Ictal Central Apnea Is Predictive of Mesial Temporal Seizure Onset: An Intracranial Investigation.

OBJECTIVE: Ictal central apnea (ICA) is a semiological sign of focal epilepsy, associated with temporal and frontal lobe seizures. In this study, using qualitative and quantitative approaches, we aimed to assess the localizational value of ICA. We also aimed to compare ICA clinical utility in relation to other seizure semiological features of focal epilepsy. METHODS: We analyzed seizures in patients with medically refractory focal epilepsy undergoing intracranial stereotactic electroencephalographic (SEEG) evaluations with simultaneous multimodal cardiorespiratory monitoring. A total of 179 seizures in 72 patients with reliable artifact-free respiratory signal were analyzed. RESULTS: ICA was seen in 55 of 179 (30.7%) seizures. Presence of ICA predicted a mesial temporal seizure onset compared to those without ICA (odds ratio = 3.8, 95% confidence interval = 1.3-11.6, p = 0.01). ICA specificity was 0.82. ICA onset was correlated with increased high-frequency broadband gamma (60-150Hz) activity in specific mesial or basal temporal regions, including amygdala, hippocampus, and fusiform and lingual gyri. Based on our results, ICA has an almost 4-fold greater association with mesial temporal seizure onset zones compared to those without ICA and is highly specific for mesial temporal seizure onset zones. As evidence of symptomatogenic areas, onset-synchronous increase in high gamma activity in mesial or basal temporal structures was seen in early onset ICA, likely representing anatomical substrates for ICA generation. INTERPRETATION: ICA recognition may help anatomoelectroclinical localization of clinical seizure onset to specific mesial and basal temporal brain regions, and the inclusion of these regions in SEEG evaluations may help accurately pinpoint seizure onset zones for resection. ANN NEUROL 2024;95:998-1008.

Intracranial stimulation and EEG feature analysis reveal affective salience network specialization.

Emotion is represented in limbic and prefrontal brain areas, herein termed the affective salience network (ASN). Within the ASN, there are substantial unknowns about how valence and emotional intensity are processed-specifically, which nodes are associated with affective bias (a phenomenon in which participants interpret emotions in a manner consistent with their own mood). A recently developed feature detection approach ('specparam') was used to select dominant spectral features from human intracranial electrophysiological data, revealing affective specialization within specific nodes of the ASN. Spectral analysis of dominant features at the channel level suggests that dorsal anterior cingulate (dACC), anterior insula and ventral-medial prefrontal cortex (vmPFC) are sensitive to valence and intensity, while the amygdala is primarily sensitive to intensity. Akaike information criterion model comparisons corroborated the spectral analysis findings, suggesting all four nodes are more sensitive to intensity compared to valence. The data also revealed that activity in dACC and vmPFC were predictive of the extent of affective bias in the ratings of facial expressions-a proxy measure of instantaneous mood. To examine causality of the dACC in affective experience, 130 Hz continuous stimulation was applied to dACC while patients viewed and rated emotional faces. Faces were rated significantly happier during stimulation, even after accounting for differences in baseline ratings. Together the data suggest a causal role for dACC during the processing of external affective stimuli.

Epilepsy monitoring unit practices and safety among NAEC epilepsy centers: A census survey.

OBJECTIVE: An epilepsy monitoring unit (EMU) is a specialized unit designed for capturing and characterizing seizures and other paroxysmal events with continuous video electroencephalography (vEEG). Nearly 260 epilepsy centers in the United States are accredited by the National Association of Epilepsy Centers (NAEC) based on adherence to specific clinical standards to improve epilepsy care, safety, and quality. This study examines EMU staffing, safety practices, and reported outcomes. METHOD: We analyzed NAEC annual report data and results from a supplemental survey specific to EMU practices reported in 2019 from 341 pediatric or adult center directors. Data on staffing, resources, safety practices and complications were collated with epilepsy center characteristics. We summarized using frequency (percentage) for categorical variables and median (inter-quartile range) for continuous variables. We used chi-square or Fisher's exact tests to compare staff responsibilities. RESULTS: The supplemental survey response rate was 100%. Spell classification (39%) and phase 1 testing (28%) were the most common goals of the 91,069 reported admissions. The goal ratio of EEG technologist to beds of 1:4 was the most common during the day (68%) and off-hours (43%). Compared to residents and fellows, advanced practice providers served more roles in the EMU at level 3 or pediatric-only centers. Status epilepticus (SE) was the most common reported complication (1.6% of admissions), while cardiac arrest occurred in 0.1% of admissions. SIGNIFICANCE: EMU staffing and safety practices vary across US epilepsy centers. Reported complications in EMUs are rare but could be further reduced, such as with more effective treatment or prevention of SE. These findings have potential implications for improving EMU safety and quality care.

