Electrical Cortical Stimulation for Language Mapping in Epilepsy Surgery-A Systematic Review

Area of Science:

• Neuroscience
• Neurosurgery
• Epileptology

Background:

• Language mapping is crucial in epilepsy surgery to prevent postoperative deficits.
• Electrical cortical stimulation (ECS) is a key tool, but variability in techniques and tasks affects outcomes.
• The precise validity of different linguistic tasks for mapping specific cortical regions is not well-defined.

Purpose of the Study:

• To systematically evaluate linguistic tasks used in ECS for epilepsy surgery language mapping.
• To analyze task-specific responses across different cortical regions.
• To assess evidence for optimal task selection in various brain areas.

Main Methods:

• Systematic literature search (PubMed, Scopus) from 2013-2025, following PRISMA guidelines.
• Screened 956 articles, including 45 meeting criteria for language testing with ECS in epilepsy surgery.
• Extracted data on language tasks, stimulation modalities, cortical regions, and error types.

Main Results:

• Identified heterogeneity in language testing techniques across centers.
• Visual naming deficits linked to temporal lobe and fusiform/parahippocampal gyri.
• Auditory naming impairments associated with temporal, angular, and fusiform gyri.
• Spontaneous speech errors: phonemic (inferior frontal/supramarginal gyri), semantic (superior temporal/parietal regions).

Conclusions:

• Task-specific language mapping reveals distinct cortical specializations.
• Variability in protocols and lack of standardization hinder reproducibility.
• Standardizing language tasks can improve outcomes and minimize language impairment.
• Future research needs prospective multicenter studies to validate task-region associations.