Stereoelectroencephalography in the Presurgical Evaluation of Drug–Resistant Epilepsy: Retrospective Analysis of Clinical Efficacy and Safety in 71 Procedures

Stereoelectroencephalography in the Presurgical Evaluation of Drug–Resistant Epilepsy: Retrospective Analysis of Clinical Efficacy and Safety in 71 Procedures | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Stereoelectroencephalography in the Presurgical Evaluation of Drug–Resistant Epilepsy: Retrospective Analysis of Clinical Efficacy and Safety in 71 Procedures Marta Codes, Alvaro Bedoya, Abel Ferres, Albert Mas, Mar Carreño, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9193268/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background Stereoelectroencephalography (SEEG) is a pivotal diagnostic and therapeutic tool in the presurgical evaluation of patients with drug-resistant epilepsy, particularly when noninvasive investigations are inconclusive. Objective To evaluate the indications, technical aspects, safety profile, and clinical outcomes of SEEG, including the adjunctive role of SEEG-guided radiofrequency thermocoagulation (RF-TC). Methods We conducted a retrospective review of 71 consecutive patients with drug-resistant epilepsy who underwent SEEG monitoring at our institution between 2016 and 2025. Demographic, neuroimaging, and electrophysiological data were analyzed, along with surgical variables, perioperative complications, and outcomes following SEEG-guided RF-TC and subsequent resective surgery. Results A total of 958 electrodes were implanted (mean 14 ± 4.5 per patient). SEEG confirmed the preimplantation hypothesis in 85% of cases. RF-TC was performed in 37 patients (52%); among them, 27 patients (73%) showed seizure improvement at 12 months. According to the Engel classification, 14% achieved class I, 27% class II, 19% class III, and 41% class IV outcomes. Complications occurred in 14 patients (20%), predominantly minor radiological findings; only one patient (1%) developed a permanent neurological deficit. Among the 37 patients who underwent resective surgery, favorable seizure outcomes (Engel classes I–II) were achieved in 76%, 70%, and 71% at 3, 6, and 12 months, respectively. Conclusions SEEG is a safe and effective modality for presurgical evaluation in drug-resistant epilepsy. It improves localization of the epileptogenic zone (EZ), guides individualized surgical decision-making and provides therapeutic benefit through RF-TC in carefully selected patients. Drug-Resistant Epilepsy Stereoelectroencephalography Thermocoagulation Treatment Outcome Complications Figures Figure 1 Figure 2 Introduction The need to offer alternative treatments to patients with drug-resistant epilepsy has led to the appearance of pre-surgical evaluation techniques that allow the better localization of the epileptogenic areas to assess the possibility of performing surgery with curative intent. Despite the continuous improvement and refinement of non-invasive techniques, which typically constitute the initial phase of the investigation, there is a considerable number of patients for whom the results of these tests are not conclusive enough to guide a clear decision, and invasive investigations are necessary. [ 1 – 3 ] Indications for invasive evaluation may differ among epilepsy centers, but SEEG is generally accepted when precise localization of the EZ is required to plan accurate surgical resection or when functional mapping is necessary to ensure surgical safety [ 2 – 3 ]. Although many of the reported metrics in this series are consistent with previously published SEEG literature, the distinctive contribution of our study lies in its comprehensive, longitudinal, and decision-oriented analysis of SEEG within a single tertiary epilepsy center over a nine-year period. Rather than focusing solely on implantation safety or postsurgical seizure outcomes, this series emphasizes the real-world clinical role of SEEG as a hypothesis-driven diagnostic tool that directly informs both surgical and non-surgical decision-making. Finally, an important and underreported contribution of this series is the analysis of patients in whom SEEG findings led to the decision not to proceed with resective surgery. In this cohort, SEEG played a critical role in identifying multifocal epilepsy, overlap with eloquent cortex, or insufficiently localized epileptogenic networks, thereby preventing ineffective or unsafe surgical interventions. In this context, SEEG should be viewed not only as a gateway to surgery, but also as a decisive tool for avoiding inappropriate surgical treatment. [ 6 – 21 ] Methods We analyzed all patients with drug-resistant epilepsy who underwent SEEG monitoring as part of a presurgical evaluation at our center between 2016 and 2025. Patients with generalized and multifocal epilepsy syndromes were excluded from the analysis, as the study focused on candidates for resective epilepsy surgery. For non-resective cases, alternative neuromodulation-based treatments, such as deep brain stimulation or vagus nerve stimulation, were considered according to institutional protocols. A comprehensive descriptive analysis was performed to define the basal characteristics of the enrolled patients, encompassing the results of previous non-invasive tests, findings from the SEEG monitoring, results of thermocoagulation if performed, and any associated complications related to the technique. The surgical results of those who underwent resection surgery for EZ were also analyzed. Data collection included demographic features; clinical features (mainly focused on the type and chronology of ictal symptoms and signs); presurgical magnetic resonance imaging (MRI); intervals of time between diagnostic and presentation in the Epilepsy Committee, and between SEEG decision in the Epilepsy Committee and performance of the technique; number and lateralization of implanted SEEG electrodes; surgery duration, monitoring duration and length of hospital stay and complications. In those patients who underwent thermocoagulation before the electrodes removal, and in those in which surgery was finally indicated and performed, data on the results and complications were also collected. Prior to selection for SEEG, all patients underwent an extensive non-invasive presurgical evaluation within a multidisciplinary epilepsy surgery team including specialists in neurology, neurosurgery, neuropsychology, nuclear medicine, and neuroradiology. This evaluation comprised a detailed clinical history, surface video-electroencephalographic (EEG) recordings, and structural and functional neuroimaging studies, including contrast-enhanced magnetic resonance imaging (MRI), thin-slice contrast-enhanced cranial computed tomography (CT), single-photon emission computed tomography (SPECT), and/or positron emission tomography (PET). Comprehensive neuropsychological assessments were also performed to evaluate higher cortical and cognitive functions. (Fig. 1 ) It should be noted that vascular anatomy was assessed using contrast-enhanced MRI and thin-slice contrast-enhanced CT, which were integrated into the stereotactic planning system to minimize vascular risk during trajectory selection. When concordant non-invasive findings allowed the formulation of a single, well-defined hypothesis regarding the localization and extent of the EZ, surgical treatment was planned without additional invasive investigation. Conversely, in cases showing discordant or inconclusive non-invasive data, invasive electrophysiological evaluation with SEEG was recommended following discussion in a multidisciplinary epilepsy surgery conference. The indications for SEEG at our center included MRI-negative epilepsy, discordance between electroclinical and neuroimaging findings, the presence of multiple or discordant lesions, and overlap of the presumed EZ with eloquent cortical areas. In this carefully selected cohort, all available non-invasive anatomical, electrophysiological, and clinical data were systematically reviewed to formulate a working hypothesis regarding EZ localization. This hypothesis-driven approach enabled meticulous planning of individualized SEEG explorations, targeting both seizure onset regions and key nodes involved in seizure propagation. Hypothesis confirmation was defined as concordance between the preimplantation electroclinical hypothesis and the seizure onset zone identified by SEEG recordings. Electrode insertion by our group was done using frameless stereotaxic with the Medtronic S8 neuronavigation system, intraoperative O-Arm® registration and the vertek® articulated passive arm (Medtronic) according to individualized case planning [ 30 ]. However, since 2023 we have replaced the Vertek articulated passive arm with the Neuromate® robotic arm (Renishaw), but following the same methodology [ 31 ] Postoperative non-contrast-enhanced computed tomography scans were employed to rule out complications. Continuous video SEEG monitoring