Onset of Epileptic Seizures Studied

Friday, January 19th 2001, 12:00 am

By: News On 6

LONDON (AP) â€” New research adds hope that epileptics could one day wear tiny brain sensors that detect an impending seizure and release medicine from implanted pumps in time to avert an attack.

In most epileptics, seizures occur without warning and can sometimes be disabling or fatal. Now, French scientists have developed a way to use electrodes on the scalp that can sense changes in brain activity an average seven minutes before seizures occur.

``This is far in the future. This is only a step,'' said Dr. Timothy Pedley of Columbia Presbyterian Medical Center in New York, who was not involved in the research. ``But it's definitely a noteworthy advance.''

About six out of every 1,000 people worldwide have epilepsy, and about 2.3 million Americans suffer from the condition, which involves periodic electrical storms in the brain. When the brain's circuits misfire fast enough, a seizure results. It can range from a short vacant stare to jerking movements or severe convulsions and loss of consciousness.

About 30 percent of epileptics are not helped by medication.

The researchers, based at the Pitie-Salpetriere Hospital in Paris, measured changes in the electrical activity of the brains of 23 epileptics using a standard scalp electroencephalograph, or EEG, a machine used routinely in the diagnosis and management of the disease.

They then used highly sophisticated mathematics to translate those recordings into tracings that show spikes in the pattern of electrical activity.

``What this does is suggest there may be another role for the standard EEG. Eventually, this might be miniaturized and implanted, like a pacemaker,'' Pedley said.

Researchers have previously detected electrical changes that signify the first stirrings of a seizure by implanting sensors in the brain, but such brain implants are not practical in real life.

Until now, scientists did not believe it would be possible to record such subtle changes from outside the head.

``The skull, spinal fluid and tissue on the scalp dampens the signals by about 50 or 100 times. These are very tiny changes,'' Pedley said. ``Until this study, no one knew it was possible to do it on the scalp with a standard EEG.''

The scientists made 26 recordings from the scalp and, to test the accuracy of the scalp analyses, also recorded activity from inside the brains of five of the patients. The changes noted by the two methods corresponded well, the study said.

The machines detected oncoming seizures in 25 of the scalp recordings.

``Prediction of seizure onset ... would provide time for the application of preventive measures to keep the risk of seizure to a minimum and, ultimately, improve quality of life,'' by reducing the chances of injury and the sense of helplessness epilepsy sufferers feel, the study said.

Dr. David Fish of the Institute of Neurology in London, said the research was an ``exciting development'' that could help scientists better understand what goes wrong in the brain in epilepsy and develop better treatments.

But there is still a long way to go, he said in a critique published in the same issue of The Lancet.

``For a given patient it will be important to establish the consistency of the transition phase, whether it can predict the precise timing of a seizure or only a window during which a seizure is likely to occur, and how often during the long-term monitoring the analysis falsely predicts a seizure,'' Fish said.

All the patients had temporal lobe epilepsy. Although that is a common type, it is not clear whether similar patterns occur in other types of epilepsy.