The whole brain is involved in absence seizures, a common type of epilepsy usually affecting children, according to a study published in the leading medical journal The Lancet Neurology. This finding contrasts with the common belief among scientists that absence seizures are caused by localized disruptions of brain activity.
For the study “Impaired consciousness in patients with absence seizures investigated by functional MRI, EEG, and behavioural measures: a cross-sectional study,” researchers led by Hal Blumenfeld, PhD, the Mark Loughridge and Michele Williams Professor of Neurology and Professor of Neuroscience and of Neurosurgery at Yale School of Medicine, analyzed 93 children and young adults with absence epilepsy. The patients, aged 6-19 years, were recruited from 59 different pediatric neurology practices in the U.S. between Jan. 1, 2005 and Sept. 1, 2013.
The researchers did simultaneous electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and behavioral testing, recording 1,032 seizures in 39 patients.
They found that disruptions to brain function during absence seizures were global and not localized as previously thought. They also found that, in more severe seizures, disruptions began even before symptoms of the seizures were apparent.
Absence seizures are the type where affected individuals lose consciousness for a brief period of time, often less than 10 seconds. These episodes are sometimes mistaken for daydreaming and, in severe cases, can happen hundreds of times in the course of a day. Blinking, chewing or hand movements sometimes accompany these “blanking-out” periods.
“These seizures significantly affect school performance, social interactions and can also pose safety risks,” Blumenfeld said in a press release. “Understanding impaired consciousness in childhood absence epilepsy can also improve understanding of other disorders of consciousness including head trauma, coma and stroke,” he added.
According to the study authors, future work should examine the physiology of the widespread changes that occur in the whole brain during absence seizures. Understanding the mechanisms that regulate the severity of absence seizures, as well as other types of seizures, might help scientists develop new therapeutic approaches to treat epilepsy.