Case report: Nocturnal low-frequency stimulation of the centromedian thalamic nucleus improves sleep quality and seizure control.

Sleep disturbances and drug-resistant seizures significantly impact people with idiopathic generalized epilepsy (IGE). Thalamic deep brain stimulation (DBS) offers potential treatment, but its effect on sleep and seizure control needs clarification. In this study, we combined wearable sleep monitoring with electroencephalogram (EEG) confirmation to investigate the impact of nocturnal centromedian nucleus (CM) DBS parameters in a patient with drug-resistant IGE. We found that high-frequency (125 Hz) CM stimulation during sleep severely disrupted sleep macro architecture and exacerbated seizures. Conversely, switching to low-frequency (10 Hz) stimulation enhanced both sleep quality and seizure control. This study underscores the critical need to personalize DBS settings, tailoring them to individual patients' sleep patterns to maximize therapeutic benefits. While larger-scale trials are needed, our findings pave the way for patient-centric approaches to thalamic neuromodulation, offering a transformative path to improve treatment outcomes and quality of life for those with refractory epilepsy.

Incidence and Types of Cardiac Arrhythmias in the Peri-Ictal Period in Patients Having a Generalized Convulsive Seizure.

BACKGROUND AND OBJECTIVES: Generalized convulsive seizures (GCSs) are the main risk factor of sudden unexpected death in epilepsy (SUDEP), which is likely due to peri-ictal cardiorespiratory dysfunction. The incidence of GCS-induced cardiac arrhythmias, their relationship to seizure severity markers, and their role in SUDEP physiopathology are unknown. The aim of this study was to analyze the incidence of seizure-induced cardiac arrhythmias, their association with electroclinical features and seizure severity biomarkers, as well as their specific occurrences in SUDEP cases. METHODS: This is an observational, prospective, multicenter study of patients with epilepsy aged 18 years and older with recorded GCS during inpatient video-EEG monitoring for epilepsy evaluation. Exclusion criteria were status epilepticus and an obscured video recording. We analyzed semiologic and cardiorespiratory features through video-EEG (VEEG), electrocardiogram, thoracoabdominal bands, and pulse oximetry. We investigated the presence of bradycardia, asystole, supraventricular tachyarrhythmias (SVTs), premature atrial beats, premature ventricular beats, nonsustained ventricular tachycardia (NSVT), atrial fibrillation (Afib), ventricular fibrillation (VF), atrioventricular block (AVB), exaggerated sinus arrhythmia (ESA), and exaggerated sinus arrhythmia with bradycardia (ESAWB). A board-certified cardiac electrophysiologist diagnosed and classified the arrhythmia types. Bradycardia, asystole, SVT, NSVT, Afib, VF, AVB, and ESAWB were classified as arrhythmias of interest because these were of SUDEP pathophysiology value. The main outcome was the occurrence of seizure-induced arrhythmias of interest during inpatient VEEG monitoring. Moreover, yearly follow-up was conducted to identify SUDEP cases. Binary logistic generalized estimating equations were used to determine clinical-demographic and peri-ictal variables that were predictive of the presence of seizure-induced arrhythmias of interest. The z-score test for 2 population proportions was used to test whether the proportion of seizures and patients with postconvulsive ESAWB or bradycardia differed between SUDEP cases and survivors. RESULTS: This study includes data from 249 patients (mean age 37.2 ± 23.5 years, 55% female) who had 455 seizures. The most common arrhythmia was ESA, with an incidence of 137 of 382 seizures (35.9%) (106/224 patients [47.3%]). There were 50 of 352 seizure-induced arrhythmias of interest (14.2%) in 41 of 204 patients (20.1%). ESAWB was the commonest in 22 of 394 seizures (5.6%) (18/225 patients [8%]), followed by SVT in 18 of 397 seizures (4.5%) (17/228 patients [7.5%]). During follow-up (48.36 ± 31.34 months), 8 SUDEPs occurred. Seizure-induced bradycardia (3.8% vs 12.5%, z = -16.66, p < 0.01) and ESAWB (6.6% vs 25%; z = -3.03, p < 0.01) were over-represented in patients who later died of SUDEP. There was no association between arrhythmias of interest and seizure severity biomarkers (p > 0.05). DISCUSSION: Markers of seizure severity are not related to seizure-induced arrhythmias of interest, suggesting that other factors such as occult cardiac abnormalities may be relevant for their occurrence. Seizure-induced ESAWB and bradycardia were more frequent in SUDEP cases, although this observation was based on a very limited number of SUDEP patients. Further case-control studies are needed to evaluate the yield of arrhythmias of interest along with respiratory changes as potential SUDEP biomarkers.

