EEG data were collected from 10 persons with medication-resistant epilepsy before their corpus callosotomy using the international 10-20 system. We analyzed 5-second epochs of awake resting-state EEG that were visually free from artifacts and epileptiform abnormalities, focusing on data from the first 24 hours of their EEG to reduce confounding effects from medication withdrawal. The EEG signals were bandpass filtered to the alpha range (8-13 Hz), and magnitude-squared coherence was computed for homologous electrode pairs in the frontal, central, and parietal regions. Differences in inter-group coherence were evaluated using two-tailed t-tests and ANOVA.

Out of 10 persons, 4 became free of all seizure types (super-responders), 2 showed seizure reduction (partial-responders), and 4 had no change in seizure burden (non-responders). The super-responders demonstrated significantly higher alpha coherence in the frontal regions (P=0.002) compared to the partial and non-responders combined, but no differences were found in the central and parietal regions. Post-hoc analysis showed the highest alpha-coherence in the super-responders, followed by partial-responders, and the lowest in the non-responders (P=0.007). No inter-group differences were observed in central or parietal regions across the three groups.

Quantitative assessment of functional connectedness between the two hemispheres in pre-surgical EEG may help prognosticate post-surgical outcomes following corpus callosotomy.