Spatial-Temporal Functional Mapping Combined With Cortico-Cortical Evoked Potentials in Predicting Cortical...

Area of Science:

• Neuroscience
• Neurosurgery
• Epileptology

Background:

• Functional human brain mapping is crucial for epilepsy surgery, often using electrocortical stimulation mapping (ESM).
• ESM is time-consuming, painful, and risks overestimating eloquent areas due to stimulation spread.
• Passive spatial-temporal functional mapping (STFM) is a potential alternative but shows less correspondence with ESM for language than motor function.

Purpose of the Study:

• To investigate why spatial-temporal functional mapping (STFM) and electrocortical stimulation mapping (ESM) show discrepancies in mapping language areas.
• To test the hypothesis that stimulation effects propagate to connected cortical areas, influencing ESM results.
• To improve the accuracy of functional brain mapping by integrating STFM with measures of effective connectivity.

Main Methods:

• Evaluated five patients undergoing invasive monitoring for epilepsy.
• Language areas were identified using electrocortical stimulation mapping (ESM).
• Passive intracranial electroencephalography (iEEG) recordings were used during language tasks.
• Cortico-cortical evoked potentials (CCEPs) were measured to assess effective connectivity.
• A logistic regression model combined high gamma power from STFM and CCEPs to predict ESM results.

Main Results:

• The combined STFM and CCEPs model achieved 87.7% accuracy in predicting ESM results.
• STFM alone achieved 71.8% accuracy, indicating a significant improvement with CCEPs.
• This suggests that considering effective connectivity enhances the agreement between STFM and ESM.

Conclusions:

• Incongruities between STFM and ESM for language mapping may stem from stimulation effects spreading to interconnected cortical areas.
• Integrating STFM with CCEPs provides a more accurate functional brain mapping approach.
• Further research with larger patient cohorts is needed to establish the clinical utility of these combined mapping techniques.