervous tissue throughout the
body. We reported that ABIs recipients are generally unable to
understand speech without lipreading, and one of our readers responded
that she is somewhat capable of doing so.
Doctor Bob Shannon of the House Ear Institute has recently implanted
new ABIs into two patients. These ABIs differ from previous ones, in
that they are inserted into the brainstem, rather than just lying
alongside it. While this technique offers the possibility of improved
performance, it is carries significantly more risk than the older ABIs.
Because the brainstem carries nerve signals from throughout the body,
damage to any portion of it can have serious and irreversible effects.
The new ABI has eight electrodes of varying lengths, intended to
provide eight channels of acoustic information (vice only one channel
from a traditional ABI). Dr. Shannon believes that the additional
acoustic information may result in much better speech understanding than
with a traditional ABI.
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April 2004
Editor: In Volume 18 Issue 3 we reported on the Penetrating Auditory
Brainstem Implant (PABI), a new device similar to a cochlear implant,
but designed for people whose auditory nerve is not intact. Here's an
update on the progress of the recent implantees. We were unable to get
permission to republish this article, so here are the first couple of
paragraphs. If your interest is piqued, the article is available
here.
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Researchers at the House Ear Institute in Los Angeles recently
reported success with two patients who were implanted with the new
penetrating electrode auditory brainstem implant (PABI) as part of a
clinical trial.
Molly Brown, one of the recent implantees, received the PABI in
November 2003. In mid-January this year, House Ear staff turned the
device on, and she was learning how to understand speech again with the
technology, reported David Lim, MD, head of House Ear's Department of
Cellular and Molecular Biology, during a recent press conference.
[Editor's note: At press time, House Ear staff reported that Brown was
progressing well with her PABI and hearing more sounds every day as she
becomes more accustomed to the device.]
"I'm very happy to be here to talk about my implant," said
Brown at the press conference. "I am happy to participate in the
clinical trial."
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May 2006
When
hearing aids lose their effectiveness in providing effective
communications, many people turn to the cochlear implant for improved
understanding. Cochlear implants are great for those who have intact
auditory nerves. But what about people whose auditory nerves are not
intact? They can use an auditory brainstem implant (ABI)!
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