Hemispheric Surgery Research Articles

Validation of Hemispherectomy Outcome Prediction Scale in Treatment of Medically Intractable Epilepsy

The Hemispherectomy Outcome Prediction Scale (HOPS) was developed to aid both clinicians and patients in determining the chance of success after hemispheric surgery for medically refractory epilepsy. The original study generating HOPS had a multi-institutional, large cohort format yielding near perfect patient stratification. Evidence suggests that methodologies utilized to create such predictive models, including cross-validation as well as stratification utilizing the same data employed for model generation, may be at risk of an undesirable modeling phenomenon known as overfitting. We posed the question of whether overfitting may be influencing HOPS results and aimed for preliminary evidence of external validation with parameters from patients at our institution not included in the original HOPS study. We found HOPS to stratify our limited post-operative cohort adequately. However, the likelihood of complete seizure freedom among the patients predicted by HOPS to be at greatest chance of success was ~75%, about 20 points lower than in the original HOPS cohort. This reduction in absolute chance of success predicted by HOPS may represent some degree of overfitting. It will be informative to aim for external validation of HOPS utilizing patient cohorts entirely separate from those used for model generation. External validation of HOPS and similar models could optimize realistic prediction of success after intervention.

Hemispheric surgery in children: perisylvian technique.

Hemispheric epilepsy is quite frequent in children, compared with adults, and encompasses pathological substrates as diverse as hemimegalencephaly, Rasmussen encephalitis, Sturge-Weber syndrome, and porencephaly, among others. These patients most often become pharmacoresistant and thus require surgical management. Although anatomical hemispherectomy is a possibility, the technique that is favored by most epilepsy surgery centers worldwide is functional hemispherotomy, which results in equivalent outcomes with fewer postoperative complications. Therefore, it is essential that pediatric epilepsy neurosurgeons become familiar with these techniques. The present video describes in detail all surgical aspects of the perisylvian hemispherotomy.

Hemimegalencephaly: A Systematic Comparison of Functional and Anatomic Hemispherectomy for Drug-Resistant Epilepsy.

Hemimegalencephaly (HME) is a rare diffuse malformation of cortical development characterized by unihemispheric hypertrophy, drug-resistant epilepsy (DRE), hemiparesis, and developmental delay. Definitive treatment for HME-related DRE is hemispheric surgery through either anatomic (AH) or functional hemispherectomy (FH). This individual patient data meta-analysis assessed seizure outcomes of AH and FH for HME with pharmacoresistant epilepsy, predictors of Engel I, and efficacy of different FH approaches. PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature were searched from inception to Jan 13th, 2023, for primary literature reporting seizure outcomes in >3 patients with HME receiving AH or FH. Demographics, neurophysiology findings, and Engel outcome at the last follow-up were extracted. Postsurgical seizure outcomes were compared through 2-tailed t -test and Fisher exact test. Univariate and multivariate Cox regression analyses were performed to identify independent predictors of Engel I outcome. Data from 145 patients were extracted from 26 studies, of which 89 underwent FH (22 vertical, 33 lateral), 47 underwent AH, and 9 received an unspecified hemispherectomy with a median last follow-up of 44.0 months (FH cohort) and 45.0 months (AH cohort). Cohorts were similar in preoperative characteristics and at the last follow-up; 77% (n = 66) of the FH cohort and 81% (n = 38) and of the AH cohort were Engel I. On multivariate analysis, only the presence of bilateral ictal electroencephalography abnormalities (hazard ratio = 11.5; P = .002) was significantly associated with faster time-to-seizure recurrence. A number-needed-to-treat analysis to prevent 1 additional case of posthemispherectomy hydrocephalus reveals that FH, compared with AH, was 3. There was no statistical significance for any differences in time-to-seizure recurrence between lateral and vertical FH approaches (hazard ratio = 2.59; P = .101). We show that hemispheric surgery is a highly effective treatment for HME-related DRE. Unilateral ictal electroencephalography changes and using the FH approach as initial surgical management may result in better outcomes due to significantly lower posthemispherectomy hydrocephalus probability. However, larger HME registries are needed to further delineate the predictors of seizure outcomes.

Hemispheric epilepsy surgery for hemimegalencephaly: The UCLA experience.

