Vertical parasagittal hemispherotomy: surgical procedures and clinical long-term outcomes in a population of 83 children

Insights on cognitive reorganization after hemispherectomy in Rasmussen's encephalitis. A narrative review

Rasmussen's encephalitis is a rare neurological pathology affecting one cerebral hemisphere, therefore, posing unique challenges. Patients may undergo hemispherectomy, a surgical procedure after which cognitive development occurs in the isolated contralateral hemisphere. This rare situation provides an excellent opportunity to evaluate brain plasticity and cognitive recovery at a hemispheric level. This literature review synthesizes the existing body of research on cognitive recovery following hemispherectomy in Rasmussen patients, considering cognitive domains and modulatory factors that influence cognitive outcomes. While language function has traditionally been the focus of postoperative assessments, there is a growing acknowledgment of the need to broaden the scope of language investigation in interaction with other cognitive domains and to consider cognitive scaffolding in development and recovery. By synthesizing findings reported in the literature, we delineate how language functions may find support from the right hemisphere after left hemispherectomy, but also how, beyond language, global cognitive functioning is affected. We highlight the critical influence of several factors on postoperative cognitive outcomes, including the timing of hemispherectomy and the baseline preoperative cognitive status, pointing to early surgical intervention as predictive of better cognitive outcomes. However, further specific studies are needed to confirm this correlation. This review aims to emphasize a better understanding of mechanisms underlying hemispheric specialization and plasticity in humans, which are particularly important for both clinical and research advancements. This narrative review underscores the need for an integrative approach based on cognitive scaffolding to provide a comprehensive understanding of mechanisms underlying the reorganization in Rasmussen patients after hemispherectomy.

Determinants of Functional Outcome after Pediatric Hemispherotomy

OBJECTIVE

We aimed to evaluate determinants of functional outcome after pediatric hemispherotomy in a large and recent multicenter cohort.

METHODS

We retrospectively investigated the functional outcomes of 455 children who underwent hemispherotomy at 5 epilepsy centers in 2000-2016. We identified determinants of unaided walking, voluntary grasping with the hemiplegic hand, and speaking through Bayesian multivariable regression modeling using missing data imputation.

RESULTS

Seventy-five percent of children were seizure-free, and 44% stopped antiseizure medication at a 5.1-year mean follow-up (range = 1-17.1). Seventy-seven percent of children could walk unaided, 8% could grasp voluntarily, and 68% could speak at the last follow-up. Children were unlikely to walk when they had contralateral magnetic resonance imaging (MRI) abnormalities (40/73, p = 0.04), recurrent seizures following hemispherotomy (62/109, p = 0.04), and moderately (50/61, p = 0.03) or severely impaired (127/199, p = 0.001) postsurgical intellectual functioning, but were likely to walk when they were older at outcome determination (p = 0.01). Children were unlikely to grasp voluntarily with the hand contralateral to surgery when they had Rasmussen encephalitis (0/61, p = 0.001) or Sturge-Weber syndrome (0/32, p = 0.007). Children were unlikely to speak when they had contralateral MRI abnormalities (30/69, p = 0.002) and longer epilepsy duration (p = 0.01), but likely to speak when they had Sturge-Weber syndrome (29/35, p = 0.01), were older at surgery (p = 0.04), and were older at outcome determination (p < 0.001).

INTERPRETATION

Etiology and bilaterality of structural brain abnormalities were key determinants of functional outcome after hemispherotomy. Longer epilepsy duration affected language outcomes. Not surprisingly, walking and talking ability increased with older age at outcome evaluation. ANN NEUROL 2024;95:377-387.

Functional hemispheric disconnection procedures for chronic epilepsy: history, indications, techniques, complications and current practice in Europe. A consensus statement on behalf of the EANS functional neurosurgery section

Introduction

The surgical procedure for severe, drug-resistant, unilateral hemispheric epilepsy is challenging. Over the last decades the surgical landscape for hemispheric disconnection procedures changed from anatomical hemispherectomy to functional hemispherotomy with a reduction of complications and stable good seizure outcome. Here, a task force of European epilepsy surgeons prepared, on behalf of the EANS Section for Functional Neurosurgery, a consensus statement on different aspects of the hemispheric disconnection procedure.

Research question

To determine history, indication, timing, techniques, complications and current practice in Europe for hemispheric disconnection procedures in drug-resistant epilepsy.

Material and methods

Relevant literature on the topic was collected by a literature search based on the PRISMA 2020 guidelines.

Results

A comprehensive overview on the historical development of hemispheric disconnection procedures for epilepsy is presented, while discussing indications, timing, surgical techniques and complications. Current practice for this procedure in European epilepsy surgery centers is provided. At present, our knowledge of long-term seizure outcomes primarily stems from open surgical disconnection procedures. Although minimal invasive surgical techniques in epilepsy are rapidly developing and reported in case reports or small case series, long-term seizure outcome remain uncertain and needs to be reported.

Discussion and conclusion

This is the first paper presenting a European consensus statement regarding history, indications, techniques and complications of hemispheric disconnection procedures for different causes of chronic, drug-resistant epilepsy. Furthermore, it serves as the pioneering document to report a comprehensive overview of the current surgical practices regarding this type of surgery employed in renowned epilepsy surgery centers across Europe.

Hemispheric epilepsy surgery for hemimegalencephaly: The UCLA experience

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

SIGNIFICANCE

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.

Clinician views regarding early surgery for paediatric epilepsy

OBJECTIVE

Many children with lesional epilepsies progress to drug resistance, a criterion required for surgical referral. Expedited surgery may reduce exposure of the developing brain to uncontrolled seizures, improving cognitive outcomes. Designing a trial comparing early surgery with standard care necessitates input from specialist clinicians regarding feasibility and measurable outcomes, which this study investigated.

METHODS

Online surveys were disseminated from June-July 2022 via regional paediatric epilepsy networks and professional societies. 51 UK clinicians responded, mostly paediatricians, paediatric neurologists and epilepsy specialist nurses. Candidacy for epilepsy surgery, outcome measures and support for the proposed study were surveyed. Clinician views were compared by speciality, using Pearson's chi-squared tests to explore differences.

RESULTS

76-98 % of clinicians would refer children for presurgical evaluation at/before drug resistance development across four subgroups (those younger/older than two years, and those with/without a detectable lesion). Earlier referral, at/before epilepsy diagnosis, was considered mostly in those with visible lesions (53 %) and those under two years (31 %). 73 % would consider early surgery before drug resistance is established. Top outcomes to measure were seizure freedom (39 %) and quality of life (22 %). Views of paediatric neurologists and paediatricians did not differ (p > .05).

SIGNIFICANCE

Clinician opinions generally aligned with published guidance regarding epilepsy surgery referral. Some remain cautious to refer young children with lesions prior to trialling more than one antiseizure medication. Most support early surgery in appropriate patients, with seizure and quality of life outcomes rated highly. Incorporating these perspectives will aid future trial design, recruitment and clinical utility.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

SIGNIFICANCE

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.

Modified Vertical Parasagittal Sub-Insular Hemispherotomy-Case Series and Technical Note

(1) Background: Hemispherotomy is the generally accepted treatment for hemispheric drug-resistant epilepsy (DRE). Lateral or vertical approaches are performed according to the surgeon's preference. Multiple technical variations have been proposed since Delalande first described his vertical technique. We propose a sub-insular variation of the vertical parasagittal hemispherotomy (VPH) and describe our case series of patients operated on using this procedure. (2) Methods: Data from a continuous series of patients with hemispheric DRE who were operated on by the senior author (CR) using the modified sub-insular VPH technique were analyzed retrospectively. Pre-operative demographic and epilepsy characteristics, functional outcome, and surgical complications were extracted from medical charts. (3) Results: Twenty-five patients were operated on between August 2008 and August 2023; 23 have at least 3 months of follow-up. Of this group, 20 (86.9%) patients are seizure-free. Only two patients developed postoperative hydrocephalus (8.7%). All patients who were able to walk autonomously preoperatively and 20 (86.9%) of those with follow-up were able to walk without assistance. A total of 17 (74%) patients were able to perform adapted social activities at the latest follow-up. (4) Conclusions: Modified sub-insular VPH is a successful surgical technique for hemispheric DRE with seizure freedom rates similar to the largest series reported in the literature. Compared to other series, patients who were operated on with our modified technique had a lower rate of postoperative hydrocephalus and excellent long-term motor and cognitive outcomes.

