Using data recorded from an FDA-approved implanted brain stimulation device, researchers have identified cyclic patterns of brain activity that can predict the onset of a seizure in patients with epilepsy. The study findings were recently published in Nature Communications.
The device, called NeuroPace RNS® System, was approved in 2013 to suppress abnormal brain activity in order to stop a potential seizure before it occurs. The study included 37 patients with NeuroPace implants. With this device, researchers were able to record years of seizure-related brain activity, a much longer time period that what epilepsy researchers had been able to record without the implantable device. The team has identified patterns in brain activity termed “brain irritability” that are linked to a higher chance of experiencing a seizure.
As previously observed, the recordings revealed daily cyclical activity explaining why many patients experience seizures at the same time during the day. Also, the study revealed that brain irritability tends to rise and fall in long cycles, commonly 20-30 days, and that seizures occur during the rising period just before activity peaks. The long cycle lengths were found to be very stable over many years in individual patients. The team made an important discovery that seizures in patients are seven times more likely to occur when there is an overlap between the high-risk times of their daily and long-term cycles compared to when the two cycles are not aligned. The research term is using the data collected to help patients be aware of the times when they are most at risk for seizure.
"I like to compare it to a weather forecast," said study senior author Vikram Rao, MD, PhD, an assistant professor of neurology at UCSF and member of the UCSF Weill Institute for Neurosciences. "In the past, the field has focused on predicting the exact moment a seizure will occur, which is like predicting when lightning will strike. That's pretty hard. It may be more useful to be able tell people there is a 5 percent chance of a thunderstorm this week, but a 90 percent chance next week. That kind of information lets you prepare."