Uncovering Individual Language Vulnerability in Epilepsy Through Functional Connectivity Laterality

Area of Science:

• Neuroscience
• Medical Imaging
• Epilepsy Research

Background:

• Brain language networks are typically left-lateralized.
• Task-based functional MRI (fMRI) is standard for assessing language lateralization.
• Standard fMRI doesn't capture individual language network variations.

Purpose of the Study:

• To introduce the functional connectivity laterality index (LI_FC) for individualizing language network analysis in epilepsy.
• To assess the clinical utility of LI_FC compared to traditional laterality indices.

Main Methods:

• Retrospective study of unilateral temporal lobe epilepsy (TLE) patients and controls using 3T fMRI.
• Computed laterality indices from fMRI activation and functional connectivity data.
• Analyzed group differences and associations with neuropsychological language performance.

Main Results:

• LI_FC indicated mostly bilateral language lateralization, unlike classical LI's left-lateralization.
• Patients with LI_FC lateralized to the seizure side exhibited significantly worse semantic fluency and lower composite language scores.
• These findings were specific to functional connectivity analysis and not seen in activation data alone.

Conclusions:

• Functional connectivity measures may reveal individual language network vulnerability in TLE patients.
• LI_FC could enhance presurgical planning by identifying patients at risk of language decline.
• Further validation in larger independent samples is required.