Sleep Deprivation Induced Photoparoxysmal Response

A 19-year-old engineering student presents after his first generalized tonic-clonic seizure that occurred the morning after an all-nighter. He reports years of brief bilateral upper-extremity jerks on waking, especially after late nights. His sister has juvenile myoclonic epilepsy. Neurologic exam and MRI are normal. After 24 hours of deliberate sleep deprivation, an EEG with intermittent photic stimulation is performed. The pattern marked **A** in the diagram is observed at flash frequencies of 12–14 Hz, accompanied by myoclonic jerks of both shoulders. Based on this EEG finding and clinical presentation, which diagnosis is most likely?