Abstract Details

Title From Scalp to Depth: Unravelling the Stereo-EEG (SEEG) Correlates of Sleep Micro-stages Within Macro-stages

Topic Sleep

Presentation(s) S3 - Research Advances in Sleep and Clinical Impact (2:12 PM-2:24 PM)

Poster/Presentation
Number 007

Objective Explore the development of a valid SEEG sleep-staging system anchored to surface EEG; compare SEEG-derived labels to scalp staging and characterize stage transitions (dwell times, sequences); and define micro-stages within macro-stages to support a simple, clinically usable framework.

Background Conventional sleep-staging in polysomnography relies on scalp EEG, but no validated system exists for SEEG, limiting the reliability of state-association of interictal epileptiform discharge, seizures, and network dynamics. Mapping scalp-defined macro-stages (Wake, N1, N2, N3 & REM) onto simultaneous SEEG may reveal intracranial signatures and micro-stages (e.g., spindle-rich or K-complex–dominant N2, slow-oscillation–dominant N3, phasic vs tonic REM), enabling reliable identification of sleep stages in cases with exclusive SEEG monitoring.

Design/Methods We systematically searched PubMed, EMBASE, and Cochrane and screened references (PRISMA). Macro-stages were assigned per American Academy of Sleep Medicine (AASM) on scalp EEG and projected onto SEEG within subjects. We extracted classic graphoelements (vertex waves, spindles, K-complexes, slow waves, sawtooth/REM activity) and compared topography, morphology, timing, and transition dynamics (onset/offset latencies).

Results Surface EEG reliably marked macro-architecture (alpha attenuation; N2 spindles/K-complexes; N3 slow waves; REM features). SEEG provided micro-architectural resolution, often showing earlier local onset of N2 spindles and K-complexes, focal N3 slow oscillations, and phasic REM activity within hippocampal, thalamic, and limbic contacts before—or without—clear scalp correlates. Across macro-stage transitions (e.g., N2→N3, NREM↔REM), SEEG highlighted local-to-global propagation and cortical–subcortical coupling. Intracranial features differentiated micro-stages within macro-stages.

Conclusions SEEG complements scalp staging by resolving micro-architecture and exposing earlier, deeper generators of sleep graphoelements and transitions. A surface-anchored, SEEG-refined approach lays the groundwork for a practical SEEG sleep-staging framework, including for SEEG-only recordings.

Authors/Disclosures
Michelle R. Cherian PRESENTER	Ms. Cherian has nothing to disclose.
Ajaz Sheikh, MD (ProMedica Neurosciences Center)	Dr. Sheikh has nothing to disclose.
Hira Burhan, MD	Dr. Burhan has nothing to disclose.

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