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

BACKGROUND AND OBJECTIVES

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.

METHODS

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.

RESULTS

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).

DISCUSSION

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.

Surgical treatment of epilepsy - Initial experience from a comprehensive epilepsy program in coastal South India

Objectives

The objectives of this study were to share our initial experience with epilepsy surgery and provide an overview on the surgical treatments of epilepsies.

Materials and Methods

This was a retrospective analysis of the demographics and clinical and investigative features of patients who underwent epilepsy surgery between January 2016 and August 2021. Postoperative seizure outcome was categorized according to modified Engel's classification, and the minimum period of follow-up was 1 year.

Results

The study group included 30 patients with an age ranging from 6 years to 45 years (mean: 22.28 years, median: 20 years) and a male: female ratio of 20:10. The epilepsy duration before surgery ranged from 3 years to 32 years (median: 7 years). Majority of our patients underwent resective surgeries (28/30 = 93.3%), and disconnection procedures were done in two patients. This included one functional hemispherotomy and one posterior quadrantic disconnection. Temporal lobe resective surgery was the most common procedure (16/30 = 53.3%), followed by eight frontal lobe and two parietal lobe surgeries. Among resective surgeries, majority were lesional surgeries and the pathologies included mesial temporal sclerosis (4), dysembryoplastic neuroepithelial tumor (8), ganglioglioma (6), cavernoma (4), focal cortical dysplasia (2), gliosis (1), and one case of hypothalamic hamartoma. Intraoperative electrocorticography was used in all cases for optimizing surgical resection/disconnection. Nearly two-thirds of our patients (66.6%) had an Engel's Class I outcome, five patients had Engel's Class II outcome, three patients had Class III outcome, and one patient did not have any worthwhile improvement. Temporal lobe surgery patients had a better seizure outcome compared to extratemporal surgeries (84% vs. 74%). Overall, complications were minimal and short lasting, and comprised meningitis in three patients (5.6%) and transient worsening of hemiparesis following hemispherotomy in two patients. There was no mortality or long-lasting major morbidity in our patients.

Conclusion

In carefully selected patients with drug-resistant epilepsy, surgery offers an excellent chance of becoming seizure-free with significant improvement in overall quality of life. Majority of the common epilepsy surgery procedures can be performed through a multidisciplinary approach even in centers with limited resources.

Hemispherotomy Revised: A complication overview and a systematic review meta-analysis

Introduction

Hemispherectomy/hemispherotomy has been employed in the management of catastrophic epilepsy. However, initial reports on the associated mortality and morbidity raised several concerns regarding the technique's safety. Their actual, current incidence needs to be systematically examined to redefine hemispherotomy's exact role.

Research question

Our current study examined their incidence and evaluated the association of the various hemispherotomy surgical techniques with the reported complications.

Material & methods

A PRISMA-compliant systematic review and meta-analysis was performed. We searched PubMed, Scopus, and Web of Science until December 2022. Fixed- and random-effects models were employed. Egger's regression test was used for estimating the publication bias, while subgroup analysis was utilized for defining the role of the different hemispherotomy techniques.

Results

We retrieved a total of 37 studies. The overall procedure mortality was 5%, with a reported mortality of 7% for hemispherectomy and 3% for hemispherotomy. The reported mortality has decreased over the last 30 years from 32% to 2%. Among the observed post-operative complications aseptic meningitis and/or fever occurred in 33%. Hydrocephalus requiring a shunt insertion occurred in 16%. Hematoma evacuation was necessary in 8%, while subgaleal effusion in another 8%. Infections occurred in 11%. A novel post-operative cranial nerve deficit occurred in 11%, while blood transfusion was necessary in 28% of the cases.

Discussion and conclusion

Our current analysis demonstrated that the evolution from hemispherectomy to hemispherotomy along with neuroanesthesia advances, had a tremendous impact on the associated mortality and morbidity. Hemispherotomy constitutes a safe surgical procedure in the management of catastrophic epilepsies.

Surgical Strategy for Hemispherotomy

Hemispherotomy is a radical treatment for drug-resistant epilepsy that targets developmental, acquired, and progressive diseases with widespread epileptogenic regions in one cerebral hemisphere. Currently, two main approaches are utilized after repeated improvements: lateral and vertical approaches. With the lateral approach, the surgical field is wide, and the approach to the lateral ventricle is relatively easy. On the other hand, the vertical approach has the advantage of reducing intraoperative bleeding and operating time as the resection line of the radial fiber is short, and understanding the three-dimensional anatomy is relatively easy. The lateral approach is generally used for atrophic lesions, whereas the vertical approach is for hypertrophic lesions. Hemispherotomy is expected to not only suppress epileptic seizures but also improve psychomotor development by protecting the unaffected cerebral hemisphere. However, this method is one of the most invasive surgeries in epilepsy surgery, and it is important to fully consider its indications. Furthermore, understanding the neural fiber pathway is important for actual surgery.

Hemispherotomy in Infants with Hemimegalencephaly: Long-Term Seizure and Developmental Outcome in Early Treated Patients

Hemimegalencephaly (HME) is a rare brain congenital malformation, consisting in altered neuronal migration and proliferation within one hemisphere, which is responsible for early onset drug-resistant epilepsy. Hemispherotomy is an effective treatment option for patients with HME and drug-resistant epilepsy. Surgical outcome may be variable among different surgical series, and the long-term neuropsychological trajectory has been rarely defined using a standardized neurocognitive test. We report the epileptological and neuropsychological long-term outcomes of four consecutive HME patients, operated on before the age of three years. All patients were seizure-free and drug-free, and the minimum follow-up duration was of five years. Despite the excellent post-surgical seizure outcome, the long-term developmental outcome is quite variable between patients, ranging from mild to severe intellectual disabilities. Patients showed improvement mainly in communication skills, while visuo-perceptive and coordination abilities were more impaired. Epileptological outcome seems to be improved in early treated patients; however, neuropsychological outcome in HME patients may be highly variable despite early surgery.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

The accuracy level that we reached supports the hypothesis that pre-surgical EEG features may have the potential to predict epilepsy outcome after HT.

SIGNIFICANCE

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.

A simulation study to investigate the use of concentric tube robots for epilepsy surgery

PURPOSE

Patients with pharmacoresistant refractory epilepsy may require epilepsy surgery to prevent future seizure occurrences. Conventional surgery consists of a large craniotomy with straight rigid tools with associated outcomes of morbidity, large tissue resections, and long post-operative recovery times. Concentric tube robots have recently been developed as a promising application to neurosurgery due to their nonlinear form and small diameter. The authors present a concept study to explore the feasibility of performing minimally invasive hemispherotomy with concentric tube robots.

METHODS

A model simulation was used to achieve the optimal design and surgical path planning parameters of the concentric tube robot for corpus callosotomy and temporal lobectomy. A single medial burr hole was chosen to access the lateral ventricles for both white matter disconnections.

RESULTS

The concentric tube robot was able to accurately reach the designated surgical paths on the corpus callosum and the temporal lobe.

CONCLUSION

In a model simulation, the authors demonstrated the feasibility of performing corpus callosotomy and temporal lobectomy using concentric tube robots. Further advancements in the technology may increase the applicability of this technique for epilepsy surgery to better patient outcomes.

