Comparative Analysis of Hemispherotomy in Adults versus Children- A Prospective Observational Series.

BACKGROUND: Hemispherotomy (HS) is an effective treatment for unilateral hemispheric onset epilepsy. There are few publications for HS in adults, and there is no series comparing adults and pediatric patients of HS. OBJECTIVE: To compare the hemispherotomies done in adult patients with pediatric ones in terms of efficacy and safety. METHODS: Data was prospectively collected for HS patients (up to 18 years and more) from Aug 2014 to Aug 2018. Comparison between the groups was made for seizure onset, duration of epilepsy, frequency of seizures, number of drugs, intraoperative blood loss, postoperative seizure control, postoperative stay, postoperative motor functions, and preoperative and postoperative intelligence quotient. Follow-up was one year. RESULTS: A total of 61 pediatric and 11 adults underwent HS. The seizure onset was earlier in children, and the duration of epilepsy was longer in adults. The frequency of seizures per day was more in children being 14.62 ± 26.34 in children, and 7.71 ± 5.21 per day in adults (P - 0.49). The mean number of drugs was similar in the preoperative and postoperative periods in both. Class I seizure outcome was similar in both the groups being 85.24% in children and 90.9% in adults (P - 0.56). Blood loss, postoperative stay, was similar in both the groups. No patient had a new permanent motor deficit. Power worsened transiently in 1 pediatric patient and in 4 adult patients. The visual word reading and object naming improved in both the groups (no intergroup difference), and IQ remained the same in both groups. One adult patient had meningitis, and another had hydrocephalus requiring shunt placement. CONCLUSION: Hemispherotomy is a safe and effective procedure in adults as in children in appropriately selected patients.

Generalisability of epileptiform patterns across time and patients.

The complexity of localising the epileptogenic zone (EZ) contributes to surgical resection failures in achieving seizure freedom. The distinct patterns of epileptiform activity during interictal and ictal phases, varying across patients, often lead to suboptimal localisation using electroencephalography (EEG) features. We posed two key questions: whether neural signals reflecting epileptogenicity generalise from interictal to ictal time windows within each patient, and whether epileptiform patterns generalise across patients. Utilising an intracranial EEG dataset from 55 patients, we extracted a large battery of simple to complex features from stereo-EEG (SEEG) and electrocorticographic (ECoG) neural signals during interictal and ictal windows. Our features (n = 34) quantified many aspects of the signals including statistical moments, complexities, frequency-domain and cross-channel network attributes. Decision tree classifiers were then trained and tested on distinct time windows and patients to evaluate the generalisability of epileptogenic patterns across time and patients, respectively. Evidence strongly supported generalisability from interictal to ictal time windows across patients, particularly in signal power and high-frequency network-based features. Consistent patterns of epileptogenicity were observed across time windows within most patients, and signal features of epileptogenic regions generalised across patients, with higher generalisability in the ictal window. Signal complexity features were particularly contributory in cross-patient generalisation across patients. These findings offer insights into generalisable features of epileptic neural activity across time and patients, with implications for future automated approaches to supplement other EZ localisation methods.

The role of preoperative [11C]methionine PET in defining tumor-related epilepsy and predicting short-term postoperative seizure control in temporal lobe low-grade gliomas.

