Localization of hypnopompic seizures - A stereo EEG study

Hypnopompic seizures, characterized by arousal from sleep as the primary clinical manifestation, are a rare and challenging seizure type. Their exact localization has been elusive, often requiring stereotactic EEG (SEEG) for accurate identification. We present the case of a 23-year-old male with drug-resistant focal epilepsy, in whom hypnopompic seizures were localized to the mesial orbitofrontal cortex, with rapid recruitment of the middle temporal gyrus, fusiform gyrus, rostral cingulate, and amygdala. SEEG captured multiple seizures, with arousal occurring 4-5 s after EEG onset, followed by ictal central apnea. The patient underwent resection of the right orbitofrontal and mesial temporal lobe regions and has remained seizure-free for over seven months. This case provides new insights into the neuroanatomical origins of seizure-induced arousal, identifying the mesial orbitofrontal cortex as a potential site for hypnopompic seizures. The findings underscore the critical role of SEEG in accurately localizing seizure foci in complex epilepsy cases, enabling targeted surgical interventions. Additionally, we discuss the orbitofrontal cortex's role as a site for extra-thalamic arousal pathways, offering new perspectives on the mechanisms underlying hypnopompic seizures.