Role of specific interictal and ictal EEG onset patterns

Area of Science:

• Neurology
• Neurophysiology
• Epileptology

Background:

• Scalp video-electroencephalogram (EEG) monitoring is crucial for localizing seizure onset zones.
• Interictal and ictal EEG patterns offer valuable insights into epilepsy localization and surgical candidacy.

Purpose of the Study:

• To review the role of specific interictal and ictal EEG onset patterns in scalp video-EEG monitoring.
• To correlate EEG findings with seizure localization and surgical outcomes in epilepsy.

Main Methods:

• Review of literature on scalp video-EEG monitoring in epilepsy.
• Analysis of specific non-epileptiform and epileptiform interictal abnormalities.
• Evaluation of ictal EEG patterns and their correlation with intracranial EEG (iEEG).

Main Results:

• Specific non-epileptiform patterns like temporal intermittent rhythmic delta activity (TIRDA) indicate temporal lobe seizure onset.
• Interictal epileptiform abnormalities, such as Type 1 and Type 2 spikes, localize temporal lobe irritative zones.
• Unilateral temporal interictal epileptiform discharges (IEDs) and specific ictal patterns predict good surgical outcomes in temporal lobe epilepsy.
• Consistently localized extratemporal IEDs also predict favorable surgical outcomes in non-lesional extratemporal epilepsy.
• Scalp-EEG and iEEG patterns show closer correspondence when clinical and EEG onsets are synchronous.

Conclusions:

• Specific interictal and ictal EEG patterns are valuable for localizing seizure onset zones.
• Certain EEG findings predict good surgical outcomes in both temporal lobe and extratemporal epilepsies.
• Understanding scalp-EEG and iEEG relationships aids in epilepsy diagnosis and treatment planning.