was performed to record the patient’s ictal manifestations. Monitoring duration varied depending on the acquisition of a sufficient number of seizures. RF-TC was performed through the implanted depth electrodes after completion of the diagnostic monitoring phase and following multidisciplinary approval by the institutional Epilepsy Committee. The procedure was carried out using a dedicated radiofrequency generator (F.L. Fischer®, Neuro N50, Germany). RF-TC was selectively applied to electrode contacts located within the EZ, as defined by ictal onset patterns and corroborated by electrical stimulation mapping, ensuring that targeted contacts did not involve eloquent cortical regions. Electrical stimulation was performed prior to thermocoagulation to assess functional relevance of the targeted contacts. Stimulation parameters included a pulse duration of 0.5ms, a stimulation frequency of 50 Hz, a train duration of 5 seconds, and current intensity gradually increased from 0.5 to 5 mA. Radiofrequency thermocoagulation was then applied to selected contacts, with each coagulation lasting between 1.5 and 10 seconds and systematically repeated four times per target contact. The goal was to produce a controlled focal thermal lesion around the electrode contacts while minimizing the risk of extension to adjacent eloquent structures. All RF-TC procedures were performed with the patient awake. Prior to lesion delivery, patients were informed in real time of each procedural step, and continuous clinical monitoring was conducted to detect any emerging neurological signs or symptoms during energy administration. This real-time interaction allowed immediate interruption of the procedure in the event of clinically relevant responses. In most cases, RF-TC resulted in attenuation or disappearance of interictal epileptiform discharges, and when seizures were captured after the procedure, a reduction or suppression of ictal onset patterns was observed at the coagulated contacts, supporting their role within the epileptogenic network. Following RF-TC, a detailed neurological examination and electroclinical review were performed. A non-contrast postoperative computed tomography (CT) scan was systematically obtained to rule out hemorrhagic complications prior to electrode removal. After completion of the monitoring period and RF-TC, electrodes were removed under general anesthesia. A postoperative CT scan was performed to confirm the absence of bleeding. Electroclinical data were reviewed to accurately characterize the EZ, and findings were discussed at the institutional Epilepsy Committee to guide multidisciplinary therapeutic decision-making. Follow-up of all included patients has been maintained to date, and outcomes of those who subsequently underwent EZ resective surgery were analyzed, including type of resection, procedure-related complications, and postoperative seizure outcomes. Results We analyzed all patients with drug-resistant epilepsy who underwent EEG monitoring via SEEG electrodes in our center from 2016 to 2025, with a total of 71 consecutive patients. (Table 1 ) Table 1 Clinical and surgical characteristics of 71 patients undergoing SEEG (2016–2025). Clinical and surgical characteristics Category Variable Result Population Included patients 71 Sex 33 males (46%), 38 females (54%) Mean age at SEEG 35.4 ± 12.1 years Mean epilepsy onset age 15 ± 10.9 years Pre-surgical evaluation Lesional epilepsy 50 (70%) Non-lesional epilepsy 21 (30%) Multiple lesions 9 (18% of lesional) Most frequent lesion type Cortical dysplasia 37 (64%), tumors 9 (15%), postsurgical gliosis 7 (12%), heterotopia 5 (9%) Time intervals Diagnosis → Epilepsy Committee 18.7 ± 13.4 years Decision for SEEG → Implantation 19 ± 32.6 months Surgical aspects Total electrodes 958 Mean electrodes per patient 14 ± 4.5 Unilateral implantation 38 patients (54%) Bilateral implantation 33 patients (46%) Mean surgical duration 200 ± 55.8 min (≈ 3 h) Monitoring & hospital stay Monitoring duration 13.7 ± 4.6 days Hospital stay 16.8 ± 5 days Complications (SEEG) Minor radiological findings without clinical impact - Small Intracerebral hemorrhage - Small Subarachnoid hemorrhage 8 (11%) 3 (4%) Clinically significant complication - Infection - Symptomatic hemorrhage requiring surgery 2 (3%) 1 (1%) Permanent deficit 1 (1%) Mortality 0 Thermocoagulation complications (n = 5, 14%) Hemiparesis 2 (5%) Aphasia/dysphasia 2 (5%) Dysnomia 1 (3%) Non-surgical patients (n = 34, 48%) Rejection of surgery 9 (26%) Multifocal epilepsy 8 (24%) Partial seizure improvement with pharmacological adjustment + RF-TC 7 (20%) High surgical risk (EZ located within eloquent brain areas) 6 (18%) Absence of disabling seizures 4 (12%) Patient demographic features A total of 71 patients underwent stereotactic procedures for intracerebral electrode implantation in our center. There were 33 males (46%) and 38 women (54%), whose mean age at the time of the SEEG examination was 35.4 ± 12.1 years and the mean age of onset of epilepsy was 15 ± 10.9 years. Pre-surgical evaluations Imaging pre-surgical tests using MRI classified the epilepsy type as lesional 50 patients (70%), or non-lesional 21 patients (30%). In those 50 patients with lesional epilepsy, 9 of them (18%) had multiple lesions in the MRI. The most frequently observed lesions were cortical dysplasia in 37 cases (64%), followed by tumoral lesions in 9 cases (15%). Other described lesions included gliosis associated with previous surgeries in 7 cases (12%) and heterotopias in 5 cases (9%). Time intervals The mean time between diagnosis of epilepsy and presentation of the case in the Epilepsy Committee of our center was 18.7 ± 13.4 years. The mean time between the SEEG decision and the performance of the technique was 19 ± 32.5 months. Surgical aspects A total of 958 electrodes were inserted. The mean number of electrodes per patient was 14 ± 4.4 electrodes. In 38 patients the electrodes were placed in one brain hemisphere (54%) while in the remaining 33 patients were placed bilaterally (46%). The mean duration of the surgical procedure was 200 ± 55.8 minutes (3 hours approx.) The mean duration of the monitoring was 13.7 +/- 4.6 days, resulting in a mean hospital stay of 16.8 +/- 5 days. (Fig. 2 ) Complications SEEG-related events were initially identified in 14 patients (20%). However, most of these corresponded to minor radiological findings without clinical consequences, mainly small postoperative hemorrhagic changes detected on routine CT imaging. Specifically, 8 patients (11%) had small intracerebral hemorrhages and 3 (4%) had limited subarachnoid hemorrhage, none of which produced symptoms or required medical or surgical treatment. Two patients (3%) developed infection. Only one patient (1%) experienced a clinically significant intracerebral hemorrhage requiring surgical evacuation , which resulted in a permanent neurological deficit. No deaths occurred in this series. Thermocoagulation (RF-TC) RF-TC was performed after an electrical stimulation study on 37 patients (52%) in our series with the following indication: electrodes located in the EZ evaluated during the monitoring to ensure that these areas were not located in eloquent brain regions. Among the 37 patients who underwent RF-TC, 27 (73%) experienced some degree of seizure improvemen t at 12 months. However, according to Engel classification, only 41% achieved favorable outcomes (Engel classes I–II), whereas 19% had Engel class III outcomes and 41% remained in Engel class IV. These findings suggest that RF-TC may provide meaningful symptomatic benefit in selected patients, although its effect is more appropriately interpreted as adjunctive or palliative rather than definitively curative. Only 5 patients (14%) developed transient complications like a hemiparesis (2 patients), aphasia/dysphasia (2 patients) and dysnomia (1 patient). Hypothesis The hypothesis was confirmed in 60 patients (85%), understanding the SEEG as a useful tool for the accurate diagnosis in drug-resistant epilepsy with diagnostic gaps when using general paraclinical tests. A total of 37 patients ultimately underwent resective epilepsy surgery. Among them, 19 had previously received RF-TC as an initial therapeutic approach. In these cases, RF-TC did not lead to clinically meaningful seizure improvement, and resective surgery was subsequently indicated following multidisciplinary evaluation. Postoperative seizure outcomes in the 37 surgically treated patients were evaluated at 3, 6, and 12 months using the Engel classification. At 3 months of follow-up, Engel class I outcomes were observed in 57% of patients, while 19% were classified as Engel class II, resulting in favorable seizure control (Engel classes I–II) in 76% of cases. At 6 months, Engel class I outcomes decreased to 51%, with Engel class II remaining stable at 19%, yielding favorable outcomes in 70% of patients. At 12 months, Engel class I outcomes were observed in 49% of patients, while