Disorders of the Nervous System
Author: Alejandro Nasimbera | Email: alejandro_nasimbera@hotmail.com
Alejandro Nasimbera1°, Santiago Cordisco Gonzalez1°, Demi Brizee2°, Nuria Campora1°, Pablo Seoane1°, Juan Pablo Princich1°, Silvia Jo1°
1° ENYS (CONICET – UNAJ – HOSPITAL EL CRUCE)
2° Oxford University, Oxford, United Kingdom
Epilepsy is characterized by recurring seizures. Surgery can benefit patients with drug-resistant epilepsy if the epileptogenic zone (EZ) is identified. In some cases, invasive studies using intracerebral electrodes are necessary. Our objective was to identify epileptogenic biomarkers in the cortex using single neuron recordings for more precise EZ mapping. Patients who underwent stereo encephalography (SEEG) were included. Electrical activity was recorded with macro-micro intracerebral electrodes in the mesial temporal regions. EZ and propagation areas (PA) were visually identified. Microelectrode signals were filtered between 1-9000 Hz and sampled at 30 kHz. Neuronal spikes were clustered using the Wave_clus algorithm and manually inspected. Units were classified as putative inhibitory or excitatory based on waveform morphology. Firing rates (FR) before and during seizures were computed using LOESS for peak FR estimation, and mixed linear models to analyze changes. We isolated 512 single units from 18 patients in 180 seizures. In the EZ, inhibitory interneurons increased FR 7 seconds before seizure onset (p<0.01), while excitatory neurons peaked 4 seconds after onset (p<0.01). In PA, both types showed no significant change during onset but peaked 12 seconds after. This suggests inhibitory interneurons’ FR increase as a biomarker for EZ localization, improving patient outcomes.