Hemimegalencephaly (HME) is a rare congenital brain malformation presenting predominantly with drug-resistant epilepsy. Hemispheric disconnective surgery is the mainstay of treatment; however, little is known about how postoperative outcomes compare across techniques. Thus we present the largest single-center cohort of patients with HME who underwent epilepsy surgery and characterize outcomes. This observational study included patients with HME at University of California Los Angeles (UCLA) from 1984 to 2021. Patients were stratified by surgical intervention: anatomic hemispherectomy (AH), functional hemispherectomy (FH), or less-than-hemispheric resection (LTH). Seizure freedom, functional outcomes, and operative complications were compared across surgical approaches. Regression analysis identified clinical and intraoperative variables that predict seizure outcomes. Of 56 patients, 43 (77%) underwent FH, 8 (14%) underwent AH, 2 (4%) underwent LTH, 1 (2%) underwent unknown hemispherectomy type, and 2 (4%) were managed non-operatively. At median last follow-up of 55 months (interquartile range [IQR] 20-92 months), 24 patients (49%) were seizure-free, 17 (30%) required cerebrospinal fluid (CSF) shunting for hydrocephalus, 9 of 43 (21%) had severe developmental delay, 8 of 38 (21%) were non-verbal, and 15 of 38 (39%) were non-ambulatory. There was one (2%) intraoperative mortality due to exsanguination earlier in this cohort. Of 12 patients (29%) requiring revision surgery, 6 (50%) were seizure-free postoperatively. AH, compared to FH, was not associated with statistically significant improved seizure freedom (hazard ratio [HR] = .48, p = .328), although initial AH trended toward greater odds of seizure freedom (75% vs 46%, p = .272). Younger age at seizure onset (HR = .29, p = .029), lack of epilepsia partialis continua (EPC) (HR = .30, p = .022), and no contralateral seizures on electroencephalography (EEG) (HR = .33, p = .039) independently predicted longer duration of seizure freedom. This study helps inform physicians and parents of children who are undergoing surgery for HME by demonstrating that earlier age at seizure onset, absence of EPC, and no contralateral EEG seizures were associated with longer postoperative seizure freedom. At our center, initial AH for HME may provide greater odds of seizure freedom with complications and functional outcomes comparable to those of FH.

The Important Role of Hemispherotomy for Rasmussen Encephalitis: Clinical and Functional Outcomes

BackgroundRasmussen encephalitis (RE) is characterized by pharmacoresistant epilepsy and progressive neurological deficits concurrent with unilateral hemispheric atrophy. Evidence of an inflammatory autoimmune process has been extensively described in the literature; however, the precise etiology of RE is still unknown. Despite data supporting a beneficial effect of early immunosuppressive and immunomodulatory interventions, surgical disconnection of the affected hemisphere is considered the treatment of choice for these patients. The aim of this study was to report a series of children and adolescents who underwent hemispheric surgery (HS) for the treatment of RE, analyzing their clinical, electrographic, and neuroimaging features pre-operatively, as well as their postoperative status, including seizure and functional outcomes. MethodsAll patients with RE who underwent HS in the Epilepsy Surgery Center (CIREP) of the University Hospital of Ribeirão Preto Medical School, between 1995 and 2020 were retrospectively reviewed. Preoperative and postoperative analyses included gender; age at epilepsy onset; seizure semiology; seizure frequency; interictal and ictal electroencephalographic (EEG) findings; age at surgery; duration of epilepsy; surgical complications; duration of follow-up; histopathological findings; and postoperative seizure, cognitive, and functional outcomes. ResultsForty-four patients were evaluated. Mean age at seizure onset and epilepsy duration was 6 years and 2.5 years, respectively. Mean age at surgery was 9 years, with an average follow-up ranging from 3 months to 23 years. All patients presented with severe epilepsy and distinct neurological abnormalities on MRI. Before HS, different degrees of abnormal intellectual performance as well as hemiparesis were seen in 86% and 90%, respectively. Histopathology examination confirmed this diagnosis in 95% patients. At the last follow-up, 68% of patients were seizure free, and 70% were classified as Engel Class I or II. Postoperatively, the cognitive status remained unchanged in 64% of patients. Likewise, the gross motor function remained unchanged in 54% of patients and 74% had functional hand ability after HS. ConclusionsConsidering the progressive damage course of RE, hemispheric surgery should be offered to pediatric patients. It has manageable risks and results in good seizure outcome, and the preoperative functional status of these children is often preserved (even when the left hemisphere is involved), thus improving their quality of life.