Engel class II increased slightly to 22%, maintaining favorable seizure control in 71% of the cohort. Across follow-up intervals, Engel class III outcomes ranged from 16% to 22%, whereas Engel class IV outcomes increased modestly over time, reaching 14% at 12 months. (Table 2 ) Table 2 All percentages are calculated based on the total cohort (n = 37). Seizure outcomes were classified according to the Engel postoperative outcome scale at 3, 6 and 12 month follow-up. Favorable outcomes were defined as Engel classes I–II. Postoperative Seizure Outcomes at 3, 6, and 12 Month Follow-up According to the Engel Classification Month Engel Class n % 3 I 21 57 II 7 19 III 6 16 IV 3 8 6 I 19 51 II 7 19 III 8 22 IV 3 8 12 I 18 49 II 8 22 III 6 16 IV 5 14 34 patients were not candidates for resective epilepsy surgery. The main reasons included rejection of surgery by the patient (26%), multifocal epilepsy (24%), partial seizure improvement achieved with pharmacological adjustment combined with effective RF-TC (21%), high surgical risk (defined as the EZ located within eloquent brain areas) (18%), and absence of disabling seizures at the time of evaluation (12%). Among the patients excluded from resective surgery due to multifocal epilepsy (n = 8), alternative neuromodulation-based surgical treatments were offered. Of these, 50% underwent deep brain stimulation of the anterior nucleus of the thalamus, 13% received deep brain stimulation of the centromedian nucleus, and 38% were treated with vagus nerve stimulation. (Table 3 ) Table 3 All percentages are calculated based on the total number of patients who were not candidates for resective surgery (n = 34). RF-TC: radiofrequency thermocoagulation. High surgical risk refers to cases in which the EZ involved eloquent cortical areas. Reasons for Not Undergoing Resective Epilepsy Surgery Characteristic n % Rejection of surgery 9 26 Multifocality 8 24 Partial seizure improvement with pharmacological adjustment + RF-TC 7 21 High surgical risk 6 18 Absence of disabling seizures 4 12 Discussion This series is distinctive in highlighting how SEEG not only guides resective surgery but also informs non-surgical decision-making and the use of RF-TC as a standalone or adjunctive therapy over a 9-year evolution of practice Technical refinements, including the introduction of robotic assistance, have further improved accuracy and safety in SEEG procedures. Gonzalez-Martinez et al (2016) reported high precision with robotic implantation, reducing trajectory error and potentially minimizing complication risk [ 32 ]. Similarly, Cardinale et al. (2019) highlighted how modern stereotactic platforms and imaging integration contribute to improved outcomes and workflow efficiency [ 33 ]. Our own experience mirrors this evolution, as since 2023 we transitioned from the Vertek passive arm to the Neuromate® robotic system, maintaining safety while enhancing implantation accuracy.[ 30 ] Moreover, the implementation of computer-assisted planning platforms has recently shown potential to optimize RF-TC trajectories and outcomes, particularly in pediatric epilepsy. [ 34 ] Our complication rate was 20% and consisted predominantly (86%) of minor intracerebral hemorrhages (< 5 cc), which had no clinical impact on patients and were therefore considered minor radiological findings; only one case (1%) developed an intracerebral hemorrhage requiring surgical drainage, resulting in permanent motor disability. These results are in line with large meta-analyses such as Mullin et al., who reported a pooled prevalence of 1.3% for clinically significant complications [ 20 ], and with McGovern et al., who emphasized the low risk of hemorrhage when proper planning and trajectory selection are applied [ 35 ]. Regarding RF-TC, our seizure improvement rate of 73% with seizure freedom in 14% compares favorably with recent long-term series. Lagarde et al. (2021) demonstrated that thermocoagulation can provide durable seizure reduction in carefully selected patients, with seizure freedom ranging from 10–20% [ 36 ]. Recent analyses have also identified clinical predictors of favorable outcomes in MRI-negative patients undergoing RF-TC, further supporting the role of this approach in carefully selected populations [ 37 ] These findings support a clinically meaningful adjunctive role for RF-TC in selected patients, particularly when resective surgery is not feasible or is deferred. Although complete seizure freedom was limited, RF-TC provided worthwhile seizure reduction in a substantial proportion of patients, supporting its value as a palliative or bridge therapy within a broader individualized surgical strategy. Limitations This study has several limitations. First, its retrospective and single-center nature may limit generalizability. Second, although all patients were consecutively included, referral bias inherent to a tertiary epilepsy center must be considered. Third, our clinical practice evolved during the 9-year study period, particularly regarding imaging quality and the adoption of robotic assistance (transitioning from the Vertek passive arm to the Neuromate® system), which may have influenced complication rates and accuracy. Fourth, although follow-up was performed in all patients, the duration varied, and longer-term data are required to assess the durability of seizure outcomes, particularly after thermocoagulation. Finally, the relatively small sample size compared to multicenter meta-analyses may partly explain the differences in infection rates observed. The patient population presented here reflects a complete series of consecutively explored patients, representative of our center’s practice over a 9-year period. Our clinical practice has evolved over this period along with other aspects of our investigation such as the acceptance of thermocoagulation and the precision of MRI studies. Conclusions SEEG represents a robust, safe, and highly effective diagnostic modality for the presurgical evaluation of patients with complex drug-resistant epilepsy. By enabling precise delineation of the EZ, SEEG substantially enhances the accuracy of surgical decision-making and optimizes the selection of candidates for resective procedures. When integrated with tailored resective surgery, SEEG contributes to achieving excellent long-term seizure control and meaningful improvements in quality of life. Furthermore, SEEG-guided RF-TC may represent a valuable adjunctive therapeutic option in carefully selected patients, particularly when resection is not feasible or when temporary seizure reduction may inform subsequent treatment decisions. Taken together, these advances underscore SEEG not merely as a diagnostic tool but as a cornerstone in the modern multidisciplinary management of drug-resistant epilepsy —bridging innovation, precision, and therapeutic success. Ultimately, SEEG redefines the limits of presurgical evaluation and paves the way toward a future where individualized epilepsy surgery becomes not the exception, but the standard of care. Declarations Funding. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Acknowledgments. None. Conflict of Interest / Disclosure. The authors declare no conflicts of interest related to this work. The authors report no conflicts of interest in this work. Author Contributions. Conceptualization: Marta Codes, Alvaro Bedoya, Pedro Roldan. Methodology: Marta Codes, Abel Ferres, Alvaro Bedoya, Eugenia Pujol-Ayach Data curation: Albert Mas, Mar Carreño, Maria Centeno, Estefania Conde. Formal analysis: Abel Ferres, Lorena Gomez, Jordi Rumia. Investigation: Marta Olivera, Estefania Conde, Antonio Donaire, Eugenia Pujol-Ayach. Writing – original draft: Marta Codes, Alvaro Bedoya. Writing – review & editing: Marta Codes, Alvaro Bedoya, Pedro Roldan. Supervision: Pedro Roldan. Project administration: Alvaro Bedoya. Visualization: Maria Centeno, Abel Ferres. AI Use Declaration. No generative artificial intelligence tools were used for the generation of content, data analysis, or manuscript writing. Only minor language and grammar edits were performed under full author supervision, in compliance with the ethical publishing policies of World Neurosurgery: X. Data Availability. The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request. Due to patient privacy and institutional regulations, raw clinical data cannot be publicly shared. Reporting Guidelines. This retrospective observational cohort study has been prepared in accordance with the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement. A completed STROBE checklist is submitted as a supplementary file. Ethical Approval and Patient Consent. This study was conducted in accordance with the principles outlined in the Declaration of Helsinki (2013 revision). The study protocol was reviewed by the Ethics Committee of Hospital Clínic of Barcelona, which granted a waiver of formal informed consent due to the retrospective, observational design of the study and the use of fully anonymized institutional data. The internal ethics committee protocol number assigned to this study was HCB/2026/0164. All patients had previously provided written informed consent for undergoing stereoelectroencephalography (SEEG) implantation and SEEG-guided radiofrequency thermocoagulation as part of their standard clinical care and presurgical evaluation protocol. Patient confidentiality and data protection were strictly maintained throughout all phases of the study, in compliance with institutional policies and applicable data protection regulations. References Cossu M, Cardinale F, Colombo N, Francione S, Lo Russo G (2005) Stereoelectroencephalography in the presurgical evaluation of children with drug-resistant focal epilepsy. J Neurosurg 103(4 Suppl):333–343 Zumsteg D, Wieser HG (2000) Presurgical evaluation: current role of invasive EEG. Epilepsia 41(Suppl 3):S55–60 McGonigal A, Bartolomei F, Régis J, Guye M, Gavaret M, Trébuchon-Da Fonseca A et al (2007) Stereoelectroencephalography in presurgical assessment of MRI-negative epilepsy. 