An implanted device that monitors brain activity may offer a way to predict
seizures in people with uncontrolled epilepsy, a small pilot study suggests.
The findings are based on only 15 patients, and the device worked far better
in some than others. But experts said the results are promising, and should
prompt further studies.
"We just wanted to see if this is feasible, and this study shows that it is,"
said lead researcher Dr Mark Cook, of the University of Melbourne and St
Vincent's Hospital in Australia.
The prospect of being able to predict seizures is "very exciting," he said,
in part because it's the uncertainty of the disorder that can dim people's
quality of life.
If people know a seizure is coming, Cook said, they can avoid driving or
swimming that day, for example. They might also be able to adjust their
Epilepsy is a neurological disorder in which the brain's normal electrical
activity is temporarily disrupted, leading to a seizure. Seizures can be
obvious, causing unconsciousness or convulsions, but often they trigger subtler
changes in a person's perceptions or behaviour - like a short staring spell,
confusion or an altered sense of taste or smell.
Resistance to drug therapy
Epilepsy is usually managed with medication, but for 30% to 40% of people
with the condition, drugs don't keep seizures at bay. The new study included 15
people who were having at least two to 12 "disabling" seizures a month that were
resistant to drug therapy.
Cook's team implanted each patient with the experimental device, which
consists of electrodes placed between the skull and the brain, plus wires that
run to a unit implanted under the skin of the chest.
That unit wirelessly sends data to a hand-held device that flashes a red
warning light if there is a "high likelihood" of an impending seizure. (A white
light signals a "moderate" likelihood, while a blue light means the odds are
For the first four months, the devices collected data on patients' seizures
without actually flashing warnings. For 11 of the 15 patients, the implants
seemed capable of correctly predicting a high risk of seizure at least 65% of
the time. Those patients went on to the next four-month phase, where the devices
were activated to give warnings.
Over those four months, the implants worked fairly well for eight patients -
correctly giving the high-risk warning anywhere from 56% to 100% of the
There are plenty of questions left, said Dr Ashesh Mehta, director of
epilepsy surgery at the North Shore-LIJ Comprehensive Epilepsy Care Center in
Great Neck, NY.
"This study is an important first step," said Mehta, who was not involved in
"The next step would be to implant these in a larger sample of patients. And
you need to see which groups of patients might be good candidates for this."
Mehta said someone who has seizures only once in a while might not get enough
benefit to outweigh the downsides of false alarms, for example. And someone who
has many seizures each month might get little added information from the warning
system, he said.
It may be the people who fall in the middle - who have disabling seizures at
unpredictable intervals -- who would stand to benefit the most, he said.
But any benefits need to be weighed against the risks. Besides false alarms
and unnecessary anxiety, the implant itself can cause problems. In this study,
three patients had serious complications, including one with an infection and
one whose chest device moved and caused her pain. Two patients ultimately had
the implants removed.
Still, Mehta agreed that the technology could prove helpful to some people
with epilepsy. If they know a seizure is coming, they might take an extra dose
of their medication, for example.
An implanted device like this could also give patients and their doctors more
information about their epilepsy, he added. In this study, the implants revealed
that most patients were suffering more seizures than they thought; one patient
who reported 11 a month was actually having more than 100.
In real life, Mehta said, it can be hard to know if you're feeling bad
because of side effects from epilepsy medication or because you're having a lot
of seizures. A device like this could help sort that out.
But what's still needed is evidence that this device does improve the quality
of patients' lives, Mehta said.
Learn more about epilepsy from the Epilepsy