Case Report: Hemispherotomy in the First Days of Life to Treat Drug-Resistant Lesional Epilepsy

Background: Neonatal drug-resistant epilepsy is often caused by perinatal epileptogenic insults such as stroke, ischemia, hemorrhage, and/or genetic defects. Rapid seizure control is particularly important for cognitive development. Since early surgical intervention and thus a short duration of epilepsy should lead to an optimal developmental outcome, we present our experience with hemispherotomy in an infant at the corrected age of 1 week.

Methods: We report successful hemispherotomy for drug-resistant epilepsy in an infant with hemimegalencephaly at a corrected age of 1 week.

Results: The infant was diagnosed with drug-resistant lesional epilepsy due to hemimegalencephaly affecting the left hemisphere. Given congruent electroclinical findings, we performed a left vertical parasagittal transventricular hemispherotomy after critical interdisciplinary discussion. No complications occurred during the surgery. Intraoperatively; 118 ml of red blood cells (30 ml/kg) and 80 ml of plasma were transfused. The patient has been seizure-free since discharge without further neurological deficits.

Conclusion: We demonstrate that early epilepsy surgery is a safe procedure in very young infants if performed in a specialized center experienced with age-specific surgical conditions and perioperative management. The specific surgical difficulties should be weighed against the risk of life-long developmental drawbacks of ongoing detrimental epilepsy.

[Hemispherotomy in pediatric epilepsy surgery-Surgical, epileptological and functional aspects]

Hemispherotomies represent a major part of surgical interventions for epilepsy in childhood (16-21%). The anatomical resection has been replaced by minimally invasive disconnection techniques with lower perioperative mortality and fewer postoperative complications. Today the procedure is not only carried out from the lateral aspect via the Sylvian fissure/insula but also via a vertical parasagittal approach. Depending on the publication, hemispherotomy leads to freedom from postoperative seizures in 60-90% of patients. Despite changes in the surgical technique, disturbances of the cerebrospinal fluid circulation continue to be the main complication in 5-15% of cases. Hemispheric epileptogenic lesions usually lead to early onset and difficult to treat epilepsy in childhood. These epilepsies are characterized by a high frequency of seizures and propagation of epileptic discharges to the healthy hemisphere. The aim of a hemispherotomy is, in addition to postoperative freedom from seizures, the complete disconnection of the affected hemisphere. When deciding on a hemispherotomy, the expected functional consequences play a major role in addition to epileptological aspects. In the case of deficits already present preoperatively (hemianopia, hemiparesis) or reorganization of functions in the contralesional hemisphere (language), no new deficits are to be expected from the operation. In terms of cognition, a hemispherotomy can improve function by releasing the neuroplastic potential of the healthy hemisphere. In order to keep the negative and often irreversible effects of epilepsy as low as possible and to be able to use as much potential for neuroplasticity of the healthy hemisphere as possible, surgery should be considered as early as possible.

Vertical parasagittal hemispherotomy: a case report of postoperative mesio-temporal seizures via amygdalofugal pathway

Vertical parasagittal hemispherotomy (VPH) is a well-established surgical treatment which is proposed for children with widespread unilateral onset of intractable epileptic seizures. VPH allows to disconnect from a vertical transventricular approach all white matter fibers of the hemisphere around a central core including the thalamus. We present the case of a girl who underwent VPH for hemimegalencephaly in early infancy. Postoperatively, she developed unexpected seizures of mesio-temporal origin. Stereo-EEG provided arguments for an amygdalar origin. High-resolution MRI with tractography confirmed the presence of the amygdalo-fugal pathway to be responsible of epileptic discharges propagation. She became seizure-free after temporal resection.

Does etiology really matter for epilepsy surgery outcome?

Multiple factors influence the outcomes of epilepsy surgery. Prognostic indicators varying from clinical characteristics, imaging findings, ictal, and interictal electrophysiological activity have been linked to surgical outcomes. In this review, we focus on the relatively under‐studied role of the underlying epilepsy histopathology in driving post‐surgical outcomes, specifically focusing on the broad categories of seizure outcomes and cognitive outcomes. For each of these two outcomes of interest, we answer two questions: 1)‐ does etiology matter? and 2)‐ how could it matter? The goal is to review the existing literature on the relationship between etiology and surgical outcomes to provide the best possible judgment as to whether a causal relationship exists between histopathology and the ultimate surgical outcome as an initial step. Then, we delve into the possible mechanisms via which such relationships can be explained. We conclude with a call to action to the epilepsy surgery and histopathology research community to push the mechanistic understanding of the pathology‐outcome interaction and identify actionable knowledge and biomarkers that could inform patient care in a timely fashion.

In this review, we focus on the relatively under‐studied role of the underlying epilepsy histopathology in driving post‐surgical outcomes, specifically focusing on the broad categories of seizure outcomes and cognitive outcomes. For each of these two outcomes of interest, we answer two questions: (1) does etiology matter? and (2) how could it matter? We then delve into the mechanisms of these answers.

Hemispherotomy for pediatric epilepsy: a systematic review and critical analysis

PURPOSE

Several variations of functional disconnection surgery have been described for the treatment of lateralized, hemispheric, drug-resistant epilepsy in children. The purpose of this study is to investigate the existing literature regarding patient selection, approach, and outcomes after hemispherotomy.

METHODS

A systematic review of the English literature through February 2019 was performed in accordance with the PRISMA statement. The articles were classified by level of evidence and summarized in an evidentiary table. Seizure outcomes, functional outcomes, surgical techniques, complications, and patient selection were critically analyzed.

RESULTS

A total of 173 papers were reviewed, of which 37 met criteria of inclusion and exclusion. Thirteen studies were classified as level III evidence, the remaining reached level IV. Vertical and lateral hemispherotomy achieve similar rates of seizure freedom and functional outcomes, though parasagittal and interhemispheric approaches may have shorter operative times and less blood loss. Etiology, bilateral MRI abnormalities, and nonlateralizing EEG did not predict worse seizure or functional outcomes.

CONCLUSIONS

Both vertical and lateral hemispherotomy approaches result in durable, reproducible benefits to epilepsy severity and functional status in appropriately selected pediatric patients.

Correlation between Hemispherectomy and Hemiparesis in Drug Resistant Epilepsy

Background and Purpose

Refractory epilepsy is when seizures are unresponsive to two or more medications. Hemispherectomy, one of the treatment options, is the complete removal or functional disconnection of a cerebral hemisphere. Hemiparesis, a symptom of epilepsy, is defined as weakness of one side of the body. Patients with refractory epilepsy, who experience extreme seizure frequency, are subjected to hemispherectomy. This study focuses on finding the correlation between hemispherectomy and hemiparesis, discovering a pattern in its severity levels before and after surgery.

Methods

Data was collected from 59 epileptic patients suffering from refractory epilepsy, who underwent hemispherectomy, at the King Faisal Specialist Hospital and Research Centre, from 1998 to 2014. Each patient was monitored over a period of 1-year post-surgery. In this study, we wanted to further explore the correlation between hemispherectomy and hemiparesis.

Results

Upon analyzing the sample size, the level of hemiparesis pre and post hemispherectomy remained the same for 32 patients, of which 13 patients had mild levels pre-surgery and 19 patients had moderate to severe levels pre-surgery. However, 20 of the patients who had moderate to severe levels of hemiparesis before the surgery had either no hemiparesis or a mild level after surgery, which signified an improvement in their severity level. On the other hand, seven of the patients went from having no hemiparesis before the surgery to having moderate or severe levels of hemiparesis post-surgery. Although the results were clinically significant, they were not statistically significant as the p-value obtained was 0.31.

Conclusions

After analyzing the results, it can be concluded that hemispherectomy does decrease the severity of hemiparesis in an epileptic patient, thereby improving his/her quality of life drastically.

