1154 Corpus Callosotomy Disrupts Interhemispheric Spindle Coherence with Stage-Dependent Morphological Effects

Abstract Introduction Pediatric patients with drug-resistant epilepsy (DRE) suffer from frequent and dangerous seizure events. With limited treatment options available, neurosurgical teams often employ corpus callosotomy (CCS) for palliation. This study aimed to investigate the effect of CCS on sleep spindles, which play a key role in brain maturation, especially during critical developmental periods. We compare changes in sleep spindle coherence and morphology before and after CCS, focusing on the N2 and N3 sleep stages. Methods Sleep EEG recordings were obtained from seven patients before and after CCS at a sampling rate of 200 or 500 Hz using 24 electrodes. Automatic sleep staging and spindle detection were performed using the YASA library. Three spindle morphologies were compared before and after CCS: spindle amplitude, duration, and density. Spindle coherence was also evaluated in sleep stages N2 and N3 for three electrode pairs: F3-F4, P3-P4, and C3-C4. Results Six patients exhibited spindles in N2 and N3 separately. Spindle density decreased post CCS across N2, N3, and combined N2–N3, but the reductions were not significant. Spindle duration decreased post CCS in N2 (5 patients, p< 0.05), in N3 (4 patients, p< 0.05), and was significantly reduced for combined N2–N3 (5 patients, p< 0.05). Spindle amplitude increased in N3 post CCS (4 patients, p< 0.05), but no consistent effect was observed in N2, and combined N2–N3 amplitude showed no significant change. Spindle coherence showed a significant post CCS reduction across all sleep stages (all p< 0.05) and all electrode pairs. Conclusion Differences in both sleep spindle coherence and characteristics in pediatric patients post CCS are much more consistent in the N3 sleep stage as compared to N2. Notably, N3 spindles are thought to be driven and propagated through cortico-cortical pathways, which are much more likely to be affected by CCS than the thalamo-cortical dependent N2 spindles. These findings suggest the N3 sleep stage provides the ideal mechanism by which to evaluate inter-hemispheric coherence after CCS. Notably, N3 spindles are thought to be more tightly linked to memory consolidation, necessitating consideration of this effect on neurocognitive outcomes in the surgical decision making for DRE patients. Support (if any)