Actigraphic correlates of neuropsychiatric symptoms in adults with focal epilepsy.

OBJECTIVES: Disability in patients with epilepsy (PWEs) is multifactorial: beyond seizure frequency/severity, PWEs are prone to a range of neuropsychiatric, cognitive, and somatic comorbidities that significantly affect quality of life. Here, we explored how variations in seizure severity and the burden of self-reported somatic/neuropsychiatric symptoms correlate with disruptions to 24 h activity patterns (rest-activity rhythms [RARs]), determined through wrist accelerometry/actigraphy. METHODS: Multiday wrist-actigraphy recordings were obtained from 59 adult patients with focal epilepsy (44% male, ages 18-72), who contemporaneously responded to validated psychometric instruments to measure anxiety, depression, sleepiness, and somatic symptoms. We conducted a similar in silico psychometric-actigraphic correlation in a publicly available data set of 1747 Hispanic subjects (35% male, ages 18-65) from the Study of Latinos (SOL) Sueño Ancillary Study. RARs were analyzed via a sigmoidally-transformed cosine model (quantifying amplitude, steepness, acrophase, and robustness) and nonparametric measures to estimate RAR stability, fragmentation, and sleep. RESULTS: Compared with matched SOL subjects, RARs from PWE subjects featured a significantly lower amplitude, a wider rest phase, and significantly more total daily sleep. Within PWEs, similar RAR distortions were associated with seizure intractability and/or anticonvulsant polytherapy, whereas high anxiety, depression, and somatic symptom scores were associated with lower RAR robustness and acrophase delay. We applied the SOL data set to train logistic regression models to dichotomously classify subjective anxiety, depression, and sleepiness symptoms using demographic and RAR parameters. When tested on PWEs, these models predicted prevalent anxiety and depression symptom burden (accuracy ~70%) but failed to predict subjective sleepiness. SIGNIFICANCE: Together these results demonstrate that RAR features may encode prevalent depression and anxiety symptoms in patients with focal epilepsy, potentially offering wearable-derived endpoints to adjunct clinical care and drug/device trials. With larger PWE-specific actigraphic-psychometric data sets, we may identify RAR signatures that may more precisely correlate with varying seizure frequency, the burden of anticonvulsant therapy, and prevalent mood/anxiety symptoms.

Epilepsy center characteristics and geographic region influence presurgical testing in the United States.

OBJECTIVE: Persons with drug-resistant epilepsy may benefit from epilepsy surgery and should undergo presurgical testing to determine potential candidacy and appropriate intervention. Institutional expertise can influence use and availability of evaluations and epilepsy surgery candidacy. This census survey study aims to examine the influence of geographic region and other center characteristics on presurgical testing for medically intractable epilepsy. METHODS: We analyzed annual report and supplemental survey data reported in 2020 from 206 adult epilepsy center directors and 136 pediatric epilepsy center directors in the United States. Test utilization data were compiled with annual center volumes, available resources, and US Census regional data. We used Wilcoxon rank-sum, Kruskal-Wallis, and chi-squared tests for univariate analysis of procedure utilization. Multivariable modeling was also performed to assign odds ratios (ORs) of significant variables. RESULTS: The response rate was 100% with individual element missingness < 11% across 342 observations undergoing univariate analysis. A total of 278 complete observations were included in the multivariable models, and significant regional differences were present. For instance, compared to centers in the South, those in the Midwest used neuropsychological testing (OR = 2.87, 95% confidence interval [CI] = 1.2-6.86; p = .018) and fluorodeoxyglucose-positron emission tomography (OR = 2.74, 95% CI = = 1.14-6.61; p = .025) more commonly. For centers in the Northeast (OR = .46, 95% CI = .23-.93; p = .031) and West (OR = .41, 95% CI = .19-.87; p = .022), odds of performing single-photon emission computerized tomography were lower by nearly 50% compared to those in the South. Center accreditation level, demographics, volume, and resources were also associated with varying individual testing rates. SIGNIFICANCE: Presurgical testing for drug-resistant epilepsy is influenced by US geographic region and other center characteristics. These findings have potential implications for comparing outcomes between US epilepsy centers and may inject disparities in access to surgical treatment.

