BACKGROUND The authors aimed to evaluate the feasibility/safety of stereo-electroencephalography (SEEG) and SEEG-guided radiofrequency thermocoagulation (RFTC) in patients with drug-resistant epilepsy previously implanted with neuromodulation devices, using a retrospective cohort design evaluating patients treated at the Mayo Clinic Florida Epilepsy Center. OBSERVATIONS Nine patients (mean age 36.3 ± 10.9 years, 33% female) with prior implantation of neuromodulation devices were included. A vagus nerve stimulator was present in 8 of 9 patients, and 4 patients had undergone previous intracranial neuromodulation. Five patients underwent SEEG-RFTC. The mean SEEG monitoring duration was 6.5 ± 2.9 days. No intraoperative or procedural complications occurred, including hardware-related issues. No permanent or significant neurological/cognitive deficits occurred. One patient experienced transient postoperative neurological symptoms attributed to perilesional edema. Seizure reduction ranged from 50% to 75% following SEEG-RFTC. LESSONS SEEG and SEEG-RFTC are feasible in patients who have implanted neuromodulation devices, including intracranial implants. These procedures may be performed without interference with existing hardware and provide meaningful seizure reduction in highly refractory populations. Further studies with larger cohorts and longer follow-up are needed to better define efficacy and patient selection. https://thejns.org/doi/10.3171/CASE26376

Statistical learning (SL) is a powerful mechanism that supports the ability to extract regularities from environmental input. Yet, its neural underpinnings are not well understood. Previous EEG studies of SL have found that the brain tracks regularities by synchronizing its activity with the presented stimuli—a phenomenon known as neural entrainment. However, EEG lacks the spatial resolution to unveil the specific brain regions where this process takes place. In our study, 18 patients with drug-resistant epilepsy who were implanted with intracranial electrodes for presurgical investigation listened to a continuous speech stream containing embedded trisyllabic words. Neural entrainment was measured at the syllable and word frequencies, with the latter providing an online index of learning. SL was further assessed through both explicit and implicit behavioral measures. Behaviorally, we found evidence of learning at the group level in both tasks. At the neural level, our analyses revealed three temporal tuning profiles: 25% of contacts showed entrainment at the syllable frequency, 11% of contacts showed entrainment at both the word and syllable frequencies, and 4% showed entrainment only to the word frequency. Word entrainment, indicating sensitivity to word structures, was most commonly found in auditory and language-related regions, including insula, middle temporal gyrus, superior temporal gyrus, and supramarginal gyrus. In contrast, evidence for neural entrainment in the hippocampus was weak. Overall, these results support the idea that speech-based SL is largely supported by modality-specific brain regions.

OBJECTIVE:This study investigates alterations in brain functional networks in patients with functional/dissociative seizures (FDS) using a novel functional connectivity framework, with the goal of showing network-level biomarkers that may differentiate FDS from healthy controls. METHODS:We conducted a 7-Tesla fMRI study involving 11 patients with FDS and 11 healthy controls (HC) gotten during both resting-state (rs) and a naturalistic-stimulus (ns) movie paradigm. Functional connectivity) was computed using parcel-wise Pearson correlations, and centrality measures, including eigenvector centrality, were derived to assess network influence. Group differences were evaluated using motion-controlled general linear models A sensitivity index found key ROIs, which were used in cross-validated logistic regression models. The classification model uses eigenvector centrality with 5-fold cross-validation. RESULTS:FDS patients showed consistent alterations in eigenvector centrality across both resting-state and naturalistic-stimulus fMRI, particularly within limbic, somatomotor, and ventral attention network. Three key ROIs during rest and fifteen during naturalistic stimulation yielded high classification accuracies (96% and 93%, respectively). Several hubs found in the movie condition remained altered at rest. Logistic regression models using these network features distinguished FDS from controls, though findings require cautious interpretation due to sample size limitations. CONCLUSIONS:Using high-field fMRI and a novel connectivity analysis, this study found abnormal network hubs across multiple systems in FDS. These findings support a predictive processing model and offer preliminary biomarkers to improve FDS differentiation, pending validation in larger cohorts.

Background and Objective: Epilepsy is a common neurological condition that significantly impacts quality of life, particularly in cases of drug-resistant epilepsy (DRE). Perampanel, a third-generation antiseizure medication (ASM), has shown promise as a treatment option. This case report describes the successful long-term management of a patient with DRE using perampanel after deferring epilepsy surgery. Materials and Methods: A 49-year-old woman with a history of multiple medical comorbidities, including morbid obesity, experienced drug-resistant focal to bilateral tonic clonic seizures since age 40. She had failed trials of various ASMs. Intracranial Electroencephalogram (iEEG) monitoring confirmed a left temporal lobe epileptic focus but the surgical intervention was deferred due to her complex medical status. Perampanel was subsequently added to her treatment regimen and the patient achieved sustained seizure remission for over 5 years. Results: This case highlights the potential utility of perampanel in the management of DRE, particularly in patients unsuitable for or deferring epilepsy surgery. The long-term seizure freedom achieved with perampanel in this complex case suggests it may serve as a valuable alternative therapeutic option. Conclusion: Further research is warranted to elucidate the role of perampanel in the comprehensive care of individuals with DRE.

