Evidence map›Paper›PMID 41427497›Full record

ArticleEpilepsia2026

Scalp-negative medial temporal interictal epileptic discharges alter large-scale brain networks: A simultaneous high-density electroencephalographic and intracranial electroencephalographic study.

Nicolas Roehri, Pia De Stefano, Laurent Spinelli, Renaud Marquis, Stanislas Lagarde, Shahan Momjian, Margitta Seeck, Serge Vulliemoz

Abstract read
In one paragraph

Article in Epilepsia, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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0citing papers in PubMed
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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

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Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

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0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

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PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Nicolas RoehriEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0002-6948-1055
Pia De StefanoEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0002-7979-0994
Laurent SpinelliEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0001-7682-2041
Renaud MarquisEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0002-1145-242X
Stanislas LagardeEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0003-2916-1302
Shahan MomjianNeurosurgery Department, Geneva University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0002-3886-0159
Margitta SeeckEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0002-6702-0167
Serge VulliemozEEG and Epilepsy Unit, University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland.ORCID https://orcid.org/0000-0002-1877-8625

Funding

Ligue Française Contre l'EpilepsiePHOCEOSchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung 10004348Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung 163398Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung 180365Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung 192749Wellcome Trust 209120Wellcome Trust 209470
6 · The paper itself

Abstract

objectiveInterictal epileptiform discharges (IEDs) observed on scalp electroencephalography (EEG) serve as a diagnostic hallmark of epilepsy. However, only a small fraction of IEDs recorded by intracranial EEG (iEEG) are detectable on the scalp; the vast majority remain invisible on scalp recordings. Nevertheless, epilepsy is associated with important brain network alterations and cognitive symptoms between seizures. Our study aims to investigate the impact of these scalp-negative IEDs on the whole-brain network, particularly those produced in medial temporal regions, given their consistent involvement across patients, their potential implications in cognitive deficit, and their relevance in both epilepsy and Alzheimer disease. To achieve this, we leveraged simultaneous iEEG and high-density EEG (hdEEG) recordings.

methodsWe analyzed IEDs occurring solely in the medial temporal regions, not visible on the scalp, in nine patients with drug-resistant epilepsy during simultaneous iEEG-hdEEG recordings. These scalp-negative IEDs were compared to epochs without any epileptic activity recorded in either modality. Spectral and network characteristics were investigated at the region of interest (ROI) for both modalities in different canonical frequency bands.

resultsROI time courses reconstructed with hdEEG during IEDs exhibited sharp wave characteristics (cluster-based corrected time-frequency analysis), confirming that some information time-locked to iEEG IEDs reached the scalp. Our findings revealed a significant frequency-dependent, large-scale increase in power and network features during scalp-negative IEDs compared to epochs without IEDs, at the whole-brain level and within specific ROIs, including the ipsilateral hippocampus (p < .05, false discovery rate corrected). SIGNIFICANCE: Despite being localized in medial temporal regions, these IEDs have a widespread impact on functional brain networks, potentially contributing to cognitive impairment in epilepsy. This study lays the groundwork for examining their real-time effects on cognition, including in neurodegenerative conditions such as Alzheimer disease, where these IEDs can be present and difficult to detect.

Indexed as

BrainDrug Resistant EpilepsyElectrocorticographyElectroencephalographyEpilepsy, Temporal LobeNerve NetTemporal LobeAdultFemaleHumansMaleMiddle AgedScalpYoung Adultepilepsyinterictal epileptiform dischargesimultaneous intracranial and high‐density EEG

Identifiers

PMID41427497
PMCPMC13075616

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.