David Martín-López1,2,3,4, Diego Jiménez-Jiménez3,5,6, Lidia Cabañés-Martínez7, Richard P Selway8, Antonio Valentín3,4,5, Gonzalo Alarcón3,4,5,9. 1. 1 Department of Clinical Neurophysiology, Kingston Hospital NHS FT, London, UK. 2. 2 Department of Clinical Neurophysiology, St George's University Hospitals NHS FT, London, UK. 3. 3 Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK. 4. 4 Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, Madrid, Spain. 5. 5 Department of Clinical Neurophysiology, King's College Hospital NHS FT, London, UK. 6. 6 Universidad San Francisco de Quito, School of Medicine, Quito, Ecuador. 7. 7 Servicio de Neurofisiología Clínica Hospital Ramón y Cajal, Madrid, Spain. 8. 8 Department of Neurosurgery, King's College Hospital NHS FT, London, UK. 9. 9 Comprehensive Epilepsy Center Neuroscience Institute, Academic Health Systems, Hamad Medical Corporation, Doha, Qatar.
Abstract
BACKGROUND: The onset of generalized seizures is a long debated subject in epilepsy. The relative roles of cortex and thalamus in initiating and maintaining the different seizure types are unclear. OBJECTIVE: The purpose of the study is to estimate whether the cortex or the centromedian thalamic nucleus is leading in initiating and maintaining seizures in humans. METHODS: We report human ictal recordings with simultaneous thalamic and cortical electrodes from three patients without anesthesia being assessed for deep brain stimulation (DBS). Patients 1 and 2 had idiopathic generalized epilepsy whereas patient 3 had frontal lobe epilepsy. Visual inspection was combined with nonlinear correlation analysis. RESULTS: In patient 1, seizure onset was bilateral cortical and the belated onset of leading thalamic discharges was associated with an increase in rhythmicity of discharges, both in thalamus and cortex. In patient 2, we observed bilateral independent interictal discharges restricted to the thalamus. However, ictal onset was diffuse, with discharges larger in the cortex even though they were led by the thalamus. In patient 3, seizure onset was largely restricted to frontal structures, with belated lagging thalamic involvement. CONCLUSION: In human generalized seizures, the thalamus may become involved early or late in the seizure but, once it becomes involved, it leads the cortex. In contrast, in human frontal seizures the thalamus gets involved late in the seizure and, once it becomes involved, it lags behind the cortex. In addition, the centromedian nucleus of the thalamus is capable of autonomous epileptogenesis as suggested by the presence of independent focal unilateral epileptiform discharges restricted to thalamic structures. The thalamus may also be responsible for maintaining the rhythmicity of ictal discharges.
BACKGROUND: The onset of generalized seizures is a long debated subject in epilepsy. The relative roles of cortex and thalamus in initiating and maintaining the different seizure types are unclear. OBJECTIVE: The purpose of the study is to estimate whether the cortex or the centromedian thalamic nucleus is leading in initiating and maintaining seizures in humans. METHODS: We report human ictal recordings with simultaneous thalamic and cortical electrodes from three patients without anesthesia being assessed for deep brain stimulation (DBS). Patients 1 and 2 had idiopathic generalized epilepsy whereas patient 3 had frontal lobe epilepsy. Visual inspection was combined with nonlinear correlation analysis. RESULTS: In patient 1, seizure onset was bilateral cortical and the belated onset of leading thalamic discharges was associated with an increase in rhythmicity of discharges, both in thalamus and cortex. In patient 2, we observed bilateral independent interictal discharges restricted to the thalamus. However, ictal onset was diffuse, with discharges larger in the cortex even though they were led by the thalamus. In patient 3, seizure onset was largely restricted to frontal structures, with belated lagging thalamic involvement. CONCLUSION: In humangeneralized seizures, the thalamus may become involved early or late in the seizure but, once it becomes involved, it leads the cortex. In contrast, in humanfrontal seizures the thalamus gets involved late in the seizure and, once it becomes involved, it lags behind the cortex. In addition, the centromedian nucleus of the thalamus is capable of autonomous epileptogenesis as suggested by the presence of independent focal unilateral epileptiform discharges restricted to thalamic structures. The thalamus may also be responsible for maintaining the rhythmicity of ictal discharges.
Authors: Marta Nowakowska; Muammer Üçal; Marios Charalambous; Sofie F M Bhatti; Timothy Denison; Sebastian Meller; Gregory A Worrell; Heidrun Potschka; Holger A Volk Journal: Front Vet Sci Date: 2022-06-16
Authors: Mayela Zamora; Sebastian Meller; Filip Kajin; James J Sermon; Robert Toth; Moaad Benjaber; Derk-Jan Dijk; Rafal Bogacz; Gregory A Worrell; Antonio Valentin; Benoit Duchet; Holger A Volk; Timothy Denison Journal: Front Neurosci Date: 2021-09-24 Impact factor: 4.677