Epilepsy surgery below the age of 5 years: Are we still in time to preserve developmental and intellectual functions?

OBJECTIVE: The aim of this study is to describe the pre- and post-operative developmental and intellectual functions in a cohort of patients who underwent surgery for drug-resistant epilepsy (DRE) before the age of 5 years. METHOD: We retrospectively reviewed the medical records and neurodevelopmental assessments of a cohort of 80 surgically treated pediatric patients with DRE. We included patients if they had at least one pre- and one post-surgical neuropsychological assessments; 27 met the inclusion criteria. We evaluated Developmental Quotient (DQ) and Intelligence Quotient (IQ) before and after surgery. We identified two groups based on psychological evaluation outcome: Group 1, with stable or improved developmental and intellectual functions, and Group 2, experiencing developmental and intellectual loss. RESULTS: The mean age at seizure onset was 1.2 ± 1.0 years, and the mean age at surgery was 2.9 ± 1.2 years. At the last follow-up (mean 4 years, SD ± 2), 19/27 (70%) patients were seizure- and drug-free; 18/27 patients (67%) fit in Group 1, and 9/27 (33%) fit in Group 2. The mean age at surgery was 2.6 years (SD ± 1.1; range 1.2-5.1) in Group 1 and 3.4 years in Group 2 (SD ± 1.1; range 1.6-5.0). Group 1 had a lower pre-operative DQ/IQ total score than Group 2 (median DQ/IQ respectively 82 vs 108, p = 0.05). Between pre- and post-assessments, we found that in Group 1, Performance scores improved (82.7 vs 102, p = 0.001), while in Group 2, the Total and Verbal scores worsened (respectively 108 vs 75, p = 0.008, and 100 vs 76, p = 0.021). SIGNIFICANCE: Our study's results emphasize the positive impact of surgery before the age of 5 years on developmental and intellectual outcomes. Despite limitations such as a small sample size, lack of a control group, and diverse etiologies, our findings support the crucial role of early intervention in preserving or enhancing developmental and intellectual functions in young patients with DRE. PLAIN LANGUAGE SUMMARY: This retrospective study, conducted at the Bambino Gesù Children Hospital in Italy, reports neuropsychological and developmental and/or cognitive data for children undergoing early epilepsy surgery (before the age of 5). It found that children with lower developmental or cognitive profiles gained the highest scores on post-operative neuropsychological evaluations. This study provides information on the potential benefits of early surgery in shortening the duration of epilepsy, preventing or arresting deterioration, and enhancing plasticity and recovery.

Seizure outcome in drug-resistant epilepsy in the setting of polymicrogyria.

OBJECTIVE: We aimed to analyze seizure outcomes and define ictal onset with intracranial electroencephalography (ICEEG) in patients with polymicrogyria (PMG)-related drug-resistant epilepsy (DRE), considering surrounding cortex and extent of surgical resection. METHODS: Retrospective study of PMG-diagnosed patients (2001 to June 2018) at a single epilepsy center was performed. Primary outcome was complete seizure freedom (SF), based on Engel classification with follow-up of ≥ 1 year. Univariate analyses identified predictive clinical variables, later integrated into multivariate Cox proportional hazards models. RESULTS: Thirty-five patients with PMG-related DRE (19 adults/16 pediatric: 20 unilateral/15 bilateral) were studied. In surgical group (n = 23), 52 % achieved SF (mean follow-up:47 months), whereas none in non-resective treatment group (n = 12) attained SF (mean follow-up:39.3 months) (p = 0.002). In surgical group, there were no significant differences in SF, based on the laterality of the PMG [uni or bilateral,p = 0.35], involvement of perisylvian region(p = 0.714), and extent of the PMG resection [total vs. partial,p = 0.159]. Patients with ictal ICEEG onset in both PMG and non-PMG cortices, and those limited to non- PMG cortices had a greater chance of achieving SF compared to those limited to the PMG cortices. CONCLUSION: Resective surgery guided by ICEEG for defining the epileptogenic zone (EZ), in DRE patients with PMG, leads to favorable seizure outcomes. ICEEG-guided focal surgical resection(s) may lead to SF in patients with bilateral or extensive unilateral PMG. ICEEG aids in EZ localization within and/or outside the MRI-identified PMG. Complete removal of PMG identified on MRI does not guarantee SF. Hence, developing preimplantation hypotheses based on epileptogenic networks evaluation during presurgical assessment is crucial in this patient population.