Robotic thermocoagulative hemispherotomy: concept, feasibility, outcomes, and safety of a new "bloodless" technique

OBJECTIVE

The authors present a new "bloodless" technique for minimally invasive robotic thermocoagulative hemispherotomy (ROTCH). Such a method is being described in the literature for the first time.

METHODS

A robotic system was used to plan five sets of different trajectories: anterior disconnection, middle disconnection, posterior disconnection, corpus callosotomy, and temporal stem and amygdalar disconnection. A special technique, called the "X" technique, allowed planar disconnection. Registration was performed with surface landmarks (n = 5) and bone fiducials (n = 1). Coregistration with O-arm images was performed one or two times to confirm the trajectories (once for middle disconnection, and once for disconnection of the temporal stem and amygdala or body of the corpus callosum). Impedance measured before ablation allowed for minor adjustments. Radiofrequency ablation was performed at 75°C-80°C for 60 seconds. Surgical procedures were performed with multiple twist drills. After removal of the electrode, glue was used to prevent CSF leak, and a single stitch was applied. Follow-up CT and MRI were immediately performed.

RESULTS

The pathologies included Rasmussen's encephalitis (n = 2), hemispheric cortical dysplasia (n = 2), posttraumatic encephalomalacia (n = 1), and perinatal insult (n = 1). The mean ± SD (range) age was 6.7 ± 3.6 years (5 months to 10.2 years), and the right side was affected in 4 patients. The mean ± SD seizure frequency was 7.4 ± 5.6 seizures per day (1 patient had epilepsia partialis continua). The mean ± SD number of trajectories was 15.3 ± 2.5, and the mean ± SD number of lesions was 108 ± 25.8. The mean ± SD maximum numbers of trajectories and lesions required for middle disconnection were 7.1 ± 1.7 and 57.5 ± 18.4, respectively. All but 1 patient had class 1 outcomes according to the International League Against Epilepsy Outcome Scale at a mean ± SD (range) follow-up of 13.5 ± 1.6 (12-16) months; the remaining patient had a class 2 outcome. The estimated blood loss was < 5 ml for all patients. Complications included repeat surgery (after 2 weeks) for a "skip" area (n = 1) and a small temporal hematoma (n = 1), which resolved.

CONCLUSIONS

ROTCH seems to be a safe, feasible, and bloodless procedure, with a very low morbidity rate and promising outcomes.

Transient water-electrolyte disturbance after hemispherotomy in young infants with epileptic encephalopathy

PURPOSE

This study aimed to elucidate the clinical features of water-electrolyte disturbance (WED) as a sequela of hemispherotomy.

METHODS

We performed a retrospective chart review to identify the clinical features of diabetes insipidus (DI) as a complication in < 12-month-old patients who underwent hemispherectomy or hemispherotomy for severe epilepsy between 2007 and 2018. Central DI was diagnosed if a patient developed polyuria (urine output > 5 mL/kg/h), abnormally high serum osmolality (> 300 mOsm/kg), high serum sodium level (> 150 mEq/L), either abnormally low urine specific gravity (< 1.005) or low urine osmolality (< 300 mOsm/kg) or both, and effective control of polyuria with arginine vasopressin (AVP). The clinical course of post-hemispherotomy WED, complications other than WED, and seizure outcomes were analyzed.

RESULTS

The review identified that 3 of 23 infants developed WED. All patients developed polyuria within 2 days after surgery, with high serum osmolality and hypotonic urine; AVP was effective in treating these symptoms. The clinical course was compatible with central DI. Two patients subsequently developed hyponatremia in a biphasic or triphasic manner. All patients had multiple seizures that were probably related to WED. Two patients developed asymptomatic cerebral sinovenous thrombosis, possibly because of the surgical procedure and dehydration; anticoagulant treatment was provided. All patients were treated for WED for up to 2 months and had no residual pituitary dysfunction.

CONCLUSION

Systemic complications other than intracranial ones can occur in patients who have undergone hemispherotomy. Perioperative systemic management of young infants undergoing this procedure should include careful water and electrolyte balance monitoring.

Minimizing blood loss in hemispherectomy for hemimegalencephaly in low-weight infants: technical note

INTRODUCTION

Drug-resistant seizures due to hemimegalencephaly in neonates and infants are a unique surgical and anesthesia challenge. While early surgery in these patients may predict a better seizure control, a lower body weight, limited blood volume, and surgical blood loss may make hemispherectomy prohibitive.

METHODS

Two infants (weight, 8.7 kg and 3.7 kg) underwent interhemispheric vertical hemispherotomy with endoscope assistance. In the first case, during the lateral disconnection, excessive bleeding prompted the surgeon to coagulate the lenticulostriate arteries at the origin from the middle cerebral artery to reduce bleeding. In the second infant, the lenticulostriate arteries were coagulated before initiating the lateral disconnection.

RESULTS

In both infants, the blood loss from lateral dissection was reduced by coagulation of lenticulostriate arteries.

CONCLUSION

The authors suggest that early coagulation of the lenticulostriate arteries is a useful strategy to minimize blood loss in low-weight infants undergoing hemispherotomy.

Hemispherotomy for drug-resistant epilepsy in an Indonesian population

Hemispherotomy is a surgical treatment indicated in patients with drug-resistant epilepsy due to unilateral hemispheric pathology. Hemispherotomy is less invasive compared with hemispherectomy. We reviewed our experience performing 24 hemispherotomy and report the results of 16 patients with prolonged follow-up of this relatively uncommon procedure in two centers in Indonesia. This is a retrospective observational study conducted from 1999 to July 2019 in two epilepsy neurosurgical centers in Semarang, Indonesia. Surgical techniques included vertical parasagittal hemispherotomy (VPH), peri-insular hemispherotomy (PIH), and modified PIH called the Shimizu approach (SA). The postoperative assessment was carried out using the Engel classification system of seizure outcome. Seizure freedom (Engel class I) outcome was achieved in 10 patients (62.5%), class II in 3 patients (18.7%), class III in 2 patients (12.5%), and class IV in 1 patient (6.3%) with follow-up duration spanning from 24 to 160 months. To the best of our knowledge, this series is the most extensive documentation of hemispherotomy in an Indonesian population.

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We report our experience performing hemispherotomy in selected cases in two centers in Indonesia

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To the best of our knowledge, this is the largest case series of hemispherotomy for drug-resistant epilepsy in Indonesia.

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Engel class I outcome was seen in 62.5% for 16 patients of which 81.3% of patients improved regarding reduction in pre-operative seizure frequency

Hemispherectomy in adults and adolescents: Seizure and functional outcomes in 47 patients

OBJECTIVE

To examine longitudinal seizure and functional outcomes after hemispherectomy in adults and adolescents.

METHODS

We reviewed 47 consecutive patients older than 16 years who underwent hemispherectomy between 1996 and 2016 at our center. Clinical, electroencephalographic (EEG), imaging, neuropsychological, surgical, and functional status data were analyzed.

RESULTS

Thirty-six patients were 18 years or older at surgery; 11 were aged between 16 and 18 years. Brain injury leading to hemispheric epilepsy occurred before 10 years of age in 41 (87%) patients. At a mean follow-up of 5.3 postoperative years (median = 2.9 years), 36 (77%) had Engel class I outcome. Longitudinal outcome analysis showed 84% seizure freedom (Engel IA) at 6 months, 76% at 2 years, and 76% at 5 years and beyond, with stable longitudinal outcomes up to 12 years from surgery. Multivariate analysis demonstrated that acute postoperative seizures and contralateral interictal spikes at 6-month follow-up EEG were associated with seizure recurrence. Patients who could walk unaided preoperatively and had no cerebral peduncle atrophy on brain magnetic resonance imaging were more likely to experience worsening of motor function postoperatively. Otherwise, postoperative ambulatory status and hand function were unchanged. Of the 19 patients who completed neuropsychological testing, 17 demonstrated stable or improved postoperative outcomes.

