Effect of Vagus Nerve Stimulation on Electroencephalogram Synchronization: A Longitudinal Study Using a...

Area of Science:

• Neuroscience
• Epilepsy Research
• Biomarker Discovery

Background:

• Vagus nerve stimulation (VNS) is an established epilepsy treatment, but reliable biomarkers for predicting response are lacking.
• Existing research shows acute EEG desynchronization post-VNS, yet longitudinal changes in EEG synchronization and their predictive value remain under-explored.

Purpose of the Study:

• To prospectively investigate longitudinal changes in EEG synchronization before and after VNS implantation.
• To correlate EEG synchronization patterns with clinical VNS response in drug-resistant epilepsy patients.
• To evaluate the predictive value of pre-implantation EEG and early VNS response for long-term outcomes.

Main Methods:

• High-density EEG recordings were collected from 12 adults with drug-resistant epilepsy pre- and post-VNS implantation (1, 3, 6 months).
• Resting-state EEG (eyes open/closed) was analyzed using the global weighted phase lag index (wPLI) to measure EEG phase synchronization.
• VNS response was assessed via seizure reduction (>50% or <50%) and the novel Clinical-Research Response Scale (CRRS).

Main Results:

• A progressive decrease in delta band wPLI during VNS OFF (eyes closed) correlated with VNS response over time, particularly with the CRRS.
• Higher pre-implantation global wPLI was predictive of a better VNS outcome.
• An early positive response to magnet stimulation also predicted a better VNS response.

Conclusions:

• Longitudinal EEG synchronization changes reflect the therapeutic efficacy of VNS in epilepsy.
• Pre-implantation EEG synchronization and early magnet response are potential predictors of VNS treatment success.
• The CRRS may offer a more sensitive method for assessing VNS response compared to traditional metrics.