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Electrophysiological characterization of a behavioral index that quantifies the degree of loss of consciousness in epileptic seizures

Claudio Sebastián Sigvard

  • Bariloche,
  • Argentina
  • Claudio Sebastián Sigvard ¹𝄒²
  • , Melisa Maidana Capitán ¹𝄒²
  • , Nuria Cámpora ³
  • , Silvia Kochen ³
  • , Inés Samengo ¹𝄒²
  • 1 Instituto Balseiro
  • 2 Departamento de Física Médica
  • 3 Neurosciences and Complex Systems Unit (ENyS), Consejo Nacional de Investigaciones Cientı́ficas y Técnicas, Hospital El Cruce “Néstor Kirchner” y Universidad Nacional Arturo Jauretche.

In 2009, the Consciousness Seizure Scale (CSS) was proposed to quantify the degree of loss of consciousness, summarizing the response of a patient to 8 behavioral items performed by a clinical practitioner during or after a seizure. The 8 items quantify the ability to interact with the practitioner, to recognize the seizure as such, and the degree of memory impairment. Here we analyzed the physiological correlates of the CSS by studying the electric potential recorded with intracranial electrodes in patients requiring an exploratory study before epilepsy surgery. We analyzed 26 seizures recorded from 5 patients, each with 5-6 electrodes and each electrode with 9 contacts (1599 signals in total). We found that the items that assessed memory impairment were positively correlated with the total duration of the seizure, with maximal correlation between the electrical anomaly and the behavioral tests approximately 60 seconds after seizure onset. The items assessing the ability to interact with the practitioner, instead, were positively correlated with the propagation velocity throughout the recruited areas, with maximal correlation between electrical and behavioral properties approximately 30 seconds after seizure onset. We conclude that the signals recorded with intracranial electrodes contain information about the different capacities that sustain conscious processing, and that the impairment of different capacities follows discernable temporal profiles.