SIGNIFICANCE

Hemispherectomy in adults is a safe and effective procedure, with seizure freedom rates and functional outcome similar to those observed in children.

Need of Immediate Drug Reduction after Epilepsy Surgery - A Prospective Observational Study

Background

Patients undergoing epilepsy surgery are on polytherapy. Drug tapering is usually done after 1 year in adults and after 6 months in children. Sometimes, drugs have to be altered during the perioperative period, which is more commonly seen in hemispherotomy (HS) patients. The present study was done to compare perioperative drug alterations between HS and temporal (TL) lobectomy patients.

Materials and Methods

Prospective analysis of postoperative HS and TL patients was done. Primary outcomes were drug number, dosage changes, and seizure outcome. Secondary outcome studied was a change in intelligence quotient (IQ) in the two groups.

Results

At total of 71 patients were included. Perioperative drug stopping (clobazam - CLB) was needed in 3/38 patients in the HS group, due to sedation. Dosage was reduced in 23/38 (60.52%) in HS group, and in 2/33 (6%) in TL group P < 0.001. The most common drug was CLB, with reduction in 21/27 (77.77%) patients, with a mean reduction of 41.21 ± 4.01%. Two patients required drug substitution in the HS group. About 64/71 (90.1%) patients achieved Class I outcome at a 1-year postoperative time point (TL - 90.9%, HS - 89.47%). There was no change in IQ in any of the groups.

Conclusion

Perioperative drug alteration is often needed in the HS patients as compared to TL patients. Benzodiazepines have to be reduced to maintain alertness in the HS patients. The increased sedation postoperatively can be due to decreased cortical drive over the reticular activating system, gamma-aminobutyric acid (GABA) receptor denervation hypersensitivity, or increased activity of drugs over the remaining active hemisphere.

Seizure Outcome and Its Prognostic Predictors After Hemispherotomy in Children With Refractory Epilepsy in a Chinese Pediatric Epileptic Center

Object: To explore the post-hemispherotomy seizure outcome and its prognostic predictors in children with refractory epilepsy.

Methods: We reviewed 83 consecutive child patients with refractory epilepsy who underwent a hemispherectomy from June 2014 to January 2017 at our Pediatric Epilepsy Center. Demographic, clinical, EEG, neuroimaging, and surgical data were collected. Seizure outcome data were collected via outpatient clinics as well as telephone visits and were graded according to Engel criteria. Logistic regression model and Cox proportional hazard regression model were, respectively, applied to explore the related factors predicting the seizure outcomes of children after a hemispherotomy.

Results: Of the 83 patients, 55 (63.2%) were male. The mean seizure onset age was 1.9 years (0–8.7 years), and the mean surgery age was 5 years (0.8–14 years). At a mean follow-up of 3 years, 69 children (83.1%) were seizure free, and 14 (16.9%) exhibited seizure recurrence. In a univariate analysis, whether or not considering follow-up time, a non-lateralized interictal EEG pattern, bilateral PET abnormalities and acute postoperative seizures (APOS) could all predict poor seizure outcomes post-hemispherotomy. Bilateral PET abnormalities were independently correlated with unfavorable seizure outcomes in the multivariate Logistic regression analysis (Odds ratio(OR) = 13.05, 95%CI = 1.52–112.29, P = 0.019) and in the multivariate Cox proportional hazard analysis(OR = 13.99, 95%CI = 2.75–71.17, P = 0.001).

Conclusions: Child epileptic patients with bilateral PET abnormalities may have poor seizure outcomes after a hemispherotomy procedure. This study will facilitate better candidate selection for hemispherotomies and early identification of unfavorable seizure outcomes.

Anatomical hemispherectomy revisited-outcome, blood loss, hydrocephalus, and absence of chronic hemosiderosis

PURPOSE

To evaluate microsurgical trans-sylvian trans-ventricular anatomical hemispherectomy with regard to seizure outcome, risk of hydrocephalus, blood loss, and risk of chronic hemosiderosis in patients with intractable seizures selected for surgery using current preoperative assessment techniques.

METHODS

Out of 86 patients who underwent hemispherectomy between February 2000 and April 2019, by a single surgeon, at a tertiary care referral center, 77 patients (ages 0.2-20 years; 40 females) who had an anatomical hemispherectomy were analyzed. Five of these were 'palliative' surgeries. One-stage anatomical hemispherectomy was performed in 55 children, two-stage anatomical hemispherectomy after extraoperative intracranial monitoring in 16, and six hemispherectomies were done following failed previous resection. Mean follow-up duration was 5.7 years (range 1-16.84 years). Forty-six patients had postoperative MRI scans.

RESULTS

Ninety percent of children with non-palliative hemispherectomy achieved ILAE Class-1 outcome. Twenty-seven patients were no longer taking anticonvulsant medications. Surgical failures (n = 4) included one patient with previous meningoencephalitis, one with anti-GAD antibody encephalitis, one with idiopathic neonatal thalamic hemorrhage, and one with extensive tuberous sclerosis. There were no failures among patients with malformations of cortical development. Estimated average blood loss during surgery was 387 ml. Ten (21%) children developed hydrocephalus and required a shunt following one-stage hemispherectomy, whereas 10 (50%) patients developed hydrocephalus among those who had extraoperative intracranial monitoring. Only 20% of the shunts malfunctioned in the first year. Early malfunctions were related to the valve and later to fracture disconnection of the shunt. One patent had a traumatic subdural hematoma. None of the patients developed clinical signs of chronic 'superficial cerebral hemosiderosis' nor was there evidence of radiologically persistent chronic hemosiderosis in patients who had postoperative MRI imaging.

CONCLUSION

Surgical results of anatomical hemispherectomy are excellent in carefully selected cases. Post-operative complications of hydrocephalus and intraoperative blood loss are comparable to those reported for hemispheric disconnective surgery (hemispherotomy). The rate of shunt malfunction was less than that reported for patients with hydrocephalus of other etiologies Absence of chronic 'superficial hemosiderosis', even on long-term follow-up, suggests that anatomical hemispherectomy should be revisited as a viable option in patients with intractable seizures and altered anatomy such as in malformations of cortical development, a group that has a reported high rate of seizure recurrence related to incomplete disconnection following hemispheric disconnective surgery.

EEG lateralization and seizure outcome following peri-insular hemispherotomy for pediatric hemispheric epilepsy

OBJECTIVE

To determine whether preoperative non-lateralizing scalp electroencephalography (EEG) influences seizure outcome following peri-insular hemispherotomy (PIH) in pediatric hemispheric epilepsy.

METHODS

Retrospective data was collected on all 45 pediatric patients who underwent PIH between 2005 and 2016. All underwent a basic pre-surgical evaluation consisting of detailed history and examination, neuropsychological assessment, MRI, and EEG. SPECT/PET, fRMI, or Wada testing were done in only eight patients. Seizure outcome was assessed using the Engel classification.

RESULTS

Among those who underwent hemispherotomy, 20 (44%) were females. Mean age at surgery was 8 ± 4.3 years and mean duration of symptoms was 5.2 ± 3.7 years. The most common etiologies of hemispheric epilepsy were hemiconvulsion-hemiplegia epilepsy syndrome, Rasmussen encephalitis, and post-encephalitic sequelae, together comprising 27 (60%) patients. Among the 44 patients with follow-up data (mean duration 48 ± 33 months), seizure freedom (Engel class I) was attained by 41 (93.2%). Anti-epileptic medications were stopped or decreased in 36 (82%). Seventeen (38.6%) patients had non-lateralizing EEG. Seizure outcome was not related to lateralization of EEG activity.

CONCLUSIONS

PIH provides excellent long-term seizure control in patients despite the presence of non-lateralizing epileptiform activity, although occurrence of acute postoperative seizures may be higher. Routine SPECT/PET may not be required in patients with a non-lateralizing EEG if there is good clinico-radiological concordance.

