Brain localization and morphological changes in NREM parasomnias. A systematic review study

Area of Science:

• Neuroscience
• Sleep Medicine
• Neurology

Background:

• NREM parasomnias are characterized by abnormal slow-wave activity and fragmented sleep.
• The prevailing theory involves sleep-state dissociation, with episodes emerging from N3/N2 sleep stages.
• Mechanisms and brain topography of NREM parasomnias remain unclear.

Purpose of the Study:

• To systematically review neurophysiological and imaging studies on brain topography and morphology in NREM parasomnia patients.
• To elucidate the underlying mechanisms and brain regions involved in NREM parasomnias.

Main Methods:

• Systematic literature search from 1/01/2015 to 20/06/2024.
• Inclusion of neurophysiological (EEG) and neuroimaging (MRI) studies.
• Focus on brain topography and morphological changes in NREM parasomnia patients.

Main Results:

• Increased delta and theta EEG spectral power preceding episodes, with reduced power in cingulate, motor, and premotor cortices.
• Cortico-cortical sleep-state dissociation observed during NREM, REM, and wakefulness, outside of clinical episodes.
• Decreased grey-matter volume in left dorsal posterior cingulate and mid-cingulate cortices in mixed NREM parasomnia patients.

Conclusions:

• Sleep-wake dissociation may be a trait-like feature of NREM parasomnias, present even outside episodes.
• Anterior cingulo-frontal regions appear to play a central role in NREM parasomnias.
• Findings suggest a fundamental disruption in vigilance state regulation in NREM parasomnias.