Associations between testing and treatment pathways in lesional temporal or extratemporal epilepsy: A census survey of NAEC center directors.

OBJECTIVE: The evaluation to determine candidacy and treatment for epilepsy surgery in persons with drug-resistant epilepsy (DRE) is not uniform. Many non-invasive and invasive tests are available to ascertain an appropriate treatment strategy. This study examines expert response to clinical vignettes of magnetic resonance imaging (MRI)-positive lesional focal cortical dysplasia in both temporal and extratemporal epilepsy to identify associations in evaluations and treatment choice. METHODS: We analyzed annual report data and a supplemental epilepsy practice survey reported in 2020 from 206 adult and 136 pediatric epilepsy center directors in the United States. Non-invasive and invasive testing and surgical treatment strategies were compiled for the two scenarios. We used chi-square tests to compare testing utilization between the two scenarios. Multivariable logistic regression modeling was performed to assess associations between variables. RESULTS: The supplemental survey response rate was 100% with 342 responses included in the analyses. Differing testing and treatment approaches were noted between the temporal and extratemporal scenarios such as chronic invasive monitoring selected in 60% of the temporal scenario versus 93% of the extratemporal scenario. Open resection was the most common treatment choice; however, overall treatment choices varied significantly (p < .001). Associations between non-invasive testing, invasive testing, and treatment choices were present in both scenarios. For example, in the temporal scenario stereo-electroencephalography (SEEG) was more commonly associated with fluorodeoxyglucose-positron emission tomography (FDG-PET) (odds ratio [OR] 1.85; 95% confidence interval [CI] 1.06-3.29; p = .033), magnetoencephalography (MEG) (OR 2.90; 95% CI 1.60-5.28; p = <.001), high density (HD) EEG (OR 2.80; 95% CI 1.27-6.24; p = .011), functional MRI (fMRI) (OR 2.17; 95% CI 1.19-4.10; p = .014), and Wada (OR 2.16; 95% CI 1.28-3.66; p = .004). In the extratemporal scenario, choosing SEEG was associated with increased odds of neuromodulation over open resection (OR 3.13; 95% CI 1.24-7.89; p = .016). SIGNIFICANCE: In clinical vignettes of temporal and extratemporal lesional DRE, epilepsy center directors displayed varying patterns of non-invasive testing, invasive testing, and treatment choices. Differences in practice underscore the need for comparative trials for the surgical management of DRE.

Home video prediction of epileptic vs. nonepileptic seizures in US veterans.

