A simple wrist sensor can gauge the severity of a seizure as accurately as an electroencephalogram (EEG) – but without the awkward scalp electrodes and electrical leads.
The sensor (pictured) – designed by Rosalind Picard and colleagues at MIT – measures the electrical conductance of skin, or how easily an electrical current travels across the skin. This is related to how much we sweat, and it’s an indicator of the state of the sympathetic nervous system, which controls our fight-or-flight response.
According to Picard, seizure-related consequences kill more people every year than breast cancer. But no one’s sure how to tell from the outside which seizures should be allowed to run their course, and which will be life-threatening.
- They conducted their study at the Children’s Hospital Boston, on patients with severe epilepsy who were in the hospital for EEG monitoring.
- The researchers packaged the sensors into typical sweatbands to make them comfortable and nonintrusive. They also let the children choose their favorite character on their wristband like Superman or Dora the Explorer.
- The team discovered that the higher a patient’s skin conductance during a seizure, the longer it took for the patient’s brain to resume their normal brain waves (which is what an EEG measures).
At least one clinical study has shown a correlation between the duration of brain-wave suppression after seizures and the incidence of sudden unexplained death in epilepsy. (As it turned out, the length of the seizure has nothing to do with severity.)
The device also lets neurologists collect useful data about patients with epilepsy as they go about their daily lives, rather than requiring them to come in for observation.
In 2009, Picard co-founded a company called Affectiva to commercialize her lab’s work. “Let’s say I have epilepsy, and I’m afraid to go to sleep at night because I don’t know if I’ll wake up,” she says. If her wristbands record a severe seizure, “I could have it call for help for me.”
The work was published in Neurology last month.
Image: M. Scott Brauer