Which statement best distinguishes PNES from epileptic seizures in terms EEG findings?

• A. PNES are always shorter in duration.
• B. During PNES, EEG typically shows no epileptiform activity, distinguishing it from epileptic seizures.
• C. PNES always respond to antiseizure medications.
• D. PNES are accompanied by epileptiform discharges on EEG.

Answer: (B)

The key idea is that EEG is used to detect electrical seizures, so PNES, being psychogenic rather than true epileptic events, typically do not produce epileptiform brain activity during the event. In epileptic seizures, the EEG shows ictal epileptiform discharges—spikes, sharp waves, or evolving rhythmic patterns—that coincide with the clinical spell. In PNES, the event may look like a seizure, but the brain’s electrical activity usually remains at baseline or shows non-epileptiform changes, so no epileptiform discharges appear during the episode. This contrast is exactly why EEG during the event is the best way to differentiate PNES from epilepsy, often confirmed with video-EEG monitoring. It’s also useful to note that interictal EEG can be normal in both conditions; the crucial feature is the absence of ictal epileptiform activity during PNES.