OBJECTIVE: Surgery is the mainstay of treatment for low-grade glioma (LGG)-related epilepsy. However, the goal of achieving both oncological radical resection and seizure freedom can be challenging. PET with [11C]methionine (MET) has been recently introduced in clinical practice for the management of patients with LGGs, not only to monitor the response to treatments, but also as a preoperative tool to define the metabolic tumor extent and to predict tumor grading, type, and prognosis. Still, its role in defining tumor-related epilepsy and postoperative seizure outcomes is limited. The aim of this preliminary study was to investigate the role of MET PET in defining preoperative seizure characteristics and short-term postoperative seizure control in a cohort of patients with newly diagnosed temporal lobe low-grade gliomas (tLGGs). METHODS: Patients with newly diagnosed and histologically proven temporal lobe grade 2/3 gliomas (2021 WHO CNS tumor classification) who underwent resection at the authors' institution between July 2011 and March 2021 were included in this retrospective study. MET PET images were acquired, fused with MRI scans, and qualitatively and semiquantitatively analyzed. Any eventual PET/MRI involvement of the temporomesial area, seizure characteristics, and 1-year seizure outcomes were reported. RESULTS: A total of 52 patients with tLGGs met the inclusion criteria. MET PET was positive in 41 (79%) patients, with a median metabolic tumor volume of 14.56 cm3 (interquartile range [IQR] 6.5-28.2 cm3). The median maximum and mean tumor-to-background ratio (TBRmax, TBRmean) were 2.24 (IQR 1.58-2.86) and 1.53 (IQR 1.37-1.70), respectively. The metabolic tumor volume was found to be related to the presence of seizures at disease onset, but only in noncodeleted tumors (p = 0.014). Regarding patients with uncontrolled seizures at surgery, only the temporomesial area PET involvement showed a statistical correlation both in the univariate (p = 0.058) and in the multivariate analysis (p = 0.030). At 1-year follow-up, seizure control was correlated with MET PET-derived semiquantitative data. Particularly, higher TBRmax (p = 0.0192) and TBRmean (p = 0.0128) values were statistically related to uncontrolled seizures 1 year after surgery. CONCLUSIONS: This preliminary study suggests that MET PET may be used as a preoperative tool to define seizure characteristics and outcomes in patients with tLGGs. These findings need to be further validated in larger series with longer epileptological follow-ups.

Outcomes following surgical interventions for hypothalamic hamartomas: protocol for a systematic review and individual patient data meta-analysis.

INTRODUCTION: Hypothalamic hamartomas (HHs) are deep-seated congenital lesions that typically lead to pharmacoresistant epilepsy and a catastrophic encephalopathic syndrome characterised by severe neuropsychological impairment and decline in quality of life. A variety of surgical approaches and technologies are available for the treatment of HH-related pharmacoresistant epilepsy. There remains, however, a paucity of literature directly comparing their relative efficacy and safety. This protocol aims to facilitate a systematic review and meta-analysis that will characterise and compare the probability of seizure freedom and relevant postoperative complications across different surgical techniques performed for the treatment of HH-related pharmacoresistant epilepsy. METHODS AND ANALYSIS: This protocol was developed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Individual Participant Data guidelines. Three major databases, PubMed, Embase and Scopus, will be systematically searched from database inception and without language restrictions for relevant articles using our predefined search strategy. Title-abstract and full text screening using inclusion and exclusion criteria created a priori will be performed by two independent reviewers to identify eligible articles. Conflicts will be resolved via discussion with a third team member. Following data extraction of both study-level and individual patient data (IPD), a study-level and IPD meta-analysis will be performed. Study-level analysis will focus on assessing the degree of heterogeneity in the data and quantifying overall seizure outcomes for each surgical technique. The IPD analysis will use multivariable regression to determine perioperative predictors of seizure freedom and complications that can guide patient and technique selection. ETHICS AND DISSEMINATION: This work will not require ethics approval as it will be solely based on previously published and available data. The results of this review will be shared via conference presentation and submission to peer-reviewed neurosurgical journals. PROSPERO REGISTRATION: CRD42022378876.

Negative MRI and a seizure onset zone close to eloquent areas in FCD type II: Application of MRg-LiTT after a SEEG re-evaluation in pediatric patients with a previous failed surgery.

OBJECTIVE: Negative MRI and an epileptogenic zone (EZ) adjacent to eloquent areas are two main issues that can be encountered during pre-surgical evaluation for epilepsy surgery. Focal Cortical Dysplasia type II (FCD type II) is the most common aetiology underlying a negative MRI. The objective of this study is to present three cases of pediatric patients exhibiting negative MRI and a seizure onset zone close to eloquent areas, who previously underwent traditional open surgery or SEEG-guided radiofrequency thermocoagulations (RF-TC). After seizure seizure recrudescence, pre-surgical SEEG was re-evaluated and Magnetic Resonance-guided laser interstitial thermal therapy (MRg-LiTT) was performed. We discuss the SEEG patterns, the planning of laser probes trajectories and the outcomes one year after the procedure. METHODS: Pediatric patients who underwent SEEG followed by MRg-LiTT for drug-resistant epilepsy associated with FCD type II at our Centre were included. Pre-surgical videoEEG (vEEG), stereoEEG (sEEG), and MRI were reviewed. Post-procedure clinical outcome (measured by Engel score) and complications rates were evaluated. RESULTS: Three patients underwent 3 MRg-LiTT procedures from January 2022 to June 2022. Epileptogenic zone was previously studied via SEEG in all the patients. All the three patients pre-surgical MRI was deemed negative. Mean age at seizure onset was 47 months (21-96 months), mean age at MRg-LiTT was 12 years (10 years 10 months - 12 years 9 months). Engel class Ia outcome was achieved in patients #2 and #3, Engel class Ib in patient #1. Mean follow-up length was of 17 months (13 months - 20 months). Complications occurred in one patient (patient #2, extradural hematoma). CONCLUSIONS: The combined use of SEEG and MRg-LiTT in complex cases can lead to good outcomes both as a rescue therapy after failed surgery, but also as an alternative to open surgery after a successful SEEG-guided Radiofrequency Thermocoagulation (RF-TC). Specific SEEG patterns and a previous good outcome from RF-TC can be predictors of a favourable outcome.

