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Quantification of Epileptogenic Network From Stereo EEG Recordings Using Epileptogenicity Ranking Method
Harilal Parasuram1,2,3, Siby Gopinath1,2,3, Ashok Pillai1,4
1Amrita Advanced Centre for Epilepsy (AACE), Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, India.
Frontiers in Neurology
|November 22, 2021
Summary
A new method, Epileptogenicity Rank (ER), accurately pinpoints the epileptogenic zone (EZ) in epilepsy surgery. This advanced technique improves seizure localization for both neocortical and mesial temporal lobe epilepsy, enhancing surgical outcomes.
Area of Science:
- Neuroscience
- Medical Imaging
- Computational Biology
Background:
- Accurate localization of the epileptogenic zone (EZ) is crucial for successful epilepsy surgery.
- Existing Epileptogenicity Index (EI) methods show reduced accuracy in neocortical epilepsy.
- A novel approach is needed to improve EZ localization, especially in complex epilepsy cases.
Purpose of the Study:
- To introduce and validate Epileptogenicity Rank (ER), a modified EI method for quantifying epileptogenicity.
- To assess the accuracy of ER in localizing the EZ for both mesial temporal lobe epilepsy (MTLE) and neocortical epilepsy.
- To compare ER's performance against established methods and surgical outcomes.
Main Methods:
- Developed Epileptogenicity Rank (ER) using spatio-temporal properties from Stereo EEG (SEEG), including energy ratio, time of involvement, and Euclidean distance.
- Retrospectively analyzed 33 epilepsy patients (9 MTLE, 24 neocortical epilepsy) with post-operative MRI and Engel 1 outcome.
- Optimized ER thresholds for differentiating seizure onset from propagation networks and validated EZ localization.
Main Results:
- ER successfully differentiated seizure onset from propagation networks in epileptic networks.
- Optimal ER thresholds achieved high sensitivity and specificity: ER < 7.1 for neocortical epilepsy (94.6% sensitivity, 98.3% specificity) and ER < 7.3 for MTLE (95% sensitivity, 98% specificity).
- In non-seizure-free patients, ER-based EZ localization identified areas beyond cortical resections.
Conclusions:
- Epileptogenicity Rank (ER) significantly improves the accuracy of EZ localization for epilepsy surgery.
- ER enhances precision for resective surgery and minimally invasive techniques like radio-frequency or laser ablation.
- Further studies with larger patient cohorts are recommended to explore ER's clinical applicability.