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Epilepsia 62(3):e65–70. 10.1111/epi.16821 Huang Q, Zhang J, Li Z, Hu S, Yang C, Jiang H et al (2024) Predictors of seizure outcomes in stereoelectroencephalography-guided radiofrequency thermocoagulation for MRI-negative epilepsy. Front Neurol 15:1368334. 10.3389/fneur.2024.1368334 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 09 Apr, 2026 Reviews received at journal 08 Apr, 2026 Reviewers agreed at journal 25 Mar, 2026 Reviewers invited by journal 24 Mar, 2026 Editor assigned by journal 23 Mar, 2026 Submission checks completed at journal 23 Mar, 2026 First submitted to journal 22 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9193268","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":612225329,"identity":"9f838119-5719-4297-96ab-a2c1c9bc5703","order_by":0,"name":"Marta Codes","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Marta","middleName":"","lastName":"Codes","suffix":""},{"id":612225330,"identity":"7e686791-451b-45d2-92fc-a6148db434b4","order_by":1,"name":"Alvaro Bedoya","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYDACdgYGZhDNDyISCojRwgzVItkA0mJAihaDA2CSCB38zTyGnwsqauWMz69O/PDAgEGeX+wAfi0Sh3mMpWecOW5sduPtZgmgwwxnzk4gYM1htgRp3rZjidtunN0A0pJgcJuAFvnDbMm/ef8dS9w84+zmH0RpMTjMfEyat6EmcQN/7zbibDEEarGeceyAscQN3m0WCQYShP0id7yx+XZBTZ0cf//ZzTd/VNjI80sT0AIFh4FhB1YpQZRyEKgDxtABolWPglEwCkbBCAMAgWpD5bQttwAAAAAASUVORK5CYII=","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":true,"prefix":"","firstName":"Alvaro","middleName":"","lastName":"Bedoya","suffix":""},{"id":612225331,"identity":"64b3b877-3380-4b9d-a7c4-1cd3c184c9fd","order_by":2,"name":"Abel Ferres","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Abel","middleName":"","lastName":"Ferres","suffix":""},{"id":612225332,"identity":"8f1b489e-b20e-4cbe-a535-62a93c744323","order_by":3,"name":"Albert Mas","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Albert","middleName":"","lastName":"Mas","suffix":""},{"id":612225334,"identity":"764b0324-ed2b-4137-a688-c6ba998f3012","order_by":4,"name":"Mar Carreño","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Mar","middleName":"","lastName":"Carreño","suffix":""},{"id":612225336,"identity":"a6681a75-82ad-4c2f-8f3b-acc9d94460d7","order_by":5,"name":"Maria Centeno","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Maria","middleName":"","lastName":"Centeno","suffix":""},{"id":612225338,"identity":"91635a12-7a86-442d-99d0-4bdfba4ec9b0","order_by":6,"name":"Estefania Conde","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Estefania","middleName":"","lastName":"Conde","suffix":""},{"id":612225340,"identity":"e4bce8f8-69ab-4f9a-bbcf-c3ac1242f86b","order_by":7,"name":"Antonio Donaire","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Antonio","middleName":"","lastName":"Donaire","suffix":""},{"id":612225342,"identity":"fc1d1ba0-0103-4f5e-bdd2-aa3a6cf6d093","order_by":8,"name":"Marta Olivera","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Marta","middleName":"","lastName":"Olivera","suffix":""},{"id":612225344,"identity":"a52d7c70-9cb4-4a0c-bc60-636a748ab144","order_by":9,"name":"Eugenia Pujol-Ayach","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Eugenia","middleName":"","lastName":"Pujol-Ayach","suffix":""},{"id":612225345,"identity":"684f3e46-efcd-43e7-bc27-9f41ce07f227","order_by":10,"name":"Lorena Gomez","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Lorena","middleName":"","lastName":"Gomez","suffix":""},{"id":612225348,"identity":"b9de77ae-8950-41b4-8a2c-fd1b5fed5c83","order_by":11,"name":"Jordi Rumia","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Jordi","middleName":"","lastName":"Rumia","suffix":""},{"id":612225349,"identity":"ad981b41-7b96-4481-a964-39b9c9889948","order_by":12,"name":"Pedro Roldan","email":"","orcid":"","institution":"Hospital Clínic of Barcelona","correspondingAuthor":false,"prefix":"","firstName":"Pedro","middleName":"","lastName":"Roldan","suffix":""}],"badges":[],"createdAt":"2026-03-22 18:53:48","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9193268/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9193268/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105497935,"identity":"5283aa18-19be-4385-ba21-3de679a6c9bb","added_by":"auto","created_at":"2026-03-26 16:53:02","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1445421,"visible":true,"origin":"","legend":"\u003cp\u003eCase of a patient with \u003cstrong\u003edrug-resistant epilepsy\u003c/strong\u003e and dual pathology. (A) Bipolar EEG montage showing rhythmic spiculated activity in the right frontotemporal region. (B) EEG during seizure onset with progression in the right temporal chain. (C) MRI demonstrating right temporal sclerosis (red arrow) and right frontobasal cavernoma (yellow arrow). (D) SPECT with hyper uptake in the right temporal pole. (E) PET showing hypometabolism in right temporal and anterobasal frontal regions. (F) SEEG confirming seizure onset in hippocampal contacts O1-2 and H1-2, leading to ipsilateral temporal lobectomy via an endoscopic transorbital approach\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-9193268/v1/3b219ae2dd9fe406d9ee03a9.png"},{"id":105497936,"identity":"a5bd7a38-a622-4899-b308-ef1635c885c8","added_by":"auto","created_at":"2026-03-26 16:53:02","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1008377,"visible":true,"origin":"","legend":"\u003cp\u003ePatient undergoing SEEG monitoring with depth electrodes anchored by bolts.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-9193268/v1/3e85a1d82bce04fadfbf857d.png"},{"id":105566818,"identity":"84eb272b-464b-4235-9cde-a901d515c7f0","added_by":"auto","created_at":"2026-03-27 12:57:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3273403,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9193268/v1/06f420ca-2870-40e3-8b9c-fb977f47a0d8.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eStereoelectroencephalography in the Presurgical Evaluation of Drug–Resistant Epilepsy: Retrospective Analysis of Clinical Efficacy and Safety in 71 Procedures\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe need to offer alternative treatments to patients with drug-resistant epilepsy has led to the appearance of pre-surgical evaluation techniques that allow the better localization of the epileptogenic areas to assess the possibility of performing surgery with curative intent.\u003c/p\u003e \u003cp\u003eDespite the continuous improvement and refinement of non-invasive techniques, which typically constitute the initial phase of the investigation, there is a considerable number of patients for whom the results of these tests are not conclusive enough to guide a clear decision, and invasive investigations are necessary. [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIndications for invasive evaluation may differ among epilepsy centers, but SEEG is generally accepted when precise localization of the EZ is required to plan accurate surgical resection or when functional mapping is necessary to ensure surgical safety [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough many of the reported metrics in this series are consistent with previously published SEEG literature, the distinctive contribution of our study lies in its comprehensive, longitudinal, and decision-oriented analysis of SEEG within a single tertiary epilepsy center over a nine-year period.\u003c/p\u003e \u003cp\u003eRather than focusing solely on implantation safety or postsurgical seizure outcomes, this series emphasizes the real-world clinical role of SEEG as a hypothesis-driven diagnostic tool that directly informs both surgical and non-surgical decision-making.