Miniature device implanted in brain could monitor and treat epilepsy
15 August 2007
Purdue University researchers have developed a new
miniature device designed to be implanted in the brain to predict and
prevent epileptic seizures.
They have developed a tiny transmitter three times the width of a human
hair to be implanted below the scalp to detect the signs of an epileptic
seizure before it occurs. The system will record neural signals relayed by
electrodes in various points in the brain.
Pedro Irazoqui uses a "radio frequency probe station" to test
tiny circuits in the miniature device designed to be implanted in the brain
to predict epileptic seizures. Photo credit Purdue News Service photo/David
"When epileptics have a seizure, a particular part of the brain starts
firing in a way that is abnormal," said Pedro Irazoqui, an assistant
professor of biomedical engineering. "Being able to record signals from
several parts of the brain at the same time enables you to predict when a
seizure is about to start, and then you can take steps to prevent it."
Data from the implanted transmitter will be picked up by an external
receiver, also being developed by the Purdue researchers.
consumes 8.8 milliwatts, about one-third as much power as other implantable
transmitters while transmitting 10 times more data, and can collect data
related to epileptic seizures from 1,000 channels, or locations in the
The electrodes that pick up data will be inserted directly in the
brain through holes in the skull and then connected to the transmitter by
A commercial implantable device that can record epilepsy data from
eight channels has been developed by other researchers is currently in
clinical trials at several sites, including the Indiana University School of
The research has been funded by Chicago-based Citizens United
for Research in Epilepsy (CURE). Irazoqui's research group also recently
received a two-year grant from the Wallace H. Coulter Foundation to further
develop the technology.
"We are planning on doing human testing in two
years," Irazoqui said. "Epilepsy affects about 1% of the global population,
and of that 1%, 30% don't respond to any drugs. There is no cure or
treatment for those 30%."
New technologies being developed aim to change
that by predicting the onset of seizures and immediately dispensing a
chemical called a neurotransmitter directly to the area of the brain where
the seizure is starting.
The research represents half of a larger
collaboration at Purdue focusing on creating a neuroprosthesis that
dispenses a neurotransmitter chemical called GABA and calms the brain once
the onset of a seizure is detected. This work is a collaboration between
Irazoqui and Jenna Rickus, an assistant professor of biomedical engineering.
Rickus has developed a 'living electrode' coated with specially engineered
neurons that, when stimulated, releases the neurotransmitter to inhibit the
seizure. The engineered neurons are living tissue stimulated with a
Rickus and Irazoqui have shown that a certain amount of
electrical current causes the neurons to release specific and controllable
quantities of neurotransmitter.
"The idea is that by using an engineered
cell to release a neurotransmitter, we have a drug pump, in essence, that
automatically refills itself and that only impacts the part of the brain
where the living electrode is implanted: the epileptic focus," Irazoqui
said. "So you are not going to get the side effects that you get by washing
the entire body in a particular pharmaceutical."
Papers on the project
will be presented at the Engineering in Medicine and Biology Society's
Sciences and Technologies for Health conference from Aug. 23-26 in Lyon,
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