Robot-assisted insular stereoelectroencephalography in pediatric drug-resistant epilepsy: accuracy and diagnostic value.

BACKGROUND: Insular epilepsy is a well-known cause of drug-resistant epilepsy (DRE) in the pediatric population. It can be a source of surgical epilepsy treatment failures when not ruled out pre-operatively. Non-invasive methods often provide limited information about its existence, being the invasive methods necessary to diagnose it in the vast majority of cases. The most used is stereoelectroencephalography (SEEG). We report a series of DRE pediatric patients in which insular SEEG was performed to rule out insular epilepsy. METHOD: We performed a retrospective review of pediatric DRE patients operated on SEEG including insular electrodes between April 2016 and September 2022. We described the different trajectories used (orthogonal or oblique) and surgical techniques. After implantation, we assessed electrodes' precision using three measures: entry point location error (EPLE), target point location error (TPLE), and target deviation (TD). We also reported complications that occurred with this technique as well as the diagnostic information provided. RESULTS: Overall, 32 DRE patients were operated on SEEG including insular electrodes. Four hundred one electrodes were implanted, 148 (39.91%) of whom were directed to the insula. One hundred twelve followed an orthogonal trajectory, and 36 were oblique. The mean EPLE was 1.45 mm, TPLE was 1.88 mm and TD was 0.71 mm. Three patients suffered from frontal hematoma, two of them diagnosed on post-operative MRI and one who required surgery, with no sequelae. One patient suffered from meningitis treated with antibiotics with no permanent sequelae. Nine patients (28.13%) had the insula included in the epileptogenic zone. CONCLUSIONS: Insular epilepsy has to be ruled out in DRE patients when little suspicion is obtained after non-invasive testing. This is especially important in the pediatric population, in which seizure semiology is more difficult to characterize and failures to control epilepsy have devastating consequences in neurocognitive development and scholarship. Given its relative low rate of relevant complications and potential benefits, we should consider widening the inclusion criteria for insular SEEG monitoring.

Hippocampal resection during hemispherotomy: is it needed?

PURPOSE: Hemispherotomy is an effective surgery for intractable pediatric hemispheric epilepsy. Over the years, the surgical goal has shifted from a complete hemispheric resection (anatomical hemispherectomy) to a disconnective hemispherotomy (DH). Multiple techniques for DH have been described, and often, anterior temporal lobectomy (ATL, with hippocampal resection) is performed. The goal of the current study is to assess the role of hippocampal resection in DH. METHODS: We retrospectively collected all clinical data of children (< 18 years old) who underwent DH between 2001 and 2022 at two tertiary large centers. Epilepsy status and surgical outcome were compared, based on whether the hippocampus was resected (as part of an ATL) or disconnected at the amygdala and atrial segment of the fornix (with no ATL). RESULTS: A total of 86 patients (32 females) were included. The most common epilepsy etiologies were stroke (31), Rasmussen's encephalitis (16), cortical dysplasia (10), and hemimegaloencephaly (9). The mean age at surgery was 7 (± 4.9) years. The average number of anti-seizure medications (ASMs) at surgery was 3 (± 1.2). Hemispherotomy techniques included peri-insular (54), vertical (23 [19 endoscopic + 4 parasagittal]), and trans-sylvian (9). The mean follow-up was 41.5 (± 38) months. Forty-three patients had hippocampal resection, and 43 patients had a hippocampal disconnection. Both groups had similar Engel outcome scores (p = 0.53). CONCLUSIONS: Disconnective hemispherotomy is highly effective for pediatric intractable hemispheric epilepsy. Our data suggest that the inclusion of hippocampal resection does not provide additional benefit.

Stereo electroencephalography in the kingdom of Saudi Arabia.

Epilepsy surgery and intracranial monitoring have a long history in the Kingdom of Saudi Arabia, spanning over 30 years. Stereo-EEG however, is a more recent offering. In this short communication, we discuss how Stereo-EEG has grown in the context of the Kingdom's healthcare model and the Vision 2030 model. We discuss the various positives of this technique and methodology as well as the various challenges that the hospitals offering Stereo-EEG have faced.

