Photo: Peder Hjulmand Søby

Alarm gives epileptics peace of mind

Wednesday 18 Oct 17
by Morten Andersen


Around one per cent of the Danish population has epilepsy—about 50,000 people. After headaches, epilepsy is the most common neurological disorder. People experiencing an epileptic seizure can lose complete or partial control of their body. Around 40 million people suffer from epilepsy globally.

The epilepsy alarm is based on extensive muscle signal measurements. These figures show measurements of muscle activity, acceleration, and angular velocities during real (figures a and c) and simulated (figures b and d) epileptic seizures. These measurements have enabled researchers to design algorithms that can decide whether or not a seizure is occurring.

Doctors and scientists have joined forces with a commercial enterprise to develop an alarm that makes life easier for patients and their relatives.

Epileptic seizures occur suddenly and can be life-threatening. But an alarm developed jointly by doctors, a technology company, and researchers at DTU Electrical Engineering is giving epileptics more peace of mind.

“The most severe seizures can paralyse epileptics, rendering them unable to call for help. Many of them are therefore nervous about leaving their homes for fear of having a seizure and ending up lying helpless somewhere. The alarm sends a message to one or more family members the moment a seizure begins,” says Consultant Sándor Beniczky, Head of the Department of Clinical Neurophysiology at the Filadelfia epilepsy hospital.

The alarm consists of two devices—a sensor the patient wears on their arm, and a receiver that is in radio contact with the sensor. “The family members greatly appreciate the alarm. For example, parents of children with epilepsy often find it difficult to sleep. They wake up at the slightest sound. Perhaps it’s a seizure? But now they know they only have to worry when they receive an alarm,” explains Sándor Beniczky.

Complete model of the body during a seizure

The product has flowed from a multiyear collaboration that began as two separate projects.

In one project, IctalCare was working to produce an alarm for patients with epilepsy. The second project involved collaboration between Helge B.D. Sørensen from DTU Electrical Engineering and a number of leading Danish epilepsy experts.

“In this project, we pursued a scientific approach. Rather than directly trying to develop an alarm, we wanted to first collect a large amount of data that describes what happens in the body during an epileptic seizure,” says Helge B.D. Sørensen.

Subjects therefore had up to 23 different sensors attached to their arms, legs, and body. The sensors measured muscle activity and accelerations and angular velocities in 3D.

“We thereby built up a complete model of the body's movements in normal circumstances and during epileptic seizures. This helped us to understand what could be modelled, and paved the way for designing algorithms for biomedical signal processing that can decide whether a seizure is occurring,” notes Helge B.D. Sørensen.

PhD project builds bridge

"In this project, we pursued a scientific approach. Rather than directly trying to develop an alarm, we wanted to first collect a large amount of data that describes what happens in the body during an epileptic seizure."
Helge B. D. Sørensen, associate professor, DTU Electrical Engineering

However, there was still a long way to go to develop an alarm, notes Helge B.D. Sørensen:

“A multitude of sensors on the body is acceptable during a trial, but not in everyday life. We hoped to be able to make do with a single sensor. Fortunately, the research showed that this was possible.”

We succeeded in getting a grant for a PhD project in which Isa Conradsen was appointed, with Helge B.D. Sørensen as principal supervisor.

IctalCare then contacted Isa Conradsen:

“The company had reached the conclusion that a sensor based on muscle signals, of the kind the DTU project was leading towards, was the most promising solution. The company also wanted to gain further expertise in the field of biomedical signal processing,” she says.

The solution was that Isa Conradsen took leave from DTU to spend a few months at the company. Following completion of her PhD project she was employed at IctalCare.

Attached using special gel

The alarm is attached to the wearer’s upper arm muscle. The patch which holds the sensor uses a ‘hydrogel’. The sensor is about the same weight and size as a box of matches, and causes no discomfort to the wearer.

“The patch has to be changed once a day. The gel is designed so that it adheres very strongly at the beginning. Its adhesiveness gradually weakens, so it’s easy to pull off the patch when 24 hours have elapsed,” explains Isa Conradsen.

Healthcare technology requires patience

If the alarm is successful, the next step will be to develop algorithms that can detect various types of epileptic seizures. “The alarm is designed to detect the most serious seizures, known as ‘tonic-clonic’ seizures. But it will definitely be possible to detect other types of seizures,” says Isa Conradsen.

There is also potential for developing other types of sensors that can be attached to the body using a gel patch.

The epilepsy alarm is not uncomfortable to wear. It has about the same weight and size as a box of matches and is attached to the upper arm using gel.

Alarm also helps doctors

During a clinical study, a total of 70 patients wore the alarm while admitted at Filadelfia, Rigshospitalet, and the University Hospital in Oslo. 20 of them experienced seizures during their hospital stays. This provides enough data to evaluate how well the alarm works. Consultant Sándor Beniczky is not yet able to reveal the precise results, but says the equipment is generally suited to detecting severe epileptic seizures.

“In addition to giving patients and their family members greater peace of mind in everyday life, the equipment can be very useful to doctors. We currently ask patients how often they experience seizures and how serious they are. But they often cannot remember the seizures, and it can be difficult for them to assess the severity. The new equipment will give us objective measurements of the frequency and nature of the seizures,” he says, noting that this will be even more useful when testing new medications:

“We’ll get an objective tool that can show us whether the medication is having an effect. This is far more satisfying than relying on the patients’ subjective assessment.”