Focal epilepsy: EEG interictal patterns and etiology correlation (S35.009)

Abstract

<h3>Objective:</h3> To evaluate the relationship between certain scalp interictal epileptiform discharges (IEDs) and the underlying seizure pathology. <h3>Background:</h3> Ictal characteristic patterns in focal epilepsy have been observed to be highly associated with certain pathologies and identifying such patterns can act as a predictor for possible underling etiology and to guide further investigations in work up of epilepsy. <h3>Design/Methods:</h3> Retrospective analysis of the interictal, ictal, and postictal epileptiform discharges recorded from scalp EEG based on frequency, amplitude, distribution, and morphology. <h3>Results:</h3> Independent or asynchronous bursts of IEDs in the form of spike trains consisting of monomorphic alpha frequencies with crescendo amplitudes, at times preceded or followed by 2–3 Hz slow waves, were associated with FCD. IEDs of spike trains with crescendo amplitudes and frequencies 5–6 Hz small spikes followed by 6–8 Hz higher amplitudes spikes with sharp peaks per second, then followed by 1–3 Hz slow waves, and at times showed broad field to the contralateral side were associated with heterotopia. An isolated spike-slow wave discharge confined to the temporal electrodes without broad field ipsilaterally were associated with MTS of possible dentate and proper hippocampus origin. IEDs of spike-slow wave discharges with broad field to the ipsilateral side were associated with MTS of possible hippocampal and para-hippocampal origin. Irregular 1–2 Hz spikes/sharp waves-slow waves and appearing as irregular “M shape” correlated with neocortical gliosis. Spike/sharp-slow wave complexes with broad field ipsilaterally and contralaterally while sustaining higher amplitudes ipsilaterally, might indicate kindling. <h3>Conclusions:</h3> Scalp EEG provides information about different epileptic parameters. IEDs are heterogeneous in terms of pattern and underlying mechanisms. EEG is not only a method to prove the presence of an epileptic focus, but can also correlate with the underlying etiology, and can be a useful tool to guide medical and surgical interventions. <b>Disclosure:</b> Dr. Lagnf has nothing to disclose. Dr. Souidan has nothing to disclose. Dr. Alsherbini has received personal compensation for serving as an employee of Detroit Medical Center. Prof. ANDRADE MACHADO has nothing to disclose. Dr. Elsayed has nothing to disclose.