Intrahippocampal ripple propagation proportion is highest in less-irritative non-seizure onset zone hippocampus compared to epileptogenic hippocampus
In a study of 49 patients (68 hemispheres) with hippocampal contacts, intrahippocampal propagation of ripples on oscillations (RonO, 80-250 Hz) was proportionally greater in less-irritative non-SOZ tissue (<6 IED/min) than in more-irritative non-SOZ (>6 IED/min) and seizure onset zone (SOZ) tissue. This suggests RonO propagation may serve as a metric to quantify hippocampal epileptogenicity along a continuous spectrum.
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Intrahippocampal ripple propagation proportion is highest in less-irritative non-seizure onset zone hippocampus compared to epileptogenic hippocampus The current body of evidence comprises 1 study. EvidenceHub rates the overall confidence at 34/100 (low).
The Claim
Intrahippocampal ripple propagation proportion is highest in less-irritative non-seizure onset zone hippocampus compared to epileptogenic hippocampus
This conclusion is most relevant to: 49 patients (68 hemispheres) with verified hippocampal contacts undergoing non-REM sleep stereo-EEG.
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Epileptogenicity alters intrahippocampal ripple propagation. (medRxiv : the preprint server for health sciences, 2026) —
How It Works
The proposed biological pathway:
- ▸Hippocampal tissue is stratified by excitability based on IED rate and seizure onset
- ▸Empirical temporal networks of HFO propagation are constructed with 150 ms maximum latency
- ▸Significant propagation pathways are validated against 1000 permutation-generated surrogates
- ▸Intrahippocampal RonO propagation proportion is highest in less-irritative non-SOZ tissue
Who Might Benefit
Evidence fit by population:
- ▸49 patients (68 hemispheres) with verified hippocampal contacts undergoing non-REM sleep stereo-EEG
Recommended Dose
N/A
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Study uses a preprint (medRxiv) and has not undergone peer review
- ▸Distinguishing physiological from pathological RonO using signal features alone remains challenging
- ▸Sample size is moderate (49 patients) and may limit generalizability
Frequently Asked Questions
What are ripples on oscillations (RonO)?▼
RonO are high-frequency oscillations in the 80-250 Hz range that occur on top of ongoing brain oscillations, measured during non-REM sleep in this study.
How was hippocampal epileptogenicity measured?▼
Hippocampi were stratified into three groups: seizure onset zone (SOZ), more-irritative non-SOZ (>6 interictal epileptiform discharges per minute), and less-irritative non-SOZ (<6 IED/min).
Did the study find differences in fast ripple propagation?▼
No, propagation proportions for fast ripples (250-600 Hz) did not differ significantly across the hippocampal epileptogenicity spectrum, even though their rates were elevated in SOZ.
What is the clinical implication of this finding?▼
The authors suggest that intrahippocampal RonO propagation may serve as a novel metric to quantify hippocampal epileptogenicity, potentially aiding in surgical planning for epilepsy.
References
- 1.Chen Y, Ye H, Ye L, Hu L, Chen C, Staba R, Wang S, Weiss SA. “Epileptogenicity alters intrahippocampal ripple propagation..” medRxiv : the preprint server for health sciences, 2026. PMID: 42369499 DOI: 10.64898/2026.06.13.26355594