OBJECTIVE: Using video-EEG (v-EEG) diagnosis as a gold standard, we assessed the predictive diagnostic value of home videos of spells with or without additional limited demographic data in US veterans referred for evaluation of epilepsy. Veterans, in particular, stand to benefit from improved diagnostic tools given higher rates of PNES and limited accessibility to care. METHODS: This was a prospective, blinded diagnostic accuracy study in adults conducted at the Houston VA Medical Center from 12/2015-06/2019. Patients with a definitive diagnosis of epileptic seizures (ES), psychogenic nonepileptic seizures (PNES), or physiologic nonepileptic events (PhysNEE) from v-EEG monitoring were asked to submit home videos. Four board-certified epileptologists blinded to the original diagnosis formulated a diagnostic impression based upon the home video review alone and video plus limited demographic data. RESULTS: Fifty patients (30 males; mean age 47.7 years) submitted home videos. Of these, 14 had ES, 33 had PNES, and three had PhysNEE diagnosed by v-EEG. The diagnostic accuracy by video alone was 88.0%, with a sensitivity of 83.9% and specificity of 89.6%. Providing raters with basic patient demographic information in addition to the home videos did not significantly improve diagnostic accuracy when comparing to reviewing the videos alone. Inter-rater agreement between four raters based on video was moderate with both videos alone (kappa = 0.59) and video plus limited demographic data (kappa = 0.60). SIGNIFICANCE: This study demonstrated that home videos of paroxysmal events could be an important tool in reliably diagnosing ES vs. PNES in veterans referred for evaluation of epilepsy when interpreted by experts. A moderate inter-rater reliability was observed in this study.

Prospective validation study of an epilepsy seizure risk system for outpatient evaluation.

OBJECTIVE: We conducted clinical testing of an automated Bayesian machine learning algorithm (Epilepsy Seizure Assessment Tool [EpiSAT]) for outpatient seizure risk assessment using seizure counting data, and validated performance against specialized epilepsy clinician experts. METHODS: We conducted a prospective longitudinal study of EpiSAT performance against 24 specialized clinician experts at three tertiary referral epilepsy centers in the United States. Accuracy, interrater reliability, and intra-rater reliability of EpiSAT for correctly identifying changes in seizure risk (improvements, worsening, or no change) were evaluated using 120 seizures from four synthetic seizure diaries (seizure risk known) and 120 seizures from four real seizure diaries (seizure risk unknown). The proportion of observed agreement between EpiSAT and clinicians was evaluated to assess compatibility of EpiSAT with clinical decision patterns by epilepsy experts. RESULTS: EpiSAT exhibited substantial observed agreement (75.4%) with clinicians for assessing seizure risk. The mean accuracy of epilepsy providers for correctly assessing seizure risk was 74.7%. EpiSAT accurately identified seizure risk in 87.5% of seizure diary entries, corresponding to a significant improvement of 17.4% (P = .002). Clinicians exhibited low-to-moderate interrater reliability for seizure risk assessment (Krippendorff's α = 0.46) with good intrarater reliability across a 4- to 12-week evaluation period (Scott's π = 0.89). SIGNIFICANCE: These results validate the ability of EpiSAT to yield objective clinical recommendations on seizure risk which follow decision patterns similar to those from specialized epilepsy providers, but with improved accuracy and reproducibility. This algorithm may serve as a useful clinical decision support system for quantitative analysis of clinical seizure frequency in clinical epilepsy practice.

A somatic mutation in MEN1 gene detected in periventricular nodular heterotopia tissue obtained from depth electrodes.

Periventricular nodular heterotopia (PNH) is a common structural malformation of cortical development. Mutations in the filamin A gene are frequent in familial cases with X-linked PNH. However, many cases with sporadic PNH remain genetically unexplained. Although medically refractory epilepsy often brings attention to the underlying PNH, patients are often not candidates for surgical resection. This limits access to neuronal tissue harboring causal mutations. We evaluated a patient with PNH and medically refractory focal epilepsy who underwent a presurgical evaluation with stereotactically placed electroencephalographic (SEEG) depth electrodes. Following SEEG explantation, we collected trace tissue adherent to the electrodes and extracted the DNA. Whole-exome sequencing performed in a Clinical Laboratory Improvement Amendments-approved genetic diagnostic laboratory uncovered a de novo heterozygous pathogenic variant in novel candidate PNH gene MEN1 (multiple endocrine neoplasia type 1; c.1546dupC, p.R516PfsX15). The variant was absent in an earlier exome profiling of the venous blood-derived DNA. The MEN1 gene encodes the ubiquitously expressed, nuclear scaffold protein menin, a known tumor suppressor gene with an established role in the regulation of transcription, proliferation, differentiation, and genomic integrity. Our study contributes a novel candidate gene in PNH generation and a novel practical approach that integrates electrophysiological and genetic explorations of epilepsy.