\u003c/p\u003e \u003cp\u003eFinally, an important and underreported contribution of this series is the analysis of patients in whom SEEG findings led to the decision not to proceed with resective surgery. In this cohort, SEEG played a critical role in identifying multifocal epilepsy, overlap with eloquent cortex, or insufficiently localized epileptogenic networks, thereby preventing ineffective or unsafe surgical interventions. In this context, SEEG should be viewed not only as a gateway to surgery, but also as a decisive tool for avoiding inappropriate surgical treatment. [\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10 CR11 CR12 CR13 CR14 CR15 CR16 CR17 CR18 CR19 CR20\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eWe analyzed all patients with drug-resistant epilepsy who underwent SEEG monitoring as part of a presurgical evaluation at our center between 2016 and 2025. Patients with generalized and multifocal epilepsy syndromes were excluded from the analysis, as the study focused on candidates for resective epilepsy surgery. For non-resective cases, alternative neuromodulation-based treatments, such as deep brain stimulation or vagus nerve stimulation, were considered according to institutional protocols.\u003c/p\u003e \u003cp\u003eA comprehensive descriptive analysis was performed to define the basal characteristics of the enrolled patients, encompassing the results of previous non-invasive tests, findings from the SEEG monitoring, results of thermocoagulation if performed, and any associated complications related to the technique. The surgical results of those who underwent resection surgery for EZ were also analyzed.\u003c/p\u003e \u003cp\u003eData collection included demographic features; clinical features (mainly focused on the type and chronology of ictal symptoms and signs); presurgical magnetic resonance imaging (MRI); intervals of time between diagnostic and presentation in the Epilepsy Committee, and between SEEG decision in the Epilepsy Committee and performance of the technique; number and lateralization of implanted SEEG electrodes; surgery duration, monitoring duration and length of hospital stay and complications. In those patients who underwent thermocoagulation before the electrodes removal, and in those in which surgery was finally indicated and performed, data on the results and complications were also collected.\u003c/p\u003e \u003cp\u003ePrior to selection for SEEG, all patients underwent an extensive non-invasive presurgical evaluation within a multidisciplinary epilepsy surgery team including specialists in neurology, neurosurgery, neuropsychology, nuclear medicine, and neuroradiology. This evaluation comprised a detailed clinical history, surface video-electroencephalographic (EEG) recordings, and structural and functional neuroimaging studies, including contrast-enhanced magnetic resonance imaging (MRI), thin-slice contrast-enhanced cranial computed tomography (CT), single-photon emission computed tomography (SPECT), and/or positron emission tomography (PET). Comprehensive neuropsychological assessments were also performed to evaluate higher cortical and cognitive functions. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eIt should be noted that vascular anatomy was assessed using contrast-enhanced MRI and thin-slice contrast-enhanced CT, which were integrated into the stereotactic planning system to minimize vascular risk during trajectory selection.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWhen concordant non-invasive findings allowed the formulation of a single, well-defined hypothesis regarding the localization and extent of the EZ, surgical treatment was planned without additional invasive investigation. Conversely, in cases showing discordant or inconclusive non-invasive data, invasive electrophysiological evaluation with SEEG was recommended following discussion in a multidisciplinary epilepsy surgery conference.\u003c/p\u003e \u003cp\u003eThe indications for SEEG at our center included MRI-negative epilepsy, discordance between electroclinical and neuroimaging findings, the presence of multiple or discordant lesions, and overlap of the presumed EZ with eloquent cortical areas.\u003c/p\u003e \u003cp\u003eIn this carefully selected cohort, all available non-invasive anatomical, electrophysiological, and clinical data were systematically reviewed to formulate a working hypothesis regarding EZ localization. This hypothesis-driven approach enabled meticulous planning of individualized SEEG explorations, targeting both seizure onset regions and key nodes involved in seizure propagation.\u003c/p\u003e \u003cp\u003eHypothesis confirmation was defined as concordance between the preimplantation electroclinical hypothesis and the seizure onset zone identified by SEEG recordings.\u003c/p\u003e \u003cp\u003eElectrode insertion by our group was done using frameless stereotaxic with the Medtronic S8 neuronavigation system, intraoperative O-Arm\u0026reg; registration and the vertek\u0026reg; articulated passive arm (Medtronic) according to individualized case planning [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. However, since 2023 we have replaced the Vertek articulated passive arm with the Neuromate\u0026reg; robotic arm (Renishaw), but following the same methodology [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e \u003cp\u003ePostoperative non-contrast-enhanced computed tomography scans were employed to rule out complications. Continuous video SEEG monitoring was performed to record the patient\u0026rsquo;s ictal manifestations. Monitoring duration varied depending on the acquisition of a sufficient number of seizures.\u003c/p\u003e \u003cp\u003eRF-TC was performed through the implanted depth electrodes after completion of the diagnostic monitoring phase and following multidisciplinary approval by the institutional Epilepsy Committee.\u003c/p\u003e \u003cp\u003eThe procedure was carried out using a dedicated radiofrequency generator (F.L. Fischer\u0026reg;, Neuro N50, Germany). RF-TC was selectively applied to electrode contacts located within the EZ, as defined by ictal onset patterns and corroborated by electrical stimulation mapping, ensuring that targeted contacts did not involve eloquent cortical regions.\u003c/p\u003e \u003cp\u003eElectrical stimulation was performed prior to thermocoagulation to assess functional relevance of the targeted contacts. Stimulation parameters included a pulse duration of 0.5ms, a stimulation frequency of 50 Hz, a train duration of 5 seconds, and current intensity gradually increased from 0.5 to 5 mA.\u003c/p\u003e \u003cp\u003eRadiofrequency thermocoagulation was then applied to selected contacts, with each coagulation lasting between 1.5 and 10 seconds and systematically repeated four times per target contact. The goal was to produce a controlled focal thermal lesion around the electrode contacts while minimizing the risk of extension to adjacent eloquent structures.\u003c/p\u003e \u003cp\u003eAll RF-TC procedures were performed with the patient awake. Prior to lesion delivery, patients were informed in real time of each procedural step, and continuous clinical monitoring was conducted to detect any emerging neurological signs or symptoms during energy administration. This real-time interaction allowed immediate interruption of the procedure in the event of clinically relevant responses.\u003c/p\u003e \u003cp\u003eIn most cases, RF-TC resulted in attenuation or disappearance of interictal epileptiform discharges, and when seizures were captured after the procedure, a reduction or suppression of ictal onset patterns was observed at the coagulated contacts, supporting their role within the epileptogenic network.\u003c/p\u003e \u003cp\u003eFollowing RF-TC, a detailed neurological examination and electroclinical review were performed. A non-contrast postoperative computed tomography (CT) scan was systematically obtained to rule out hemorrhagic complications prior to electrode removal.\u003c/p\u003e \u003cp\u003eAfter completion of the monitoring period and RF-TC, electrodes were removed under general anesthesia. A postoperative CT scan was performed to confirm the absence of bleeding. Electroclinical data were reviewed to accurately characterize the EZ, and findings were discussed at the institutional Epilepsy Committee to guide multidisciplinary therapeutic decision-making. Follow-up of all included patients has been maintained to date, and outcomes of those who subsequently underwent EZ resective surgery were analyzed, including type of resection, procedure-related complications, and postoperative seizure outcomes.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eWe analyzed all patients with drug-resistant epilepsy who underwent EEG monitoring via SEEG electrodes in our center from 2016 to 2025, with a total of 71 consecutive patients. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical and surgical characteristics of 71 patients undergoing SEEG (2016\u0026ndash;2025).