Thalamic stereoelectroencephalography in epilepsy surgery: a scoping literature review

Abstract

OBJECTIVE Stereoelectroencephalography (sEEG) is a well-established surgical method for defining the epileptogenic network. Traditionally reserved for identifying discrete cortical regions for resection or ablation, sEEG in current practice is also used for identifying more broadly involved subcortical epileptic network components, driven by the availability of brain-based neuromodulation strategies. In particular, sEEG investigations including thalamic nuclei are becoming more frequent in parallel with the increase in therapeutic strategies involving thalamic targets such as deep brain stimulation (DBS) and responsive neurostimulation (RNS). The objective to this study was to evaluate existing evidence and trends regarding the purpose, techniques, and relevant electrographic findings of thalamic sEEG. METHODS MEDLINE and Embase databases were systematically queried for eligible peer-reviewed studies involving sEEG electrode implantation into thalamic nuclei of patients with epilepsy. Available data were abstracted concerning preoperative workup and purpose for implanting the thalamus, thalamic targets and trajectories, and electrophysiological methodology and findings. RESULTS sEEG investigations have included thalamic targets for both basic and clinical research purposes. Medial pulvinar, dorsomedial, anterior, and centromedian nuclei have been the most frequently studied. Few studies have reported any complications with thalamic sEEG implantation, and no studies have reported long-term complications. Various methods have been utilized to characterize thalamic activity in epileptic disorders including evoked potentials, power spectrograms, synchronization indices, and the epileptogenicity index. Thalamic intracranial recordings are beginning to be used to guide neuromodulation strategies including RNS and DBS, as well as to understand complex, network-dependent seizure disorders. CONCLUSIONS Inclusion of thalamic coverage during sEEG evaluation in drug-resistant epilepsy is a growing practice and is amenable to various methods of electrographic data analysis. Further study is required to establish well-defined criteria for thalamic implantation during invasive investigations as well as safety and ethical considerations.

Towards network-guided neuromodulation for epilepsy

“…Although invasive, SEEG offers a clinically-viable opportunity for network-guided and individualized neuromodulation planning and has already begun transitioning in routine clinical practice. 18 , 43 , 178 , 179 Richardson’s 18 review of paradigm shifts in closed-loop neuromodulation suggests that by changing the current ‘(seizure) focus-guided’ decision-making framework to a ‘network-orientated’ framework, SEEG implantation that includes potential propagation points may identify both sites for seizure detection in RNS and sites for the delivery of neuromodulation (DBS or RNS). Similarly, the latest ‘DBS Think Tank’ report describes ‘reassessing the purpose of SEEG’ by moving away from a ‘node based philosophy’ towards a ‘network based philosophy’.…”

Altered Functional Brain Network Structure between Patients with High and Low Generalized Anxiety Disorder

“…Various electrophysiological techniques, such as positron emission tomography, magnetic resonance imaging, and electroencephalography (EEG), have been widely used to measure neuronal activity [ 9 , 10 , 11 , 12 ]. Among them, EEG technology has the advantages of low cost, good portability, and strong portability [ 13 , 14 , 15 , 16 ]. The electrical signals sent by the human brain through the EEG instrument are captured by placing electrodes on the scalp through EEG technology to record brain activity [ 17 , 18 , 19 , 20 ].…”

Human thalamic recordings reveal that epileptic spikes block sleep spindle production during non-rapid eye movement sleep

“…Observations in animals (Steriade & Contreras, 1998) and in humans (Velasco et al, 1991(Velasco et al, , 2002 demonstrate that cortical epileptic spike activity may propagate to the thalamus (Gadot et al, 2022). Epileptic spikes have been proposed to hijack the circuitry that produces spindles and thereby disrupt sleep-dependent memory consolidation (Beenhakker & Huguenard, 2009;Kramer et al, 2021).…”