Temporal PLGG and epilepsy.

Temporal lobe epilepsy in children is often secondary to various low-grade glial and glioneural tumors and rarely secondary to mesial temporal sclerosis. Despite the benign nature, tumor-associated TLE in children often becomes refractory over time. Abundant literature has shown the significant advantage of tumor resection compared to conservative treatment, in achieving seizure control, as well as the rates of antiseizure medication reduction. Despite these advantages, several considerations are to be related to when considering surgery. These include the impact of surgery on linguistic and neurocognitive development, especially at the younger age; the extent of resection and the role of ECoG; and the need for mesial temporal resection. Over recent years, traditional resection has been complemented with newer treatment options such as laser ablation and biological treatment, and these should be taken into account depending on the exact location and the ability to perform extensive resection in eloquent regions. In this overview manuscript, we discuss the various considerations treating tumor-associated pediatric temporal epilepsy.

The effect of SEEG on the long-term outcomes of different side anterior temporal lobectomy: A single-center retrospective study.

PURPOSE: Anterior temporal lobectomy (ATL) is the most common surgical treatment for temporal lobe epilepsy (TLE), and Stereoelectroencephalography (SEEG) plays a critical role in precisely localizing the epileptogenic zone (EZ). This study aimed to explore the effect of SEEG on the long-term outcomes of different side ATL. METHODS: From March 2012 to February 2020, a retrospective analysis was conducted on 231 TLE patients who underwent standard ATL surgery. According to the surgical sides and the utilization of SEEG during preoperative evaluation, the patients were categorized into four groups, with a follow-up period exceeding two years. RESULTS: Among the 231 TLE patients, the probability of being seizure-free two years after the surgery was 80.52%, which decreased to 65.65% after five years. There was no significant difference in outcomes between SEEG and non-SEEG patients. For overall and non-SEEG patients, there was no significant difference in short-term outcomes between different surgical sides. However, the long-term outcomes of right ATL patients were significantly better than left. Interestingly, for patients who underwent SEEG, there was no significant difference in both short-term and long-term outcomes between different surgical sides. CONCLUSION: Some TLE patients encounter challenges in localizing the EZ through non-invasive evaluation, necessitating the use of SEEG for precise localization. Furthermore, their seizure outcomes after surgery can be the same with the patients who have a clear epileptogenic zone in non-invasive evaluation. And SEEG patients can achieve a more stable long-term prognosis than non-SSEEG patients.

Machine learning for (non-)epileptic tissue detection from the intraoperative electrocorticogram.

OBJECTIVE: Clinical visual intraoperative electrocorticography (ioECoG) reading intends to localize epileptic tissue and improve epilepsy surgery outcome. We aimed to understand whether machine learning (ML) could complement ioECoG reading, how subgroups affected performance, and which ioECoG features were most important. METHODS: We included 91 ioECoG-guided epilepsy surgery patients with Engel 1A outcome. We allocated 71 training and 20 test set patients. We trained an extra trees classifier (ETC) with 14 spectral features to classify ioECoG channels as covering resected or non-resected tissue. We compared the ETC's performance with clinical ioECoG reading and assessed whether patient subgroups affected performance. Explainable artificial intelligence (xAI) unveiled the most important ioECoG features learnt by the ETC. RESULTS: The ETC outperformed clinical reading in five test set patients, was inferior in six, and both were inconclusive in nine. The ETC performed best in the tumor subgroup (area under ROC curve: 0.84 [95%CI 0.79-0.89]). xAI revealed predictors of resected (relative theta, alpha, and fast ripple power) and non-resected tissue (relative beta and gamma power). CONCLUSIONS: Combinations of subtle spectral ioECoG changes, imperceptible by the human eye, can aid healthy and pathological tissue discrimination. SIGNIFICANCE: ML with spectral ioECoG features can support, rather than replace, clinical ioECoG reading, particularly in tumors.

Transient Ipsilateral Hemineglect Following Brain Laser Ablation in Patient with Focal Cortical Dysplasia.

