1-3 In these individuals, the random occurrence of seizures, sometimes referred to as “a bolt from the blue,” constitutes substantial disability. In the more than 50 million individuals with epilepsy worldwide, a dynamic brain disorder renders them susceptible to seizures that cause physical harm, diminish quality of life, and increase mortality risk. On the basis of thalamocortical EEG, pro-ictal states - pathologic brain activities during periods of heightened seizure risk - could be identified in patients with temporal lobe epilepsy and were detected, in our small sample, more than one half hour before seizure onset. Pro-ictal states were distinguished at least 45 minutes before seizure onset in 13 of 15 participants in 2 of 15 participants, they were distinguished up to 35 minutes prior. The median area under the receiver-operating characteristic curve of the classifier was 0.92 (interquartile range, 0.90–0.96). Distinct pro-ictal states were detected in each participant. We analyzed 1800 patient-hours of continuous thalamocortical EEG. A deep neural classifier was applied to distinguish pro-ictal from interictal brain activities in a patient-specific fashion. For each participant, pro-ictal (45 minutes before seizure onset) and interictal (4 hours removed from all seizures) EEG segments were divided into 10-minute, nonoverlapping windows, which were randomly distributed into training and validation cohorts in a 1:1 ratio. We studied a prospective, consecutive series of 15 patients with temporal lobe epilepsy who underwent limbic thalamic recordings in addition to routine (cortical) intracranial EEG for seizure localization. Studies of continuous electroencephalography (EEG) suggest that seizures in individuals with focal-onset epilepsies preferentially occur during periods of heightened risk, typified by pathologic brain activities, termed pro-ictal states however, the presence of (pathologic) pro-ictal states among a plethora of otherwise physiologic (e.g., sleep–wake cycle) states has not been established.

Abnormal eeg normal vs epilepsy