Strabismus outcomes in pediatric patients undergoing disconnective hemispheric surgery for intractable epilepsy: a systematic review

ContexteLes enfants qui subissent une chirurgie hémisphérique en raison d'une épilepsie rebelle sont exposés à des complications visuelles, notamment le strabisme. Notre revue de synthèse systématique vise à examiner les taux d'apparition et les caractéristiques du strabisme après une chirurgie hémisphérique et à évaluer les retombées cliniques pour les soins d'ophtalmologie. MéthodesOn a procédé à une recherche systématique des bases de données MEDLINE, EMBASE, Cochrane, PsychINFO et Web of Science depuis leur création jusqu’à mai 2022. Les articles inclus portaient sur la présence de strabisme chez des enfants qui ont subi une hémisphérectomie ou une hémisphérotomie. Ont été exclues les revues de synthèse et les publications dans une langue autre que l'anglais. Les outils d'évaluation critique du Joanna Briggs Institute ont servi à évaluer le risque de biais. On a par la suite extrait et analysé les données démographiques et les caractéristiques du strabisme. RésultatsSur les 41 articles évalués, 10 études regroupant 384 enfants (48 % de sujets de sexe féminin) âgés de 6 mois à 16 ans au moment de la chirurgie ont été incluses. Les taux de strabisme préopératoire s’échelonnaient de 3 à 56 %, tandis que les taux postopératoires s’échelonnaient de 38 à 100 %. Quant au site de la chirurgie hémisphérique, la forme la plus fréquente était l'exodéviation controlatérale (16 à 67 %; n = 7), suivie de l'exodéviation ipsilatérale (16 à 56 %; n = 2); l’ésodéviation ipsilatérale était peu fréquente (4 à 9 %; n = 3). ConclusionsL'exotropie controlatérale et l’ésotropie ipsilatérale sont des conséquences possibles de la chirurgie hémisphérique qui peuvent entraîner un élargissement du champ visuel. Il est important de soupeser les réactions sociales négatives par rapport au risque de réduction du champ visuel et/ou de diplopie à la suite d'une chirurgie pour corriger le strabisme. On devra réaliser des études de meilleure qualité comportant des populations homogènes, bien décrites (évaluations ophtalmologiques pré- et postopératoires complètes) et de grande envergure si l'on aspire à connaître véritablement le risque de strabisme et son taux d'apparition après une chirurgie hémisphérique.

Long-term seizure outcome and mobility after surgical treatment for Rasmussen encephalitis in children: A single-center experience.

Rasmussen Encephalitis (RE) is a rare inflammatory neurodegenerative disease associated with refractory seizures, hemiparesis, and cognitive deterioration, due to lateralized cortical atrophy. Hemispheric surgery (hemispherotomy) is the mainstay of treatment, but its unavoidable motor deficits and lack of long-term data regarding seizure outcomes can make patients and families apprehensive to undergo this procedure. The present study aimed at analyzing the results of surgical treatment for RE from a motor and epilepsy standpoint, and mitigate such concerns. Clinical and operative data were retrospectively collected from medical records of pharmacoresistant patients treated with functional hemispherectomy at a tertiary reference center for epilepsy surgery, during a 24-year period (1996-2020). Variables such as age of epilepsy onset, seizure semiology, seizure frequency, immunomodulatory therapy, age at surgery, duration of epilepsy, surgical procedures and complications, number of medications used preoperatively and postoperatively were described and statistically analyzed. Forty-three (43) patients were included in this study. Mean age of epilepsy onset was 6.14 years, the average interval between epilepsy onset and hemispherotomy was 2.21 years. and the mean age at surgery was 8.28 years. Thirty patients (69.7%) were Engel I at their last follow-up, of whom 23 (56.4%) were Engel Ia, within a mean follow-up of 11.3 years. Duration of epilepsy, seizure frequency, and age at surgery, among others, did not correlate with seizure outcome, except the use of immunotherapy which led to worse outcomes (p < .05). Also, after surgery, motor functionality was significantly recovered (i.e., most patients returned to their previous status) with time. This study tackled some issues regarding the surgical treatment of this disease, particularly showing that hemispherotomy is safe and leads to potentially recoverable disability of motor functions while providing high rates of effective and long-lasting seizure control; therefore, early surgical indication should be warranted once medical refractoriness has been established.

Clinical outcomes of pediatric hemispherectomy following unsuccessful subhemispheric resection for refractory epilepsy: a case review study.