Sensory integration is the province of the parietal lobe. The non-dominant hemisphere is responsible for both body sides, while the dominant hemisphere is responsible for the contralateral hemi-body. Furthermore, the posterior cingulate cortex (PCC) participates in a network involved in spatial orientation, attention, and spatial and episodic memory. Laser interstitial thermotherapy (LiTT) is a minimally invasive surgery for focal drug-resistant epilepsy (DRE) that can target deeper brain regions, and thus, region-specific symptoms can emerge. Here, we present an 18-year-old right-handed male with focal DRE who experienced seizures characterized by sensations of déjà vu, staring spells, and language disruption. A comprehensive evaluation localized the seizure focus and revealed a probable focal cortical dysplasia (FCD) in the left posterior cingulate gyrus. The patient underwent uneventful LiTT of the identified lesion. Post-operatively, he developed transient ipsilateral spatial neglect and contralateral sensory loss, as well as acalculia. His sensory symptoms gradually improved after the surgery, and he remained seizure-free after the intervention for at least 10 months (until the time of this writing). This rare case of ipsilateral spatial and visual hemineglect post-LiTT in epilepsy underscores the importance of recognizing atypical neurosurgical outcomes and considering individual variations in brain anatomy and function. Understanding the dynamics of cortical connectivity and handedness, particularly in pediatric epilepsy, may be crucial in anticipating and managing neurocognitive effects following epilepsy surgery.

Pediatric peri-insular hemispherotomy and functional hemispherectomy for severe medically refractory epilepsy: comparison of two techniques.

PURPOSE: Since it was first described in the 1970s, functional hemispherotomy has been an essential tool in treating disabling, medically refractory epilepsy resulting from diffuse unilateral hemispheric disease. We report our experience with 23 patients who underwent hemispherotomy, both using the functional hemispherotomy (FH) as well as a modified peri-insular hemispherotomy (PIH) technique. We present the surgical technique for the latter, review outcomes following disconnection surgery and discuss the differences between the techniques when it comes to complications and postoperative results. METHODS: A retrospective study of 23 patients with refractory seizures who underwent cerebral hemispherectomy. A thorough analysis of the clinical, imaging, surgical features and postoperative results was performed. We also present the surgical technique for a modified PIH technique. RESULTS: Between 2000 and 2020, 23 pediatric patients with refractory seizures underwent hemispherotomy (12 FHs, 11 modified PIHs). 91.3% of patients were seizure free at 6 months, 87% at 1 year, and 78.3% at last follow-up. None of the 23 patients presented Engel IV outcome. FH was found to have statistically longer surgical duration (5 ± 1.5 vs. 3.83 ± 0.5 h; p = <0.001). Neurocognition was improved in two thirds of the patients (66.9%). Our study also shows improvement of motor activity in the majority of the patients, regardless of the pathology and surgical technique. In the present report we modified the Cook et al. technique by implementing an amygdalohippocampectomy with resection of the tail of the hippocampus posteriorly and medially, to achieve temporo-occipital disconnection, instead of a complete temporal lobectomy. CONCLUSION: When patients are wisely selected, the hemispherectomy procedure should be considered as a most attractive and curative treatment for children with refractory seizures, not only giving the patient a high chance of seizure freedom but also providing an improvement in motor and cognitive skills. In our particular case and based on the present study, the modified PIH proves to be a highly effective technique. It not only has a shorter surgical time but also a very low complication rate.

Novel technique of switching TIVA and sevoflurane during epilepsy surgery for combined intraoperative motor evoked potentials monitoring and electrocorticography: an illustrative case report.

BACKGROUND: During epilepsy surgery, it is equally important to record electrocorticography (ECoG) for detecting epileptogenic activity and guiding brain resection, and to evaluate neuromonitoring data, particularly motor evoked potentials (MEP), for avoidance of postoperative neurological complications. However, sevoflurane, which is commonly used during recording of ECoG, may attenuate the MEP response. It enforces anesthesiologists and neurosurgeons to select one anesthetic agent over another, facilitating either ECoG or MEP monitoring. CASE PRESENTATION: In the presented case of a 20-year-old man, who underwent surgery for temporal lobe epilepsy, a novel technique of neuroanesthesia was introduced, integrating initial induction of the total intravenous anesthesia (TIVA) with propofol (effect-site concentration, 2.3-3.0 µg/ml), its subsequent switching to sevoflurane (end-tidal concentration, 2.5%) for ECoG recording, and further change back to TIVA for MEP monitoring during brain resection. CONCLUSIONS: Intraoperative switch of anesthetic agents according to specific intraoperative requirements may be useful for cases of brain surgery requiring both ECoG recordings and MEP monitoring.