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eClinical and surgical characteristics\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCategory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eResult\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003ePopulation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIncluded patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e71\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33 males (46%), 38 females (54%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean age at SEEG\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.4\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1 years\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean epilepsy onset age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15\u0026thinsp;\u0026plusmn;\u0026thinsp;10.9 years\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003ePre-surgical evaluation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLesional epilepsy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50 (70%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-lesional epilepsy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21 (30%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMultiple lesions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (18% of lesional)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMost frequent lesion type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCortical dysplasia 37 (64%), tumors 9 (15%), postsurgical gliosis 7 (12%), heterotopia 5 (9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTime intervals\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDiagnosis \u0026rarr; Epilepsy Committee\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.7\u0026thinsp;\u0026plusmn;\u0026thinsp;13.4 years\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDecision for SEEG \u0026rarr; Implantation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19\u0026thinsp;\u0026plusmn;\u0026thinsp;32.6 months\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eSurgical aspects\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal electrodes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e958\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean electrodes per patient\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnilateral implantation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38 patients (54%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBilateral implantation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33 patients (46%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean surgical duration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200\u0026thinsp;\u0026plusmn;\u0026thinsp;55.8 min (\u0026asymp;\u0026thinsp;3 h)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMonitoring \u0026amp; hospital stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMonitoring duration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6 days\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHospital stay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5 days\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eComplications (SEEG)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eMinor radiological findings without clinical impact\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e- Small Intracerebral hemorrhage\u003c/p\u003e \u003cp\u003e- Small Subarachnoid hemorrhage\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (11%)\u003c/p\u003e \u003cp\u003e3 (4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eClinically significant complication\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e- Infection\u003c/p\u003e \u003cp\u003e- Symptomatic hemorrhage requiring surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (3%)\u003c/p\u003e \u003cp\u003e1 (1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePermanent deficit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMortality\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eThermocoagulation complications (n\u0026thinsp;=\u0026thinsp;5, 14%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHemiparesis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAphasia/dysphasia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDysnomia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-surgical patients\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;34, 48%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRejection of surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (26%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMultifocal epilepsy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (24%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePartial seizure improvement with pharmacological adjustment\u0026thinsp;+\u0026thinsp;RF-TC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (20%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHigh surgical risk (EZ located within eloquent brain areas)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (18%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbsence of disabling seizures\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (12%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003ePatient demographic features\u003c/h3\u003e\n\u003cp\u003eA total of 71 patients underwent stereotactic procedures for intracerebral electrode implantation in our center. There were 33 males (46%) and 38 women (54%), whose mean age at the time of the SEEG examination was 35.4 \u0026plusmn; 12.1 years and the mean age of onset of epilepsy was 15 \u0026plusmn; 10.9 years.\u003c/p\u003e\n\u003ch3\u003ePre-surgical evaluations\u003c/h3\u003e\n\u003cp\u003eImaging pre-surgical tests using MRI classified the epilepsy type as lesional 50 patients (70%), or non-lesional 21 patients (30%). In those 50 patients with lesional epilepsy, 9 of them (18%) had multiple lesions in the MRI.\u003c/p\u003e \u003cp\u003eThe most frequently observed lesions were cortical dysplasia in 37 cases (64%), followed by tumoral lesions in 9 cases (15%).\u003c/p\u003e \u003cp\u003eOther described lesions included gliosis associated with previous surgeries in 7 cases (12%) and heterotopias in 5 cases (9%).\u003c/p\u003e\n\u003ch3\u003eTime intervals\u003c/h3\u003e\n\u003cp\u003eThe mean time between diagnosis of epilepsy and presentation of the case in the Epilepsy Committee of our center was 18.7 \u0026plusmn; 13.4 years. The mean time between the SEEG decision and the performance of the technique was 19 \u0026plusmn; 32.5 months.\u003c/p\u003e\n\u003ch3\u003eSurgical aspects\u003c/h3\u003e\n\u003cp\u003eA total of 958 electrodes were inserted. The mean number of electrodes per patient was 14 \u0026plusmn; 4.4 electrodes. In 38 patients the electrodes were placed in one brain hemisphere (54%) while in the remaining 33 patients were placed bilaterally (46%). The mean duration of the surgical procedure was 200 \u0026plusmn; 55.8 minutes (3 hours approx.)\u003c/p\u003e \u003cp\u003eThe mean duration of the monitoring was 13.7 +/- 4.6 days, resulting in a mean hospital stay of 16.8 +/- 5 days. (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eComplications\u003c/h2\u003e \u003cp\u003eSEEG-related events were initially identified in 14 patients (20%). However, most of these corresponded to minor radiological findings without clinical consequences, mainly small postoperative hemorrhagic changes detected on routine CT imaging. Specifically, 8 patients (11%) had small intracerebral hemorrhages and 3 (4%) had limited subarachnoid hemorrhage, none of which produced symptoms or required medical or surgical treatment. Two patients (3%) developed infection. Only \u003cb\u003eone patient (1%) experienced a clinically significant intracerebral hemorrhage requiring surgical evacuation\u003c/b\u003e, which resulted in a permanent neurological deficit. No deaths occurred in this series.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eThermocoagulation (RF-TC)\u003c/h3\u003e\n\u003cp\u003eRF-TC was performed after an electrical stimulation study on 37 patients (52%) in our series with the following indication: electrodes located in the EZ evaluated during the monitoring to ensure that these areas were not located in eloquent brain regions.\u003c/p\u003e \u003cp\u003eAmong the 37 patients who underwent RF-TC, 27 (73%) experienced some degree of seizure improvemen\u003cb\u003et\u003c/b\u003e at 12 months. However, according to Engel classification, only 41% achieved favorable outcomes (Engel classes I\u0026ndash;II), whereas 19% had Engel class III outcomes and 41% remained in Engel class IV. These findings suggest that RF-TC may provide meaningful symptomatic benefit in selected patients, although its effect is more appropriately interpreted as adjunctive or palliative rather than definitively curative.\u003c/p\u003e \u003cp\u003eOnly 5 patients (14%) developed transient complications like a hemiparesis (2 patients), aphasia/dysphasia (2 patients) and dysnomia (1 patient).