Counseling by epileptologists affects contraceptive choices of women with epilepsy.

INTRODUCTION: There are several important interactions between antiepileptic drugs (AEDs) and hormonal contraception that need to be carefully considered by women with epilepsy (WWE) and their practitioners. Many AEDs induce hepatic enzymes and decrease the efficacy of hormonal contraception. In addition, estrogen-containing hormonal contraception can increase the metabolism of lamotrigine, the most commonly prescribed AED in women of childbearing age. The intrauterine device (IUD) is a highly effective form of reversible contraception without AED drug interactions that is considered by many to be the contraceptive of choice for WWE. Women with epilepsy not planning pregnancy require effective contraceptive counseling that should include discussion of an IUD. There are no guidelines, however, on who should deliver these recommendations. The objective of this study was to explore the hypothesis that contraceptive counseling by a neurologist can influence the contraceptive choices of WWE. In particular, we explored the relationship between contraceptive counseling in the epilepsy clinic and the likelihood that patients would obtain an IUD. METHODS: We conducted a retrospective chart review of female patients age 18-45 seen at our institution for an initial visit between 2010 and 2014 to ascertain the type of contraceptive counseling each patient received as well as AED use and contraceptive methods. Patients who were pregnant or planning pregnancy at the first visit were excluded from further analyses as were patients with surgical sterilization. We also examined a subgroup of 95 patients with at least 4 follow-up visits to evaluate the efficacy of epileptologists' counseling. Specifically, we looked at the likelihood a patient obtained an IUD based on the type of counseling she had received. Fisher exact tests assessed associations between counseling type and whether patients had obtained an IUD. RESULTS: Three hundred and ninety-seven women met criteria for inclusion. Only 35% of female patients were counseled about contraception at the first visit. If women were not counseled at the first visit, they were unlikely to be counseled at subsequent visits; only 37% had ever received counseling by their fourth visit. Of the 95 patients who completed 4 visits, 28.4% were counseled about an IUD as an optimal contraceptive choice, 38.9% were generally counseled about contraceptive interactions, and 32.6% were not counseled about contraception. Women with epilepsy who received IUD-specific counseling were significantly more likely to switch to an IUD (44.4%) compared with women who received no contraceptive counseling (6.5%; p=0.0009). Women with epilepsy who received IUD-specific counseling also tended to switch to an IUD more often than those women receiving general counseling about AEDs and contraceptive interactions (18.9%; p=0.027). There was no significant difference in the likelihood of acquiring an IUD between the general counseling and no counseling groups. CONCLUSIONS: Contraceptive counseling by epileptologists and specific mention of an IUD is significantly associated with patient selection of an IUD as a contraceptive method. This suggests that neurologists can play an important role in patients' contraceptive choices.

New-Onset Seizure in Adults and Adolescents: A Review.

Importance: Approximately 8% to 10% of the population will experience a seizure during their lifetime. Only about 2% to 3% of patients go on to develop epilepsy. Understanding the underlying etiology leading to an accurate diagnosis is necessary to ensure appropriate treatment and that patients with low risk for recurrence are not treated unnecessarily. Observations: Patients can present with new-onset seizure for a variety of reasons such as acute symptomatic seizures due to acute brain injury or metabolic derangements, or unprovoked seizures that are the initial manifestation of epilepsy. A patient history and physical examination may identify features more consistent with an epileptic event and laboratory studies and brain imaging can identify an acute insult contributing to the presentation. Patients diagnosed with first-time unprovoked seizure require electroencephalography and epilepsy protocol-specific magnetic resonance imaging of the brain, which includes thin-cut coronal slices to determine risk of recurrence and the need for long-term treatment. In patients who meet the criteria for diagnosis of epilepsy, a carefully selected antiepileptic medication with consideration of comorbidities, adverse effect profile, and type of epilepsy is essential along with appropriate counseling. Conclusions and Relevance: Approximately 3% of the population will develop epilepsy but 2 to 3 times as many patients will experience a single seizure or seizure-like event. A diagnosis of epilepsy has significant medical, social, and emotional consequences. A careful patient history and physical examination, electroencephalography, and brain imaging are necessary to separate patients with acute symptomatic seizures, single unprovoked seizures, and nonepileptic events from those with new-onset epilepsy.

