Outcome of hemispheric surgeries for refractory epilepsy in pediatric patients

Development of an online calculator for the prediction of seizure freedom following pediatric hemispherectomy using the Hemispherectomy Outcome Prediction Scale (HOPS)

OBJECTIVES

Although hemispheric surgeries are among the most effective procedures for drug-resistant epilepsy (DRE) in the pediatric population, there is a large variability in seizure outcomes at the group level. A recently developed HOPS score provides individualized estimation of likelihood of seizure freedom to complement clinical judgement. The objective of this study was to develop a freely accessible online calculator that accurately predicts the probability of seizure freedom for any patient at 1-, 2-, and 5-years post-hemispherectomy.

METHODS

Retrospective data of all pediatric patients with DRE and seizure outcome data from the original Hemispherectomy Outcome Prediction Scale (HOPS) study were included. The primary outcome of interest was time-to-seizure recurrence. A multivariate Cox proportional-hazards regression model was developed to predict the likelihood of post-hemispheric surgery seizure freedom at three time points (1-, 2- and 5- years) based on a combination of variables identified by clinical judgment and inferential statistics predictive of the primary outcome. The final model from this study was encoded in a publicly accessible online calculator on the International Network for Epilepsy Surgery and Treatment (iNEST) website (https://hops-calculator.com/).

RESULTS

The selected variables for inclusion in the final model included the five original HOPS variables (age at seizure onset, etiologic substrate, seizure semiology, prior non-hemispheric resective surgery, and contralateral fluorodeoxyglucose-positron emission tomography [FDG-PET] hypometabolism) and three additional variables (age at surgery, history of infantile spasms, and magnetic resonance imaging [MRI] lesion). Predictors of shorter time-to-seizure recurrence included younger age at seizure onset, prior resective surgery, generalized seizure semiology, FDG-PET hypometabolism contralateral to the side of surgery, contralateral MRI lesion, non-lesional MRI, non-stroke etiologies, and a history of infantile spasms. The area under the curve (AUC) of the final model was 73.0%.

SIGNIFICANCE

Online calculators are useful, cost-free tools that can assist physicians in risk estimation and inform joint decision-making processes with patients and families, potentially leading to greater satisfaction. Although the HOPS data was validated in the original analysis, the authors encourage external validation of this new calculator.

Seizure outcomes in children with Sturge-Weber syndrome undergoing epilepsy surgery: An individual participant data meta-analysis

BACKGROUND

A subpopulation of patients with Sturge-Weber syndrome (SWS) develop medically intractable epilepsy. There is a paucity of literature on preoperative factors that predict postoperative seizure outcomes in these patients. An individual participant data meta-analysis (IPDMA) was performed to discern preoperative variables associated with favorable seizure outcomes in pediatric SWS patients undergoing epilepsy surgery.

METHODS

PubMed, Cochrane, Web of Science, and Scopus were independently queried following PRISMA guidelines. Studies that reported seizure outcomes in individual pediatric SWS patients were selected. Preoperative demographic variables and disease characteristics were recorded and evaluated in a time-to-event fashion via Cox regression and Kaplan-Meier analysis with log-rank test.

RESULTS

A total of 18 studies with 108 patients were included for meta-analysis. Median age at seizure onset was 4.5 months, and 85 patients (78.7%) were seizure-free at last follow-up (median: 72 months). On multivariable Cox regression, no variables were independent predictors of post-operative seizure freedom duration, including the extent of hemispheric resection. There were also no differences in time-to-seizure recurrence on Kaplan-Meier analysis when comparing those treated with hemispheric surgery and those with less than hemispheric surgery (p = 0.52).

CONCLUSION

This IPDMA showed that both resective and hemispheric epilepsy surgery achieve favorable and comparable seizure outcomes in pediatric SWS patients. The best available evidence using IPD suggests that resective surgery may be an appropriate alternative to hemispheric epilepsy surgery in well-selected patients. Prospective multi-institutional studies with greater follow-up are warranted to further investigate predictors of seizure outcome in pediatric SWS patients.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Hemispherectomy Outcome Prediction Scale: Development and validation of a seizure freedom prediction tool

OBJECTIVE

To develop and validate a model to predict seizure freedom in children undergoing cerebral hemispheric surgery for the treatment of drug-resistant epilepsy.

METHODS

We analyzed 1267 hemispheric surgeries performed in pediatric participants across 32 centers and 12 countries to identify predictors of seizure freedom at 3 months after surgery. A multivariate logistic regression model was developed based on 70% of the dataset (training set) and validated on 30% of the dataset (validation set). Missing data were handled using multiple imputation techniques.

