Spike-Associated Networks Predict Postsurgical Outcomes in Children With Refractory Epilepsy

Area of Science:

• Neuroscience
• Epileptology
• Computational Neuroscience

Background:

• Epilepsy surgery aims to resect the epileptogenic zone but often fails to achieve complete seizure control.
• Functional connectivity analysis offers a promising approach to better delineate the epileptogenic zone.
• Identifying specific biomarkers of the epileptogenic zone is crucial for improving surgical success rates.

Purpose of the Study:

• To investigate whether cortical areas with high information outflow during interictal epileptiform discharges (IEDs) are part of the epileptogenic zone.
• To determine if resecting these high outflow regions improves seizure freedom after epilepsy surgery.
• To evaluate the predictive value of information outflow for postsurgical seizure control.

Main Methods:

• Studied 22 children with focal epilepsy who underwent stereo electroencephalography (SEEG) and epilepsy surgery.
• Calculated the mean phase slope index (a measure of directed functional connectivity) during IEDs for each electrode contact.
• Assessed the association between resecting high information outflow regions and seizure-free outcomes, calculating positive and negative predictive values.

Main Results:

• Resection of electrode contacts with high (z-score ≥ 1) and very high (z-score ≥ 2) information outflow was significantly associated with increased seizure freedom (P < 0.001).
• The positive predictive value for seizure freedom reached 0.86, and the negative predictive value reached 0.9 at higher z-score thresholds.
• These findings indicate a strong correlation between information outflow and surgical success.

Conclusions:

• Enhanced identification of the epileptogenic zone using information outflow analysis can potentially improve epilepsy surgery outcomes.
• Incorporating very high outflow areas into surgical plans may lead to higher rates of seizure freedom.
• Conversely, understanding these areas can help avoid ineffective surgeries and guide alternative treatment strategies.