Continuous EEG monitoring: a survey of neurophysiologists and neurointensivists.

OBJECTIVE: Continuous EEG monitoring (cEEG) of critically ill adults is being used with increasing frequency, and practice guidelines on indications for cEEG monitoring have recently been published. However, data describing the current practice of cEEG in critically ill adults is limited. We aimed to describe the current practice of cEEG monitoring in adults in the United States. METHODS: A survey assessing cEEG indications and procedures was sent to one intensivist and one neurophysiologist responsible for intensive care unit (ICU) cEEG at 151 institutions in the United States. At some institutions only one physician could be identified. RESULTS: One hundred thirty-seven physicians from 97 institutions completed the survey. Continuous EEG is utilized by nearly all respondents to detect nonconvulsive seizures (NCS) in patients with altered mental status following clinical seizures, intra cerebral hemorrhage (ICH), traumatic brain injury, and cardiac arrest, as well as to characterize abnormal movements suspected to be seizures. The majority of physicians monitor comatose patients for 24-48 h. In an ideal situation with unlimited resources, 18% of respondents would increase cEEG duration. Eighty-six percent of institutions have an on-call EEG technologist available 24/7 for new patient hookups, but only 26% have technologists available 24/7 in-house. There is substantial variability in who reviews EEG and how frequently it is reviewed as well as use of quantitative EEG. SIGNIFICANCE: Although there is general agreement regarding the indications for ICU cEEG, there is substantial interinstitutional variability in how the procedure is performed.

The United States Stereotactic EEG Survey: Current Practice and Future Opportunities.

PURPOSE: Stereotactic EEG (SEEG) is being increasingly used in the intracranial evaluation of refractory epilepsy in the United States. A 2022 survey of SEEG practices among National Association of Epilepsy Centers tertiary referral (NAEC level IV) centers found largely similar practices across institutions. However, a few significant differences were noted in technical and patient care practice, and in the level of SEEG background training. In the year since publication, we review the identified challenges facing SEEG practice and suggest specific corrective action. CONCLUSIONS: Stereotactic EEG has rapidly become the principal method for intracranial EEG monitoring in epilepsy surgery centers in the United States. The rate of adoption of SEEG is currently higher than the growth of invasive monitoring overall. Most report similar indications for SEEG, although significant variability exists in personnel expertise and technical and patient care practice. Consensus statements, guidelines, and review of postgraduate training curricula are urgently needed to benchmark SEEG practice and develop appropriate skillsets in the next generation of practitioners in the United States.

Characterizing Seizure-Onset Patterns With the Responsive Neurostimulation System.

PURPOSE: The responsive neurostimulation system (RNS) aims to improve seizures by delivering electrical stimulation in response to epileptiform patterns detected by electrocorticograms. Seizure-onset patterns (SOPs) correspond to outcomes in intracranial EEG (IC-EEG), although whether this is true for RNS is unknown. This study characterizes common RNS SOPs and correlates them with seizure outcomes. METHODS: Among 40 patients with RNS implants, long-episode electrocorticogram characteristics of each patient's seizures were classified by visual analysis as one of the eight patterns previously described in IC-EEG. Correlation between each type of SOP and eventual seizure outcome was analyzed, with ≥50% improvement in a number of patient-reported seizure counts defined as a favorable outcome. RESULTS: Across 263 LEs analyzed, the most common SOP observed was low-voltage fast activity. There was no difference between the distribution of RNS SOPs and that of IC-EEG SOPs described in the literature (Kolmogorov-Smirnov test, P = 0.98). Additionally, there was no correlation between any particular SOP and favorable outcomes (Fisher's omnibus test, P = 0.997). CONCLUSION: This initial description of RNS SOPs finds them to be similar to previously described IC-EEG SOPs, which suggests similar prognostic/therapeutic potential. However, we found that RNS efficacy is independent of patient SOP, suggesting that RNS is likely an equally effective treatment for all SOPs. Future research on stimulation parameters for particular RNS SOPs and correlation with IC-EEG SOPs in the same patients would be instrumental in guiding personalized neurostimulation.

