People with epilepsy have to learn to cope with the unpredictable nature of seizures 鈥� but that could soon be a thing of the past. A new brain implant can warn of seizures minutes before they strike, enabling them to get out of situations that could present a safety risk.
Epileptic seizures are triggered by erratic brain activity. The seizures last for seconds or minutes, and their unpredictability makes them hazardous and disruptive for people with epilepsy, says of the University of Melbourne in Australia. Like earthquakes, 鈥測ou can鈥檛 stop them, but if you knew when one was going to happen, you could prepare鈥�, he says.
With funding from , a medical device company in Seattle, Cook and his colleagues have developed a brain implant to do just that. The device consists of a small patch of electrodes that measure brain wave activity.
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Warning light
Over time, the device鈥檚 software learns which patterns of brainwave activity indicate that a seizure is about to happen. When it detects such a pattern, the implant then transmits a signal through a wire to a receiver implanted under the wearer鈥檚 collarbone. This unit alerts the wearer by wirelessly activating a handheld gadget with coloured lights 鈥� a red warning light, for example, signals that a seizure is imminent.
Cook鈥檚 team tested the device in 15 people with epilepsy over four months. In 11 of them, the system correctly predicted 鈥渞ed light鈥� seizures 鈥� those likely to occur in a minimum of 4 minutes 鈥� more than 65 per cent of the time. In two of these people the device was able to predict every seizure, but it didn鈥檛 work as well in the remaining four, two of whom experienced side effects.
Although the implant would only be used in severe cases, advance notice of a seizure could give those individuals a chance to stop driving, get out of social situations and avoid hazards, says Cook. 鈥淛ust being able to predict them could improve people鈥檚 independence enormously,鈥� he says.
The device could also be linked to deep-brain-stimulation implants, which deliver small electric currents to the brain in order to halt seizures. These implants switch on automatically when seizures start. Triggering them in advance could prevent seizures more effectively, says Cook.
An early warning system for seizures could also improve the effectiveness of anti-epileptic drugs such as benzodiazepines. They take 15 minutes to act and are usually ineffective once a seizure starts, says of the University of Bonn in Germany, who was not involved in the research. If seizure prediction devices prove effective, they could encourage research and development of more of these types of drugs.
Monitoring seizures
For some people with epilepsy, the device can detect seizures that they themselves aren鈥檛 aware of. One volunteer鈥檚 implant had recorded 102 seizures, but the individual himself only recalled 11 of them, since the seizure disrupted the memory centre of his brain. Other studies have shown that patients only report about a quarter of their seizures, says Elger. More accurate monitoring could allow physicians to better assess how well a drug is working, he says.
Elger has high hopes for the device, but cautions that it too early to tell whether it prevents or lessens the effects of seizures, and whether patients can tolerate false alarms.
at the University of Minnesota in Minneapolis agrees that the results are promising. Given that the people in the study had epilepsy that was particularly difficult to treat, the device may prove even more effective in those with milder forms of the condition. 鈥淚t may be life-changing even if it has limited predictive power,鈥� he says.
Journal ref: , DOI: 10.1016/s1474-4422(13)70075-9
