Summary, originally published in Scientific American
Seizures are like storms in the brain—sudden bursts of abnormal electrical activity that can cause disturbances in movement, behavior, feelings and awareness. For people with epilepsy, not knowing when their next seizure will hit can be psychologically debilitating. Clinicians have no way of telling people with epilepsy whether a seizure will likely happen five minutes from now, five weeks from now or five months from now, says Vikram Rao, a neurologist at the University of California, San Francisco. “That leaves people in a state of looming uncertainty.”
Despite the apparent unpredictability of seizures, they may not actually be random events. Hints of cyclical patterns associated with epilepsy date back to ancient times, when people believed seizures were tied to the waxing and waning of the moon. While this particular link has yet to be definitively proven, scientists have pinpointed patterns in seizure-associated brain activity. Studies have shown that seizures are more likely during specific periods in the day, indicating an association with sleep–wake cycles, or circadian rhythms.
In 2018, Rao and his colleagues reported the discovery of long-term seizure-associated brain rhythms—most commonly in the 20- to 30-day range—which they dubbed as “multidien” (multiday) rhythms. By examining these rhythms in brain activity, the group has now demonstrated that seizures can be forecast 24 hours in advance—and in some patients, up to three days prior. Their findings, published December 17 in Lancet Neurology, raise the possibility of eventually providing epilepsy patients with seizure forecasts that could predict the likelihood that a seizure will occur days in advance.