Advancing the frontiers of thalamic neuromodulation: A review of emerging targets and paradigms.

The thalamus is a key structure that plays a crucial role in initiating and propagating seizures. Recent advancements in neuroimaging and neurophysiology have identified the thalamus as a promising target for neuromodulation in drug-resistant epilepsies. This review article presents the latest innovations in thalamic targets and neuromodulation paradigms being explored in pilot or pivotal clinical trials. Multifocal temporal plus or posterior quadrant epilepsies are evaluated with pulvinar thalamus neuromodulation, while centromedian thalamus is explored in generalized epilepsies and Lennox Gastaut syndrome. Multinodal thalamocortical neuromodulation with novel stimulation paradigms such as long bursting or low-frequency stimulation is being investigated to quench the epileptic network excitability. Beyond seizure control, thalamic neuromodulation to restore consciousness is being studied. This review highlights the promising potential of thalamic neuromodulation in epilepsy treatment, offering hope to patients who have not responded to conventional medical therapies. However, it also emphasizes the need for larger randomized controlled trials and personalized stimulation paradigms to improve patient outcomes further.

Pulvinar neuromodulation for seizure monitoring and network modulation in temporal plus epilepsy.

Deep brain stimulation (DBS) is a promising treatment for drug-refractory epilepsies (DRE) when targeting the anterior nuclei of thalamus (ANT). However, targeting other thalamic nuclei, such as the pulvinar, shows therapeutic promise. Our pioneering case study presents the application of ambulatory seizure monitoring using spectral fingerprinting (12.15-17.15 Hz) recorded through Medtronic Percept DBS implanted bilaterally in the medial pulvinar thalami. This technology offers unprecedented opportunities for real-time monitoring of seizure burden and thalamocortical network modulation for effective seizure reduction in patients with bilateral mesial temporal and temporal plus epilepsies that are not suitable for resection.

Stimulation-induced respiratory enhancement in corticothalamic regions.

OBJECTIVE: We aimed to identify corticothalamic areas and electrical stimulation paradigms that optimally enhance breathing. METHODS: Twenty-nine patients with medically intractable epilepsy were prospectively recruited in an epilepsy monitoring unit while undergoing stereoelectroencephalographic evaluation. Direct electrical stimulation in cortical and thalamic regions was carried out using low (<1 Hz) and high (≥10 Hz) frequencies, and low (<5 mA) and high (≥5 mA) current intensities, with pulse width of .1 ms. Electrocardiography, arterial oxygen saturation (SpO2 ), end-tidal carbon dioxide (ETCO2 ), oronasal airflow, and abdominal and thoracic plethysmography were monitored continuously during stimulations. Airflow signal was used to estimate breathing rate, tidal volume, and minute ventilation (MV) changes during stimulation, compared to baseline. RESULTS: Electrical stimulation increased MV in the amygdala, anterior cingulate, anterior insula, temporal pole, and thalamus, with an average increase in MV of 20.8% ± 28.9% (range = 0.2%-165.6%) in 19 patients. MV changes were associated with SpO2 and ETCO2 changes (p < .001). Effects on respiration were parameter and site dependent. Within amygdala, low-frequency stimulation of the medial region produced 78.49% greater MV change (p < .001) compared to high-frequency stimulation. Longer stimulation produced greater MV changes (an increase of 4.47% in MV for every additional 10 s, p = .04). SIGNIFICANCE: Stimulation of amygdala, anterior cingulate gyrus, anterior insula, temporal pole, and thalamus, using certain stimulation paradigms, enhances respiration. Among tested paradigms, low-frequency, low-intensity, long-duration stimulation of the medial amygdala is the most effective breathing enhancement stimulation strategy. Such approaches may pave the way for the future development of neuromodulatory techniques that aid rescue from seizure-related apnea, potentially as a targeted sudden unexpected death in epilepsy prevention method.

