Electrocorticographic frequency alteration mapping for extraoperative localization of speech cortex.

Area of Science:

• Neuroscience
• Clinical Neurophysiology
• Brain Mapping

Background:

• Electrocortical stimulation (ECS) is a standard but limited technique for mapping eloquent cortex.
• Existing methods for cortical mapping are coarse, inefficient, and prone to afterdischarges.
• Electrocorticography (ECoG) signal changes offer a potential adjunct for functional cortex delineation.

Purpose of the Study:

• To explore electrocorticography (ECoG) signal alterations in speech cortex during activation.
• To assess the potential of ECoG signal changes as a clinical brain mapping tool.
• To investigate ECoG frequency alterations for improved speech cortex identification.

Main Methods:

• Evaluated 7 patients undergoing invasive monitoring for seizure localization.
• Utilized extraoperative electrocorticography (ECoG) and electrocortical stimulation (ECS) mapping.
• Patients performed overt speech tasks to identify associated frequency power changes.

Main Results:

• Electrocorticographic frequency alteration mapping (EFAM) demonstrated 83.9% sensitivity and 40.4% specificity for language sites.
• EFAM was more sensitive for Wernicke area (100%) than Broca area (72.2%).
• High-frequency bands (HFBs) are key for Wernicke area; both HFBs and low-frequency bands (LFBs) are crucial for Broca area.

Conclusions:

• Concordance between ECS and spectral power changes supports EFAM's utility.
• EFAM can potentially enhance the efficiency and resolution of speech cortex identification.
• EFAM offers a promising adjunct method for clinical brain mapping applications.