Epilepsy surgery remains one of the most underutilized procedures in epilepsy despite its proven superiority to other available therapies. This underutilization is greater in patients in whom initial surgery fails. This case series examined the clinical characteristics, reasons for initial surgery failure, and outcomes in a cohort of patients who underwent hemispherectomy following unsuccessful smaller resections for intractable epilepsy (subhemispheric group [SHG]) and compared them to those of a cohort of patients who underwent hemispherectomy as the first surgery (hemispheric group [HG]). The objective of this paper was to determine the clinical characteristics of patients in whom a small, subhemispheric resection failed, who went on to become seizure free after undergoing a hemispherectomy. Patients who underwent hemispherectomy at Seattle Children's Hospital between 1996 and 2020 were identified. Inclusion criteria for SHG were as follows: 1) patients ≤ 18 years of age at the time of hemispheric surgery; 2) initial subhemispheric epilepsy surgery that did not produce seizure freedom; 3) hemispherectomy or hemispherotomy after the subhemispheric surgery; and 4) follow-up for at least 12 months after hemispheric surgery. Data collected included the following: patient demographics; seizure etiology; comorbidities; prior neurosurgeries; neurophysiological studies; imaging studies; and surgical details-plus surgical, seizure, and functional outcomes. Seizure etiology was classified as follows: 1) developmental, 2) acquired, or 3) progressive. The authors compared SHG to HG in terms of demographics, seizure etiology, and seizure and neuropsychological outcomes. There were 14 patients in the SHG and 51 patients in the HG. All patients in the SHG had Engel class IV scores after their initial resective surgery. Overall, 86% (n = 12) of the patients in the SHG had good posthemispherectomy seizure outcomes (Engel class I or II). All patients in the SHG who had progressive etiology (n = 3) had favorable seizure outcomes, with eventual hemispherectomy (1 each with Engel classes I, II, and III). Engel classifications posthemispherectomy between the groups were similar. There were no statistical differences in postsurgical Vineland Adaptive Behavior Scales Adaptive Behavior Composite scores or postsurgical full-scale IQ scores between groups when accounting for presurgical scores. Hemispherectomy as a repeat surgery after unsuccessful subhemispheric epilepsy surgery has a favorable seizure outcome, with stable or improved intelligence and adaptive functioning. Findings in these patients are similar to those in patients who had hemispherectomy as their first surgery. This can be explained by the relatively small number of patients in the SHG and the higher likelihood of hemispheric surgeries to resect or disconnect the entire epileptogenic lesion compared to smaller resections.

Comparison of Hemispheric Surgery Techniques for Pediatric Drug-Resistant Epilepsy: An Individual Patient Data Meta-analysis.

Hemispheric surgery effectively treats unihemispheric pediatric drug-resistant epilepsy (DRE) by resecting and/or disconnecting the epileptic hemisphere. Modifications to the original anatomic hemispherectomy have generated multiple functionally equivalent, disconnective techniques for performing hemispheric surgery, termed functional hemispherotomy. While a myriad of hemispherotomy variants exist, all of them can be categorized according to the anatomic plane they are performed in, which includes vertical approaches at or near the interhemispheric fissure and lateral approaches at or near the Sylvian fissure. This meta-analysis of individual patient data (IPD) aimed to compare seizure outcomes and complications between the hemispherotomy approaches to better characterize their relative efficacy and safety in the modern neurosurgical treatment of pediatric DRE, given emerging evidence that outcomes may differ between them. CINAHL, Embase, PubMed, and Web of Science were searched from inception to September 9, 2020, for studies reporting IPD from pediatric patients with DRE who underwent hemispheric surgery. Outcomes of interest were seizure freedom at last follow-up, time-to-seizure recurrence, and complications including hydrocephalus, infection, and mortality. The χ2 test compared the frequency of seizure freedom and complications. Multivariable mixed-effects Cox regression controlling for predictors of seizure outcome was performed on propensity score-matched patients to compare time-to-seizure recurrence between approaches. Kaplan-Meier curves were made to visualize differences in time-to-seizure recurrence. Fifty-five studies reporting on 686 unique pediatric patients treated with hemispheric surgery were included for meta-analysis. Among the hemispherotomy subgroup, vertical approaches resulted in a greater proportion of seizure free patients (81.2% vs 70.7%, p = 0.014) than lateral approaches. While there were no differences in complications, lateral hemispherotomy had higher rates of revision hemispheric surgery due to incomplete disconnection and/or recurrent seizures than vertical hemispherotomy (16.3% vs 1.2%, p < 0.001). After propensity score matching, vertical hemispherotomy approaches independently conferred longer time-to-seizure recurrence than lateral hemispherotomy approaches (hazard ratio 0.44, 95% CI 0.19-0.98). Among functional hemispherotomy techniques, vertical hemispherotomy approaches confer more durable seizure freedom than lateral approaches without compromising safety. Future prospective studies are required to definitively determine whether vertical approaches are indeed superior and how it should influence clinical guidelines for performing hemispheric surgery.