Preoperative structural-functional coupling at the default mode network predicts surgical outcomes of temporal lobe epilepsy.

OBJECTIVE: Structural-functional coupling (SFC) has shown great promise in predicting postsurgical seizure recurrence in patients with temporal lobe epilepsy (TLE). In this study, we aimed to clarify the global alterations in SFC in TLE patients and predict their surgical outcomes using SFC features. METHODS: This study analyzed presurgical diffusion and functional magnetic resonance imaging data from 71 TLE patients and 48 healthy controls (HCs). TLE patients were categorized into seizure-free (SF) and non-seizure-free (nSF) groups based on postsurgical recurrence. Individual functional connectivity (FC), structural connectivity (SC), and SFC were quantified at the regional and modular levels. The data were compared between the TLE and HC groups as well as among the TLE, SF, and nSF groups. The features of SFC, SC, and FC were categorized into three datasets: the modular SFC dataset, regional SFC dataset, and SC/FC dataset. Each dataset was independently integrated into a cross-validated machine learning model to classify surgical outcomes. RESULTS: Compared with HCs, the visual and subcortical modules exhibited decoupling in TLE patients (p < .05). Multiple default mode network (DMN)-related SFCs were significantly higher in the nSF group than in the SF group (p < .05). Models trained using the modular SFC dataset demonstrated the highest predictive performance. The final prediction model achieved an area under the receiver operating characteristic curve of .893 with an overall accuracy of .887. SIGNIFICANCE: Presurgical hyper-SFC in the DMN was strongly associated with postoperative seizure recurrence. Furthermore, our results introduce a novel SFC-based machine learning model to precisely classify the surgical outcomes of TLE.

Surgical Outcome of Pharmaco Refractory Epilepsy in the National Epilepsy Center of Sri Lanka.

BACKGROUND: The National Epilepsy Center (NEC) in Sri Lanka was established in 2017. Seizure outcome, effects on quality of life (QOL) and surgical complications among nonpediatric patients who underwent epilepsy surgery from October 2017 to February 2023 are described. METHODS: Nineteen patients (≥14 years) underwent epilepsy surgery at the NEC. We used Engel classification and Quality of Life in Epilepsy 31 (QOLIE-31) questionnaire to assess seizure outcome and QOL respectively. Surgical complications were categorized into neurological and complications related to surgery. RESULTS: Nine female and 10 male patients underwent surgery (mean age 27.5 years (range 14-44 years). The mean follow-up duration was 10.5 months (range 6-55 months). Twelve patients underwent temporal lobe resections. At 6-months follow-up, 83.3% (10/12) had favorable seizure outcomes with Engel class I/II. At 1-year follow-up 6/8 patients (75.0%) and at 2-year follow-up, 5/7 patients (71.4%) had a favorable outcome. Seven patients had extra-temporal lobe surgeries and one defaulted. Seizure freedom was observed in 6/6 at 6 months, 3/3 at 1-year, and 2/2 at 2-year follow-up. Five patients (26.3%) experienced minor post-operative surgical site infection. Two (11.1%) had persistent quadrantanopia. Meaningful improvement in QOL (change in QOLIE-31 score ≥11.8) was observed irrespective of seizure outcome or type of surgery (P < 0.001). CONCLUSIONS: Epilepsy surgery is effective in developing countries. Seizure outcomes in our patients are comparable to those worldwide. Clinically important QOL improvement was observed in our series. This is the first published data on epilepsy surgery outcomes in nonpediatric patients from Sri Lanka.