Stereoelectroencephalography of the Deep Brain: Basal Ganglia and Thalami.

SUMMARY: Stereoelectroencephalography (SEEG) has emerged as a transformative tool in epilepsy surgery, shedding light on the complex network dynamics involved in focal epilepsy. This review explores the role of SEEG in elucidating the role of deep brain structures, namely the basal ganglia and thalamus, in epilepsy. SEEG advances understanding of their contribution to seizure generation, propagation, and control by permitting precise and minimally invasive sampling of these brain regions. The basal ganglia, comprising the subthalamic nucleus, globus pallidus, substantia nigra, and striatum, have gained recognition for their involvement in both focal and generalized epilepsy. Electrophysiological recordings reveal hyperexcitability and increased synchrony within these structures, reinforcing their role as critical nodes within the epileptic network. Furthermore, low-frequency and high-frequency stimulation of the basal ganglia have demonstrated potential in modulating epileptogenic networks. Concurrently, the thalamus, a key relay center, has garnered prominence in epilepsy research. Disrupted thalamocortical connectivity in focal epilepsy underscores its significance in seizure maintenance. The thalamic subnuclei, including the anterior nucleus, centromedian, and medial pulvinar, present promising neuromodulatory targets, suggesting pathways for personalized epilepsy therapies. The prospect of multithalamic SEEG and thalamic SEEG stimulation trials has the potential to revolutionize epilepsy management, offering tailored solutions for challenging cases. SEEG's ability to unveil the dynamics of deep brain structures in epilepsy promises enhanced and personalized epilepsy care in our new era of precision medicine. Until deep brain SEEG is accepted as a standard of care, a rigorous informed consent process remains paramount for patients for whom such an exploration is proposed.

High-Frequency Stimulation of the Centromedian Thalamic Nucleus Aborts Seizures and Ictal Apnea.

SUMMARY: A 32-year-old right-handed woman presented with medically and surgically refractory left temporal neocortical epilepsy secondary to focal cortical dysplasia who underwent stereoelectroencephalography involving the centromedian nucleus of the thalamus. With the use of real-time stereoelectroencephalography monitoring, four electroclinical seizures were aborted by administering high-frequency stimulation at the centromedian nucleus at seizure onset. Seizures before stimulation were all associated with ictal apnea, while those with stimulation had no ictal apnea. This case demonstrates how providing high-frequency stimulation to the centromedian nucleus of the thalamus can abort electroclinical seizures and ictal apnea.

Benchmarking signal quality and spatiotemporal distribution of interictal spikes in prolonged human iEEG recordings using CorTec wireless brain interchange.

Neuromodulation through implantable pulse generators (IPGs) represents an important treatment approach for neurological disorders. While the field has observed the success of state-of-the-art interventions, such as deep brain stimulation (DBS) or responsive neurostimulation (RNS), implantable systems face various technical challenges, including the restriction of recording from a limited number of brain sites, power management, and limited external access to the assessed neural data in a continuous fashion. To the best of our knowledge, for the first time in this study, we investigated the feasibility of recording human intracranial EEG (iEEG) using a benchtop version of the Brain Interchange (BIC) unit of CorTec, which is a portable, wireless, and externally powered implant with sensing and stimulation capabilities. We developed a MATLAB/SIMULINK-based rapid prototyping environment and a graphical user interface (GUI) to acquire and visualize the iEEG captured from all 32 channels of the BIC unit. We recorded prolonged iEEG (~ 24 h) from three human subjects with externalized depth leads using the BIC and commercially available clinical amplifiers simultaneously in the epilepsy monitoring unit (EMU). The iEEG signal quality of both streams was compared, and the results demonstrated a comparable power spectral density (PSD) in all the systems in the low-frequency band (< 80 Hz). However, notable differences were primarily observed above 100 Hz, where the clinical amplifiers were associated with lower noise floor (BIC-17 dB vs. clinical amplifiers < - 25 dB). We employed an established spike detector to assess and compare the spike rates in each iEEG stream. We observed over 90% conformity between the spikes rates and their spatial distribution captured with BIC and clinical systems. Additionally, we quantified the packet loss characteristic in the iEEG signal during the wireless data transfer and conducted a series of simulations to compare the performance of different interpolation methods for recovering the missing packets in signals at different frequency bands. We noted that simple linear interpolation has the potential to recover the signal and reduce the noise floor with modest packet loss levels reaching up to 10%. Overall, our results indicate that while tethered clinical amplifiers exhibited noticeably better noise floor above 80 Hz, epileptic spikes can still be detected successfully in the iEEG recorded with the externally powered wireless BIC unit opening the road for future closed-loop neuromodulation applications with continuous access to brain activity.

