ORIGINAL RESEARCH

Interictal epileptiform activity in sleep and wakefulness in patients with temporal lobe epilepsy

Broutian AG, Belyakova-Bodina AI, Dolgova SM, Pushkar TN, Abramova AA
About authors

Research Center of Neurology, Moscow, Russia

Correspondence should be addressed: Amayak G. Broutian
Leningradsky Prospect, 33, Moscow, 125284; ur.liam@naituorba

About paper

Author contribution: Broutian AG — research planning, literature analysis, data interpretation, manuscript drafting; Belyakova-Bodina AI, Abramova AA — data collection, analysis, interpretation, manuscript drafting; Dolgova SM, Pushkar TN — data collection, analysis.

Received: 2019-08-23 Accepted: 2019-09-30 Published online: 2019-11-07
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Sleep is an important activator of epileptiform activity, with epileptiform discharge (ED) probability varying among sleep stages. The aim of our study was to analyze the association between epileptiform activity and sleep stages or wakefulness in adults with temporal discharges. We analyzed 32 long-term overnight EEG recordings. All focal discharges were marked, and the entire sleep was staged. Absolute general epileptiform discharge index (EDI), defined as a ratio of total ED number to the full recording time in hours, as well as absolute EDIs for REM, N1, N2 and N3 stages were calculated. The majority of patients (28) had the highest EDI in N3. EDI increased significantly while sleep progressed to deeper stages, reaching its peak in N3. In REM sleep, EDI sharply declined (p < 0.01) reaching the levels of wakefulness. Increasing synchronization of cortical neurons is thought to be the major mechanism of EDI rise in NREM sleep. Hence, N3 seems to be the most sensitive stage to capture EDs, which highlights the importance of deep sleep recording in patients with temporal epilepsy.

Keywords: epilepsy, electroencephalography, sleep, epileptiform activity, temporal lobe epilepsy

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