OBJECTIVE:The aim of this study was to compare 3 electrode designs-a novel 22-contact circular grid, standard 6-contact strip, and high-density (HD) grid between 32 and 64 contacts-for the detection of epileptiform activity during awake craniotomy. METHODS:This study included patients who underwent functional brain mapping with and without direct electrical stimulation during awake craniotomy. Demographic, clinical, and electrocorticography (ECoG) data were collected. RESULTS:A total of 194 patients were included, with 264 instances of electrode use: 113 circular grid, 96 strip electrode, and 55 HD grid. The HD grid (15%) was used less to record ECoG during direct electrical stimulation than the circular grid (80%, p < 0.001) and strip electrodes (69%, p < 0.001). Sporadic interictal epileptiform activity was better detected with circular (45%, p < 0.001) and HD (40%, p = 0.006) grids compared with strip electrodes (16%). Spontaneous seizures were recorded more frequently with the circular grid (16%, p = 0.018) compared with the strip electrode (9.4%) and HD grid (1.8%). Afterdischarges were more frequently detected by the circular grid (69%, p = 0.031) and with circular and HD grids (combined) compared with strip electrodes (67% vs 48%, p = 0.024), at lower median intensity (3 mA vs 5 mA, p < 0.001). Multivariable analyses demonstrated circular grids (p < 0.001) to be more sensitive in detecting spontaneous epileptiform activity than strip and HD grid electrodes, and grids (circular and HD) to be better in recording stimulus-induced epileptiform activity (p = 0.01). CONCLUSIONS:This study demonstrates a higher rate of detection of epileptiform activity with circular and standard grids when compared with strip electrodes. The standard HD grid was used less during electrical stimulation, demonstrating the importance of both the number of contacts and design array when considering optimal conditions for ECoG and functional brain mapping.

OBJECTIVE:To compare the rate of EEG and MRI abnormalities in psychogenic nonepileptic seizures (PNES) patients with and without suspected epilepsy. Patients were also compared in terms of their demographic and clinical profiles.METHODS:A retrospective analysis of 271 newly diagnosed PNES patients admitted to the epilepsy monitoring unit between May 2000 and April 2008, with follow-up clinical data collected until September 2015.RESULTS:One hundred ninety-four patients were determined to have PNES alone, 16 PNES plus possible epilepsy, 14 PNES plus probable epilepsy, and 47 PNES plus confirmed epilepsy. Fifty-seven of the 77 patients (74.0%) with possible, probable, or definite epilepsy exhibited epileptiform activity on EEG, versus only 16 of the 194 patients (8.2%) in whom epilepsy was excluded. Twenty-four of these 194 patients (12.4%) had MRI abnormalities. Three of 38 patients (7.9%) with both EEG and MRI abnormalities were confirmed not to have epilepsy. In PNES patients with EEG or MRI abnormalities compared with those without, patients with abnormalities were more likely to have epilepsy risk factors, such as central nervous system structural abnormalities, and less likely to report minor head trauma. The presence of EEG abnormalities in PNES-only patients did not influence antiseizure medication reduction, whereas those with MRI abnormalities were less likely to have their antiseizure medications reduced.CONCLUSIONS:Psychogenic nonepileptic seizure patients without MRI or EEG abnormalities are less likely to have associated epilepsy, risk factors for epilepsy, and had different demographic profiles. There is a higher-than-expected level of EEG and MRI abnormalities in PNES patients without epilepsy.

This case report describes a woman cold-induced reflex seizures.

Stereoelectroencephalography-guided radiofrequency thermocoagulation (SEEG-guided RF-TC) is a treatment option for focal drug-resistant epilepsy. In previous studies, this technique has shown seizure reduction by ≥50% in 50% of patients at 1 year. However, the relationship between the location of the ablation within the epileptogenic network and clinical outcomes remains poorly understood. Seizure outcomes were analyzed for patients who underwent SEEG-guided RF-TC and across subgroups depending on the location of the ablation within the epileptogenic network, defined as SEEG sites involved in seizure generation and spread. Eighteen patients who had SEEG-guided RF-TC were included. SEEG-guided seizure-onset zone ablation (SEEG-guided SOZA) was performed in 12 patients, and SEEG-guided partial seizure-onset zone ablation (SEEG-guided P-SOZA) in 6 patients. The early spread was ablated in three SEEG-guided SOZA patients. Five patients had ablation of a lesion. The seizure freedom rate in the cohort ranged between 22% and 50%, and the responder rate between 67% and 85%. SEEG-guided SOZA demonstrated superior results for both outcomes compared to SEEG-guided P-SOZA at 6 months (seizure freedom p = .294, responder rate p = .014). Adding the early spread ablation to SEEG-guided SOZA did not increase seizure freedom rates but exhibited comparable effectiveness regarding responder rates, indicating a potential network disruption.

