[Broca's area intraoperative mapping with cortico-cortical evoked potentials]

Area of Science:

• Neuroscience
• Neurosurgery
• Speech Pathology

Background:

• Effective speech communication relies on intricate connections between the frontal and temporal lobes.
• Brain tumors in the frontoparietal region can disrupt these critical speech pathways.
• Accurate mapping of these connections is essential for surgical planning and preserving speech function.

Purpose of the Study:

• To map effective speech connections between the frontal and temporal lobes using cortico-cortical evoked potentials (CCEPs).
• To assess the feasibility and significance of CCEPs for analyzing speech pathway projections.
• To validate CCEP findings with direct cortical stimulation.

Main Methods:

• Cortico-cortical evoked potentials were recorded intraoperatively in 3 patients with brain tumors near dominant hemisphere speech centers.
• Bipolar stimulation was delivered via subdural electrodes, with responses averaged from electrocorticography (ECoG).
• Direct cortical stimulation was employed to confirm CCEP mapping results.

Main Results:

• CCEPs were successfully obtained from the inferior frontal gyrus upon stimulation of the superior temporal gyrus.
• Effective speech relationships were unidirectional in one patient and reciprocal in two.
• Mean N1 peak latency was 65 ms, with a mean amplitude of 71 µV; CCEP data correlated with direct cortical stimulation findings in 2 out of 3 cases.

Conclusions:

• Cortico-cortical evoked potentials demonstrate practical significance in analyzing frontal-temporal speech communication pathways.
• This method shows potential for pre-surgical mapping of speech-related brain networks.
• Further investigation with larger patient cohorts is warranted to confirm these initial findings.