From Resection to Disconnection for Seizure Control in Pediatric Epilepsy Children

Epilepsy surgery revealed dramatically improved seizure outcomes over medical therapy in drug-resistant epilepsy patients. Children with epilepsy, however, have multiple epileptic focuses which require multilobar resection for better seizure outcome. Multilobar resection has not only the several severe surgical complications, such as hydrocephalus and shunt-related craniosynostosis, due to intracranial volume reduction. Isolation method (disconnection surgery) was progressively studied over epileptic focus removal (resective surgery) for seizure control. This concept was first introduced for functional hemispherotomy, and its primary principle is to preserve the vital vascularized brain that is functionally disconnected from the contralateral healthy brain. Currently in most epilepsy centers, the predominant disconnection surgical methods, including functional hemispherotomy, are continually being refined and are showing excellent results. They allow the functional isolation of the hemisphere or multi-lobe, affected by severe epilepsy. This review describes recent findings concerning the indication, surgical technique, seizure outcome and complications in several disconnection surgeries including the functional hemispherotomy for refractory pediatric epilepsy.

Neurosurgical approaches to pediatric epilepsy: Indications, techniques, and outcomes of common surgical procedures

Epilepsy is a common pediatric neurological condition, and approximately one-third of children with epilepsy are refractory to medical management. For these children neurosurgery may be indicated, but operative success is dependent on complete delineation of the epileptogenic zone. In this review, surgical techniques for pediatric epilepsy are considered. First, potentially-curative operations are discussed and broadly divided into resections and disconnections. Then, two palliative approaches to seizure control are reviewed. Finally, future neurosurgical approaches to epilepsy are considered.

Hemispherotomy and Functional Hemispherectomy: Indications and Outcomes

Hemispherectomy constitutes an established surgical method in the management of patients with medically intractable epilepsy secondary to severe unilateral hemisphere damage. As opposed to focal resections, in hemispherotomies, the entire hemisphere is disconnected from the remaining nervous system, including the functional regions and fibers. Despite this, hemispherotomy is recommended for certain indications, and has good functional and epilepsy outcomes. Here we describe the indications, epilepsy outcomes, and surgical techniques for several hemispheric surgeries.

Drug-Resistant Epilepsy and Surgery

BACKGROUND

Epilepsy is a chronic brain disease that is caused by various factors and characterized by recurrent, episodic and temporary central nervous system dysfunction which results due to excessive discharge of brain neurons. In the past decades, despite the continuous development of antiepileptic drugs, there are still many patients with epilepsy progressing to drugresistant epilepsy. Currently, surgical treatment is one of important way to cure drug-resistant epilepsy.

METHODS

Data were collected from Web of Science, Medline, Pubmed, through searching of these keywords: "surgery" and "drug-resistant epilepsy".

RESULTS

An increasing number of studies have shown that surgery plays an important role in the treatment of drug-resistant epilepsy. Moreover, the comprehensive treatment mainly based on surgery can achieve the remission and even cure of drug-resistant epilepsy.

CONCLUSION

In this review, we discuss the pathogenesis of drug-resistant epilepsy and the comprehensive treatment mainly based on surgery; this review may provide a reference for the clinical treatment of drug-resistant epilepsy.

Volumetric Analysis of Cerebral Peduncles and Cerebellar Hemispheres for Predicting Hemiparesis After Hemispherectomy

BACKGROUND

In some cases of refractory epilepsy, hemispherectomy is the final invasive treatment option. However, predictors of postoperative hemiparesis in these patients have not been widely studied.

OBJECTIVE

To investigate how the volumetric analysis of cerebral peduncles and cerebellar hemispheres in patients who have undergone hemispherectomy may determine prognostic implications for postoperative hemiparesis.

METHODS

Twenty-two patients who underwent hemispherectomy at our institution were retrospectively included. Using iPlan/BrainLAB (BrainLAB, Feldkirchen, Germany) imaging software and a semiautomatic voxel-based segmentation method, we calculated the preoperative cerebral peduncle and cerebellar hemisphere volumes. Cerebral peduncle and cerebellar hemisphere ratios were compared between patients with worsened or unchanged/better hemiparesis postoperatively.

RESULTS

The ratios of ipsilateral/contralateral cerebral peduncles (0.570 vs 0.828; P = .02) and contralateral/ipsilateral cerebellar hemispheres (0.885 vs 1.031; P = .009) were significantly lower in patients who had unchanged/improved hemiparesis postoperatively compared with patients who had worsened hemiparesis. Relative risk of worsening hemiparesis was significantly higher in patients with a cerebral peduncle ratio < 0.7 (relative risk, 4.3; P = .03) or a cerebellar ratio < 1.0 (relative risk, 6.4; P = .006).

CONCLUSION

Although patients who undergo hemispherectomy are heterogeneous, we report a method of predicting postoperative hemiparesis using only standard volumetric magnetic resonance imaging. This information could be used in preoperative discussions with patients and families to help better understand that chance of retaining baseline motor function.

ABBREVIATIONS

CST, corticospinal tractfMRI, functional magnetic resonance imagingTMS, transcranial magnetic stimulation.

Trapped ipsilateral lateral ventricle: a delayed complication of hemispherotomy for Rasmussen's encephalitis

Hemispherotomy is the currently preferred surgical treatment option for refractory unihemispheric epilepsies. The incidence of hydrocephalus is greatly reduced in this disconnective procedure when compared with the resective procedure of anatomical hemispherectomy. We describe the occurrence of ipsilateral trapped lateral ventricle months after hemispherotomy for Rasmussen's encephalitis. There is enough evidence to suggest that this rare and interesting complication is due to the local inflammatory changes associated with the surgical trauma.

Vertical parasagittal hemispherotomy for Sturge-Weber syndrome in early infancy: case report and literature review

INTRODUCTION

The authors here present a rare case of a 3-month-old infant with unilateral Sturge-Weber syndrome (SWS) who had excellent seizure control and no aggravation of previous existed neurological deficits after vertical parasagittal hemispherotomy (VPH). To our knowledge, this patient with SWS was the youngest one who received VPH.

CASE DESCRIPTION

The use of VPH results in a successful treatment of intractable epilepsy in a patient with seizure onset in early infancy. At follow-up, the patient's neurodevelopmental status has been improved since the surgery.

DISCUSSION

It is generally accepted that early-onset seizures in children with SWS are associated with worse neurological and developmental outcomes. However, when surgical treatment should be considered and how it should be performed remain a longstanding controversy. We promote early surgery in children with SWS and early-onset epilepsy.

CONCLUSION

We suggest that VPH may be a useful adjuvant in the management of SWS with refractory epilepsy in early infancy and this procedure carries low neurological risk.

Analysis of Epileptic Discharges from Implanted Subdural Electrodes in Patients with Sturge-Weber Syndrome

OBJECTIVE

Almost two-thirds of patients with Sturge-Weber syndrome (SWS) have epilepsy, and half of them require surgery for it. However, it is well known that scalp electroencephalography (EEG) does not demonstrate unequivocal epileptic discharges in patients with SWS. Therefore, we analyzed interictal and ictal discharges from intracranial subdural EEG recordings in patients treated surgically for SWS to elucidate epileptogenicity in this disorder.

METHODS

Five intractable epileptic patients with SWS who were implanted with subdural electrodes for presurgical evaluation were enrolled in this study. We examined the following seizure parameters: seizure onset zone (SOZ), propagation speed of seizure discharges, and seizure duration by visual inspection. Additionally, power spectrogram analysis on some frequency bands at SOZ was performed from 60 s before the visually detected seizure onset using the EEG Complex Demodulation Method (CDM).

RESULTS

We obtained 21 seizures from five patients for evaluation, and all seizures initiated from the cortex under the leptomeningeal angioma. Most of the patients presented with motionless staring and respiratory distress as seizure symptoms. The average seizure propagation speed and duration were 3.1 ± 3.6 cm/min and 19.4 ± 33.6 min, respectively. Significant power spectrogram changes at the SOZ were detected at 10-30 Hz from 15 s before seizure onset, and at 30-80 Hz from 5 s before seizure onset.