AB076. Underutilization of epilepsy surgery in Pakistan: 10-year experience from the only comprehensive epilepsy center in the country.

BACKGROUND: Eighty percent of the global epilepsy burden is borne by developing countries, and 30% of these patients have drug-resistant epilepsy (DRE). Epilepsy surgery (ES) can significantly improve the cognition and quality of life in DRE. A comprehensive epilepsy center was established in Pakistan in 2010, the only facility for ES in a country of 231 million people. Hundreds of epilepsy patients are medically managed at the center each year. We aimed to study seizure control in all ES cases performed at the only comprehensive epilepsy center in the country during last 10 years. METHODS: It was a retrospective cohort study. Medical records of all cases of ES performed at our center from 2012 to 2021 were retrieved, through the Hospital's Information Management System. Patients were also contacted via phone calls where needed, to collect information about their seizure control as per Engel Classification. Data was analyzed using SPSSv21. RESULTS: Thirty-three surgeries including 10 temporal lobectomies with amygdalohippocampectomy, 11 selective amygdalohippocampectomies, 9 corpus callosotomies, 1 callosotomy with lesionectomy, 1 lesionectomy and 1 temporal lobectomy were performed. The median age of patients was 23: [18-31] years. Complex partial seizures were most common (14; 42.4%), followed by generalized seizures (10; 30.3%). The median duration of AEDs before surgery was 6 (IQR: 3.25-13.75) years. Eighteen (54.5%) patients had complete freedom from disabling seizures (Engel Class IA) at a median follow-up of 3.25 (IQR: 1.12-6) years. All patients continued to receive antiepileptic drugs after surgery, and all procedures had nearly 50% optimum seizure control outcomes. CONCLUSIONS: The clinical outcomes of ES performed at our center are consistent with evidence. However, the small volume highlights the underutilization of this extremely important service. More studies are needed to identify the factors responsible for this disparity, so that all DRE patients have access to ES.

AB083. Epilepsy and low-grade glioma-seizure control after surgical resection: a retrospective cohort study.

BACKGROUND: Seizures are a common manifestation in patients with low grade glioma (60-75%), and 60-90% patients attain seizure freedom after resection. Seizure control varies with histopathology, extent of resection and type of seizures. There is inconsistency in literature regarding utility of anti-epileptic drugs (AEDs) after tumor resection. We aimed to determine factors associated with seizure control in patients after low-grade glioma (LGG) resection. METHODS: It was a retrospective cohort study. Medical record of all patients who underwent LGG resection at our center from 2019 to 2021 were reviewed; 77 patients fulfilled the selection criteria. Patients were also contacted via phone calls to collect information about their seizure control as per Engel Classification. Data was analyzed using SPSSv21. RESULTS: The mean age was 34.9±11.3 years, and there was male predominance (62; 80.5%). Generalized seizures were the most common type (54; 70%), and Levetiracetam was the most commonly prescribed AED (60; 77.9%). The median duration of pre-operative AED use was 4 [interquartile range (IQR): 1-24] months. Frontal lobe was the most common location of tumor (36; 46.8%). Most of the patients had their surgery under general anesthesia (51; 61.4%), while 29 (37.7%) underwent awake craniotomy. Nearly half of the patients had a gross total resection (31; 40.3%), and another 15 (19.5%) had near-total resection. Sixteen patients (20.8%) had their AEDs stopped within first 6 months post-operatively (at variable intervals), and all of them had Engel Class IA to ID control at time of follow-up (P=0.008). The 12 patients with grade I glioma also had optimum seizure control (P=0.03). CONCLUSIONS: Patients with grade I glioma have better seizure control after surgery. Tumor biopsy is associated with worse seizure outcome, though not statistically significant. Larger studies are needed to determine the ideal time and patient group for discontinuing AED after surgery.