RESULTS

Overall, 817 of 1237 (66%) hemispheric surgeries led to seizure freedom (median follow-up = 24 months), and 1050 of 1237 (85%) were seizure-free at 12 months after surgery. A simple regression model containing age at seizure onset, presence of generalized seizure semiology, presence of contralateral 18-fluoro-2-deoxyglucose-positron emission tomography hypometabolism, etiologic substrate, and previous nonhemispheric resective surgery is predictive of seizure freedom (area under the curve = .72). A Hemispheric Surgery Outcome Prediction Scale (HOPS) score was devised that can be used to predict seizure freedom.

SIGNIFICANCE

Children most likely to benefit from hemispheric surgery can be selected and counseled through the implementation of a scale derived from a multiple regression model. Importantly, children who are unlikely to experience seizure control can be spared from the complications and deficits associated with this surgery. The HOPS score is likely to help physicians in clinical decision-making.

Hemispherotomy for Epilepsy: The Procedure Evolution and Outcome

Hemispherectomy is a unique epilepsy surgery procedure that has undergone significant modification and evolution since Dandy's early description. This procedure is mainly indicated to treat early childhood and infancy medically intractable epilepsy. Various epileptic syndromes have been treated with this procedure, including hemimegalencephaly (HME), Rasmussen's encephalitis, Sturge-Weber syndrome (SWS), perinatal stroke, and hemispheric cortical dysplasia. In terms of seizure reduction, hemispherectomy remains one of the most successful epilepsy surgery procedures. The modification of this procedure over many years has resulted in lower mortality and morbidity rates. HME might increase morbidity and lower the success rate. Future studies should identify the predictors of outcomes based on the pathology and the type of hemispherectomy. Here, based on a literature review, we discuss the evolution of hemispherectomy techniques and their outcomes and complications.

Functional hemispherectomy: can preoperative imaging predict outcome?

OBJECTIVE

Although hemispherectomy is an effective treatment for children with intractable hemispheric epilepsy syndromes, as many as 40% of patients eventually develop seizure recurrence. The causes of seizure recurrence in these patients are incompletely understood. The authors sought to evaluate the efficacy of hemispherectomy at their center and determine whether contralateral MRI abnormalities can predict seizure recurrence.

METHODS

A retrospective review of consecutive hemispherectomies performed at Miami Children's Hospital between January 2000 and June 2014 was performed. Time-to-event analysis was performed. The "event" was defined as any seizures following resective epilepsy surgery (not including seizures in the first postoperative week and auras). Several preoperative variables were analyzed to determine their suitability to predict seizure recurrence following surgery.

RESULTS

Sixty-nine patients (44 boys) with a mean age of 8.2 ± 5.9 years (range 0.1-20.8 years) underwent 72 hemispherectomies; 67 of these were functional hemispherectomies, while another 5 were completion of a previous functional hemispherectomy (2 completions of functional hemispherectomies, 3 anatomical hemispherectomies). The duration of epilepsy was 5.8 ± 5.5 years with 66 cases (91.7%) having daily seizures. Etiology included stroke (n = 28), malformation of cortical development (n = 11), hemimegalencephaly (n = 11), encephalitis (n = 13), and other (n = 7). Engel class I outcome was achieved in 59 (86%) and 56 (81%) patients at 1 and 2 years of follow-up, respectively. The mean time to seizure recurrence was 33.5 ± 31.1 months. In univariate analyses, the absence of contralateral abnormalities on MRI (HR 4.09, 95% CI 1.41-11.89, p = 0.009) was associated with a longer duration of seizure freedom. The presence of contralateral MRI abnormalities was associated with contralateral ictal seizures on preoperative scalp EEG (p = 0.002). Fifteen patients experienced 20 complications (20/72, 27.8%), including the development of hydrocephalus necessitating CSF diversion in 9 cases (13%), hygroma in 1, hemispheric edema in 1, aseptic meningitis in 2, postoperative hemorrhage in 2, infection in 2, ischemic stroke in 2, and blood transfusion-contracted hepatitis C in 1 case.

CONCLUSIONS

Patients with bihemispheric abnormalities, as evidenced by contralateral MRI abnormalities, have a higher risk of earlier seizure recurrence following functional hemispherectomy.

ABBREVIATIONS

EVD = external ventricular drain; MCD = malformation of cortical development; MEG = magnetoencephalography; PVWM = periventricular white matter; TTE = time-to-event; VPS = ventriculoperitoneal shunt.

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.

Outcome after hemispherotomy in patients with intractable epilepsy: Comparison of techniques in the Italian experience

OBJECTIVE

The objective of the study was to evaluate clinical characteristics and outcome of hemispherotomy in children and adolescents with hemispheric refractory epilepsy in an Italian cohort of patients.

