Termination patterns of complex partial seizures: An intracranial EEG study

Abstract

Purpose While seizure onset patterns have been the subject of many reports, there have been few studies of seizure termination. In this study we report the incidence of synchronous and asynchronous termination patterns of partial seizures recorded with intracranial arrays. Methods Data were collected from patients with intractable complex partial seizures undergoing presurgical evaluations with intracranial electrodes. Patients with seizures originating from mesial temporal and neocortical regions were grouped into three groups based on patterns of seizure termination: synchronous only (So), asynchronous only (Ao), or mixed (S/A, with both synchronous and asynchronous termination patterns). Results 88% of the patients in the MT group had seizures with a synchronous pattern of termination exclusively (38%) or mixed (50%). 82% of the NC group had seizures with synchronous pattern of termination exclusively (52%) or mixed (30%). In the NC group, there was a significant difference of the range of seizure durations between So and Ao groups, with Ao exhibiting higher variability. Seizures with synchronous termination had low variability in both groups. Conclusions Synchronous seizure termination is a common pattern for complex partial seizures of both mesial temporal or neocortical onset. This may reflect stereotyped network behavior or dynamics at the seizure focus.

Ictal time-irreversible intracranial EEG signals as markers of the epileptogenic zone

“…Comparing the pre-ictal and the immediate postictal time periods in regard to iEEG characteristics or neuropsychiatric state of the patient (Ito, 2010) clearly reveals that the dynamics leading into a seizure are qualitatively different from those occurring at seizure termination (Afra et al, 2015) and bringing about the post-ictal state. If pre-seizure dynamics were similar to the often slowly fading, post-ictal phenomena, seizure prediction might be much easier to achieve (Mormann et al, 2007).…”

“…Unequivocal seizure onset was defined as any epileptiform signal pattern that became clearly identifiable without knowing that a seizure followed. Seizure termination was determined as the time point when epileptiform signals vanished, which often manifested itself as a generalized and sudden decrease of amplitude and frequency (Schindler et al, 2007, Afra et al, 2015.…”

Postictal clinical and electroencephalographic activity following intracranially recorded bilateral tonic–clonic seizures

“…It has commonly been assumed that seizures and their immediate clinical manifestations stop simultaneously, after which there is a period of gradual postictal recovery. In reality, seizure activity may continue in some regions after having ceased in others 1 , and the postictal period may contain striking electrographic or clinical features. Postictal EEG analysis has largely focused on regional slowing or attenuation 2 and postictal generalized EEG suppression, or PGES 3 .…”

Towards Operational Definition of Postictal Stage: Spectral Entropy as a Marker of Seizure Ending

“…Similarly, a recent work showed that an increase of the synchronization between the thalamus and the cortex facilitates the end of the seizures [35]. Moreover, 88% of CP seizures in mesial temporal epilepsy had a synchronous pattern of termination [36]. Our hypothesis is that if the disconnection originated by the decrease in DoL, found in the PS, is not able to stop the seizure, there would be a spread of the seizure to other brain areas, causing longer and worse behavioral postictal changes, as seen during CP seizures.…”