AB082. Navigating barriers to epilepsy surgery: a national survey of patient and neurologist perspectives.

BACKGROUND: Potential barriers to epilepsy surgery can be divided into two broad groups: reluctance of patients/caregivers and deficient knowledge of neurologists. Pakistan, in particular, faces an epilepsy surgery treatment gap of 70-94%. This study aimed to assess the knowledge and practice of neurologists and the knowledge of the patients diagnosed with epilepsy to identify the barriers to adequate provision of this modality in Pakistan. METHODS: We conducted a cross-sectional study comprising two surveys. Records of patients diagnosed with epilepsy at our hospital during 2.5 years were retrieved from the Neurophysiology database. The second form was designed for neurologists working in Pakistan. The questionnaires were disseminated via email to neurologists and phone calls to patients. RESULTS: In the patients' survey, we obtained 194 responses from caregivers. The median age of patients was 10 years [interquartile range (IQR): 6-14 years]. We found that 74.2% (n=144) of patients were unaware of surgical options in medically refractory epilepsy (MRE). Therefore, most did not comment on it due to the limited information. Forty-eight patients (24.8%) reported more than 1 seizure per month, and 29 (60.4%) were unaware of the surgical treatment. Seizures were disabling in 88% (n=171) of patients. Patients taking more AEDs were significantly more likely to be aware of surgical options (P=0.001). In the survey from neurologists, only 6.6% (n=4) always discussed epilepsy surgery with MRE patients. Around half of the neurologists, 44.3% (n=27), had never referred a patient for epilepsy surgery. However, 95.1% (n=58) were aware of the under-utilization of epilepsy surgery, and 67.2% (n=41) believed that epilepsy surgery is under-recommended. Almost all neurologists (n=60; 98.4%) believe that comprehensive epilepsy treatment centers are required in the country. CONCLUSIONS: In our survey, we found a lack of awareness in both patients and neurologists to be a major barrier. This contrasts the literature from developed or high-income countries, where physician awareness seems adequate, and stigmas associated with surgery seem to be the major barrier. Multifaceted approaches catered to local concerns are necessary to address these hindrances.

Seizure outcome in surgically treated pediatric gangliogliomas and dysembryoplastic neuroepitheliomas according to imaging and resection strategies.

PURPOSE: Imaging and resection strategies for pediatric gangliogliomas (GG) and dysembryoplastic neuroepitheliomas (DNET) presenting with epilepsy were retrospectively analyzed in a consecutive institutional series of surgically treated patients. METHODS: Twenty-two children (median 8 years, 3-18 years) presented with seizures for 30 months median (14-55.2 months) due to a histologically verified GG/DNET. RESULTS: There were 20 GG and 2 DNT, 68 % located temporal, 32 % extra-temporal. Seizure history was significantly longer in temporal cases (38 versus 14 months median, p < 0.01). MRI contrast enhancement was present in 50 % and methionine (MET) positron emission tomography (PET) uptake in 70 % (standard uptake values (SUVs) 2.92 mean, from 1.6 to 6.4). 27 % had glucose PET hypometabolism. Primarily, in temporal GG, ECoG (electrocorticography) -guided lesionectomies were performed in 87 % and antero-mesial temporal lobe resections (AMTLR) in 13 %, whereas in extra-temporal GG/DNETs, lesionectomies were performed in 100 %. ILAE Class 1 seizure outcome was primarily achieved in 73 % of the temporal cases, and was increased to 93 % by performing six repeat surgeries using AMTLR. Extratemporal patients experienced ILAE Class 1 seizure outcomes in 86 % without additional surgeries, although harboring significantly more residual tumor (p < 0.005, mean follow-up 28 months). CONCLUSION: In children, MET PET imaging for suspected GG is proposed preoperatively showing a high diagnostic sensitivity and an option to delineate the lesions for navigated resection, whereas MRI contrast behavior was of no differential diagnostic use. As a surgical strategy we propose primarily lesionectomies for extratemporal but AMTLR for temporal GG respecting eloquent brain areas.

Pausing propofol during neurosurgery to record intraoperative electrocorticography is feasible;10 years of clinical experience.

