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:10.1002/acn3.50835

Cited by 21 publications

(15 citation statements)

References 18 publications

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“…With these results, we propose that if patients are fully informed of the risks involved, there are significant benefits to 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 the following: 1) periictal electrophysiological changes occurring in the thalamus during the seizures, 2) cortical responsiveness to thalamic stimulation, and 3) a temporal predictive model to determine ictal and interictal thalamic states in TLE. In concordance with the growing evidence from various centers around the world, there is a possibility to envisage a more patient-oriented closed-loop DBS system.…”

Section: Discussionmentioning

confidence: 99%

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Robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy: implantation technique and complications in the first 24 patients

Chaitanya¹,

Romeo

Ilyas

et al. 2020

Neurosurgical Focus

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OBJECTIVEDespite numerous imaging studies highlighting the importance of the thalamus in a patient’s 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 robot-assisted stereotactic electrode placement in the limbic thalamic nuclei of patients with suspected temporal lobe epilepsy (TLE).METHODSAfter providing informed consent, 24 adults with drug-resistant, suspected TLE undergoing evaluation with stereoelectroencephalography (SEEG) were enrolled in the prospective study. The trajectory of one electrode planned for clinical sampling of the operculoinsular cortex was modified to extend it to the thalamus, thereby preventing the need for additional electrode placement for research. The anterior nucleus of the thalamus (ANT) (n = 13) and the medial group of thalamic nuclei (MED) (n = 11), including the mediodorsal and centromedian nuclei, were targeted. The postimplantation CT scan was coregistered to the preoperative MR image, and Morel’s thalamic atlas was used to confirm the accuracy of implantation.RESULTSTen (77%) of 13 patients in the ANT group and 10 (91%) of 11 patients in the MED 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, who 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 those of the MED group at the entry point—i.e., the precentral gyrus in the former and the postcentral gyrus in the latter.CONCLUSIONSUsing judiciously planned robot-assisted SEEG, the authors demonstrate the safety of electrophysiological sampling from various thalamic nuclei for research recordings, presenting a technique that avoids implanting additional depth electrodes or compromising 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: Discussionmentioning

confidence: 99%

“…The electrophysiological data thus obtained were analyzed and published previously, addressing key clinical questions. 26,27,29,40…”

Section: Targeting Accuracymentioning

confidence: 99%

Robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy: implantation technique and complications in the first 24 patients

Chaitanya¹,

Romeo

Ilyas

et al. 2020

Neurosurgical Focus

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“…This result echoed our study that disclosed bilateral thalami were structurally affected in unilateral temporal epilepsy. In the previous literatures, the most commonly reported thalamic subfields that are involved in TLE are the medial pulvinar [by SEEG ( 7 ) and resting-state fMRI (rs-fMRI) ( 20 )], the anterior nucleus [by rs-fMRI ( 20 )], and the midline nuclei ( 37 ). Their ipsilateral involvement was present in both TLE groups in our study, and we further defined the structures in more detail.…”

Section: Discussionmentioning

confidence: 99%

“…The ipsilateral central medial (CeM) and medial ventral (MVRe) nuclei showed significant atrophy in our study. The SEEG investigation found that the midline thalamic nuclei were involved in early recruitment in seizure initiation and propagation ( 36 , 37 ). Therefore, their significant volume reduction on the side ipsilateral to the side affected by epilepsy was expected.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Hippocampal-Thalamic-Cortical Morphometric Reorganization in Temporal Lobe Epilepsy

et al. 2022

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IntroductionBrain cortico-subcortical connectivity has been investigated in epilepsy using the functional MRI (MRI). Although structural images cannot demonstrate dynamic changes, they provide higher spatial resolution, which allows exploration of the organization of brain in greater detail.MethodsWe used high-resolution brain MRI to study the hippocampal-thalamic-cortical networks in temporal lobe epilepsy (TLE) using a volume-based morphometric method. We enrolled 22 right-TLE, 33 left-TLE, and 28 age/gender-matched controls retrospectively. FreeSurfer software was used for the thalamus segmentation.ResultsAmong the 50 subfields, ipsilateral anterior, lateral, and parts of the intralaminar and medial nuclei, as well as the contralateral parts of lateral nuclei had significant volume loss in both TLE. The anteroventral nucleus was most vulnerable. Most thalamic subfields were susceptible to seizure burden, especially the left-TLE. SPM12 was used to conduct an analysis of the gray matter density (GMD) maps. Decreased extratemporal GMD occurred bilaterally. Both TLE demonstrated significant GMD loss over the ipsilateral inferior frontal gyrus, precentral gyrus, and medial orbital cortices.SignificanceThalamic subfield atrophy was related to the ipsilateral inferior frontal GMD changes, which presented positively in left-TLE and negatively in right-TLE. These findings suggest prefrontal-thalamo-hippocampal network disruption in TLE.

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“…We make measurements of these types with recordings of the convexity brain surface electrocorticography (ECoG) or in deeper structures from stereoelectrocorticography (stereoEEG; sEEG) and deep brain stimulation (DBS) electrodes with our neurosurgical patients [7]. Despite the “CCEP” name, these stimulation-evoked potential changes are seen with stimulation and recording of non-cortical structures such as white matter, basal ganglia, thalamus, and others [8, 9].…”

Section: Introductionmentioning

confidence: 99%

Canonical Response Parameterization: Quantifying the structure of responses to single-pulse intracranial electrical brain stimulation

Miller

Mueller

Valencia

et al. 2022

Preprint

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Single-pulse electrical stimulation in the nervous system, often called cortico-cortical evoked potential (CCEP) measurement, is an important technique to understand how brain regions interact with one another. Voltages are measured from implanted electrodes in one brain area while stimulating another with brief current impulses separated by several seconds. Historically, researchers have tried to understand the significance of evoked voltage polyphasic deflections by visual inspection, but no general-purpose tool has emerged to understand their shapes or describe them mathematically. We describe and illustrate a new technique to parameterize brain stimulation data, where voltage response traces are projected into one another using a semi-normalized dot product. The length of timepoints from stimulation included in the dot product is varied to obtain a temporal profile of structural significance, and the peak of the profile uniquely identifies the duration of the response. Using linear kernel PCA, a canonical response shape is obtained over this duration, and then single-trial traces are parameterized as a projection of this canonical shape with a residual term. Such parameterization allows for dissimilar trace shapes from different brain areas to be directly compared by quantifying cross-projection magnitudes, response duration, canonical shape projection amplitudes, signal-to-noise ratios, explained variance, and statistical significance. Artifactual trials are automatically identified by outliers in sub-distributions of cross-projection magnitude, and rejected. This technique, which we call "Canonical Response Parameterization" (CRP) dramatically simplifies the study of CCEP shapes, and may also be applied in a wide range of other settings involving event-triggered data.

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Early ictal recruitment of midline thalamus in mesial temporal lobe epilepsy

Cited by 21 publications

References 18 publications

Robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy: implantation technique and complications in the first 24 patients

Robot-assisted stereoelectroencephalography exploration of the limbic thalamus in human focal epilepsy: implantation technique and complications in the first 24 patients

Characterization of Hippocampal-Thalamic-Cortical Morphometric Reorganization in Temporal Lobe Epilepsy

Canonical Response Parameterization: Quantifying the structure of responses to single-pulse intracranial electrical brain stimulation

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