Study: Predicting Seizures a Possibility
L O N D O N, Jan. 19, 2001 -- New research adds hope that epileptics could oneday wear tiny brain sensors that detect an impending seizure andrelease medicine from implanted pumps in time to avert an attack.
In most epileptics, seizures occur without warning and cansometimes be disabling or fatal. Now, French scientists havedeveloped a way to use electrodes on the scalp that can sensechanges in brain activity an average seven minutes before seizuresoccur.
"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, which was published in The Lancet. "But it's definitely anoteworthy advance."
About six out of every 1,000 people worldwide have epilepsy, andabout 2.3 million Americans suffer from the condition, whichinvolves periodic electrical storms in the brain. When the brain'scircuits misfire fast enough, a seizure results. It can range froma short vacant stare to jerking movements or severe convulsions andloss of consciousness.
About 30 percent of epileptics are not helped by medication.
The researchers, based at the Pitie-Salpetriere Hospital inParis, measured changes in the electrical activity of the brains of23 epileptics using a standard scalp electroencephalograph, or EEG,a machine used routinely in the diagnosis and management of thedisease.
They then used highly sophisticated mathematics to translatethose recordings into tracings that show spikes in the pattern ofelectrical activity.
"What this does is suggest there may be another role for thestandard EEG. Eventually, this might be miniaturized and implanted,like a pacemaker," Pedley said.
Researchers have previously detected electrical changes thatsignify the first stirrings of a seizure by implanting sensors inthe brain, but such brain implants are not practical in real life.
Until now, scientists did not believe it would be possible torecord such subtle changes from outside the head.
"The skull, spinal fluid and tissue on the scalp dampens thesignals by about 50 or 100 times. These are very tiny changes,"Pedley said. "Until this study, no one knew it was possible to doit on the scalp with a standard EEG."
The scientists made 26 recordings from the scalp and, to testthe accuracy of the scalp analyses, also recorded activity frominside the brains of five of the patients. The changes noted by thetwo methods corresponded well, the study said.
Prediction Would Improve Quality of Life
The machines detected oncoming seizures in 25 of the scalprecordings.
"Prediction of seizure onset … would provide time for theapplication of preventive measures to keep the risk of seizure to aminimum and, ultimately, improve quality of life," by reducing thechances of injury and the sense of helplessness epilepsy sufferersfeel, the study said.
Dr. David Fish of the Institute of Neurology in London said theresearch was an "exciting development" that could help scientistsbetter understand what goes wrong in the brain in epilepsy anddevelop better treatments.
But there is still a long way to go, he said in a critiquepublished in the same issue of The Lancet.
"For a given patient it will be important to establish theconsistency of the transition phase, whether it can predict theprecise timing of a seizure or only a window during which a seizureis likely to occur, and how often during the long-term monitoringthe analysis falsely predicts a seizure," Fish said.
All the patients had temporal lobe epilepsy. Although that is acommon type, it is not clear whether similar patterns occur inother types of epilepsy.