SIGNIFICANCE

In patients with SWS, seizures initiate from the cortex under the leptomeningeal angioma, and seizure propagation is slow and persists for a longer period. CDM indicated beta to low gamma-ranged seizure discharges starting from shortly before the visually detected seizure onset. Our ECoG findings indicate that ischemia is a principal mechanism underlying ictogenesis and epileptogenesis in SWS.

Hemispheric surgery for refractory epilepsy: a systematic review and meta-analysis with emphasis on seizure predictors and outcomes

OBJECT

Conflicting conclusions have been reported regarding several factors that may predict seizure outcomes after hemispheric surgery for refractory epilepsy. The goal of this study was to identify the possible predictors of seizure outcome by pooling the rates of postoperative seizure freedom found in the published literature.

METHODS

A comprehensive literature search of PubMed, Embase, and the Cochrane Library identified English-language articles published since 1970 that describe seizure outcomes in patients who underwent hemispheric surgery for refractory epilepsy. Two reviewers independently assessed article eligibility and extracted the data. The authors pooled rates of seizure freedom from papers included in the study. Eight potential prognostic variables were identified and dichotomized for analyses. The authors also compared continuous variables within seizure-free and seizure-recurrent groups. Random- or fixed-effects models were used in the analyses depending on the presence or absence of heterogeneity.

RESULTS

The pooled seizure-free rate among the 1528 patients (from 56 studies) who underwent hemispheric surgery was 73%. Patients with an epilepsy etiology of developmental disorders, generalized seizures, nonlateralization on electroencephalography, and contralateral MRI abnormalities had reduced odds of being seizure-free after surgery.

CONCLUSIONS

Hemispheric surgery is an effective therapeutic modality for medically intractable epilepsy. This meta-analysis provides useful evidence-based information for the selection of candidates for hemispheric surgery, presurgical counseling, and explanation of seizure outcomes.

The development of pragmatic skills in children after hemispherotomy: Contribution from left and right hemispheres

PURPOSE

Hemispherotomy (H) is the standard treatment used to cure hemispheric epileptic syndromes in childhood. The postoperative linguistic profile involves hemispheric specialization processes and developmental cognitive plasticity. This research concerns pragmatic aspects of language as a tool for communication which involves both linguistic and extralinguistic communication in context. Our aim was to analyze whether any correlation exists with age at surgery and side of surgery on pragmatic skills following H.

METHOD

Forty children who underwent H (23 females, 16 right H) were evaluated at a mean age of 12.8 years (±2.6) with two receptive tasks (oral comprehension and syntactic judgment), the Children's Communication Checklist (CCC) rating scale, and the Behavioral Rating Inventory of Executive Function (BRIEF) questionnaire in order to evaluate the role of executive functions on pragmatic skills. Children operated on before the age of 18 months were considered the "early" group (5 right H and 9 left H), while those operated on later were called the "late" group (11 right H and 15 left H).

KEY FINDINGS

The whole group had significant deficits in all three measures. We demonstrated a statistically significant crossed interaction between the side of H and the age at H with pragmatic language impairments (F(1,36)=17.48; p=.0002) and disorders in executive function (F(1,36)=5.80; p=.021) in left early H and in right late H patients. These findings are consistent with the previous studies of pragmatic language impairments concerning adolescents and adults with right hemisphere damage and emphasize the contribution of structural language in the early stage of verbal communication.

SIGNIFICANCE

These results emphasize for the first time that hemispherotomized children have pragmatic language impairments that are independent of receptive language. Our findings are congruent with the recent theory on pragmatic language development in childhood with evidence of a participation of the left hemisphere at the early age followed by right hemispheric specialization and involvement of executive functions, independently of receptive language.

Language recovery after left hemispherotomy for Rasmussen encephalitis

PURPOSE

Hemispherotomy (H) is the gold standard treatment to cure epilepsy in Rasmussen encephalitis (RE). Linguistic prognosis after surgery remains the main issue when the dominant hemisphere is involved. The topic of the present research is to specify the long-term linguistic profile of the right hemisphere after left dominant H for RE.

METHODS

We followed 6 children 8.4 to 14.6 years of age who underwent left H for RE. Preoperatively, four children experienced aphasia, but for two, worsening occurred after surgery. Age at H ranged from 4.1 to 8.4 years. The mean duration of epilepsy was 1.2 years and 5.6 years for follow-up. Neuropsychological evaluation included longitudinal follow-up of intellectual efficiency measurement and a long-term outcome of language using various components of receptive and expressive oral speech with computerized tasks.

KEY FINDINGS

Preoperatively, verbal comprehension index (VCI) was dramatically decreased in 4/6 patients, and performance reasoning index (PRI) was low in 5/6 participants, demonstrating a global impact of RE itself. Postoperatively, all children recovered sufficiently to attend a regular VCI (above 70) in a mean of 5 years after H, and 5/6 recovered normal or adapted school. There was a dissociation in favor of VCI, while PRI decreased in 5/6 patients. We found a specific linguistic profile for these children recovering language in the right hemisphere: normal verbal comprehension, and weakness of grammatical judgment, word repetition, statement production, semantic verbal fluency and metaphonological abilities. Language recovery scores were statistically correlated with those of Working Memory Index.

SIGNIFICANCE

This study emphasizes for the first time the ability of the right hemisphere to functionally reorganize language over a long period of time following left H for RE. Syntactic abilities and phonology remain low and support the hypothesis of an early left hemispheric specialization. Nevertheless, lexico-semantic processes recover in the right hemisphere that could reflect a pre-existing potential of both hemispheres. Our results support a decision to proceed to H in classical left RE disease until the late childhood even if there is no complete aphasia before surgery. These data should be taken in account in the overall postoperative follow-up and rehabilitation strategy.

Endoscopic corpus callosotomy and hemispherotomy

OBJECT

Corpus callosotomy and hemispherotomy are conventionally performed via a large craniotomy with the aid of a microscope for children with intractable epilepsy. Primary technical considerations include completeness of disconnection and blood loss. The authors describe an endoscopic technique performed through a microcraniotomy for these procedures.

METHODS

Four patients with drop attacks and 2 with intractable seizures related to a neonatal stroke underwent endoscopic complete corpus callosotomy and hemispherotomy, respectively. The surgeries were performed through a 2- to 3-cm precoronal microcraniotomy. Interhemispheric dissection to the corpus callosum was done using the standard technique. Subsequently, the bimanual technique with a suction device mounted on an endoscope was used to perform a complete corpus callosotomy, including interforniceal and anterior commissure disconnection. In patients who had hemispherotomy, the fornix was resected posteriorly and lateral disconnection was done by unroofing the temporal horn. Anteriorly, endoscopic corticectomy was done along the ipsilateral anterior cerebral artery to reach the bifurcation of the internal carotid artery to complete the anterior disconnection. Postoperative MRI and diffusion tensor imaging (DTI) of the brain were performed to confirm complete disconnection.

RESULTS

The procedure was accomplished successfully in all patients, with excellent visualization secured. None of the patients required a blood transfusion. Postoperative MRI and DTI confirmed completeness of the disconnection. Patients who underwent corpus callosotomy had complete resolution of drop attacks at a mean follow-up of 6 months, and patients who underwent hemispherotomy became seizure free.

CONCLUSIONS

Endoscopic corpus callosotomy and hemispherotomy are surgically feasible procedures associated with minimal blood loss, minimal risk, and excellent visualization.

