According to a recent study, between 7 and 17 percent of all epilepsy-related deaths are due to a complication known as Sudden Unexpected Death in Epilepsy (SUDEP). Although SUDEP isn't well understood, it is hoped that a new armband may help stop it in its tracks.

SUDEP typically occurs when the victim is asleep at night, and is thought to be associated with severe seizures. Currently, such nocturnal seizures are detected using motion-sensitive sensors in the patient's bed. Led by the Netherlands' Kempenhaeghe epilepsy centre, along with the Eindhoven University of Technology, a Dutch consortium set out to design a system that worked better than such sensors. The result is the NightWatch armband.

Designed for use by individuals with an intellectual disability and severe therapy-resistant epilepsy (who are particularly at risk of SUDEP), the device is worn on their upper arm as they sleep. As they do so, it uses optical sensors to measure their heart rate, along with accelerometers to detect the rhythmic jolting movements that are distinctive to seizures.

If such movements are detected – along with an abnormally fast heartbeat – the device sounds an alarm and wirelessly alerts caregivers, so they can quickly come to the wearer's aid.

The device was tested on 28 intellectually handicapped epilepsy patients for an average of 65 nights per patient, with video cameras also being used to capture all of their nocturnal seizures. When compared to the video footage, the NightWatch was found to successfully detect 85 percent of all serious attacks, and 96 percent of the most severe ones. By contrast, a traditional bed-based sensor that was additionally in use only detected 21 percent of the serious seizures.

Eindhoven's Prof. Johan Arends, who is the leader of the study, hopes that the armband could ultimately reduce SUDEP deaths by two thirds. The technology is being developed by spinoff company LivAssured, and is described in a paper that was recently published in the journal Neurology.

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