METHODS

We retrospectively evaluated the clinical course and outcome of 92 patients with refractory epilepsy who underwent hemispherotomy in three Italian epilepsy centers between 2006 and 2016. Three different approaches for hemispherotomy were used: parasagittal, modified parasagittal, and lateral.

RESULTS

Mean age at epilepsy onset was 1.8 ± 2.51 years, and mean duration of epilepsy prior to surgery was 7.4 ± 5.6 years. Mean age at surgery was 9.2 ± 8.0 years. After a mean follow-up of 2.81 ± 2.4 years, 66 of 90 patients (two lost from follow-up, 73.3%) were seizure-free (Engel class I). The etiology of epilepsy was related to acquired lesions (encephalomalacia or gliosis) in 44 patients (47.8%), congenital malformations (cortical dysplasia, hemimegalencephaly, other cortical malformations) in 38 (41.3%), and progressive conditions (Rasmussen or Sturge-Weber syndrome) in 10 patients (10.9%). Regarding seizure outcome, we could not identify statistically significant differences between vertical and lateral approaches (p = 0.154). Seizure outcome was not statistically different in patients with congenital vs acquired or progressive etiologies (p = 0.43). Acute postoperative seizures (APOS) correlated with poor outcome (p < 0.05). On multivariate analysis, presurgical focal to bilateral tonic-clonic seizures (Odds Ratio (OR) = 3.63, 95% Confidence Interval (CI): 1.86-15.20, p = 0.048) independently predicted seizure recurrence. Twenty-one patients (22.8%) exhibited postoperative complications, with no unexpected and persistent neurological deficit. More than 50% of the patients completely tapered drugs.

SIGNIFICANCE

Our data confirm hemispherotomy to be a safe and effective procedure in patients with drug resistant epilepsies due to hemispheric lesions. Presurgical focal to bilateral tonic-clonic seizures are the strongest predictor of seizure recurrence after surgery, independently from the type of hemispherotomy.

Generalized seizures presurgically in a cohort of children with hemispherectomy: Predictors and a potential link to surgical outcome?

PURPOSE

Generalized seizures were often thought to be contraindications for hemispherectomy. However, few studies had investigated this issue comprehensively, as well as the predictors for generalized seizures in hemispheric lesion. We studied the predictors of generalized seizures and their potential link to seizure outcomes in a cohort of children who underwent hemispherectomy.

METHODS

A cohort of 76 children with hemispherectomy were reviewed and dichotomized into two groups with and without generalized seizures confirmed by vEEG presurgically. All preoperative evaluation data correlated to generalized seizures and postoperative prognosis were collected and analysed.

RESULTS

Of 76 patients, 11 (14.5%) cases were documented with various generalized seizures, including atypical absence (54.5%, 6/11), myoclonic (45.5%, 5/11), atonic (36.4%, 4/11), myoclonic-atonic (18.2%, 2/11), myoclonic-absence (9.1%, 1/11) and spasms (9.1%). Electrical status epilepticus during sleep (ESES) was recorded in 3 patients (27.3%, 3/11). At last follow-up, 72.7% (8/11) patients remained seizure-free. ESES was a predictor of generalized seizures (χ² = 4.69, P = 0.043). No correlation was found between generalized seizures and unfavourable postoperative seizure outcome (P = 0.153). For different seizure types, focal to bilateral tonic-clonic seizures (P = 0.020) and myoclonic-atonic seizures (P = 0.002) might correlate with unfavourable outcomes.

CONCLUSION

Generalized seizures were not an absolute contraindication for hemispherectomy. Those patients with ESES might experience generalized seizures presurgically. Focal to bilateral tonic-clonic seizures and myoclonic-atonic seizures pre-surgery may indicate unfavourable post-operative seizure outcomes.

Emergency Surgery for Refractory Status Epilepticus

BACKGROUND

Management of refractory status epilepticus in children is extremely challenging.

CASE CHARACTERISTICS

Two children with medically refractory status epilepticus, both of whom had lesional pathology on MRI and concordant data on EEG and PET scan.

INTERVENTION

Emergency hemispherotomy performed in both patients. A complete, sustained seizure freedom obtained postoperatively.

MESSAGE

Emergency surgery is a treatment option in selected cases of drug refractory status epilepticus with lesional pathology and concordant data.

Functional reorganization after hemispherectomy in humans and animal models: What can we learn about the brain's resilience to extensive unilateral lesions?