Epilepsy surgery for pediatric epilepsy: optimal timing of surgical intervention

Pediatric epilepsy has a wide variety of etiology and severity. A recent epidemiological study suggested that surgery might be indicated in as many as 5% of the pediatric epilepsy population. Now, we know that effective epilepsy surgery can result in seizure freedom and improvement of psychomotor development. Seizure control is the most effective way to improve patients neurologically and psychologically. In this review, we look over the recent evidence related to pediatric epilepsy surgery, and try to establish the optimal surgical timing for patients with intractable epilepsy. Appropriate surgical timing depends on the etiology and natural history of the epilepsy to be treated. The most common etiology of pediatric intractable epilepsy patients is malformation of cortical development (MCD) and early surgery is recommended for them. Patients operated on earlier than 12 months of age tended to improve their psychomotor development compared to those operated on later. Recent progress in neuroimaging and electrophysiological studies provide the possibility of very early diagnosis and comprehensive surgical management even at an age before 12 months. Epilepsy surgery is the only solution for patients with MCD or other congenital diseases associated with intractable epilepsy, therefore physicians should aim at an early and precise diagnosis and predicting the future damage, consider a surgical solution within an optimal timing.

Exceptional verbal intelligence after hemispherotomy in a child with Rasmussen encephalitis

We report a longitudinal case study of a left-handed girl who underwent left hemispherotomy at 7 years for Rasmussen encephalitis (RE). Presurgical evaluation showed mild hemiparesis, no visual defect, and light neuropsychological impairment with short-term memory weakness. Language fMRI showed a right hemispheric dominance. Postoperatively, the patient exhibited right hemiplegia and hemianopsia but preserved intellectual capacities. She became seizure-free, and antiepileptic medication was discontinued. Long-term follow-up showed very high verbal intelligence at 11 years of age (VCI of 155) and improvement in working memory as well as language and reading abilities. Furthermore, a significant visuoverbal discrepancy became increasingly pronounced. Thus, early surgical treatment of epilepsy avoided the global cognitive deterioration usually associated with RE. Finally, such a high level of verbal functioning combined with low spatial reasoning with a single hemisphere provides additional information on the neurocognitive profile of children with RE after hemispherotomy.

Interhemispheric Vertical Hemispherotomy: A Single Center Experience

PURPOSE

Hemispheric epileptogenic lesions such as hemimegalencephaly often manifest as intractable epilepsy in early infancy. Hemispherotomy is the treatment of choice for controlling intractable hemispheric epilepsy. Less invasive procedures are desirable for surgery on infants with low body weight. This study compared our experience with interhemispheric vertical hemispherotomy (IVH) and peri-insular lateral hemispherotomy (PIH).

METHODS

Thirteen consecutive patients underwent hemispherotomy for treatment of intractable epilepsy in our institution between 2001 and 2012. The etiology of epilepsy included hemimegalencephaly in 7 patients and cortical dysplasia in 3. PIH was performed on the first 5 patients and IVH on the last 8 patients. In the latter procedure, complete section of the corpus callosum was first performed via the interhemispheric approach. After removing part of the cingulate gyrus, section of the descending fibers was performed anterolaterally to the thalamus. Clinical characteristics, duration of operation and amount of blood transfusion were compared between the PIH and IVH groups.

RESULTS

There was no difference in age at surgery, body weight and age of epilepsy onset between the two groups. No surgery-related death was observed. No patients required shunt operation. One patient who underwent IVH required reoperation for incomplete disconnection. The amount of intraoperative blood transfusion was smaller and the total duration of operation was shorter in the IVH group than in the PIH group.

CONCLUSION

The interhemispheric approach minimizes cortical resection and may be less invasive than PIH. IVH is advantageous for treating infants with low body weight.

Trends in outcomes, complications, and hospitalization costs for hemispherectomy in the United States for the years 2000-2009

OBJECTIVE

Hemispherectomy is an established surgical treatment for carefully selected pediatric patients with intractable epilepsy. Published perioperative data report low mortality rates and seizure reduction rates of 50-89%. This study investigates trends in the demographics, hospital utilization, and in-hospital complication rates of patients undergoing hemispherectomy over the past decade in the United States, using the nationally representative Kids' Inpatient Database (KID).

METHODS

The KID was queried for all discharges with the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure code for hemispherectomy in the years 2000, 2003, 2006, and 2009. The patient cohorts from these four time points were compared, analyzing differences in demographic data, insurance and payer status, total cost, length of stay, in-hospital mortality, and complications. National estimates and 95% confidence intervals are reported given the weighted sample design of KID.

RESULTS

This study identified an estimated total of 552 hospital admissions for hemispherectomy surgery during the years studied in this cohort. The incidence of this procedure increased from 1.2/100,000 admissions in 2000 to 2.2/100,000 in 2009 (p=0.05). Mean age was 6.7 years (range 0-20). There were no significant changes in demographics (age, gender, or race), hospital descriptors (size or type), insurance type, or zip code income quartile. There was a significant increase in total cost, from $42,807 in 2003 to $57,443 in 2009 (p=0.015) (adjusted to 2009 dollars). There were no trends in postoperative complications. In-hospital mortality occurred in five subjects (0.9%). Ventricular shunt placement during hemispherectomy hospitalizations increased over time from 6.7% to 16.5% (p=0.056). Hospitals that performed two or more hemispherectomies yearly had a significantly decreased incidence of in-hospital mortality (odds ratio [OR] 0.08, p=0.04) and an increased incidence of blood transfusion (OR 3.7, p=0.01) compared to hospitals that performed 0-1 procedures a year.

SIGNIFICANCE

Hemispherectomy procedures increased slightly in frequency over the past decade, with no change in demographic characteristics of the patients over time. Rates of mortality and perioperative complications remained low. Total costs have increased significantly over time. In-hospital mortality was lower in higher volume hospitals.

Perioperative anesthetic implications of epilepsy surgery: a retrospective analysis

PURPOSE

Drug-resistant epilepsy (DRE) occurs in about 30 % of individuals with epilepsy. For seizure control, a wide range of surgical procedures are performed, depending on the underlying pathology. To address the anesthetic and perioperative concerns in these patients, we analyzed the data of persons with DRE who underwent epilepsy surgery at our institute.

METHODS

A retrospective analysis of patients who underwent epilepsy surgery from 2005-2010 was performed. For data collection and analysis, patients were divided into three groups: Group I (temporal lobe epilepsy), Group II (extratemporal lobe epilepsy), and Group III (multilobar epilepsy and others).

RESULTS

A total of 241 surgical procedures were performed on 235 persons with DRE. The procedures included temporal (149) and extratemporal (47) lobe resection, hemispherotomy (31), corpus callosotomy (5), vagus nerve stimulation (3), and implantation of invasive cerebral electrodes (6). General anesthesia was the more common anesthetic technique; awake craniotomy was performed in only five cases. Intraoperative neuromonitoring was used most frequently in Group II. Patients in Group III had the longest intraoperative course and the greatest blood loss. The overall incidence of postoperative mechanical ventilation was 17.84 %, with 53.84 % of patients in Group III alone. At one-year follow-up, a good outcome was seen in 78 % of temporal lobe resection, 55 % of extratemporal cortical resection, 82 % of hemispherotomy, and 80 % of corpus callosotomy procedures.

CONCLUSIONS

Careful preoperative selection and meticulous perioperative management are the most significant factors for success of epilepsy surgery. Although temporal and extratemporal lobe surgeries have a fairly stable perioperative course, multilobar epilepsy requiring disconnective surgery poses a greater challenge.

Hemispherectomy in the treatment of seizures: a review

The term hemispherectomy refers to the complete removal or functional disconnection of a cerebral hemisphere. The technique was initially developed over 85 years ago to treat infiltrating brain tumors but is now used exclusively for medically refractory epilepsy. Hemispherectomy surgery has progressed from an extremely morbid procedure fraught with complications to a fairly routine one performed at most pediatric epilepsy centers with relatively low risk and great efficacy. The author reviews the history and evolution of hemispherectomy surgery, the relevant pathological conditions, as well as outcomes and complications.