Evidence of dissociated arousal states during NREM parasomnia from an intracerebral neurophysiological study.

Study Objectives: Arousal parasomnias are expressions of sleep/ wake state dissociations in which wakefulness and NREM sleep seem to coexist. We describe the results of a neurophysiological (intracerebral EEG) investigation that captured an episode of confusional arousal.

Design: Observational analysis.

Setting: Tertiary sleep center.

Subject: A 20-year-old male with refractory focal epilepsy.

Measurements And Results: The intracerebral EEG findings documented the presence of a local arousal of the motor and cingulate cortices associated with increased delta activity in the frontoparietal associative cortices; these findings were noted preceding the onset and persisting throughout the episode.

Conclusions: The presence of dissociated sleep/wake states in confusional arousals is the expression not of a global phenomenon, but rather of the coexistence of different local states of being: arousal of the motor and cingulate cortices and inhibition of the associative ones. Whether this is an exclusive feature of NREM parasomnias, or a common substrate on which other triggering elements act, needs to be clarified.