24-Hour video EEG in the evaluation of the first unprovoked seizure

Abstract

Objective: To assess the gain in detection of epileptiform abnormalities in 24-hour EEG recordings following the first seizure.

Methods: We identified patients who underwent 24-hour video EEG (VEEG) with "first seizure" as an indication. We noted the presence or absence of epileptiform discharges (EDs) in the VEEG study and the latency for the appearance of such discharges. We compared the rate of EDs during the initial 60 min with those occurring only later during the recording.

Results: Data from 25 patients, aged 15 to 59, were included. Of the 11 patients with EDs, eight (73%) appeared only after 60 min of recording. This equates to a 32% absolute increase in the detection of EDs across all patients. The latency to first EDs varied from one to 1080 min with a median of 170 min. In four cases, actual subtle seizures were recorded.

Conclusion: This study suggests an increase in the detection of EDs with the 24-hour studies compared to the traditional shorter recordings, in the context of a first seizure.

Significance: A standard EEG can be performed close to the seizure, followed by a longer up to 24-hour recording if the initial shorter study is unrevealing.

Keywords: 24-Hour video EEG; Diagnostic yield; EDs, epileptiform discharges; Epilepsy; Epileptiform discharges; First unprovoked seizure; VEEG, Video EEG.

Fig. 1

Samples of ictal EEG collected from four patients. A: Case 10, subtle seizure out of sleep with a left temporal evolving discharge (patient opens eyes and fidgets in bed, amnestic to event). B: Case 11, brief seizure during wakefulness with a left temporal subtle theta/delta rhythmic evolving activity, followed by focal delta slowing (patient exhibits repetitive grimacing and manual automatisms, amnestic to event). C: Case 20, three events during wakefulness and sleep, with a seemingly frontal onset (right) and evolution. No video available for the event during wakefulness, with minor arousal like movements noted during sleep related events. Patient unaware of any events. D: Case 23, multiple EEG seizures during wakefulness and sleep with no clear consistent clinical manifestations, onset at Fz-Cz midline electrodes with bilateral electrographic evolution. The shown sample exhibits discontinuous portions of a seizure to better visually demonstrate the ictal evolution.