Language network reorganization before and after temporal lobe epilepsy surgery.

Area of Science:

• Neuroscience
• Neurosurgery
• Medical Imaging

Background:

• Drug-resistant temporal lobe epilepsy (TLE) often requires surgery, which carries a risk of postoperative language impairment.
• Existing neurocognitive assessments in TLE patients show variability not fully explained by surgical extent or white matter integrity.
• Task-based functional MRI (fMRI) has limitations in capturing complex language organization changes.

Purpose of the Study:

• To investigate pathology- and surgery-triggered language organization in TLE using fMRI activation and network analysis.
• To correlate functional and structural imaging findings with neuropsychological measures.
• To understand the bihemispheric remodeling of language networks after epilepsy surgery.

Main Methods:

• Twenty-eight patients with unilateral TLE underwent pre- and postoperative T1-weighted imaging, diffusion tensor imaging, and language fMRI.
• Functional connectivity, activation maps, and laterality indices were analyzed from fMRI data.
• Verbal fluency and naming scores were correlated with imaging parameters.

Main Results:

• fMRI network analysis revealed widespread, bihemispheric language network alterations not detected by activation analysis, present pre- and postoperatively.
• Ipsilesional fronto-temporal connectivity decreased in both left and right TLE patients.
• Presurgical atypical language dominance in left TLE and left frontal dominance in right TLE predicted better postoperative language function.

Conclusions:

• Functional connectivity analysis provides unique insights into language network remodeling after TLE surgery.
• Presurgical contralateral language recruitment is associated with better postsurgical language outcomes in both left and right TLE.
• Language network changes are characteristic and differ between left and right TLE, independent of resection extent or white matter integrity.