A 19-year-old female college student is brought to the emergency department by her roommate after experiencing a sudden episode of unresponsiveness during a class presentation. The roommate reports that the patient appeared anxious before the presentation and, upon starting, she became unresponsive, with her eyes closed and minimal movement. The episode lasted approximately 10 minutes, after which the patient regained consciousness but was confused and fatigued. She denies any recollection of the event. Over the past month, she has experienced similar episodes, especially during stressful situations. Her medical history is unremarkable, and she denies any substance use. Neurological examination and routine laboratory tests are normal. An electroencephalogram (EEG) performed during wakefulness and sleep shows no epileptiform activity.Which of the following is the most likely diagnosis?
