Interictal short-term high-frequency cortical stimulation modulates epileptogenic zone and distributed network.

Area of Science:

• Neuroscience
• Epileptology
• Neuromodulation

Background:

• Refractory epilepsy often requires advanced treatment strategies.
• Understanding neuromodulatory effects is crucial for developing effective therapies.
• Interictal stimulation's impact on brain networks remains an area of active research.

Purpose of the Study:

• Investigate the neuromodulatory effects of interictal short-term high-frequency stimulation (STHFS) on the epileptogenic zone (EZ) and distributed networks.
• Elucidate mechanisms behind chronic subthreshold cortical stimulation's efficacy in refractory epilepsy.
• Assess the impact of stimulation intensity on seizure control.

Main Methods:

• Stereoelectroencephalography (SEEG) monitoring in eight epilepsy patients.
• Application of STHFS and incremental current stimulation to the EZ.
• Quantitative assessment of spike rate, amplitude, and spectral power.
• Functional network connectivity analysis using directed transfer function and partial directed coherence.

Main Results:

• STHFS significantly decreased spike rate, amplitude, and spectral power in the EZ compared to baseline.
• Post-stimulation, these parameters rebounded, fluctuating around baseline levels.
• Incremental current stimulation showed intensity-dependent inhibition of seizure activity.
• Functional connectivity patterns varied individually, with some regions showing consistent reduction during stimulation.

Conclusions:

• STHFS effectively inhibits neuronal excitability within the local EZ.
• The degree of seizure inhibition is dependent on stimulation intensity.
• STHFS demonstrates an anti-epileptic effect locally and stably regulates distributed brain networks.