Impact of intracranial subclinical seizures on seizure outcomes after SLAH in patients with mesial temporal lobe epilepsy.

OBJECTIVE: To investigate the association between subclinical seizures detected on intracranial electroencephalographic (i-SCSs)recordings and mesial temporal sclerosis (MTS), as well as their impact on surgical outcomes of stereotactic laser amygdalohippocampotomy (SLAH). METHODS: A retrospective review was conducted on 27 patients with drug-resistant mesial temporal lobe epilepsy (MTLE) who underwent SLAH. The number of seizures detected on scalp EEG and iEEG was assessed. Patients were followed for a minimum of 3 years after SLAH. RESULTS: Of the 1715 seizures recorded from mesial temporal regions, 1640 were identified as i-SCSs. Patients with MTS were associated with favorable short- and long-term surgical outcomes. Patients with MTS had a higher number of i-SCSs compared to patients without MTS. The numbers of i-SCSs were higher in patients with Engel I-II outcomes, but no significant statistical difference was found. However, it was observed that patients with MTS who achieved Engel I-II classification had higher numbers of i-SCSs than patients without MTS (P < 0.05). CONCLUSION: Patients with MTS exhibited favorable short-term and long-term surgical outcome after SLAH. A higher number of i-SCSs was significantly associated with MTS in patients with MTLE. The number of i-SCSs tended to be higher in patients with Engel Ⅰ-Ⅱ surgical outcomes. SIGNIFICANCE: The association between i-SCSs, MTS, and surgical outcomes in MTLE patients undergoing SLAH has significant implications for understanding the underlying mechanisms and identifying potential therapeutic targets to enhance surgical outcomes.

Discontinuation of Antiseizure Medications in Patients With Brain Tumors.

Patients with brain tumors will experience seizures during their disease course. While providers can use antiseizure medications to control these events, patients with brain tumors can experience side effects, ranging from mild to severe, from these medications. Providers in subspecialties such as neurology, neuro-oncology, neurosurgery, radiation oncology, and medical oncology often work with patients with brain tumor to balance seizure control and the adverse toxicity of antiseizure medications. In this study, we sought to explore the problem of brain tumor-related seizures/epilepsy in the context of how and when to consider antiseizure medication discontinuation. Moreover, we thoroughly evaluate the literature on antiseizure medication discontinuation for adult and pediatric patients and highlight recommendations relevant to patients with both brain tumors and seizures.

Pediatric cerebral cavernous malformations and stereotactic radiosurgery: an analysis of 50 cases from a multicentric study.

OBJECTIVE: Cerebral cavernous malformations (CCMs) are the second most common vascular anomaly affecting the CNS in children. Although stereotactic radiosurgery (SRS) has been proposed as an alternative to microsurgery in the management of selected cases in adults, there is a paucity of studies focusing on pediatric patients. The aim of this study was to present the outcomes and associated risks of SRS in this subgroup of patients. METHODS: This retrospective multicenter study included pediatric patients treated with single-session SRS for CCMs. The annual hemorrhage rate (AHR) was calculated before and after SRS in hemorrhagic lesions. The Engel classification was used to describe post-SRS epileptic control. Adverse radiation effects (AREs) and the occurrence of new neurological deficits were recorded. RESULTS: The study included 50 patients (median age 15.1 [IQR 5.6] years) harboring 62 CCMs. Forty-two (84%) and 22 (44%) patients had a history of hemorrhage or epilepsy prior to SRS, respectively. The AHR from diagnosis to SRS excluding the first hemorrhage was 7.19 per 100 CCM-years, dropping to 3.15 per 100 CCM-years after treatment. The cumulative risk of first hemorrhage after SRS was 7.4% (95% CI 0%-14.3%) at 5 years and 23.6% (95% CI 0%-42.2%) at 10 years. Eight hemorrhagic events involving 6 CCMs in 6 patients were recorded in the post-SRS follow-up period; 4 patients presented with transient symptoms and 4 with permanent symptoms. Of the 22 patients with pre-SRS seizures, 11 were seizure free at the last follow-up (Engel class I), 6 experienced improvement (Engel class II or III), 5 had no improvement (Engel class IVA or IVB), and 1 experienced worsening (Engel class IVC). Radiographic AREs were documented in 14.5% (9/62) of CCMs, with 4 being symptomatic. CONCLUSIONS: Single-session SRS reduces the CCM hemorrhage rate in the pediatric population and provides adequate seizure control.

