Absence seizures show which EEG pattern?

• A. 1 Hz spike-and-wave
• B. 3 Hz spike-and-wave patterns
• C. Focal epileptiform discharges
• D. Delta activity

Answer: (B)

Absence seizures are marked on EEG by a generalized, symmetric spike-and-wave discharge occurring at about 3 Hz. This rapid, evenly spaced rhythm reflects synchronized thalamocortical oscillations that briefly disrupt consciousness with minimal motor activity. The generalized nature of the pattern—seen across the entire brain—fits absence seizures, in contrast to focal epileptiform discharges that would appear localized to one area, or delta activity that indicates diffuse slowing from other states. The 3 Hz spike-and-wave signature is the classic EEG hallmark of this type of seizure.