Impact of Etiology on Seizure and Quantitative Functional Outcomes in Children with Cerebral Palsy and Medically Intractable Epilepsy Undergoing Hemispherotomy/Hemispherectomy

To compare functional and seizure outcomes in children with vascular and dysplastic etiologies of cerebral palsy and medically intractable epilepsy following functional hemispherotomy or anatomic hemispherectomy. Consecutive patients satisfying inclusion criteria from 07/01/2015 to 12/01/2019 were reviewed for demographic data and seizure (Engel classification) and functional (Functional Independence Measure for Children) outcomes. After a mean follow-up of 2years 8months (1year 2months), 11 of 18 patients achieved post-operative seizure freedom without significant difference between vascular (5/7) and dysplastic (6/11) etiologies (P= 0.64). Functional assessments were completed for 15 of 18 of subjects, split comparably between groups. Mean change in the Functional Independence Measure for Children from pre-operative baseline to inpatient rehabilitation admission (vascular,-35.3 [13.2]; malformation of cortical development{MCD},-34.5 [25.0]; P= 0.69), inpatient rehabilitation admission to discharge (vascular, 18.7 [9.0]; MCD, 20.8 [11.4]; P= 0.60), and pre-operative evaluation to clinic follow-up (vascular,-7.6 [9.7]; MCD,-3.6 [19.3]; P= 0.61) did not differ between groups. Quantitative functional and seizure outcomes following functional hemispherotomy or anatomic hemispherectomy did not differ significantly between vascular and dysplastic etiologies of cerebral palsy and medically intractable epilepsy in this study. Hemispheric surgery resulted in minor functional declines from baseline following comprehensive multidisciplinary therapy.

Not surgical technique, but etiology, contralateral MRI, prior surgery, and side of surgery determine seizure outcome after pediatric hemispherotomy.

We aimed to assess determinants of seizure outcome following pediatric hemispherotomy in a contemporary cohort. We retrospectively analyzed the seizure outcomes of 457 children who underwent hemispheric surgery in five European epilepsy centers between 2000 and 2016. We identified variables related to seizure outcome through multivariable regression modeling with missing data imputation and optimal group matching, and we further investigated the role of surgical technique by Bayes factor (BF) analysis. One hundred seventy seven children (39%) underwent vertical and 280 children (61%) underwent lateral hemispherotomy. Three hundred forty-four children (75%) achieved seizure freedom at a mean follow-up of 5.1 years (range 1 to 17.1). We identified acquired etiology other than stroke (odds ratio [OR] 4.4, 95% confidence interval (CI) 1.1-18.0), hemimegalencephaly (OR 2.8, 95% CI 1.1-7.3), contralateral magnetic resonance imaging (MRI) findings (OR 5.5, 95% CI 2.7-11.1), prior resective surgery (OR 5.0, 95% CI 1.8-14.0), and left hemispherotomy (OR 2.3, 95% CI 1.3-3.9) as significant determinants of seizure recurrence. We found no evidence of an impact of the hemispherotomy technique on seizure outcome (the BF for a model including the hemispherotomy technique over the null model was 1.1), with comparable overall major complication rates for different approaches. Knowledge about the independent determinants of seizure outcome following pediatric hemispherotomy will improve the counseling of patients and families. In contrast to previous reports, we found no statistically relevant difference in seizure-freedom rates between the vertical and horizontal hemispherotomy techniques when accounting for different clinical features between groups.

Outcome prediction of pediatric moyamoya disease using midterm cerebral blood flow measured between staged anastomoses.

Cognitive outcomes of pediatric moyamoya disease are variable and difficult to predict on the basis of initial neurological signs and examinations. To determine the best early time point for outcome prediction, we retrospectively analyzed the correlation between cognitive outcomes and the cerebrovascular reserve capacity (CRC) measured before, between, and after staged bilateral anastomoses. Twenty-two patients aged 4-15years were included in this study. CRC was measured before the first hemispheric surgery (preoperative CRC), 1year after the first surgery (midterm CRC), and 1year after the surgery on the other side (final CRC). The cognitive outcome was the Pediatric Cerebral Performance Category Scale (PCPCS) grade more than 2years after the final surgery. The 17 patients with favorable outcomes (PCPCS grades 1 or 2) showed a preoperative CRC of 4.9% ± 11.2%, which was not better than that of the five patients with unfavorable outcomes (grade 3; 0.3% ± 8.5%, p = 0.5). The 17 patients with favorable outcomes showed a midterm CRC of 23.8% ± 15.3%, which was significantly better than that of the five patients with unfavorable outcomes (-2.5% ± 12.1%, p = 0.004). The difference was much more significant for the final CRC, which was 24.8% ± 13.1% in the patients with favorable outcomes and -11.3% ± 6.7% in those with unfavorable outcomes (p = 0.00004). Cognitive outcomes were first clearly discriminated by the CRC after the first-side unilateral anastomosis, which is the optimal early timing for the prediction of individual prognosis.

