MIT researchers, together with a team from two Boston hospitals, have provided early evidence in this week’s issue of Neurology, that a simple, unobtrusive wrist sensor can measure the severity of epileptic seizures as accurately as electroencephalograms (EEGs) yet without requiring scalp electrodes and electrical leads.
The device could potentially collect clinically useful data from epilepsy patients during their daily routines instead of having to visit the hospital for observation. If the early results are confirmed, the device would even be able to alert patients to seek immediate medical attention when their seizures are severe enough.
Professor of media arts and sciences at MIT, Rosalind Picard, and her team originally designed the sensors to measure the emotional states of children with autism given that their outward behavior can be different to that what they actual feel. The sensor measures the skin’s electrical conductance, which indicates the state of the sympathetic nervous system that controls the human fight-or-flight response.
The study, conducted at the Children’s Hospital in Boston, revealed that the higher a patient’s skin conductance is during a seizure, the longer it took for the patient’s brain to resume neural oscillations, i.e. brain waves that are measured by EEGs.
According to at least one clinical study, there is a correlation between the duration of brain-wave suppression after seizures and the number of sudden unexplained deaths in epilepsy (SUDEP) that can occur hours after a seizure. In the U.S. alone, thousands of people die from SUDEP.
At present, epileptic patients may use various criteria, one of them being the duration of the seizure, to establish whether a seizure is severe enough to seek immediate medical attention.
However, Picard says:
“What we found was that this severity measure had nothing to do with the length of the seizure.”
The data from the wrist sensor could ultimately provide patients with vital information as to whether they can continue what they were doing or going to the emergency room.The benefits of the wrist sensors for treating epilepsy turned out to be a supplemental discovery.
Picard explains:
“We’d been working with kids on the autism spectrum, and I didn’t realize, but a lot of them have seizures.”
When Picard and her team reviewed the data from their autism studies, they observed that huge spikes in skin conductance sometimes preceded seizures. This led to the conclusion that the sensors may actually be able to predict seizure onset.
Many of Picard’s MIT students were working at her lab through MIT’s Undergraduate Research Opportunities Program (UROP), amongst them also Joseph Madsen’s daughter, the director of the Epilepsy Surgery Program at the Children’s Hospital. Picard remarks: “I decided it was time to meet my UROP’s dad.”
Madsen agreed to allow the team to test the sensors on patients with severe epilepsy who were hospitalized for up to a week for constant EEG monitoring. Picard and her team debated to use several off-the-shelf sensors for the project, but, she says: “At the time, there was nothing we could buy that did what we needed. Finally, we just built our own.”
According to Picard’s student Ming-Zher Poh:
“It’s a big challenge to make a device robust enough to withstand long hours of recording. We were recording days or weeks in a row.”
Some of their early sensor versions showed that some fairly common gestures could produce false signals and Picard says that eliminating the sensors’ susceptibility to such sources of noise proved to be a process of trial and error.
Poh adds:
“I put a lot of thought into how to make it really comfortable and as non-intrusive as possible. So I packaged it all into typical sweatbands.”
Given that his study participants were children, Poh says:
“I allowed them to choose their favorite character on their wristband – for example, Superman, or Dora the Explorer, whatever they like. To them, they were wearing a wristband. But there was a lot of complicated sensing going on inside the wristband.”
Picard continues investigating the device’s potential to predict seizures, whilst her collaborators at the Children’s Hospital are performing a follow-up study on the one reported in Neurology. A similar study is about to start at the Brigham and Women’s Hospital that will use customized sensors produced by Picard’s company Affectiva.
Written By Petra Rattue