Mapping the thickness of retinal layers using Spectralis spectral domain optical coherence tomography in Indian eyes.

Purpose: This study aimed at establishing the normative data for the thickness of macular layers on Spectralis Spectral-domain optical coherence tomography (SD-OCT) in healthy Indian eyes and testing the effects of age, gender, central corneal thickness (CCT), and intraocular pressure (IOP) on such values. Methods: This cross-sectional study was done on 308 eyes of 159 healthy subjects. OCT scans were obtained using the posterior pole asymmetry scan protocol. From the thickness map, data were grouped into nine Early Treatment Diabetic Retinopathy Study (ETDRS) macular sectors. Correlation between retinal thickness and age/IOP/CCT was done using Pearson correlation. Correcting for age as a covariate, multivariate regression analysis was done to know which retinal layers showed significant differences in thickness between males and females. Results: The mean age was 46.06 ± 13.06 years (range: 20-75 years). Significant central subfield (CSF) thickening with age was noted in retinal nerve fiber layer (RNFL), inner nuclear layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), and outer nuclear layer (ONL) (P < 0.04). The average thickness of the outer ring reduced with age in the ganglion cell layer (GCL)/IPL/INL (P = 0.001). Women had thinner inner and outer retinal thickness than men in all ETDRS rings (P < 0.001). There was no interocular asymmetry (P > 0.05) and no correlation between IOP/CCT and retinal layer thickness. Conclusion: In CSF, age-related thickening was noted in RNFL, IPL, INL, OPL, and ONL. The average inner ring thickness decreased with age in GCL and IPL and increased in the RPE layer. The average outer ring thickness decreased with age in GCL, IPL, and INL layers and increased in OPL. The average IR and OR thickness was significantly less in women compared to men in all sub-fields. There was no correlation between IOP/CCT and retinal layer thickness.

Time-Series Generative Adversarial Network Approach of Deep Learning Improves Seizure Detection From the Human Thalamic SEEG.

Seizure detection algorithms are often optimized to detect seizures from the epileptogenic cortex. However, in non-localizable epilepsies, the thalamus is frequently targeted for neuromodulation. Developing a reliable seizure detection algorithm from thalamic SEEG may facilitate the translation of closed-loop neuromodulation. Deep learning algorithms promise reliable seizure detectors, but the major impediment is the lack of larger samples of curated ictal thalamic SEEG needed for training classifiers. We aimed to investigate if synthetic data generated by temporal Generative Adversarial Networks (TGAN) can inflate the sample size to improve the performance of a deep learning classifier of ictal and interictal states from limited samples of thalamic SEEG. Thalamic SEEG from 13 patients (84 seizures) was obtained during stereo EEG evaluation for epilepsy surgery. Overall, TGAN generated synthetic data augmented the performance of the bidirectional Long-Short Term Memory (BiLSTM) performance in classifying thalamic ictal and baseline states. Adding synthetic data improved the accuracy of the detection model by 18.5%. Importantly, this approach can be applied to classify electrographic seizure onset patterns or develop patient-specific seizure detectors from implanted neuromodulation devices.

Limbic and paralimbic respiratory modulation: From inhibition to enhancement.

