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

ABSTRACT

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.