Design and validation of a hemispherectomy simulator for neurosurgical education.

Early adaptors of surgical simulation have documented a translation to improved intraoperative surgical performance. Similar progress would boost neurosurgical education, especially in highly nuanced epilepsy surgeries. This study introduces a hands-on cerebral hemispheric surgery simulator and evaluates its usefulness in teaching epilepsy surgeries. Initially, the anatomical realism of the simulator and its perceived effectiveness as a training tool were evaluated by two epilepsy neurosurgeons. The surgeons independently simulated hemispherotomy procedures and provided questionnaire feedback. Both surgeons agreed on the anatomical realism and effectiveness of this training tool. Next, construct validity was evaluated by modeling the proficiency (task-completion time) of 13 participants, who spanned the experience range from novice to expert. Poisson regression yielded a significant whole-model fit (χ2 = 30.11, p < 0.0001). The association between proficiency when using the training tool and the combined effect of prior exposure to hemispherotomy surgery and career span was statistically significant (χ2 = 7.30, p = 0.007); in isolation, pre-simulation exposure to hemispherotomy surgery (χ2 = 6.71, p = 0.009) and career length (χ2 = 14.21, p < 0.001) were also significant. The mean (± SD) task-completion time was 25.59 ± 9.75 minutes. Plotting career length against task-completion time provided insights on learning curves of epilepsy surgery. Prediction formulae estimated that 10 real-life hemispherotomy cases would be needed to approach the proficiency seen in experts. The cerebral hemispheric surgery simulator is a reasonable epilepsy surgery training tool in the quest to increase preoperative practice opportunities for neurosurgical education.

Can Presurgical Interhemispheric EEG Connectivity Predict Outcome in Hemispheric Surgery? A Brain Machine Learning Approach.

Hemispherotomy (HT) is a surgical option for treatment of drug-resistant seizures due to hemispheric structural lesions. Factors affecting seizure outcome have not been fully clarified. In our study, we used a brain Machine Learning (ML) approach to evaluate the possible role of Inter-hemispheric EEG Connectivity (IC) in predicting post-surgical seizure outcome. We collected 21 pediatric patients with drug-resistant epilepsy; who underwent HT in our center from 2009 to 2020; with a follow-up of at least two years. We selected 5-s windows of wakefulness and sleep pre-surgical EEG and we trained Artificial Neuronal Network (ANN) to estimate epilepsy outcome. We extracted EEG features as input data and selected the ANN with best accuracy. Among 21 patients, 15 (71%) were seizure and drug-free at last follow-up. ANN showed 73.3% of accuracy, with 85% of seizure free and 40% of non-seizure free patients appropriately classified. The accuracy level that we reached supports the hypothesis that pre-surgical EEG features may have the potential to predict epilepsy outcome after HT. The role of pre-surgical EEG data in influencing seizure outcome after HT is still debated. We proposed a computational predictive model, with an ML approach, with a high accuracy level.

Prognostic Value of Preoperative and Postoperative Electroencephalography Findings in Pediatric Patients Undergoing Hemispheric Epilepsy Surgery

