Early Ictal Recruitment of Midline Thalamus in Mesial Temporal Lobe Epilepsy

Romeo, Andrew; Roach, Alexandra T. Issa; Tóth, Emília; Chaitanya, Ganne; Ilyas, Adeel; Riley, Kristen; Pati, Sandipan

doi:10.1101/647586

Cited by 2 publications

(3 citation statements)

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“…The overall complication rates are low and comparable to electrodes placed in any other location. With these results, we propose that if patients are fully informed of the risks involved, there are significant benefits of obtaining robust signals from thalamic nuclei involved in seizure networks which may help guide future therapies 26,27,29 . Some of the early studies by our group have shown (1) the periictal electrophysiological changes occurring in the thalamus during the seizures, (2) the cortical responsiveness to thalamic…”

Section: Figurementioning

confidence: 98%

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Implantation technique, safety and complications of robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy

Chaitanya

Romeo

Ilyas

et al. 2020

Preprint

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Introduction:Despite numerous imaging studies highlighting the importance of thalamus in surgical prognosis, human electrophysiological studies involving the limbic thalamic nuclei are limited. The objective of this study was to evaluate the safety and accuracy of robotassisted stereotactic electrode placement in the limbic thalamic nuclei in patients with suspected temporal lobe epilepsy (TLE).Methods: After obtaining informed consent, 24 adults with drug-resistant suspected TLE undergoing Stereo-EEG evaluation were enrolled in this prospective study. The trajectory of one electrode planned for clinical sampling the operculo-insular cortex was modified to extend to the thalamus, thereby preventing the need for additional electrode placement for research. The anterior thalamus (ANT) (N=13) and the medial group of thalamic nuclei (MED) (N=11), including mediodorsal (MD) and centromedian (CeM) were targeted. The post-implantation CT was co-registered to the pre-operative MRI, and Morel's thalamic atlas was used to confirm the accuracy of implantation.Results: Ten out of 13 (77%) in the ANT group and 10 out of 11 patients (90%) in the medial group had electrodes accurately placed in the thalamic nuclei. None of the patients had a thalamic hemorrhage. However, trace asymptomatic hemorrhages at the cortical level entry site were noted in 20.8% of patients and they did not require additional surgical intervention. SEEG data from all the patients were interpretable and analyzable. The trajectories for the ANT implant differed slightly from the medial group at the entry point i.e., precentral gyrus in the former and postcentral gyrus in the latter.Conclusions: Using judiciously planned robot-assisted SEEG, we demonstrate the safety of electrophysiological sampling from various thalamic nuclei for research recordings, presenting a technique that avoids implanting additional depth electrodes, or comprising clinical care. With these results, we propose that if patients are fully informed of the risks involved, there are potential benefits of gaining mechanistic insights to seizure genesis, which may help to develop neuromodulation therapies.

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Section: Figurementioning

confidence: 98%

“…However, the local field potentials (LFPs) of the thalamus were of a lower amplitude compared to the cortical LFPs ( Fig 6). The electrophysiological data thus obtained has been analyzed and published previously addressing key clinical questions 26,27,29,41 .…”

Section: Table 1 Seeg Implantation and Complicationsmentioning

confidence: 99%

Implantation technique, safety and complications of robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy

Chaitanya

Romeo

Ilyas

et al. 2020

Preprint

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“…Experimental studies suggest that the thalamic nuclei play diverse roles in initiation, propagation, and termination (collectively termed as ictogenesis) of limbic seizures (Bertram et al, 2001;Takebayashi et al, 2007;Langlois et al, 2010;Feng et al, 2017). In TLE, prior clinical studies have explored the influence of lateral and medial thalamic nuclei in ictogenesis, but none to date have studied the anterior nucleus of the thalamus (ANT) -a node that is integral to the limbic network (Child and Benarroch, 2013;Evangelista et al, 2015;Romeo et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Ictal recruitment of anterior nucleus of thalamus in human focal epilepsy

Tóth

Chaitanya

Pizarro

et al. 2019

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The thalamic nuclei play diverse roles in the initiation, propagation, and termination of temporal lobe seizures. The role of the anterior nucleus of the thalamus (ANT) -a node that is integral to the limbic network is unclear. The objective of this study was to characterize temporal andspectral patterns of ANT ictal recruitment in drug-resistant temporal lobe epilepsy (TLE). We hypothesized that seizures localized to the temporolimbic network are likely to recruit ANT, and the odds of recruitment were higher in seizures that had altered consciousness. Ten patients undergoing stereo-electroencephalography (SEEG) were recruited prospectively to record field potentials from the ANT. Using epileptogenicity index and line length, we computed the number of seizures that recruited the ANT (recruitment ratio), the recruitment latencies between the ANT and the epileptogenic zone (EZ), and latency of ANT recruitment to clinical manifestation for seventy-nine seizures. We observed that seizures localized to mesial temporal subregions (hippocampus, amygdala, anterior cingulate) have a higher predilection for ANT recruitment, and the recruitment was faster (ranged 5-12 secs) and preceded clinical onset for seizures that impaired consciousness. Seizures that recruited ANT lasted significantly longer (t=1.795, p=0.005). Recruitment latency was inversely correlated to seizure duration (r=-0.78, p=0.004).Electrical stimulation of the EZ induced seizures, in which early recruitment of ANT was confirmed. Stimulation of ANT did not induce a seizure. Finally, we tested the hypothesis that spectral and entropy-based features extracted from thalamic field potentials can distinguish its state of ictal recruitment from other interictal states (including awake, sleep). For this, we employed classification machine learning that discriminated thalamic ictal state from other interictal states with high accuracy (92.8%) and precision (93.1%). Among the features, the emergence of the theta rhythm (4-8 Hz) maximally discriminated the endogenous ictal state from

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Early Ictal Recruitment of Midline Thalamus in Mesial Temporal Lobe Epilepsy

Cited by 2 publications

References 18 publications

Implantation technique, safety and complications of robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy

Implantation technique, safety and complications of robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy

Ictal recruitment of anterior nucleus of thalamus in human focal epilepsy

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