Hemispherectomy (HS) is an effective surgical procedure aimed at managing otherwise intractable epilepsy in cases of diffuse unihemispheric pathologies. Neurological recovery in subjects treated with HS is not limited to seizure reduction, rather, sensory-motor and behavioral improvement is often observed. This outcome highlights the considerable capability of the brain to react to such an extensive lesion, by functionally reorganizing and rewiring the cerebral cortex, especially early in life. In this narrative review, we summarize the animal studies as well as the human neurophysiological and neuroimaging studies dealing with the reorganizational processes that occur after HS. These topics are of particular interest in understanding mechanisms of functional recovery after brain injury. HS offers the chance to investigate contralesional hemisphere activity in controlling ipsilateral limb movements, and the role of transcallosal interactions, before and after the surgical procedure. These post-injury neuroplastic phenomena actually differ from those observed after less extensive brain damage. Therefore, they illustrate how different lesions could lead the contralesional hemisphere to play the "good" or "bad" role in functional recovery. These issues may have clinical implications and could inform rehabilitation strategies aiming to improve functional recovery following unilateral hemispheric lesions. Future studies, involving large cohorts of hemispherectomized patients, will be necessary in order to obtain a greater understanding of how cerebral reorganization can contribute to residual sensorimotor, visual and auditory functions.

Utility of diffusion tensor imaging studies linked to neuronavigation and other modalities in repeat hemispherotomy for intractable epilepsy

OBJECT Hemispherectomy for unilateral, medically refractory epilepsy is associated with excellent long-term seizure control. However, for patients with recurrent seizures following disconnection, workup and investigation can be challenging, and surgical options may be limited. Few studies have examined the role of repeat hemispherotomy in these patients. The authors hypothesized that residual fiber connections between the hemispheres could be the underlying cause of recurrent epilepsy in these patients. Diffusion tensor imaging (DTI) was used to test this hypothesis, and to target residual connections at reoperation using neuronavigation. METHODS The authors identified 8 patients with recurrent seizures following hemispherectomy who underwent surgery between 1995 and 2012. Prolonged video electroencephalography recordings documented persistent seizures arising from the affected hemisphere. In all patients, DTI demonstrated residual white matter association fibers connecting the hemispheres. A repeat craniotomy and neuronavigation-guided targeted disconnection of these residual fibers was performed. Engel class was used to determine outcome after surgery at a minimum of 2 years of follow-up. RESULTS Two patients underwent initial hemidecortication and 6 had periinsular hemispherotomy as their first procedures at a median age of 9.7 months. Initial pathologies included hemimegalencephaly (n = 4), multilobar cortical dysplasia (n = 3), and Rasmussen's encephalitis (n = 1). The mean duration of seizure freedom for the group after the initial procedure was 32.5 months (range 6-77 months). In all patients, DTI showed limited but definite residual connections between the 2 hemispheres, primarily across the rostrum/genu of the corpus callosum. The median age at reoperation was 6.8 years (range 1.3-14 years). The average time taken for reoperation was 3 hours (range 1.8-4.3 hours), with a mean blood loss of 150 ml (range 50-250 ml). One patient required a blood transfusion. Five patients are seizure free, and the remaining 3 patients are Engel Class II, with a minimum follow-up of 24 months for the group. CONCLUSIONS Repeat hemispherotomy is an option for consideration in patients with recurrent intractable epilepsy following failed surgery for catastrophic epilepsy. In conjunction with other modalities to establish seizure onset zones, advanced MRI and DTI sequences may be of value in identifying patients with residual connectivity between the affected and unaffected hemispheres. Targeted disconnection of these residual areas of connectivity using neuronavigation may result in improved seizure outcomes, with minimal and acceptable morbidity.

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.

Seizures in children with dysembryoplastic neuroepithelial tumors of the brain--A review of surgical outcomes across several studies

PURPOSE

In children and adolescents, dysembryoplastic neuroepithelial tumors (DNETs) of the brain present with seizures almost 100% of the time, potentially creating significant long-term morbidity and disability despite the generally indolent course of the lesion. These tumors also tend to be quite resistant to anti-epileptic drugs which, themselves, can be associated with long-term side effects and resultant disability. Many clinicians advocate early surgical resection of these lesions, but how effective this approach is, and how aggressive tumor removal should be, continues to be debated.

METHODS

We performed a systematic review of the relevant literature to identify all reports of DNET resections in pediatric patients published over the past 20 years. In all, over 3000 MEDLINE abstracts were reviewed, ultimately resulting in 13 studies with 185 pediatric DNET patients to review.

RESULTS

Surgical resection of the lesion was effective at improving seizures in over 98% of patients and at achieving long-term seizure freedom in 86%. Surgical resection of DNETs also appeared to be quite safe, with no reported perioperative deaths and an overall rate of postoperative complications of 12%; the vast majority of these complications were transient.

CONCLUSIONS

Total gross resection of the lesion was the only factor statistically correlated with long-term seizure freedom (r = 0.63, p = 0.03). However, data remain lacking regarding whether this translates into more extensive procedures-like brain mapping and partial lobectomies-being any more effective than simple lesionectomies alone. Further research is clearly needed to address this and other crucial questions.