\u003c/p\u003e\n\u003ch3\u003eHypothesis\u003c/h3\u003e\n\u003cp\u003eThe hypothesis was confirmed in 60 patients (85%), understanding the SEEG as a useful tool for the accurate diagnosis in drug-resistant epilepsy with diagnostic gaps when using general paraclinical tests.\u003c/p\u003e \u003cp\u003eA total of 37 patients ultimately underwent resective epilepsy surgery. Among them, 19 had previously received RF-TC as an initial therapeutic approach. In these cases, RF-TC did not lead to clinically meaningful seizure improvement, and resective surgery was subsequently indicated following multidisciplinary evaluation.\u003c/p\u003e \u003cp\u003ePostoperative seizure outcomes in the 37 surgically treated patients were evaluated at 3, 6, and 12 months using the Engel classification. At 3 months of follow-up, Engel class I outcomes were observed in 57% of patients, while 19% were classified as Engel class II, resulting in favorable seizure control (Engel classes I\u0026ndash;II) in 76% of cases. At 6 months, Engel class I outcomes decreased to 51%, with Engel class II remaining stable at 19%, yielding favorable outcomes in 70% of patients. At 12 months, Engel class I outcomes were observed in 49% of patients, while Engel class II increased slightly to 22%, maintaining favorable seizure control in 71% of the cohort. Across follow-up intervals, Engel class III outcomes ranged from 16% to 22%, whereas Engel class IV outcomes increased modestly over time, reaching 14% at 12 months. (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAll percentages are calculated based on the total cohort (n\u0026thinsp;=\u0026thinsp;37). Seizure outcomes were classified according to the Engel postoperative outcome scale at 3, 6 and 12 month follow-up. Favorable outcomes were defined as Engel classes I\u0026ndash;II.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003ePostoperative Seizure Outcomes at 3, 6, and 12 Month Follow-up According to the Engel Classification\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMonth\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEngel Class\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e34 patients were not candidates for resective epilepsy surgery. The main reasons included rejection of surgery by the patient (26%), multifocal epilepsy (24%), partial seizure improvement achieved with pharmacological adjustment combined with effective RF-TC (21%), high surgical risk (defined as the EZ located within eloquent brain areas) (18%), and absence of disabling seizures at the time of evaluation (12%).\u003c/p\u003e \u003cp\u003eAmong the patients excluded from resective surgery due to multifocal epilepsy (n\u0026thinsp;=\u0026thinsp;8), alternative neuromodulation-based surgical treatments were offered. Of these, 50% underwent deep brain stimulation of the anterior nucleus of the thalamus, 13% received deep brain stimulation of the centromedian nucleus, and 38% were treated with vagus nerve stimulation. (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAll percentages are calculated based on the total number of patients who were not candidates for resective surgery (n\u0026thinsp;=\u0026thinsp;34). RF-TC: radiofrequency thermocoagulation. High surgical risk refers to cases in which the EZ involved eloquent cortical areas.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eReasons for Not Undergoing Resective Epilepsy Surgery\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRejection of surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMultifocality\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePartial seizure improvement with pharmacological adjustment\u0026thinsp;+\u0026thinsp;RF-TC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh surgical risk\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbsence of disabling seizures\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis series is distinctive in highlighting how SEEG not only guides resective surgery but also informs non-surgical decision-making and the use of RF-TC as a standalone or adjunctive therapy over a 9-year evolution of practice\u003c/p\u003e \u003cp\u003eTechnical refinements, including the introduction of robotic assistance, have further improved accuracy and safety in SEEG procedures. Gonzalez-Martinez et al (2016) reported high precision with robotic implantation, reducing trajectory error and potentially minimizing complication risk [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Similarly, Cardinale et al. (2019) highlighted how modern stereotactic platforms and imaging integration contribute to improved outcomes and workflow efficiency [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Our own experience mirrors this evolution, as since 2023 we transitioned from the Vertek passive arm to the Neuromate\u0026reg; robotic system, maintaining safety while enhancing implantation accuracy.[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] Moreover, the implementation of computer-assisted planning platforms has recently shown potential to optimize RF-TC trajectories and outcomes, particularly in pediatric epilepsy. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eOur complication rate was 20% and consisted predominantly (86%) of minor intracerebral hemorrhages (\u0026lt;\u0026thinsp;5 cc), which had no clinical impact on patients and were therefore considered minor radiological findings; only one case (1%) developed an intracerebral hemorrhage requiring surgical drainage, resulting in permanent motor disability. These results are in line with large meta-analyses such as Mullin et al., who reported a pooled prevalence of 1.3% for clinically significant complications [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], and with McGovern et al., who emphasized the low risk of hemorrhage when proper planning and trajectory selection are applied [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRegarding RF-TC, our seizure improvement rate of 73% with seizure freedom in 14% compares favorably with recent long-term series. Lagarde et al. (2021) demonstrated that thermocoagulation can provide durable seizure reduction in carefully selected patients, with seizure freedom ranging from 10\u0026ndash;20% [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRecent analyses have also identified clinical predictors of favorable outcomes in MRI-negative patients undergoing RF-TC, further supporting the role of this approach in carefully selected populations [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThese findings support a clinically meaningful adjunctive role for RF-TC in selected patients, particularly when resective surgery is not feasible or is deferred. Although complete seizure freedom was limited, RF-TC provided worthwhile seizure reduction in a substantial proportion of patients, supporting its value as a palliative or bridge therapy within a broader individualized surgical strategy.\u003c/p\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eThis study has several limitations. First, its retrospective and single-center nature may limit generalizability. Second, although all patients were consecutively included, referral bias inherent to a tertiary epilepsy center must be considered. Third, our clinical practice evolved during the 9-year study period, particularly regarding imaging quality and the adoption of robotic assistance (transitioning from the Vertek passive arm to the Neuromate\u0026reg; system), which may have influenced complication rates and accuracy. Fourth, although follow-up was performed in all patients, the duration varied, and longer-term data are required to assess the durability of seizure outcomes, particularly after thermocoagulation. Finally, the relatively small sample size compared to multicenter meta-analyses may partly explain the differences in infection rates observed.\u003c/p\u003e \u003cp\u003eThe patient population presented here reflects a complete series of consecutively explored patients, representative of our center\u0026rsquo;s practice over a 9-year period. Our clinical practice has evolved over this period along with other aspects of our investigation such as the acceptance of thermocoagulation and the precision of MRI studies.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eSEEG represents a robust, safe, and highly effective diagnostic modality for the presurgical evaluation of patients with complex drug-resistant epilepsy. By enabling precise delineation of the EZ, SEEG substantially enhances the accuracy of surgical decision-making and optimizes the selection of candidates for resective procedures. When integrated with tailored resective surgery, SEEG contributes to achieving excellent long-term seizure control and meaningful improvements in quality of life. Furthermore, SEEG-guided RF-TC may represent a valuable adjunctive therapeutic option in carefully selected patients, particularly when resection is not feasible or when temporary seizure reduction may inform subsequent treatment decisions. Taken together, these advances underscore SEEG not merely as a diagnostic tool but as a cornerstone in the modern multidisciplinary management of drug-resistant epilepsy \u0026mdash;bridging innovation, precision, and therapeutic success. Ultimately, SEEG redefines the limits of presurgical evaluation and paves the way toward a future where individualized epilepsy surgery becomes not the exception, but the standard of care.