OBJECTIVE: Intraoperative electrocorticography (ioECoG) during neurosurgery is influenced by anesthetics. In our center we stop the propofol to enable interpretation of ioECoG. We reported our clinical experience and evaluated awareness and hemodynamic changes during the propofol-free periods (PFP). METHODS: We retrospectively included surgeries with paused propofol administration to record ioECoG (period: 2008-2019). Clinical reports were screened for symptoms of awareness. We compared mean arterial blood pressure (MAP; mmHg) and heart rate (HR;bpm) during PFP to baseline (ten minutes preceding PFP). An increase > 15% was defined as clinically relevant. The association between hemodynamic changes and clinical characteristics was analyzed using logistic regression models. RESULTS: Propofol administration was paused 742 times in 352 surgeries (mean PFP duration 9 ± 5 min). No signs of awareness were reported. MAP and HR increased > 15% in 54 and six PFPs. Five PFPs showed both MAP and HR increases. Prolonged PFP was associated with having MAP and HR increase during surgery (OR=1.18, 95%CI [1.12-1.26]). CONCLUSIONS: Signs of inadequate sedation depth were rare. MAP and HR increases were related to the length of PFP. SIGNIFICANCE: We summarize 10 years of clinical experience with pausing propofol administration during epilepsy surgery to record ioECoG without evidence of awareness.

Postoperative seizure outcomes and antiseizure medication utilization based on histopathological diagnosis: A retrospective cohort study.

OBJECTIVE: Analyze the association between histopathology, seizure outcomes, and drug load of antiseizure medications (ASMs) 5-8 years after epilepsy surgery to inform preoperative decision-making and consultation. METHODS: In this retrospective, non-interventional, single-center study, patients who visited the epilepsy clinic at West China Hospital, Sichuan University from Jan 1, 2015 to Dec 31, 2020 were assessed. Patients with postoperative histopathology after epilepsy resection were included and categorized into 13 etiological groups. The primary outcomes were achieving Engel class 1 at 1, 2, 3, 5, and 8 years postoperative. Secondary outcomes included the use of ASMs and comparison of postoperative seizure outcomes between adults and children. Univariate and multivariable analyses were conducted to explore the association between clinical characteristics such as histopathology and seizure outcomes. RESULTS: A total of 315 patients were include. Patients with embryonic dysplastic neuroepithelial tumor (DNT) achieved the best seizure outcomes (84.6 % Engel class 1). DNT (odds ratio, OR=0.103, 95 %CI=0.012-0.899), cavernous hemangiomas (OR=0.140, 95 %CI=0.024-0.819) and meningioma (OR=0.137, 95 %CI=0.021-0.910) were independently associated with a higher probability of seizure-free outcome. The results of epileptic seizures in adult and pediatric groups with different pathologies were significantly different, and the preoperative and postoperative ASM dosages were also different among adult patients with various etiologies. Additionally, multivariate analysis showed that early age at onset (adjusted hazard ratio (HR) = 1.754, 95 % CI=1.049-2.934, P=0.032), late surgical age (HR=0.569, 95 %CI=0.339-0.954, P=0.032), and longer duration from seizure onset to surgery (HR=1.735, 95 % CI=1.028-2.928, P=0.039) were independent predictors of unfavorable outcomes in epileptic seizures. CONCLUSIONS: we demonstrated that the seizure outcomes of focal epilepsy have high pathological specificity, with histopathological diagnosis serving as a crucial and independent determinant of seizure outcome. Surgical assessment should be contemplated for all patients with presumed refractory focal epilepsy, irrespective of their age.

Normative atlases of high-frequency oscillation and spike rates under Sevoflurane anesthesia.

