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

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.