The value of additional electrodes when stereo-electroencephalography is inconclusive.

OBJECTIVE: Stereo-electroencephalography (SEEG) is the preferred method for intracranial localization of the seizure-onset zone (SOZ) in drug-resistant focal epilepsy. Occasionally SEEG evaluation fails to confirm the pre-implantation hypothesis. This leads to a decision tree regarding whether the addition of SEEG electrodes (two-step SEEG - 2sSEEG) or placement of subdural electrodes (SDEs) after SEEG (SEEG2SDE) would help. There is a dearth of literature encompassing this scenario, and here we aimed to characterize outcomes following unplanned two-step intracranial EEG (iEEG). METHODS: All 225 adult SEEG cases over 8 years at our institution were reviewed to extract patient data and outcomes following a two-step evaluation. Three raters independently quantified benefits of additional intracranial electrodes. The relationship between two-step iEEG benefit and clinical outcome was then analyzed. RESULTS: Fourteen patients underwent 2sSEEG and nine underwent SEEG2SDE. In the former cohort, the second SEEG procedure was performed for these reasons-precise localization of the SOZ (36%); defining margins of eloquent cortex (21%); and broadening coverage in the setting of non-localizable seizure onsets (43% of cases). Sixty-four percent of 2sSEEG cases were consistently deemed beneficial (Light's κ = 0.80). 2sSEEG performed for the first two indications was much more beneficial than when onsets were not localizable (100% vs 17%, p = .02). In the SEEG2SDE cohort, SDEs identified the SOZ and enabled delineation of margins relative to eloquent cortex in all cases. SIGNIFICANCE: The two-step iEEG is useful if the initial evaluation is broadly concordant with the original electroclinical hypothesis, where it can clarify onset zones or delineate safe surgical margins; however, it provides minimal benefit when the implantation hypothesis is erroneous, and we recommend that 2sSEEG not be generally utilized in such cases. SDE implantation after SEEG minimizes the need for SDEs and is helpful in delineating surgical boundaries relative to ictal-onset zones and eloquent cortex.

Impact of augmented reality fiber tractography on the extent of resection and functional outcome of primary motor area tumors.

OBJECTIVE: This study aimed to evaluate the impact of augmented reality intraoperative fiber tractography (AR-iFT) on extent of resection (EOR), motor functional outcome, and survival of patients with primary motor area (M1) intra-axial malignant tumors. METHODS: Data obtained from patients who underwent AR-iFT for M1 primary tumors were retrospectively analyzed and compared with those from a control group who underwent unaugmented reality intraoperative fiber tractography (unAR-iFT). A full asleep procedure with electrical stimulation mapping and fluorescein guidance was performed in both groups. The Neurological Assessment in Neuro-Oncology (NANO), Medical Research Council (MRC), and House-Brackmann grading systems were used for neurological, motor, and facial nerve assessment, respectively. Three-month postoperative NANO and MRC scores were used as outcome measures of the safety of the technique, whereas EOR and survival curves were related to its cytoreductive efficacy. In this study, p < 0.05 indicated statistical significance. RESULTS: This study included 34 and 31 patients in the AR-iFT and unAR-iFT groups, respectively. The intraoperative seizure rate, 3-month postoperative NANO score, and 1-week and 1-month MRC scores were significantly (p < 0.05) different and in favor of the AR-iFT group. However, no difference was observed in the rate of complications. Glioma had incidence rates of 58.9% and 51.7% in the study and control groups, respectively, with no statistical difference. Metastasis had a slightly higher incidence rate in the control group, without statistical significance, and the gross-total resection and near-total resection rates and progression-free survival (PFS) rate were higher in the study group. Overall survival was not affected by the technique. CONCLUSIONS: AR-iFT proved to be feasible, effective, and safe during surgery for M1 tumors and positively affected the EOR, intraoperative seizure rate, motor outcome, and PFS. Integration with electrical stimulation mapping is critical to achieve constant anatomo-functional intraoperative feedback. The accuracy of AR-iFT is intrinsically limited by diffusion tensor-based techniques, parallax error, and fiber tract crowding. Further studies are warranted to definitively validate the benefits of augmented reality navigation in this surgical scenario.

