Seizure spread marks loss of consciousness

Loss of consciousness can pose real dangers for people with seizure disorders. And while not all seizures cause loss of consciousness, Yale researchers have now discovered how one common type of seizures do.

Frontal lobe seizures are classified as “focal” seizures, a subtype in which the problematic activity generates in a single region of the brain. In the case of frontal lobe seizures, activity originates in the brain’s frontal lobes, located behind the forehead. 

But while some cause loss of consciousness, others don’t.

The reason, researchers found, is that not all frontal lobe seizures are equal.

For the study, primary author and former Yale postdoc Elaheh Salardini, working with Yale’s Hal Blumenfeld, analyzed a trove of data of human brain activity recordings collected from three different medical facilities — including65 seizure episodes in 30 different patients.

“We discovered a subset that cause impaired consciousness by spreading to other large areas of the brain,” saidBlumenfeld, the lead author, who is the Mark Loughridge and Michele Williams Professor of Neurology at YSM and a professor in neuroscience and neurosurgery and director of the Yale Clinical Neuroscience Imaging Center. “The activity invades much wider areas that are thought to be important for consciousness, whereas activity from other frontal lobe seizures remains restricted to the frontal lobe.”

The findings were published in the journal Neurology.

This new understanding may help scientists better predict seizure activity and develop treatments, including brain stimulation, that can restore consciousness during seizures.

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