The seizure outcomes after hemispheric epilepsy surgery have been excellent, with 54%-90% of patients achieving long-term freedom from seizures. Similarly, the neuropsychological outcomes have been favorable. The prognostic value of pre- and postoperative electroencephalography (EEG) has not been well-studied. In the present study, we characterized the value of the pre- and postoperative EEG findings for predicting the seizure and neuropsychological outcomes for pediatric patients undergoing hemispherectomy. A total of 22 children who had undergone functional hemispherectomy at our institution from 2010 to 2020 were included. The ictal and interictal findings were categorized as ipsilateral to the operated hemisphere, independently arising from the contralateral hemisphere, and/or generalized. The seizure outcomes were classified using the Engel scale. All neuropsychological evaluations were performed in accordance with our institution's protocol. The relationship between the EEG findings and outcomes was analyzed. Of the 22 patients, 19 (86%) were seizure free (Engel class IA) at the latest follow-up (mean, 4.2 years). On the preoperative EEGs, 9 had had seizures, all had had ipsilateral interictal discharges, and 9 had had contralateral interictal discharges. On the postoperative EEGs, obtained a median of 1 year after surgery, 3 had had seizures, 16 had had ipsilateral interictal discharges, and 5 had had contralateral interictal discharges. Of the 3 patients with seizures found on the postoperative EEG, all were clinically free of seizures. The patients who had not achieved Engel class IA were not significantly more likely to have abnormalities found on the EEG. The neuropsychological scores were stable from before to after surgery, with no evidence of EEG abnormalities having predictive value. The seizure and neuropsychology outcomes after hemispherectomy were excellent in our study, with 86% of our cohort achieving freedom from seizures. The presence, lateralization, and evolution of pre- and postoperative EEG abnormalities were not predictive of the outcomes.

Commentary: Midline Brain Shift After Hemispheric Surgery: Natural History, Clinical Significance, and Association With Cerebrospinal Fluid Diversion.

Commentary: Midline Brain Shift After Hemispheric Surgery: Natural History, Clinical Significance, and Association With Cerebrospinal Fluid Diversion.

Midline Brain Shift After Hemispheric Surgery: Natural History, Clinical Significance, and Association With Cerebrospinal Fluid Diversion.

Hemispherectomy and its modern variants are effective surgical treatments for medically intractable unihemispheric epilepsy. Although some complications such as posthemispherectomy hydrocephalus are well documented, midline brain shift (MLBS) after hemispheric surgery has only been described anecdotally and never formally studied. To assess the natural history and clinical relevance of MLBS and determine whether cerebrospinal fluid (CSF) shunting of the ipsilateral surgical cavity exacerbates MLBS posthemispheric surgery. A retrospective review of consecutive pediatric patients who underwent hemispheric surgery for intractable epilepsy and at least 6 months of follow-up at UCLA between 1994 and 2018 was performed. Patients were grouped by MLBS severity, shunt placement, valve type, and valve opening pressure (VOP). MLBS was evaluated using the paired samples t-test and analysis of covariance adjusting for follow-up time and baseline postoperative MLBS. Seventy patients were analyzed, of which 23 (33%) required CSF shunt placement in the ipsilateral surgical cavity for posthemispherectomy hydrocephalus. MLBS increased between first and last follow-up for nonshunted (5.3 ± 4.9-9.7 ± 6.6 mm, P < .001) and shunted (6.6 ± 3.5-16.3 ± 9.4 mm, P < .001) patients. MLBS progression was greater in shunted patients (P = .001). Shunts with higher VOPs did not increase MLBS relative to nonshunted patients (P = .834), whereas MLBS increased with lower VOPs (P = .001). Severe MLBS was associated with debilitating headaches (P = .048). Patients undergoing hemispheric surgery often develop postoperative MLBS, ie, exacerbated by CSF shunting of the ipsilateral surgical cavity, specifically when using lower VOP settings. MLBS exacerbation may be related to overshunting. Severe MLBS is associated with debilitating headaches.

Lesional resective epilepsy surgery in childhood: Comparison of two decades and long-term seizure outcome from a single center

ObjectiveEpilepsy surgery has shown efficacy in children. We aimed to assess long-term seizure outcome in children who underwent epilepsy surgery and determine predictive factors for seizure freedom. MethodsThis is a retrospective study of 196 children who underwent epilepsy surgery between 1994 and 2015 and had a minimum postoperative follow-up of 5 years. ResultsThe median age at the time of surgery was 9.5 (0.08–19.8) years; 110 (56.1%) had temporal, 62 (31.6%) had extratemporal resections, and 24 (12.2%) had hemispheric surgery. The duration of postsurgical follow-up was between 5 and 20 years (mean±SD: 7 ± 3.2). Overall, 129 of 196 (65.8%) patients had Engel class I outcome at final visit. Among patients who underwent temporal, extratemporal and hemispheric surgery; 84 of 110 (76.4%), 34 of 62 (54.8%), and 11 of 24 (45.8%) patients had complete seizure freedom, respectively (p: 0.016). Patients with tumors had the best outcome, with 83.1% seizure freedom. The number of preoperative antiseizure medications (OR 3.19, 95% CI 1.07–9.48), the absence of postoperative focal epileptiform discharges (OR 8.98, 95% CI 4.07–19.79) were independent predictors of seizure freedom. Across two decades, the age at surgery was decreased (p: 0.003), overall seizure freedom (61.8% vs 68%) did not differ. In the past decade, a higher proportion of malformations of cortical development was operated (14.7% vs 35.9%, p: 0.007). SignificanceOur findings showed favorable long-term seizure outcome in children who underwent epilepsy surgery. The results are encouraging for developing centers with limited resources to establish pediatric epilepsy programs.