Hemispherectomy for treatment of refractory epilepsy in the pediatric age group: a systematic review

OBJECT

Evidence in support of hemispherectomy stems from a multitude of retrospective studies illustrating individual institutions' experience. A systematic review of this topic, however, is lacking in the literature.

METHODS

A systematic review of hemispherectomy for the treatment of refractory epilepsy available up to October 2013 was performed using the following inclusion criteria: reports of a total of 10 or more patients in the pediatric age group (≤ 20 years) undergoing hemispherectomy, seizure outcome reported after a minimum follow-up of 1 year after the initial procedure, and description of the type of hemispherectomy. Only the most recent paper from institutions that published multiple papers with overlapping study periods was included. Two reviewers independently applied the inclusion criteria and extracted all the data.

RESULTS

Twenty-nine studies with a total of 1161 patients met the inclusion criteria. Seizure outcome was available for 1102 patients, and the overall rate of seizure freedom at the last follow-up was 73.4%. Sixteen studies (55.2%) exclusively reported seizure outcomes of a single type of hemispherectomy. There was no statistically significant difference in seizure outcome and type of hemispherectomy (p = 0.737). Underlying etiology was reported for 85.4% of patients with documented seizure outcome, and the overall distribution of acquired, developmental, and progressive etiologies was 30.5%, 40.7%, and 28.8%, respectively. Acquired and progressive etiologies were associated with significantly higher seizure-free rates than developmental etiologies (p < 0.001). Twenty of the 29 studies (69%) reported complications. The overall rate of hydrocephalus requiring CSF diversion was 14%. Mortality within 30 days was 2.2% and was not statistically different between types of hemispherectomy (p = 0.787).

CONCLUSIONS

Hemispherectomy is highly effective for treating refractory epilepsy in the pediatric age group, particularly for acquired and progressive etiologies. While the type of hemispherectomy does not have any influence on seizure outcome, hemispherotomy procedures are associated with a more favorable complication profile.

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.

Fifty consecutive hemispherectomies: outcomes, evolution of technique, complications, and lessons learned

BACKGROUND

Techniques for achieving hemispheric disconnection in patients with epilepsy continue to evolve.

OBJECTIVE

To review the outcomes of the first 50 hemispherectomy surgeries performed by a single surgeon with an emphasis on outcomes, complications, and how these results led to changes in practice.

METHODS

The first 50 hemispherectomy cases performed by the lead author were identified from a prospectively maintained database. Patient demographics, surgical details, clinical outcomes, and complications were critically reviewed.

RESULTS

From 2004 to 2012, 50 patients underwent hemispherectomy surgery (mean follow-up time, 3.5 years). Modified lateral hemispherotomy became the preferred technique and was performed on 44 patients. Forty patients (80%) achieved complete seizure freedom (Engel I). Presurgical and postsurgical neuropsychological evaluations demonstrated cognitive stability. Two cases were performed for palliation only. Previous hemispherectomy surgery was associated with worsened seizure outcome (2 of 6 seizure free; P .005). The use of Avitene was associated with a higher incidence of postoperative hydrocephalus (56% vs 18%; P = .03). In modified lateral hemispherotomy patients without the use of Avitene, the incidence of hydrocephalus was 13%. Complications included infection (n = 3), incomplete disconnection requiring reoperation (n = 1), reversible ischemic neurological deficit (n = 1), and craniosynostosis (n = 1). There were no (unanticipated) permanent neurological deficits or deaths. Minor technique modifications were made in response to specific complications.

CONCLUSION

The modified lateral hemispherotomy is effective and safe for both initial and revision hemispherectomy surgery. Avitene use appears to result in a greater incidence of postoperative hydrocephalus.

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.

Intractable epilepsy, hemispheric malformation, and generalized electroencephalography abnormalities

We present a case of a young boy with a large hemispheric dysplasia, generalized EEG abnormalities and intractable epilepsy who achieved seizure freedom and markedly improved cognitive outcome after functional hemispherectomy.

Towards early diagnosis and treatment to save children from catastrophic epilepsy -- focus on epilepsy surgery

OBJECTIVE

To analyze and to discuss whether by paying attention to the many recent advancements in the field of pediatric epilepsy surgery catastrophic childhood epilepsies caused by definitive or suspected structural lesions can be prevented more often these days in comparison to the past.

METHODS

Based on data from the literature and supplemented by the authors own experience, risks for children suffering from structural focal epilepsies that the epilepsy becomes catastrophic and ways how such evolutions can possibly be prevented are discussed for the different lesion-types separately - in the order of their frequency as they are seen at pediatric epilepsy surgery centers. Special emphasis is put on data regarding attempts to prevent permanent severe mental retardations.

