This study quantifies ictal gamma dynamics in a large SEEG dataset, revealing that ictal gamma increases are significantly associated with seizure onset zone (SOZ) contacts.
Background
Accurate localization of seizure onset activity is crucial for interpreting intracranial EEG, particularly in the presurgical evaluation of drug-resistant epilepsy. This study leverages a large dataset to explore the relationship between ictal gamma activity and SOZ contacts.
Data Highlights
Measure
SOZ Contacts
Non-SOZ Contacts
p-value
Median Gamma Log-Ratio
1.838
0.696
9.46 × 10^-23
Key Findings
SOZ contacts exhibited higher gamma log-ratio values compared to non-SOZ contacts (median 1.838 vs. 0.696).
Hierarchical mixed-effects modeling confirmed SOZ status was significantly associated with higher gamma log-ratio values (β = 0.802, p < 2 × 10^-16).
Top-gamma contacts were enriched in SOZ contacts (28.8% vs. 6.7%, odds ratio 5.65, p = 2.92 × 10^-123).
Region-stratified analyses indicated the strongest SOZ versus non-SOZ separation in mesial temporal contacts.
Significant differences in gamma activity were also observed in lateral temporal, insular, parietal, and central sensorimotor regions.
Clinical Implications
The findings indicate a significant association between ictal gamma activity and seizure onset zones in patients with drug-resistant epilepsy.
Conclusion
Ictal gamma activity is consistently associated with seizure onset contacts, providing important insights into the spatial dynamics of seizures. These results highlight the potential of gamma activity as a tool for improving seizure localization in clinical practice.