Survey of Clinical Neurophysiology and Epilepsy Fellowship Programs in the United States During COVID-19.

PURPOSE: The COVID-19 pandemic impacted clinical practice, education, and research in Neurophysiology/Epilepsy. Although there is published literature on clinical impact, its educational impact is not well described. A national survey of Clinical Neurophysiology (CNP) and Epilepsy fellowship programs was conducted to assess the impact of COVID-19 on fellowship education. METHODS: A list of accredited Clinical Neurophysiology and Epilepsy fellowship programs was obtained from the Accreditation Council for Graduate Medical Education. Program directors at individual locations were contacted to complete a brief survey about the program and impact of COVID-19. Fellows from responding programs were subsequently invited to share their perceptions about the impact of the pandemic on their training. RESULTS: From 176 programs, 40 PDs responded (22.7%). From these 40 programs, fellows from 26 completed surveys (65.0% response). There was a reduction in EEG and epilepsy monitoring unit volumes post-COVID-19, with a trend of change for EMG, whereas continuous EEG volumes were mostly unchanged. The impact of the pandemic on training was rated as moderate to severe (≥50%) by 30.0% of PDs and 49.0% of trainees. In remarkable agreement, 20.0% of PDs and 20.4% of fellows believed that additional fellowship training was needed before graduation. Lack of fellow satisfaction was correlated with the perceived impact of the pandemic on education ( p = 0.008). CONCLUSIONS: This survey revealed a considerable impact on EEG/EMG clinical volume because of COVID-19, although continuous EEG was not as impacted. More fellows than PDs believed that training was considerably impacted by COVID-19, but a similar number thought that additional training was needed. It was unclear from this study whether the fellows' perception of educational impact was solely because of the pandemic or in addition to preexisting training deficiencies in the training programs.

High-Frequency Oscillations in Tumor-Related Epilepsy.

INTRODUCTION: To define the patient characteristics, tumor characteristics, and clinical course of patients with primary brain tumors with high-frequency oscillations (HFOs) recorded on electrocorticography. Furthermore, we evaluated whether the presence of HFOs portends a greater risk of postoperative tumor-related epilepsy and whether the resection of HFO-generating tissue reduces likelihood of postoperative tumor-related epilepsy. METHODS: This was a retrospective study of 35 patients undergoing awake craniotomy for tumor resection, all of whom underwent intraoperative electrocorticography. Electrocorticography data were reviewed to assess the presence of HFOs and determine their contact locations. The data were analyzed to determine whether HFO-generating tissue was included in the resection and relationship to postoperative seizure outcome. RESULTS: Seventeen patients (48.5%) were found to have HFOs. Very few patients (4 of 35, 11.4%) had sharp waves. Patients with and without HFOs did not significantly differ in demographics, presentation, tumor characteristics, or tumor molecular genetics. A history of seizures prior to resection was not associated with the presence of HFOs ( P = 0.62), although when patients had seizures during the same hospitalization as the resection, HFOs were more likely to be present ( P = 0.045). Extent of HFO resection was not associated with the likelihood of postoperative seizure freedom. CONCLUSIONS: Approximately half (48.5%) of patients undergoing resection for a primary brain tumor had HFOs. Although HFO resection was not shown to lead to improved seizure freedom, this study was limited by a small sample size, and further investigation into HFO resection and patient outcomes in this population is warranted.

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.