Interictal and Ictal Electroencephalography Findings in Focal (Partial) Epilepsy

Ülkühan ÖZTOPRAKa, Güzide TURANLIa

aÇocuk Nörolojisi Kliniği, Sağlık Bilimleri Üniversitesi Ankara Dr. Sami Ulus Kadın Doğum, Çocuk Sağlığı ve Hastalıkları Eğitim ve Araştırma Hastanesi,
aÇocuk Nörolojisi BD, Hacettepe Üniversitesi Tıp Fakültesi, Emekli Öğretim Üyesi, Ankara, TÜRKİYE

ABSTRACT
The aim of this review is to summarize the findings of interictal and ictal electroencephalography (EEG) in focal epilepsy. In the mesial temporal lobe epilepsy, focal epileptiform discharges are seen in the anterior temporal lobe electrodes of the interictal EEG, whereas in the same region, unilateral rhythmic theta or alpha activity is observed in the ictal EEG. Interictal focal epileptiform activity with maximal voltage over the midtemporal electrodes and ictal onset consisting of irregular, hemispheric 2-5 Hz delta activity are the electrophysiologic features of neocortical temporal lobe epilepsy. Extratemporal seizures can show various types of interictal and ictal discharges consisting of spikes, spike and wave, sharp waves, paroxysmal fast activity, or rhythmic activity. The discharges can occur as focal, regional, lateralized or secondarily generalized. Ictal EEG rarely localizing in parietal lobe epilepsy, and invasive EEG is often required for definitive localization and functional mapping. High-amplitude occipital spikes are seen in interictal EEG in occipital lobe epilepsy, while ictal discharges may show a wide distrubition including parietal and posterior temporal electrodes. Most patients with frontal lobe epilepsy have non-localized ictal onset and interictal EEG is often normal. Inspite of rapid progression of neuroradiological investigations and other diagnostic techniques in the last century, EEG continues to play a central role in the diagnosis, management of epilepsy and in the classification of an epilepsy syndrome.
Keywords: Electroencephalography; epilepsies, partial; ictal discharges, interictal discharges

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