RESULTS

There are common factors predisposing to catastrophic courses in all structural focal epilepsies, such as early onset and a longer duration of epilepsy (with respect to cognitive outcome not with respect to seizure outcome), but there are also differences. Moreover the better perspectives now in comparison to the past for children with conditions like MRI-negative focal epilepsies, subtle focal cortical dysplasias, epilepsies post hypoxic-ischemic events, tuberous sclerosis etc. are not well recognized yet. While there is agreement that "early" (and successful) surgery is essential in many instances to prevent permanent mental retardations there is insufficient data regarding the issue that "early surgery "might not be early enough under certain circumstances and there is also only little data regarding variables which would allow to keep calm when a child is presenting with early onset difficult to control seizures. One of the biggest changes seen over the last decade is the fact that children with very severe epilepsies, who have unilateral lesions, but "generalized" seizures and/or "generalized" EEGs, are not excluded anymore from considerations for epilepsy surgery. Even children with bilateral lesions can be surgical candidates.

CONCLUSION

The gradually widening spectrum of indications for epilepsy surgery in children is resulting in an increasing number of preventions of catastrophic epilepsies. Insufficient data regarding timing of surgery in order to prevent permanent mental retardations are calling for prospective multi-center studies.

Hemispherectomy in adults patients with severe unilateral epilepsy and hemiplegia

OBJECTIVES

To study postoperative seizure control of hemispherectomy in adults with epilepsy and evaluate changes of movement and speech function, intelligence quotient (IQ) and quality of life (QOL) after hemispherectomy.

METHODS

We retrospectively analyzed 25 adults who presented severe unilateral epilepsy and hemiplegia and underwent anatomic or functional hemispherectomy in between 2006 and 2011. Surgical outcomes, including seizure-control at last follow-up, changes of aphasia quotient, hemiplegic side motor function, IQ and QOL from pre-operative to 2 years follow-up, were investigated. Results were statistically analyzed with SPSS 18.0.

RESULTS

Nine functional hemispherectomies and 16 anatomic hemispherectomies were performed. Ninety-two percent of patients were seizure-free and 8% displayed Engel II grade seizure control after the procedure. Impaired movement function was present in 9 (36%) adults' upper limbs and 5 (20%) patients' lower limbs. The patients with age at seizure onset <3 years showed improvement in mean motor function of the upper limbs. Impaired speech was seen in 7 patients with left hemispherectomies. There was an overall improvement in the mean aphasia quotient and significant difference was found in amount of change in aphasia quotients between patients with different ages of onset. All of the patients' postoperative scores of overall QOL, full IQ, verbal IQ and performance IQ improved compared with pretreatment scores and those improvements were not associated with patient's age at seizure onset or surgical approach. However, significant difference was found in change of verbal IQ between patients with right hemispherectomies and those with left hemispherectomies. Surgical complications included a single case of hydrocephalus, and 6 transient complications.

CONCLUSIONS

Hemispherectomy presented good seizure control and improvement in QOL and IQ, and impairment on motor and speech function were mild. Furthermore, patients with early seizure onset could maintain movement function of upper limb and speech function improvement. Therefore, it is worth pursuing hemispherectomy in well-selected adults with severe unilateral epilepsy and hemiplegia.

Pediatric functional hemispherectomy: outcome in 92 patients

BACKGROUND

The revival of epilepsy surgery after the introduction of modern presurgical evaluation procedures has led to an increase in hemispherectomy or hemispherotomy procedures. Since a large part of our pediatric series was done using a newer hemispherotomy technique, we focus mainly on the outcomes after a recently developed hemispherotomy technique (transsylvian keyhole).

METHODS

Ninety-six pediatric patients (aged 4 months to 18 years, mean 7.3) were operated on between 1990 and 2009; 92 were available with follow-up.

RESULTS

The most frequent diagnosis was porencephaly in 46 % of all patients. Progressive etiologies were present in 20 % and developmental etiologies in 22 %. At last available outcome (LAO), 85 % of the patients were seizure free (ILAE class 1). Year-to-year outcome was rather stable; usually over 80 % were class 1 for up to 13 years (n = 24). Of 92 assessable patients, 71 were treated with the transsylvian keyhole technique, with 89 % being seizure free. The overall shunt rate was 5.3 % for the whole series and 3 % for the keyhole technique subgroup. Mortality was 1 of 96 patients. Excluding patients with hemimegalencephaly (HME), patients with the shortest duration of epilepsy and the lowest age at seizure onset had the highest rates of seizure freedom. The etiology does influence outcome, with HME patients having the poorest seizure outcome and patients with Sturge-Weber syndrome and porencephaly having excellent seizure control.