OBJECTIVE: Increased understanding of the role of cortical structures in respiratory control may help the understanding of seizure-induced respiratory dysfunction that leads to sudden unexpected death in epilepsy (SUDEP). The aim of this study was to characterize respiratory responses to electrical stimulation (ES), including inhibition and enhancement of respiration. METHODS: We prospectively recruited 19 consecutive patients with intractable epilepsy undergoing stereotactic electroencephalography (EEG) evaluation from June 2015 to June 2018. Inclusion criteria were patients ≥18 years in whom ES was indicated for clinical mapping of ictal onset or eloquent cortex as part of the presurgical evaluation. ES was carried out at 50 Hz, 0.2 msec, and 1-10 mA current intensity. Common brain regions sampled across all patients were amygdala (AMY), hippocampus (HG), anterior cingulate gyrus (CING), orbitofrontal cortex (OrbF), temporal neocortex (TNC), temporal pole (TP), and entorhinal cortex (ERC). Seven hundred fifty-five stimulations were conducted. Quantitative analysis of breathing signal, that is, changes in breathing rate (BR), depth (TV), and minute ventilation (MV), was carried out during ES using the BreathMetrics breathing waveform analysis toolbox. Electrocardiography, arterial oxygen saturation, end-tidal and transcutaneous carbon dioxide, nasal airflow, and abdominal and thoracic plethysmography were monitored continuously during stimulations. RESULTS: Electrical stimulation of TP and CING (at lower current strengths <3 mA) increased TV and MV. At >7-10 mA, CING decreased TV and MV. On the other hand, decreased TV and MV occurred with stimulation of mesial temporal structures such as AMY and HG. Breathing changes were dependent on stimulation intensity. Lateral temporal, entorhinal, and orbitofrontal cortices did not affect breathing either way. SIGNIFICANCE: These findings suggest that breathing responses other than apnea can be induced by ES. Identification of two regions-the temporal pole and anterior cingulate gyrus-for enhancement of breathing may be important in paving the way to future development of strategies for prevention of SUDEP.

Ictal high-frequency activity in limbic thalamic nuclei varies with electrographic seizure-onset patterns in temporal lobe epilepsy.

OBJECTIVE: To characterize ictal high-frequency activity (HFA, 80-500 Hz) within the limbic thalami and correlate HFA with seizure onset patterns in patients with temporal lobe epilepsy (TLE). METHODS: Patients with TLE undergoing stereoelectroencephalography (SEEG) for presurgical workup were prospectively recruited for electrode implantation in one of the anterior (AN), centromedian (CeM), or mediodorsal (MD) thalamic nuclei. HFA was computed by three complementary methods: (1.) power-spectral density (PSD), (2.) power-law based (i.e., 1/f) regression, and (3.) envelope-based (ENV) power analysis. Electrographic onset patterns in the seizure onset zone were classified in three distinct patterns, including low amplitude fast activity (LAFA). RESULTS: From 11 patients, 44 seizures were analyzed. Ictal HFA was observed in all three thalamic nuclei. HFA was greatest during ictal onset in the AN and MD and greatest during termination in the CeM (P < 0.001). LAFA-onset seizures were associated with earlier peak HFA compared to those with other onset patterns (P = 0.006). CONCLUSIONS: Dynamics of ictal HFA seem to vary by thalamic subnuclei. AN and MD may facilitate seizure propagation while CeM may play a role in termination. LAFA-onset seizures rapidly propagate to the thalamus. SIGNIFICANCE: Characterizing nucleus-specific ictal dynamics of neural activities facilitates precise therapy for epilepsy treatment with closed-loop deep brain stimulation.

Digital Eye Strain Epidemic amid COVID-19 Pandemic - A Cross-sectional Survey.

Purpose: There has been an enormous increase in the use of gadgets for online classes and entertainment during the COVID-19 pandemic. This study aimed to estimate the prevalence of digital eye strain (DES), describe the pattern of gadget usage, and analyse the risk factors for DES.Methods: This online survey analysed 941 responses from students of online classes (688), teachers of online classes (45), and general population (208). A pre-validated questionnaire was used to calculate the DES score. Non-parametric tests of medians were used to compare the median DES score, Chi-square test to compare categorical variables, and binary logistic regression to find the predictors of DES.Results: The prevalence of eye strain was higher among students taking online classes compared to the general public (50.6% vs 33.2%; χ2 = 22.5, df = 1, p < .0001). There was an increase in screen time during the pandemic compared to pre-pandemic time. The DES score was highest among students attending online classes (p < .0001), in those with eye diseases (p = .001), greater screen time (p = <0.0001), screen distance <20 cm (p = .002), those who used gadgets in dark (p = .017) and those who took infrequent/no breaks (p = .018). The DES scores were proportional to the increase in the number of hours of gadget usage during the pandemic.Conclusion: There is a need to educate people about limiting overall screen exposure and ergonomic methods of screen viewing. Efforts from policymakers to reduce the duration of online classes for students and online work hours for professionals are warranted to control this epidemic of eye strain.