EEG Source Imaging in Presurgical Evaluations.

SUMMARY: Presurgical evaluations to plan intracranial EEG implantations or surgical therapies at most epilepsy centers in the United States currently depend on the visual inspection of EEG traces. Such analysis is inadequate and does not exploit all the localizing information contained in scalp EEG. Various types of EEG source modeling or imaging can provide sublobar localization of spike and seizure sources in the brain, and the software to do this with typical long-term monitoring EEG data are available to all epilepsy centers. This article reviews the fundamentals of EEG voltage fields that are used in EEG source imaging, the strengths and weakness of dipole and current density source models, the clinical situations where EEG source imaging is most useful, and the particular strengths of EEG source imaging for various cortical areas where spike/seizure sources are likely.

Stereoelectroencephalography: a review of complications and outcomes in a new Australian centre.

BACKGROUND: Surgical management of refractory focal epilepsy requires preoperative localisation of the epileptogenic zone (EZ). To augment noninvasive studies, stereoelectroencephalography (SEEG) is being increasingly adopted as a form of intracranial monitoring. AIMS: This study aimed to determine the rate of complications for patients undergoing SEEG and to report the success of SEEG with regard to EZ detection and seizure outcome following definitive surgery. METHODS: A retrospective cohort design investigated all cases of SEEG at our institution. Surgical, anaesthetic and medical complications with subsequent epilepsy surgery and seizure outcome data were extracted from medical records. Multivariate logistic regression was used to investigate the relationship between both the number of electrodes per patient and the duration of SEEG recording with the rate of complications. RESULTS: Sixty-four patients with 66 implantations were included. Headache was the most common complication (n = 54, 82%). There were no major surgical or medical complications. Two anaesthetic complications occurred. EZ localisation was successful in 63 cases (95%). Curative intent surgery was performed in 39 patients (59%) and 23 patients achieved an Engel class I outcome (59% of those undergoing surgery). The number of electrodes and duration of recording were not associated with complications. CONCLUSIONS: No patients in our series experienced major surgical or medical complications and we have highlighted the challenges associated with neuroanaesthesia in SEEG. Our complication rates and seizure outcomes are equivalent to published literature indicating that this technique can be successfully established in newer centres using careful case selection. Standardised reporting of SEEG complications should be adopted.

Pearls & Oy-sters: Mesial Temporal Seizures in the Absence of the Mesial Temporal Lobe. Seizure Onset vs Seizure Network

Seizure semiology represents the clinical expression of the activation of the several brain regions comprising an epileptic network. In mesial temporal lobe epilepsy (MTLE), this network includes the insular-opercular-neocortical temporal-hippocampal (IONTH) regions. In this study, we present the case of a patient with pharmacoresistant seizures characterized by nausea, lip-smacking, semipurposeful hand movements, and speechlessness, suggesting dominant hemisphere MTLE, with scalp video-EEG findings and left hippocampal sclerosis on brain MRI confirming the diagnosis. She underwent anterior temporal lobectomy with amygdalohippocampectomy and was seizure-free for 14 years before relapsing. Recurrent seizure semiology was similar to preoperative seizures, that is, consistent with left MTLE, despite the medial temporal lobe missing. Seizures were therefore assumed to arise from remnant portions of the IONTH network-the insula, operculum, and posterolateral temporal neocortex. Reinvestigation including MEG localization of spikes and acute MRI changes following a seizure cluster suggested a left opercular region epilepsy. Our patient thus demonstrated the principle that seizures with mesial temporal characteristics may arise from outside the mesial temporal lobe (MTL). MTLE semiology arises from the activation of a set of structures (the seizure network) associated with the MTL, which can be triggered by foci both within and outside the MTL itself, and indeed even in its absence. However, it is not necessary to resect the entire extended network to bring about extended periods of seizure freedom in patients with refractory MTLE.

Approach, complications, and outcomes for 37 consecutive pediatric patients undergoing laser ablation for medically refractory epilepsy at Stanford Children's Health.

