NEW ORLEANS – For people with epilepsy, “the sudden and apparently unpredictable nature of seizures is one of the most disabling aspects of having the disorder,” said Michael Privitera, MD.
Dr. Michael Privitera
If a patient knew that “tomorrow will be a dangerous day” with a 50% chance of having a seizure, the patient could avoid hazardous activities, try to reduce stress, or increase supervision to reduce the risk of sudden, unexpected death in epilepsy, said Dr. Privitera, professor of neurology and director of the epilepsy center at the University of Cincinnati Gardner Neuroscience Institute. Physicians might be able to intervene during high-risk periods by altering antiepileptic drug regimens.
Evidence suggests that seizure prediction is possible today and that advances in wearable devices and analysis of chronic EEG recordings likely will improve the ability to predict seizures, Dr. Privitera said at the annual meeting of the American Epilepsy Society. Studies have found that some patients can predict the likelihood of seizures in the next 24 hours better than chance. In the future, algorithms that incorporate variables such as pulse, stress, mood, electrodermal activity, circadian rhythms, and EEG may further refine seizure prediction.
A complex picture
One problem with predicting seizures is that “you can have substantial changes in the seizure tendency, but not have a seizure,” Dr. Privitera said. Stress, alcohol, and missed medications, for example, may affect the seizure threshold. “They may be additive, and it may be when those things all hit at once that a seizure happens.”
Many patients report prodromal or premonitory symptoms before a seizure. “Most of us as clinicians will say, ‘Well, maybe you have some inkling, but I don’t think you’re really able to predict it,’ ” Dr. Privitera said.
Sheryl R. Haut, MD, professor of neurology at the Albert Einstein College of Medicine, New York, and her colleagues prospectively looked at patient self-prediction in 2007 (Neurology. 2007 Jan 23;68[4]:262-6). The investigators followed 74 people with epilepsy who completed a daily diary in which they predicted the likelihood of a seizure occurring in the next 24 hours. Their analysis included approximately 15,000 diary days and 1,400 seizure days.
A subset of participants, about 20%, was significantly better than chance at predicting when a seizure would happen. If a patient in this subgroup said that a seizure was extremely likely, then a seizure occurred approximately 37% of the time. If a patient predicted that a seizure was extremely unlikely, there was about a 10% chance of having a seizure.
“This was a pretty substantial difference,” Dr. Privitera said. Combining patients’ predictions with their self-reported stress levels seemed to yield the most accurate predictions.
Stress and the SMILE study
About 90% of people with epilepsy identify at least one seizure precipitant, and the most commonly cited trigger is stress. When Dr. Privitera and his colleagues surveyed patients in their clinic, 82% identified stress as a trigger (Epilepsy Behav. 2014 Dec;41:74-7). More than half of these patients had used some form of stress reduction, such as exercise, yoga, or meditation; 88% of those patients thought that stress reduction helped their seizures.