Mapping the Epileptogenic Brain Using Low-Frequency Stimulation: Two Decades of Advances and Uncertainties

Area of Science:

• Neuroscience
• Epileptology
• Neurosurgery

Background:

• High-frequency stimulation is standard for epilepsy surgery evaluation, but low-frequency stimulation (<1-2 Hz) is underutilized.
• Cortico-cortical evoked potentials (CCEPs) offer insights into brain network function and excitability.

Purpose of the Study:

• To review innovations in low-frequency stimulation for pre-surgical epilepsy evaluation over the past two decades.
• To explore the utility of CCEPs as biomarkers for cortical excitability, seizure onset, and network dysfunction.
• To consider the relationship between stimulation-induced and spontaneous seizures.

Main Methods:

• Review of literature on low-frequency stimulation and CCEPs in pre-surgical epilepsy evaluation.
• Analysis of CCEP features (early/delayed responses, high-frequency oscillations, network metrics) as biomarkers.
• Examination of the link between stimulation and spontaneous seizures.

Main Results:

• CCEP features demonstrate potential as biomarkers for tissue excitability and abnormal connectivity.
• Emerging evidence suggests CCEPs can guide neuromodulatory therapies like responsive neurostimulation.
• Low-frequency stimulation techniques and CCEP interpretation have advanced significantly.

Conclusions:

• Low-frequency stimulation and CCEPs hold promise for enhancing pre-surgical epilepsy evaluation.
• Further research is necessary to overcome challenges and integrate these methods into routine clinical practice.
• Understanding CCEP dynamics can improve surgical planning and neuromodulation strategies for epilepsy.