A 33-year-old man with two bilateral tonic-clonic seizures of unknown onset 12 years earlier was admitted to our epilepsy monitoring unit for characterization of his nocturnal groaning spells suspicious for catathrenia. Video-scalp electroencephalogram (EEG) was suggestive of drug-resistant non-lesional localization-related focal epilepsy in the right hemisphere. Intracranial EEG showed right frontal opercular origin of seizures with insular spread as the cause of his spells. This illustrative case shows the importance of video-EEG monitoring to distinguish nocturnal frontal opercular seizures from catathrenia. We review the evidence on distinguishing the two disorders.

Objectives This study aimed to investigate the differences in ASMs prescription, seizure characteristics and predictors of polypharmacy in patients with epilepsy and Intellectual disabilities (IDs) residing in group homes versus family homes. Methods This nine-year retrospective study analyzed patients with epilepsy and IDs who were admitted to the EMU, epilepsy clinics at LHSC and rehabilitation clinics for patients with IDs at Parkwood Institution. The study included individuals aged 16 years and older residing in either group homes or family homes. Data on demographics, epilepsy characteristics, and ASMs use were collected and analyzed using the Statistical Package for Social Sciences. The study utilized binary logistic regression to identify predictors of polypharmacy in patients with epilepsy and IDs. Results The study enrolled a total of 81 patients, of which 59.3 % resided in family homes. Group home residents were significantly older (41 vs. 24.5 years; p = 0.0001) and were prescribed more ASMs (3 vs. 2; p = 0.002). Specific ASMs were more common in group homes, including valproic acid (54.5 % vs. 25.0 %), lacosamide (54.5 % vs. 22.9 %), topiramate (33.3 % vs. 14.6 %), and phenytoin (30.3 % vs. 6.2 %). Admission to the EMU was more prevalent in group homes (93.9 % vs. 52.1 %; p = 0.0001). Living in a group home increased the risk of polypharmacy (OR = 10.293, p = 0.005), as did older epilepsy onset age (OR = 1.135, p = 0.031) and generalized or focal & generalized epilepsy (OR = 7.153, p = 0.032 and OR = 10.442, p = 0.025, respectively). Significance Our study identified notable differences in the demographic and clinical characteristics of patients with epilepsy and IDs living in group homes versus family homes. Age of epilepsy onset, EMU admissions, epilepsy types, and residency setting were significant predictors of polypharmacy. These findings highlight the need for personalized care strategies and increased awareness of the potential risks associated with polypharmacy.

Temporal lobe epilepsy is a common form of epilepsy that is often associated with hippocampal sclerosis (HS). Although HS is commonly considered a binary assessment in radiologic evaluation, it is known that histopathologic changes occur in distinct clusters. Some subtypes of HS only affect certain subfields, resulting in minimal changes to the overall volume of the hippocampus. This is likely a major reason why whole hippocampal volumetrics have underperformed versus expert readers in the diagnosis of HS. With recent advancements in MRI technology, it is now possible to characterize the substructure of the hippocampus more accurately. However, this is not consistently addressed in radiographic evaluations. The histologic subtype of HS is critical for prognosis and treatment decision-making, necessitating improved radiologic classification of HS. The International League Against Epilepsy (ILAE) has issued a consensus classification scheme for subtyping HS histopathologic changes. This review aims to explore how the ILAE subtypes of HS correlate with radiographic findings, introduce a grading system that integrates radiologic and pathologic reporting in HS, and outline an approach to detecting HS subtypes by using MRI. This framework will not only benefit current clinical evaluations, but also enhance future studies involving high-resolution MRI in temporal lobe epilepsy.

