Modulation of neural complexity and consciousness in temporal lobe seizures: Effects of high-frequency pulvinar stimulation.

Loss of consciousness during temporal lobe seizures is linked to reduced brain signal complexity and abnormal synchronization in the thalamocortical system. The medial pulvinar nucleus (PUM) is involved in seizure spread and awareness impairment. In eight patients with drug-resistant temporal epilepsy, high-frequency PUM stimulation during hippocampus-induced seizures attenuated the decline in neural complexity measured by permutation entropy. Reduced entropy alterations correlated with improved awareness scores on the Consciousness Seizure Scale. The findings suggest that PUM stimulation preserves neural complexity and may help maintain consciousness and cognitive function during seizures, though larger studies are needed.

Study at a glance

Abstract

Loss of consciousness/awareness during temporal lobe seizures significantly affects quality of life and is closely linked to pathological thalamocortical synchronization and loss of cortical signal complexity. The medial pulvinar nucleus (PUM) contributes to seizure propagation and awareness impairment, making it a potential target for neuromodulation. Acute high-frequency PUM stimulation has previously been shown to reduce seizure severity and improve awareness, potentially by disrupting excessive synchrony. In this study, we investigated the effects of PUM stimulation on signal complexity and its relationship to ictal awareness using permutation entropy (PE) in SEEG recordings. Eight patients with focal drug-resistant temporal epilepsy underwent hippocampus-induced seizures with and without additional high-frequency PUM stimulation. SEEG complexity changes were quantified using PE and ictal awareness was assessed using the Consciousness Seizure Scale (CSS). Our results showed that PUM stimulation attenuated entropy reductions during seizures, suggesting a preservation of neural complexity. Moreover, reduced entropy alterations correlated with improved CSS scores. These findings support the role of PUM stimulation in mitigating pathological neural complexity alterations, with potential implications for preserving both consciousness and cognitive function in epilepsy. Further studies are needed to confirm these findings in larger cohorts and to explore the long-term effects of thalamic deep brain stimualtion in drug-resistant epilepsy as well as the interaction between neural complexity, awareness, and cognition in this context.