Implantable Devices Detect and Stop Epileptic Seizures

New miniature implantable devices could both predict and prevent epileptic seizures when implanted in the brain.

Researchers at Purdue University (West Lafayette, In, USA) designed the 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 has been planned to record neural signals relayed by electrodes in various points in the brain, and the data from the implanted transmitter to be picked up by an external receiver--that last also being developed by the Purdue researchers. The novel transmitter consumes 8.8 mW, one-third as much power as other implantable transmitters, while transmitting 10 times more data. The transmitter has the capacity to collect data specifically related to epileptic seizures from 1,000 channels (i.e., locations) in the brain. The device was presented at the Engineering in Medicine and Biology Society's Sciences and Technologies for Health conference, held during August 2007 in Lyon (France). Human testing is planned to begin within two years.

"When epileptics have a seizure, a particular part of the brain starts firing in a way that is abnormal,” said lead researcher Pedro Irazoqui, Ph.D., 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.”

The research represents part of a larger collaboration at Purdue focusing on creating a neuroprosthesis that dispenses a neurotransmitter called Gamma-aminobutyric acid (GABA), which calms the brain once the onset of a seizure is detected. The technology is designed to prevent an epileptic focal seizure, which starts in a specific area of the brain but can then quickly spread to the rest of the brain. The researchers have developed a living electrode coated with specially engineered neurons that, when stimulated, releases the neurotransmitter to inhibit the seizure. A certain amount of electrical current causes the neurons to release specific and controllable quantities of the 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,” continued Dr. Irazoqui. "So you are not going to get the side effects that you get by washing the entire body in a particular pharmaceutical.”


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