CONCLUSION

Hemispherotomies/functional hemispherectomies are very effective and safe procedures for treating drug-resistant epilepsy with extensive unihemispheric pathology. Etiology and surgery type clearly influence seizure outcome.

Outcomes of disconnective surgery in intractable pediatric hemispheric and subhemispheric epilepsy

OBJECTIVES

To study the outcome of disconnective epilepsy surgery for intractable hemispheric and sub-hemispheric pediatric epilepsy.

METHODS

A retrospective analysis of the epilepsy surgery database was done in all children (age <18 years) who underwent a peri-insular hemispherotomy (PIH) or a peri-insular posterior quadrantectomy (PIPQ) from April 2000 to March 2011. All patients underwent a detailed pre surgical evaluation. Seizure outcome was assessed by the Engel's classification and cognitive skills by appropriate measures of intelligence that were repeated annually.

RESULTS

There were 34 patients in all. Epilepsy was due to Rasmussen's encephalitis (RE), Infantile hemiplegia seizure syndrome (IHSS), Hemimegalencephaly (HM), Sturge Weber syndrome (SWS) and due to post encephalitic sequelae (PES). Twenty seven (79.4%) patients underwent PIH and seven (20.6%) underwent PIPQ. The mean follow up was 30.5 months. At the last follow up, 31 (91.1%) were seizure free. The age of seizure onset and etiology of the disease causing epilepsy were predictors of a Class I seizure outcome.

CONCLUSIONS

There is an excellent seizure outcome following disconnective epilepsy surgery for intractable hemispheric and subhemispheric pediatric epilepsy. An older age of seizure onset, RE, SWS and PES were good predictors of a Class I seizure outcome.

The role of magnetoencephalography in children undergoing hemispherectomy

OBJECT

Hemispherectomy is an established neurosurgical procedure for medication-resistant epilepsy in children. Despite the effectiveness of this technique, there are patients who do not achieve an optimum outcome after surgery; possible causes of suboptimal results include the presence of bilateral independent epileptogenic foci. Magnetoencephalography (MEG) is an emerging tool that has been found to be useful in the management of lesional and nonlesional epilepsy. The authors analyzed the relative contribution of MEG in patient selection for hemispherectomy.

METHODS

The medical records of children undergoing hemispherectomy at the Hospital for Sick Children were reviewed. Those patients who underwent MEG as part of the presurgical evaluation were selected.

RESULTS

Thirteen patients were included in the study. Nine patients were boys. The mean age at the time of surgery was 66 months (range 10-149 months). Seizure etiology was Rasmussen encephalitis in 6 patients, hemimegalencephaly in 2 patients, and cortical dysplasia in 4 patients. In 8 patients, video-EEG and MEG results were consistent to localize the primary epileptogenic hemisphere. In 2 patients, video-EEG lateralized the ictal onset, but MEG showed bilateral spikes. Two patients had bilateral video-EEG and MEG spikes. Engel Class I, II, and IV outcomes were seen in 10, 2, and 1 patients, respectively. In 2 of the patients who had an outcome other than Engel Class I, the MEG clusters were concentrated in the disconnected hemisphere. The third patient had bilateral clusters and potentially independent epileptogenic foci from bilateral cortical dysplasia.

CONCLUSIONS

The presence of unilateral MEG spike waves correlated with good outcomes following hemispherectomy. In some cases, MEG provides information that differs from that obtained from video-EEG and conventional MR imaging studies. Further studies with a greater number of patients are needed to assess the role of MEG in the preoperative assessment of candidates for hemispherectomy.

Hemispherectomy in pediatric patients with epilepsy: a study of 45 cases with special emphasis on epileptic syndromes

OBJECTIVE

In this study we report the clinical outcomes of hemispherectomy for epilepsy in pediatric patients with special emphasis on the epileptic syndromes and their etiologies.

MATERIAL AND METHODS

We retrospectively studied 45 patients with medically refractory epilepsy with hemispheric lesions who underwent hemispherectomy at the "Hospital de Pediatría Prof. Dr. Juan P. Garrahan", Buenos Aires, Argentina between February 1990 and February 2010. Patients had been assessed using a standard protocol involving clinical, neuroradiological, neurophysiological, and neuropsychological teams.

RESULTS

Twenty-seven males and 18 females with a mean age of 8.5 years (range, 2 months to 18 years) who underwent epilepsy surgery for refractory epilepsy were assessed. The mean time of follow-up was 9.5 years (range, 1 to 16 years). The following epileptic syndromes were recognized: West syndrome in 15 patients (33.5%), Rasmussen syndrome in 13 (29%), focal symptomatic epilepsy in 8 (17.5%), startle epilepsy in 6 (13.5%), Lennox-Gastaut syndrome in 2 (5%), and continuous spikes and waves during slow sleep in 1 (2%). The surgical specimens revealed malformations of cortical development in 18 patients (40%), Rasmussen encephalitis in 13 (29%), porencephalic lesions in 10 (22%), gliosis in 2 (4.4%), tumor in 1 (2.2%), and Sturge-Weber syndrome in 1 (2.2%).