Direct Cortical Stimulation to Probe the Ictogenicity of the Epileptogenic Nodes in Temporal Lobe Epilepsy.

Accurate mapping of the seizure onset zone (SOZ) is critical to the success of epilepsy surgery outcomes. Epileptogenicity index (EI) is a statistical method that delineates hyperexcitable brain regions involved in the generation and early propagation of seizures. However, EI can overestimate the SOZ for particular electrographic seizure onset patterns. Therefore, using direct cortical stimulation (DCS) as a probing tool to identify seizure generators, we systematically evaluated the causality of the high EI nodes (>0.3) in replicating the patient's habitual seizures. Specifically, we assessed the diagnostic yield of high EI nodes, i.e., the proportion of high EI nodes that evoked habitual seizures. A retrospective single-center study that included post-stereo encephalography (SEEG) confirmed TLE patients (n = 37) that had all high EI nodes stimulated, intending to induce a seizure. We evaluated the nodal responses (true and false responder rate) to stimulation and correlated with electrographic seizure onset patterns (hypersynchronous-HYP and low amplitude fast activity patterns-LAFA) and clinically defined SOZ. The ictogenicity (i.e., the propensity to induce the patient's habitual seizure) of a high EI node was only 44.5%. The LAFA onset pattern had a significantly higher response rate to DCS (i.e., higher evoked seizures). The concordance of an evoked habitual seizure with a clinically defined SOZ with good outcomes was over 50% (p = 0.0025). These results support targeted mapping of SOZ in LAFA onset patterns by performing DCS in high EI nodes to distinguish seizure generators (true responders) from hyperexcitable nodes that may be involved in early propagation.

Machine learning approach to detect focal-onset seizures in the human anterior nucleus of the thalamus.

Objective.There is an unmet need to develop seizure detection algorithms from brain regions outside the epileptogenic cortex. The study aimed to demonstrate the feasibility of classifying seizures and interictal states from local field potentials (LFPs) recorded from the human thalamus-a subcortical region remote to the epileptogenic cortex. We tested the hypothesis that spectral and entropy-based features extracted from LFPs recorded from the anterior nucleus of the thalamus (ANT) can distinguish its state of ictal recruitment from other interictal states (including awake, sleep).Approach. Two supervised machine learning tools (random forest and the random kitchen sink) were used to evaluate the performance of spectral (discrete wavelet transform-DWT), and time-domain (multiscale entropy-MSE) features in classifying seizures from interictal states in patients undergoing stereo-electroencephalography (EEG) evaluation for epilepsy surgery. Under the supervision of IRB, field potentials were recorded from the ANT in consenting adults with drug-resistant temporal lobe epilepsy. Seizures were confirmed in the ANT using line-length and visual inspection. Wilcoxon rank-sum method was used to test the differences in spectral patterns between seizure and interictal (awake and sleep) states.Main results.79 seizures (10 patients) and 158 segments (approx. 4 h) of interictal stereo-EEG data were analyzed. The mean seizure detection latencies with line length in the ANT varied between seizure types (range 5-34 s). However, the DWT and MSE in the ANT showed significant changes for all seizure types within the first 20 s after seizure onset. The random forest (accuracy 93.9% and false-positive 4.6%) and the random kitchen sink (accuracy 97.3% and false-positive 1.8%) classified seizures and interictal states.Significance.These results suggest that features extracted from the thalamic LFPs can be trained to detect seizures that can be used for monitoring seizure counts and for closed-loop seizure abortive interventions.

Preparedness of the cancer hospitals and changes in oncosurgical practices during COVID-19 pandemic in India: A cross-sectional study.