OBJECTIVE: The objective of this study was to better understand the safety and efficacy of laser interstitial thermal therapy (LITT) for children with medically refractory epilepsy. METHODS: Thirty-seven consecutive pediatric epilepsy patients at a single pediatric center who underwent LITT ablation of epileptogenic foci between May 2017 and December 2021 were retrospectively reviewed. Patient demographics, medication use, seizure frequency, prior surgical interventions, procedural details, and pre- and postoperative seizure history were analyzed. RESULTS: Thirty-seven pediatric patients (24 male, 13 female) with severe medically refractory epilepsy were included; all underwent stereo-electroencephalography (SEEG) prior to LITT. The SEEG electrode placement was based on the preoperative workup and tailored to each patient by the epileptologist and neurosurgeons working together to identify the epileptic network and hopefully quiet borders. Seizure onset was at a mean age of 2.70 ± 2.82 years (range 0.25-12 years), and the mean age at the time of LITT was 9.46 ± 5.08 years (range 2.41-17.86 years). Epilepsy was lesional in 23 patients (18 tuberous sclerosis, 4 focal cortical dysplasia, 1 gliosis) and nonlesional in 14. Eighteen patients had prior surgical interventions including open resections (n = 13: 11 single and 2 multiple), LITT (n = 4), or both (n = 1). LITT targeted a region adjacent to the previous target in 5 cases. The median number of lasers placed during the procedure was 3 (range 1-5). Complications occurred in 14 (37.8%) cases, only 3 (8.11%) of which resulted in a permanent deficit: 1 venous hemorrhage requiring evacuation following laser ablation, 1 aseptic meningitis, 2 immediate postoperative seizures, and 10 neurological deficits (7 transient and 3 permanent). Postoperatively, 22 (59.5%) patients were seizure free at the last follow-up (median follow-up 18.35 months, range 7.40-48.76 months), and the median modified Engel class was I (Engel class I in 22 patients, Engel class II in 2, Engel class III in 2, and Engel class IV in 11). Patients having tried a greater number of antiseizure medications before LITT were less likely to achieve seizure improvement (p = 0.046) or freedom (p = 0.017). Seizure improvement following LITT was associated with a shorter duration of epilepsy prior to LITT (p = 0.044), although postoperative seizure freedom was not associated with a shorter epilepsy duration (p = 0.667). Caregivers reported postoperative neurocognitive improvement in 17 (45.9%) patients. CONCLUSIONS: In this large single-institution cohort of pediatric patients with medically refractory seizures due to various etiologies, LITT was a relatively safe and effective surgical approach for seizure reduction and seizure freedom at 1 year of follow-up.

Early Postoperative Seizures Following Awake Craniotomy and Functional Brain Mapping for Lesionectomy.

OBJECTIVE: Awake craniotomy with electrocorticography (ECoG) and direct electrical stimulation (DES) facilitates lesionectomy while avoiding adverse effects. Early postoperative seizures (EPS), occurring within 7 days following surgery, can lead to morbidity. However, risk factors for EPS after awake craniotomy including clinical and ECoG data are not well defined. METHODS: We retrospectively studied the incidence and risk factors of EPS following awake craniotomy for lesionectomy, and report short-term outcomes between January 1, 2020, and December 31, 2022. RESULTS: We included 138 patients (56 female) who underwent 142 awake craniotomies, average age was 50.78 ± 15.97 years. Eighty-eight (63.7%) patients had a preoperative history of tumor-related epilepsy treated with antiseizure medication (ASM), 12 (13.6%) with drug-resistance. All others (36.3%) received ASM prophylaxis with levetiracetam perioperatively and continued for 14 days. An equal number of cases (71) each utilized a novel circle grid or strip electrodes for ECoG. There were 31 (21.8%) cases of intraoperative seizures, 16 with EPS (11.3%). Acute abnormality on early postoperative neuroimaging (P = 0.01), subarachnoid hemorrhage (P = 0.01), young age (P = 0.01), and persistent postoperative neurologic deficits (P = 0.013) were associated with EPS. Acute abnormality on neuroimaging remained significant in multivariate analysis. Outcomes during hospitalization and early outpatient follow up were worse with EPS. CONCLUSIONS: We report novel findings using ECoG and clinical features to predict EPS, including acute perioperative brain injury, persistent postoperative deficits and young age. Given worse outcomes with EPS, clinical indicators for EPS should alert clinicians of potential need for early postoperative EEG monitoring and perioperative ASM adjustment.