PURPOSE:Drug-resistant epilepsy (DRE) affects one-third of patients with focal epilepsy. A large portion of patients are not candidates for epilepsy surgery, thus alternative options, such as vagus nerve stimulation (VNS), are proposed. Our objective is to study the effect of vagus nerve stimulation on lesional versus non-lesional epilepsies. METHODS:This is a retrospective cohort study in a single center in London, Ontario, which includes patients with DRE implanted with VNS, implanted between 1997-2018 and the date of analysis is December 2023. PARTICIPANTS:Patients implanted with VNS were classified by lesional (VNS-L) and non-lesional (VNS-NL) based on their MRI head findings. We further subdivided the VNS groups into patients with VNS alone versus those who also had additional epilepsy surgeries. RESULTS:A total of 29 patients were enrolled in the VNS-L, compared to 29 in the VNS-NL. The median age of the patients in the study was 31.8 years, 29.31 % were men (N = 17). 41.4 % (n = 12) of the patients were VNS responders (≥50 % seizure reduction) in the VNS-L group compared to 62.0 % (n = 18) in the VNS-NL group (p = 0.03). When other epilepsy surgeries were combined with VNS in the VNS-L group, the median rate of seizure reduction was greater (72.4 (IQR 97.17-45.88) than the VNS-NL group 53.9 (IQR 92.22-27.92); p = 0.27). CONCLUSIONS:VNS is a therapeutic option for patients with lesional epilepsy, with slightly inferior results compared to patients with non-lesional epilepsy. Patients implanted with VNS showed higher seizure reduction rates if they had previous epilepsy surgeries. This study demonstrates that VNS in lesional epilepsies can be an effective treatment.

Objective: To examine trends of Antiseizure Medication (ASM) reduction and discontinuation, as well as Psychogenic Non-Epileptic Seizure (PNES) spell reduction and resolution in patients with PNES, with and without comorbid epileptic seizures (ES). Methods: A retrospective analysis was conducted on data from 145 patients with PNES, including 109 with PNES alone and 36 with PNES plus comorbid epilepsy. Patients were admitted to the Epilepsy Monitoring Unit (EMU) between May 2000 and April 2008, with follow-up clinical data collected until September 2015. Clinical records were thoroughly examined, encompassing the period preceding the PNES diagnosis until either loss to follow-up or September 2015. A subsequent chart review was conducted by two neurologists, covering the period following the diagnosis of PNES until either loss to follow-up or September 2015, which ever came first. Results: Patients with PNES alone had higher rates of ASM reduction for all variables of ASM reduction measured compared to those with comorbid epilepsy (all at p < 001). Among patients with PNES alone, reductions in ASMs were observed after EMU discharge, but an uptick and plateau were seen in later follow-up years (100% of patients free of ASMs at years 2-3, 20% on at least one ASM by year 7). This pattern differs greatly in PNES + ES patients, in which the only time point at which any patient was able to discontinue all ASMs was at EMU discharge (4.5% of patients), with all patients taking at least one ASM for every other follow-up time point. Reductions in PNES spell frequency did not differ significantly between the two groups (for example PNES spells reduced at final FU 47.2% vs 42.9%, p = 0.65). In both groups, despite an initial drop in variables of PNES spell reduction and resolution in the early years post discharge, there is an eventual rebound and plateau (for example in PNES only patients, 33.9% of patients having no resolution in 1st year FU, which rises to 78% at years 4-5, and plateus around 52.8% at more than 7 years follow-up.) Significance: This study contributes to the growing body of research focused on improving the current approach to management and prognostic outlook of PNES. Although PNES only patients had higher rates of ASM reduction, the uptick and plateau observed in later years highlights the challenges in managing PNES. Similarly, the continued persistence and rebound of PNES spells underline the continued poor prognostic outcomes associated with this condition.

Li, Cathy Meng Fei MD; Thorne, Michael W. D. MSc, MD; Boissé Lomax, Lysa MSc, MD, CSCN (EEG); Mirsattari, Seyed M. MD, PhD, CSCN (EEG); Fraser, J. Alexander MDEditor(s): Avery, Robert DO; Golnik, Karl C. MD; Froment, Caroline MD, PhD; Wang, An-Guor MD Author Information

Objective: To analyze the involvement of the posterior cingulate gyrus (PCG) during mesial temporal lobe seizures (MTLS).Methods: We retrospectively reviewed the stereo-EEG (SEEG) recordings of patients with MTLS performed in our institution from February 2013 to December 2020. Only patients who had electrode implantation in the PCG were included. Patients with lesions that could potentially alter the seizure spread pathways were excluded. We assessed the propagation patterns of MTLS with respect to the different structures sampled.Results: Nine of 97 patients who had at least one seizure originating in the mesial temporal region met the inclusion criteria. A total of 174 seizures were analyzed. The PCG was the first site of propagation in most of the cases (8/9 patients and 77.5% of seizures, and 7/8 patients and 65.6% of seizures after excluding an outlier patient). The fastest propagation times were towards the contralateral mesial temporal region and ipsilateral PCG. Seven patients underwent standard anterior temporal lobectomy and, of these, all but one were Engel 1 at last follow up.Conclusion: We found the PCG to be the first propagation site of MTLS in this group of patients. These results outline the relevance of the PCG in SEEG planning strategies. Further investigations are needed to corroborate whether fast propagation to the PCG predicts a good surgical outcome.