Phase-amplitude coupling between interictal high-frequency activity and slow waves in epilepsy surgery

Area of Science:

• Neuroscience
• Epilepsy Research
• Biomarker Discovery

Background:

• Epilepsy surgery aims for seizure freedom but requires accurate prediction of outcomes.
• Current prediction models utilize clinical, imaging, and seizure onset zone (SOZ) data.
• Novel biomarkers are needed to enhance the precision of postoperative seizure outcome prediction.

Purpose of the Study:

• To evaluate the modulation index (MI) as an interictal biomarker for predicting epilepsy surgery outcomes.
• To determine if incorporating MI improves the predictive accuracy of existing models for seizure freedom.

Main Methods:

• Investigated 123 epilepsy patients undergoing focal cortical resection with electrocorticography.
• Measured MI (phase-amplitude coupling) during interictal sleep at electrode sites.
• Compared logistic regression models with and without MI for predicting International League Against Epilepsy class 1 outcome.

Main Results:

• The model including MI demonstrated superior predictive ability (R²=0.409, AUC=0.838) compared to the model without MI (R²=0.266, AUC=0.767).
• Incomplete SOZ resection, higher antiepileptic drug counts, and greater MI in non-resected tissue predicted poorer outcomes.
• Adjusting MI for anatomical variability further enhanced the model's predictive performance (R²=0.422, AUC=0.844).

Conclusions:

• Modulation index (MI) measured during interictal periods is a valuable biomarker for predicting epilepsy surgery outcomes.
• MI enhances the accuracy of predicting postoperative seizure freedom.
• This finding supports the use of MI in presurgical evaluation for epilepsy.