BACKGROUND AND OBJECTIVES: Coronavirus disease-2019 (COVID-19) pandemic has impacted cancer care across India. This study aimed to assess (a) organizational preparedness of hospitals (establishment of screening clinics, COVID-19 wards/committees/intensive care units [ICUs]/operating rooms [ORs]), (b) type of major/minor surgeries performed, and (c) employee well-being (determined by salary deductions, paid leave provisions, and work in-rotation). METHODS: This online questionnaire-based cross-sectional study was distributed to 480 oncosurgeons across India. We used χ2 statistics to compare responses across geographical areas (COVID-19 lockdown zones and city tiers) and type of organization (government/private, academic/nonacademic, and dedicated/multispecialty hospitals). P < .05 was considered significant. RESULTS: Total of 256 (53.3%) oncologists completed the survey. About 206 hospitals in 85 cities had screening clinics (98.1%), COVID-19 dedicated committees (73.7%), ward (67.3%), ICU's (49%), and OR's (36%). Such preparedness was higher in tier-1 cities, government, academic, and multispecialty hospitals. Dedicated cancer institutes continued major surgeries in all oncological subspecialties particularly in head and neck (P = .006) and colorectal oncology (P = .04). Employee well-being was better in government hospitals. CONCLUSION: Hospitals have implemented strategies to continue cancer care. Despite limited resources, the significant risk associated and financial setbacks amidst nationwide lockdown, oncosurgeons are striving to prioritize and balance the oncologic needs and safety concerns of cancer patients across the country.

Precision mapping of the epileptogenic network with low- and high-frequency stimulation of anterior nucleus of thalamus.

OBJECTIVE: The goal of thalamic deep brain stimulation in epilepsy is to engage and modulate the epileptogenic network. We demonstrate how the anterior nucleus of thalamus (ANT) stimulation engages the epileptogenic network using electrophysiological measures (gamma response and post-stimulation excitability). METHODS: Five patients with suspected temporal lobe epilepsy syndrome, undergoing stereo-electroencephalography (SEEG), were enrolled in the IRB approved study to undergo recording and stimulation of the ANT. We analyzed the extent of gamma-band response (activation or suppression) and post-stimulation change in excitability in various cortical regions during low (10 Hz) and high (50 Hz) frequency stimulations. RESULTS: 10 Hz stimulation increased cortical gamma, whereas 50 Hz stimulation suppressed the gamma responses. The maximum response to stimuli was in the hippocampus. High epileptogenicity regions were more susceptible to stimulation. Both 10-and 50 Hz stimulations decreased post-stimulation cortical excitability. The greater the gamma-band activation with 10 Hz stimulation, the greater was the decrease in post-stimulation excitability. CONCLUSIONS: We define an EEG marker that delineates stimulation-specific nodal engagement. We proved that nodes that were engaged with the thalamus during stimulation were more likely to show a short term decrease in post-stimulation excitability. SIGNIFICANCE: Patient-specific engagement patterns during stimulation can be mapped with SEEG that can be used to optimize stimulation parameters.

Acute modulation of the limbic network with low and high-frequency stimulation of the human fornix.

Targeted stimulation of white matter has opened newer perspectives in the field of neuromodulation, towards an attempt to improve memory or as a therapy for epilepsy. Stimulation of the fornix, being a part of the Papez circuit, is likely to modulate the limbic network excitability. However, the stimulation-frequency dependent variability in network excitability is unknown. In the case study, which involved stereo electroencephalographic (SEEG) recording of field potentials in a 48-year old left-handed woman with suspected temporal lobe epilepsy, we demonstrated the network effects of acute low (1 and 10 Hz) and high (50 Hz) frequency electrical stimulation of fornix. Mapping the short-latency evoked responses to forniceal stimulation confirmed the SEEG target localization within the Papez circuit. Low and high-frequency stimulation of the fornix produced opposite effects in the post-stimuli excitability, with the latter causing increased excitability in the limbic network that culminated in a clinical seizure. A distinct spectral peak around 8 Hz confirmed that sensing field potentials from the forniceal white matter is feasible. This is the first case study that provided an insight into how the temporal patterning of forniceal stimulation altered the downstream limbic network excitability.

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

OBJECTIVE: Despite 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). METHODS: After 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. RESULTS: Ten (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. CONCLUSIONS: Using 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.