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003cbr\u003e\u003cstrong\u003eAcknowledgments.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;None.\u003cbr\u003e\u003cstrong\u003eConflict of Interest / Disclosure.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The authors declare no conflicts of interest related to this work.\u003c/p\u003e\n\u003cp\u003eThe authors report no conflicts of interest in this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;Conceptualization: Marta Codes, Alvaro Bedoya, Pedro Roldan.\u003cbr\u003e\u0026nbsp;Methodology: Marta Codes, Abel Ferres, Alvaro Bedoya, Eugenia Pujol-Ayach\u003cbr\u003e\u0026nbsp;Data curation: Albert Mas, Mar Carre\u0026ntilde;o, Maria Centeno, Estefania Conde.\u003cbr\u003e\u0026nbsp;Formal analysis: Abel Ferres, Lorena Gomez, Jordi Rumia.\u003cbr\u003e\u0026nbsp;Investigation: Marta Olivera, Estefania Conde, Antonio Donaire, Eugenia Pujol-Ayach.\u003cbr\u003e\u0026nbsp;Writing \u0026ndash; original draft: Marta Codes, Alvaro Bedoya.\u003cbr\u003e\u0026nbsp;Writing \u0026ndash; review \u0026amp; editing: Marta Codes, Alvaro Bedoya, Pedro Roldan.\u003cbr\u003e\u0026nbsp;Supervision: Pedro Roldan.\u003cbr\u003e\u0026nbsp;Project administration: Alvaro Bedoya.\u003cbr\u003e\u0026nbsp;Visualization: Maria Centeno, Abel Ferres.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAI Use Declaration.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;No generative artificial intelligence tools were used for the generation of content, data analysis, or manuscript writing. Only minor language and grammar edits were performed under full author supervision, in compliance with the ethical publishing policies of World Neurosurgery: X.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request. Due to patient privacy and institutional regulations, raw clinical data cannot be publicly shared.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eReporting Guidelines.\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;This retrospective observational cohort study has been prepared in accordance with the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement. A completed STROBE checklist is submitted as a supplementary file.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval and Patient Consent.\u003c/strong\u003e\u003cbr\u003e\u003cem\u003eThis study was conducted in accordance with the principles outlined in the Declaration of Helsinki (2013 revision). The study protocol was reviewed by the Ethics Committee of Hospital Cl\u0026iacute;nic of Barcelona, which granted a waiver of formal informed consent due to the retrospective, observational design of the study and the use of fully anonymized institutional data. The internal ethics committee protocol number assigned to this study was HCB/2026/0164.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAll patients had previously provided written informed consent for undergoing stereoelectroencephalography (SEEG) implantation and SEEG-guided radiofrequency thermocoagulation as part of their standard clinical care and presurgical evaluation protocol. Patient confidentiality and data protection were strictly maintained throughout all phases of the study, in compliance with institutional policies and applicable data protection regulations.\u003c/em\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCossu M, Cardinale F, Colombo N, Francione S, Lo Russo G (2005) Stereoelectroencephalography in the presurgical evaluation of children with drug-resistant focal epilepsy. J Neurosurg 103(4 Suppl):333\u0026ndash;343\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZumsteg D, Wieser HG (2000) Presurgical evaluation: current role of invasive EEG. Epilepsia 41(Suppl 3):S55\u0026ndash;60\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcGonigal A, Bartolomei F, R\u0026eacute;gis J, Guye M, Gavaret M, Tr\u0026eacute;buchon-Da Fonseca A et al (2007) Stereoelectroencephalography in presurgical assessment of MRI-negative epilepsy. 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Front Neurol 15:1368334. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fneur.2024.1368334\u003c/span\u003e\u003cspan address=\"10.3389/fneur.2024.1368334\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"acta-neurochirurgica","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"anch","sideBox":"Learn more about [Acta Neurochirurgica](http://link.springer.com/journal/701)","snPcode":"701","submissionUrl":"https://submission.springernature.com/new-submission/701/3","title":"Acta Neurochirurgica","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Drug-Resistant Epilepsy, Stereoelectroencephalography, Thermocoagulation, Treatment Outcome, Complications","lastPublishedDoi":"10.21203/rs.3.rs-9193268/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9193268/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eStereoelectroencephalography (SEEG) is a pivotal diagnostic and therapeutic tool in the presurgical evaluation of patients with drug-resistant epilepsy, particularly when noninvasive investigations are inconclusive.\u003c/p\u003e\u003cp\u003e\u003cb\u003eObjective\u003c/b\u003e\u003c/p\u003e \u003cp\u003eTo evaluate the indications, technical aspects, safety profile, and clinical outcomes of SEEG, including the adjunctive role of SEEG-guided radiofrequency thermocoagulation (RF-TC).\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003e We conducted a retrospective review of 71 consecutive patients with drug-resistant epilepsy who underwent SEEG monitoring at our institution between 2016 and 2025. Demographic, neuroimaging, and electrophysiological data were analyzed, along with surgical variables, perioperative complications, and outcomes following SEEG-guided RF-TC and subsequent resective surgery.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eA total of 958 electrodes were implanted (mean 14\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5 per patient). SEEG confirmed the preimplantation hypothesis in 85% of cases. RF-TC was performed in 37 patients (52%); among them, 27 patients (73%) showed seizure improvement at 12 months. According to the Engel classification, 14% achieved class I, 27% class II, 19% class III, and 41% class IV outcomes. Complications occurred in 14 patients (20%), predominantly minor radiological findings; only one patient (1%) developed a permanent neurological deficit. Among the 37 patients who underwent resective surgery, favorable seizure outcomes (Engel classes I\u0026ndash;II) were achieved in 76%, 70%, and 71% at 3, 6, and 12 months, respectively.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusions\u003c/b\u003e\u003c/p\u003e \u003cp\u003eSEEG is a safe and effective modality for presurgical evaluation in drug-resistant epilepsy. It improves localization of the epileptogenic zone (EZ), guides individualized surgical decision-making and provides therapeutic benefit through RF-TC in carefully selected patients.\u003c/p\u003e","manuscriptTitle":"Stereoelectroencephalography in the Presurgical Evaluation of Drug–Resistant Epilepsy: Retrospective Analysis of Clinical Efficacy and Safety in 71 Procedures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-26 16:52:57","doi":"10.21203/rs.3.rs-9193268/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-09T12:51:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-08T15:12:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"213193704776221431632067254977496116924","date":"2026-03-25T18:59:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-24T18:14:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-23T08:52:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-23T08:51:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Acta Neurochirurgica","date":"2026-03-22T18:48:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"acta-neurochirurgica","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"anch","sideBox":"Learn more about [Acta Neurochirurgica](http://link.springer.com/journal/701)","snPcode":"701","submissionUrl":"https://submission.springernature.com/new-submission/701/3","title":"Acta Neurochirurgica","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"630e7b92-fd42-4dc7-88b4-02af7a88d186","owner":[],"postedDate":"March 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-08T08:53:55+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-26 16:52:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9193268","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9193268","identity":"rs-9193268","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}