Figure 1. EEG recording time to establish study eligibility (n = 445).

Time (in minutes) needed to record the first burst of generalized spike wave (GSW) lasting ≥3 seconds, with or without clinical signs, is shown on the horizontal axis. This initial seizure was considered the defining absence seizure for study eligibility. Median time to EEG confirmation of childhood absence epilepsy diagnosis was 5.96 minutes (range 0–58.9 minutes). In 427 of 445 subjects (94%), the first seizure was recorded within the first 30 minutes of pretreatment EEG.