OBJECTIVE: We analyzed the dose-dependent effects of Sevoflurane anesthesia on high-frequency oscillations (HFOs) and spike discharges at non-epileptic sites and evaluated their effectiveness in identifying the epileptogenic zone. METHODS: We studied 21 children with drug-resistant focal epilepsy who achieved seizure control after focal resective surgery. Open-source detectors quantified HFO and spike rates during extraoperative and intraoperative intracranial EEG recordings performed before resection. We determined under which anesthetic conditions HFO and spike rates differentiated the seizure onset zone (SOZ) within the resected area from non-epileptic sites. RESULTS: We analyzed 925 artifact-free electrodes, including 867 at non-epileptic sites and 58 at SOZ sites. Higher Sevoflurane doses significantly increased HFO and spike rates at non-epileptic sites, exhibiting spatial variability among different detectors. These biomarkers were elevated in the SOZ more than in non-epileptic sites under 2-4 vol% Sevoflurane anesthesia, with Cohen's d effect sizes above 3.0 and Mann-Whitney U-Test r effect sizes above 0.5. CONCLUSIONS: We provided normative atlases of HFO and spike rates under different Sevoflurane anesthesia conditions. Sevoflurane elevates HFO and spike rates preferentially in the epileptogenic zone. SIGNIFICANCE: Assessing the relative severity of biomarker levels across sites may be relevant for localizing the epileptogenic zone under Sevoflurane anesthesia.

Dynamic functional connectivity in verbal cognitive control and word reading.

Cognitive control processes enable the suppression of automatic behaviors and the initiation of appropriate responses. The Stroop color naming task serves as a benchmark paradigm for understanding the neurobiological model of verbal cognitive control. Previous research indicates a predominant engagement of the prefrontal and premotor cortex during the Stroop task compared to reading. We aim to further this understanding by creating a dynamic atlas of task-preferential modulations of functional connectivity through white matter. Patients undertook word-reading and Stroop tasks during intracranial EEG recording. We quantified task-related high-gamma amplitude modulations at 547 nonepileptic electrode sites, and a mixed model analysis identified regions and timeframes where these amplitudes differed between tasks. We then visualized white matter pathways with task-preferential functional connectivity enhancements at given moments. Word reading, compared to the Stroop task, exhibited enhanced functional connectivity in inter- and intra-hemispheric white matter pathways from the left occipital-temporal region 350-600 ms before response, including the posterior callosal fibers as well as the left vertical occipital, inferior longitudinal, inferior fronto-occipital, and arcuate fasciculi. The Stroop task showed enhanced functional connectivity in the pathways from the left middle-frontal pre-central gyri, involving the left frontal u-fibers and anterior callosal fibers. Automatic word reading largely utilizes the left occipital-temporal cortices and associated white matter tracts. Verbal cognitive control predominantly involves the left middle frontal and precentral gyri and its connected pathways. Our dynamic tractography atlases may serve as a novel resource providing insights into the unique neural dynamics and pathways of automatic reading and verbal cognitive control.

Resting state connectivity biomarkers of seizure freedom after epilepsy surgery.

Alterations in brain networks may cause the lowering of the seizure threshold and hypersynchronization that underlie the recurrence of unprovoked seizures in epilepsy. The aim of this work is to estimate functional network characteristics, which may help predicting outcome of epilepsy surgery. Twenty patients were studied (11 females, 9 males, mean age 33 years) with scalp-recorded HD-EEG in resting state (eyes closed, no interictal discharges) before intracranial evaluation, which allowed the precise determination of the epileptogenic zone. Dipole source time courses in the brain were estimated using Weighted Minimum Norm Estimate based on HD-EEG signals. Information inflow and outflow of atlas-based brain regions were computed using partial directed connectivity. A set of graph measures for pairwise connections in standard EEG frequency bands was calculated. After epilepsy surgery 10 patients were seizure-free (Engel 1a) and 10 patients continued suffering from seizures (Engel outcome worse than 1a). Inflow of the regions containing the epileptogenic zone in the beta and delta frequency bands was significantly lower in patients who achieved seizure-freedom after surgery, compared with patients who continued to have seizures (p = 0.012, and p = 0.026, respectively). Average path length in the beta frequency band was significantly higher in patients who achieved seizure freedom (p = 0.012). In the delta frequency band, local efficiency and clustering coefficient were significantly higher in patients who achieved seizure freedom (0.033, 0.046). In patients who achieved seizure freedom after surgery, the preoperative analysis of the epileptic network exhibited stronger separation of the region containing the seizure onset zone, with less inflow of information. In contrast, shorter paths within the epileptic network may facilitate hypersynchronous neuronal activity and thus the recurrence of seizures in non-seizure free patients. This study supports the hypothesis that epileptic network properties might help to define suitable candidates for epilepsy surgery.