Evidence of language network reorganization and compromised cognitive functioning in pediatric patients with focal refractory epilepsy

Objective

Patients with focal refractory frontal or temporal lobe epilepsy are at risk for overlap between the epileptogenic zone and eloquent language cortex, potentially resulting in language reorganization or atypical language representation. While such reorganization may indicate functional resilience, it may reflect compromised neural networks and poorer language outcomes. We hypothesized that patients with left frontal or temporal seizure onset zones would more often demonstrate atypical language dominance and lower cognitive and language compared to patients with right seizure onset zones.

Methods

We retrospectively reviewed 26 patients with frontal (n = 12) or temporal (n = 14) lobe epilepsy who underwent Phase I Surgical Evaluation, including structural and functional MRI and neuropsychological evaluation. FMRI using Auditory Description Decision Task provided language laterality indices. Participants were grouped as reorganized (Left seizure onset zones, Right/Bilateral LI; n = 8), not reorganized (Left seizure onset zones, Left LI; n = 10), and right seizure onset zones (n = 8). Neuropsychological assessments included Wechsler IQ tests, Boston Naming Test and Delis-Kaplan Executive Function System.

Results

Patients with left seizure onset zones had earlier seizure onset and longer epilepsy duration than the right seizure onset zones group. The reorganized group showed lower Perceptual/Fluid Reasoning Index scores compared to other groups.

Significance

This study is one of the few to investigate the combination of neuropsychological measures and fMRI language lateralization and found that fMRI language reorganization was associated with lower cognitive and perceptual/fluid reasoning. Language reorganization may indicate compromised neural networks or developmental persistence.