Prediction tools and risk stratification in epilepsy surgery.

OBJECTIVE: This study was undertaken to conduct external validation of previously published epilepsy surgery prediction tools using a large independent multicenter dataset and to assess whether these tools can stratify patients for being operated on and for becoming free of disabling seizures (International League Against Epilepsy stage 1 and 2). METHODS: We analyzed a dataset of 1562 patients, not used for tool development. We applied two scales: Epilepsy Surgery Grading Scale (ESGS) and Seizure Freedom Score (SFS); and two versions of Epilepsy Surgery Nomogram (ESN): the original version and the modified version, which included electroencephalographic data. For the ESNs, we used calibration curves and concordance indexes. We stratified the patients into three tiers for assessing the chances of attaining freedom from disabling seizures after surgery: high (ESGS = 1, SFS = 3-4, ESNs > 70%), moderate (ESGS = 2, SFS = 2, ESNs = 40%-70%), and low (ESGS = 2, SFS = 0-1, ESNs < 40%). We compared the three tiers as stratified by these tools, concerning the proportion of patients who were operated on, and for the proportion of patients who became free of disabling seizures. RESULTS: The concordance indexes for the various versions of the nomograms were between .56 and .69. Both scales (ESGS, SFS) and nomograms accurately stratified the patients for becoming free of disabling seizures, with significant differences among the three tiers (p < .05). In addition, ESGS and the modified ESN accurately stratified the patients for having been offered surgery, with significant difference among the three tiers (p < .05). SIGNIFICANCE: ESGS and the modified ESN (at thresholds of 40% and 70%) stratify patients undergoing presurgical evaluation into three tiers, with high, moderate, and low chance for favorable outcome, with significant differences between the groups concerning having surgery and becoming free of disabling seizures. Stratifying patients for epilepsy surgery has the potential to help select the optimal candidates in underprivileged areas and better allocate resources in developed countries.

A multi-center comparison of surgical techniques for corpus Callosotomy in pediatric drug-resistant epilepsy.

OBJECTIVES: Corpus callosotomy (CC) is used to reduce seizures, primarily in patients with generalized drug-resistant epilepsy (DRE). The invasive nature of the procedure contributes to underutilization despite its potential superiority to other palliative procedures. The goal of this study was to use a multi-institutional epilepsy surgery database to characterize the use of CC across participating centers. METHODS: Data were acquired from the Pediatric Epilepsy Research Consortium (PERC) Surgery Database, a prospective observational study collecting data on children 0-18 years referred for surgical evaluation of DRE across 22 U.S. pediatric epilepsy centers. Patient, epilepsy, and surgical characteristics were collected across multiple CC modalities. Outcomes and complications were recorded and analyzed statistically. RESULTS: Eighty-three patients undergoing 85 CC procedures at 14 participating epilepsy centers met inclusion criteria. Mean age at seizure onset was 2.3 years (0-9.4); mean age for Phase I evaluation and surgical intervention were 9.45 (.1-20) and 10.46 (.2-20.6) years, respectively. Generalized seizure types were the most common (59%). Complete CC was performed in 88%. The majority of CC procedures (57%) were via open craniotomy, followed by laser interstitial thermal therapy (LiTT) (20%) and mini-craniotomy/endoscopic (mc/e) (22%). Mean operative times were significantly longer for LiTT, whereas mean estimated blood loss was greater in open cases. Complications occurred in 11 cases (13%) and differed significantly between surgical techniques (p < .001). There was no statistically significant difference in length of postoperative stay across approaches. Mean follow-up was 12.8 months (range 1-39). Favorable Engel outcomes were experienced by 37 (78.7%) of the patients who underwent craniotomy, 10 (58.8%) with LiTT, and 12 (63.2%) with mc/e; these differences were not statistically significant. SIGNIFICANCE: CC is an effective surgical modality for children with DRE. Regardless of surgical modality, complication rates are acceptable and seizure outcomes generally favorable. Newer, less-invasive, surgical approaches may lead to increased adoption of this efficacious therapeutic option for pediatric DRE.