Protocol for Thalamocortical Functional Connectivity and Loss of Consciousness Investigation in Children with Epilepsy Using Stereo-EEG Data

Introduction:

Seizure-related loss of consciousness (LOC) in pediatric epilepsy significantly impacts safety, cognitive development, and quality of life. The thalamus is believed to play a central role in sustaining consciousness via its integrative cortical connectivity. Disruption of thalamocortical networks may underlie impaired awareness during seizures, yet mechanistic insights remain limited. Stereo-electroencephalography (sEEG) offers high-resolution intracranial recordings that enable in vivo exploration of these neural dynamics. Here, we present a protocol designed to systematically evaluate thalamocortical functional connectivity during seizures with and without LOC in pediatric patients with drug-resistant epilepsy. This protocol serves as a foundation for future hypothesis-driven investigations and network-targeted therapeutic strategies.

Methods:

Postoperative CT scans are co-registered with preoperative MRI to localize and label electrode contacts. sEEG data are exported from the Natus system into Brainstorm for preprocessing and quantitative analysis. Recordings include at least 10 minutes of pre-ictal, ictal, and post-ictal data. Seizures with and without LOC are identified and time-marked using synchronized video-EEG. LOC severity is scored independently by two experienced reviewers. Functional connectivity is assessed via Coherence (Coh) and maps are generated to visualize thalamocortical network dynamics.

Results:

Fourteen pediatric patients underwent thalamic sEEG implantation. Etiologies included focal cortical dysplasia, periventricular nodular heterotopia, neonatal HIE, and non-lesional epilepsy. Pre-implant hypotheses included temporal, frontal, insular, and multifocal seizure onset. Thalamic sampling included anterior and pulvinar nuclei. Interictal thalamic abnormalities were present in most of the patients. A protocol of the analysis was created and will be presented as a flow chart with the major analysis steps in the poster.

Conclusions:

This protocol-based approach enables rigorous investigation of thalamocortical connectivity and its role in LOC during epileptic seizures. Ongoing analyses will evaluate frequency-specific functional connectivity associated with altered awareness. Findings from this study may enhance patient-specific neuromodulation strategies and advance our understanding of consciousness disruption in epilepsy.