Knowledge gaps for functional outcomes after multilobar resective and disconnective pediatric epilepsy surgery: Conference Proceedings of the Patient-Centered Stakeholder Meeting 2019.

For children with medication-resistant epilepsy who undergo multilobar or hemispheric surgery, the goal of achieving seizure freedom is met with a variety of potential functional consequences, both favorable and unfavorable. However, there is a paucity of literature that comprehensively addresses the cognitive, medical, behavioral, orthopedic, and sensory outcomes across the lifespan following large epilepsy surgeries in childhood, leaving all stakeholders underinformed with regard to counseling and expectations. Through collaboration between clinicians, researchers, and patient/caregiver stakeholders, the "Functional Impacts of Large Resective or Disconnective Pediatric Epilepsy Surgery: Identifying Gaps and Setting PCOR Priorities" meeting was convened on July 18, 2019, to identify gaps in knowledge and inform various patient-centered research initiatives. Clinicians and researchers with content expertise presented the best available data in each functional domain which is summarized here. As a result of the meeting, the top three consensus priorities included research focused on postoperative: (1) hydrocephalus; (2) mental health issues; and (3) literacy and other educational outcomes. The proceedings of this meeting mark the first time research on functional outcomes after resective and disconnective pediatric epilepsy surgery has been codified and shared among multidisciplinary stakeholders. This joint initiative promotes continued collaboration in the field and ensures that advancements align with actual patient and family needs and experiences. Collaboration around common objectives will lead to better informed counseling around postoperative expectations and management for children undergoing epilepsy surgery.

Comparison of the real-world effectiveness of vertical versus lateral functional hemispherotomy techniques for pediatric drug-resistant epilepsy: A post hoc analysis of the HOPS study.

ObjectiveThis study was undertaken to determine whether the vertical parasagittal approach or the lateral peri‐insular/peri‐Sylvian approach to hemispheric surgery is the superior technique in achieving long‐term seizure freedom.MethodsWe conducted a post hoc subgroup analysis of the HOPS (Hemispheric Surgery Outcome Prediction Scale) study, an international, multicenter, retrospective cohort study that identified predictors of seizure freedom through logistic regression modeling. Only patients undergoing vertical parasagittal, lateral peri‐insular/peri‐Sylvian, or lateral trans‐Sylvian hemispherotomy were included in this post hoc analysis. Differences in seizure freedom rates were assessed using a time‐to‐event method and calculated using the Kaplan–Meier survival method.ResultsData for 672 participants across 23 centers were collected on the specific hemispherotomy approach. Of these, 72 (10.7%) underwent vertical parasagittal hemispherotomy and 600 (89.3%) underwent lateral peri‐insular/peri‐Sylvian or trans‐Sylvian hemispherotomy. Seizure freedom was obtained in 62.4% (95% confidence interval [CI] = 53.5%–70.2%) of the entire cohort at 10‐year follow‐up. Seizure freedom was 88.8% (95% CI = 78.9%–94.3%) at 1‐year follow‐up and persisted at 85.5% (95% CI = 74.7%–92.0%) across 5‐ and 10‐year follow‐up in the vertical subgroup. In contrast, seizure freedom decreased from 89.2% (95% CI = 86.3%–91.5%) at 1‐year to 72.1% (95% CI = 66.9%–76.7%) at 5‐year to 57.2% (95% CI = 46.6%–66.4%) at 10‐year follow‐up for the lateral subgroup. Log‐rank test found that vertical hemispherotomy was associated with durable seizure‐free progression compared to the lateral approach (p = .01). Patients undergoing the lateral hemispherotomy technique had a shorter time‐to‐seizure recurrence (hazard ratio = 2.56, 95% CI = 1.08–6.04, p = .03) and increased seizure recurrence odds (odds ratio = 3.67, 95% CI = 1.05–12.86, p = .04) compared to those undergoing the vertical hemispherotomy technique.SignificanceThis pilot study demonstrated more durable seizure freedom of the vertical technique compared to lateral hemispherotomy techniques. Further studies, such as prospective expertise‐based observational studies or a randomized clinical trial, are required to determine whether a vertical approach to hemispheric surgery provides superior long‐term seizure outcomes.