Cortico-cortical evoked potential by single-pulse electrical stimulation is a generally safe procedure

Area of Science:

• Neuroscience
• Epileptology
• Clinical Electrophysiology

Background:

• Cortico-cortical evoked potentials (CCEPs) are crucial for assessing effective connectivity and cortical excitability.
• Single-pulse electrical stimulation (SPES) is a key technique in CCEP generation.
• The safety profile of CCEPs, particularly during presurgical evaluation for epilepsy, requires thorough investigation.

Purpose of the Study:

• To evaluate the safety of CCEP recording using repetitive single-pulse electrical stimulation (SPES) in patients with intractable partial epilepsy.
• To determine the incidence of afterdischarges (ADs) and clinical seizures induced by CCEP stimulation.
• To compare the safety of stimulating seizure onset zones (SOZ) versus non-SOZ regions.

Main Methods:

• Retrospective analysis of 29 epilepsy patients undergoing chronic subdural grid implantation and CCEP recording.
• Systematic application of repetitive SPES (1 Hz) to adjacent electrode pairs.
• Evaluation of ADs and clinical seizures in relation to stimulated electrode pairs and patient groups.

Main Results:

• Afterdischarges (ADs) occurred in 0.94% of electrode pairs and clinical seizures in 0.39%.
• ADs were observed in 23.3% of patients, and clinical seizures in 10.0%.
• Clinical seizures were significantly more frequent when stimulating SOZ (2.5%) compared to non-SOZ (0.09%) (p=0.001).

Conclusions:

• CCEP is a safe procedure for presurgical evaluation in epilepsy patients when following established protocols.
• Caution is advised when stimulating seizure onset zones due to a higher incidence of seizures.
• CCEPs offer valuable, safe insights into brain function for surgical planning.