CONCLUSION

The outcome of hemispherectomy in pediatric patients is good for those with refractory epilepsies, such as West syndrome, Lennox-Gastaut syndrome, epileptic encephalopathy with continuous spikes and waves during slow sleep, and startle epilepsy arising from a hemispheric lesion associated with hemiplegia.

Hemispherectomy for the control of intractable epilepsy in childhood: comparison of 2 surgical techniques in a single institution

BACKGROUND

Hemispherectomy is an established neurosurgical procedure for catastrophic epilepsy in childhood. However, the technique used to achieve an optimum outcome remains to be determined.

OBJECTIVE

We examined the influence of hemidecortication (HD) vs peri-insular hemispherotomy (PIH) on patient outcome.

METHODS

The medical records of 41 children undergoing hemispherectomy were reviewed for patient demographics, clinical criteria, and surgical outcomes.

RESULTS

HD and PIH were performed in 21 and 20 children, respectively. The mean age at surgery for HD was 54 months and 61 months for PIH. The median durations of surgery for HD and PIH were 5 hours and 7 hours, respectively (P < .001). For HD, 6 patients required a second surgery and 3 required a third. One PIH patient required a second procedure. Postoperative shunting was required in 5 HD patients, but only 1 PIH patient. All patients had increased hemiparesis after surgery. The overall mean follow-up time was 72 months. Engel class I or II outcomes after initial surgery were better after PIH (85%) compared with HD (48%) (P < .02). After subsequent surgeries for seizure control, 4 HD patients and 1 PIH patient improved to Engel class I or II.

CONCLUSION

Hemispherectomy is an effective surgical procedure for childhood intractable catastrophic epilepsy. In patients with diffuse hemispheric disorder, PIH tends to have fewer major complications, more favorable seizure outcomes, and a decreased need for subsequent surgical procedures, including shunting for hydrocephalus, compared with HD.

Tailored resections for intractable rolandic cortex epilepsy in children: a single-center experience with 48 consecutive cases

OBJECTIVE

A single-center experience with pediatric patients who underwent surgery for intractable rolandic epilepsy was reviewed with the aim of identifying putative factors that could influence postoperative seizure outcome in this population.

METHODS

Clinical data of 48 patients under 18 years of age with diagnosis of intractable rolandic epilepsy who underwent surgery from January 1996 to September 2009 were reviewed.

RESULTS

Patients' mean age at surgery was 9.9 ± 5.3 years; mean age at epilepsy onset was 3.9 years; mean seizure duration prior to surgery was 6 years; and mean follow-up was 5.1 years. The most frequent etiologies were cortical dysplasia, astrogliosis, tumors, tuberous sclerosis complex, and Sturge-Weber syndrome, which were observed in 20/48 (41.6%), 10/48 (20.8%), 10/48 (20.8%), 5/48 (10.4%), and 3/48 (6.2%) of the patients, respectively. After surgery, 20 patients (41.6%) showed neurological deficits, which in turn recovered within no longer than 6 months after surgery. Seizure outcome was classified as Engel class I in 29 (60.4%), Engel class II in 10 (20.8%), and Engel class III in 9 (18.8%) of the patients. The factors significantly related with seizure outcome were histological features (tumor versus non-tumor cases, p = 0.04) and lesion site (focal lesions versus non-focal lesions, p = 0.04).

CONCLUSIONS

Tailored resection of rolandic cortex for intractable epilepsy can be safely performed in children. Accurate mapping of both functional cortex and epileptogenic areas may lead to improved seizure outcome. Tumor as well as focal lesions in hand and face motor areas are associated with good seizure outcome.

Bilateral Rasmussen encephalitis

Rasmussen encephalitis (RE) is a rare, chronic, inflammatory neurological disorder that usually affects one hemisphere of the brain. RE is characterized by frequent and severe seizures, progressive neurological dysfunction, and unilateral brain atrophy. This article documents a case of RE with bilateral involvement occurring at the age of 2. The patient's seizures consisted of focal motor seizures (epilepsia partialis continua in the fingers on the right hand); tonic convulsions of the right arm and head turning to the right with impairment of consciousness; and secondarily generalized tonic-clonic seizures. Antiepileptic drugs did not effectively control the seizures. The pathology of the left frontoparietal lobe biopsy of the abnormal MRI signal showed typical neuronal loss, abundant lymphocytic infiltration into the perivascular space, and numerous microglial nodules. Bipolar electrocoagulation on functional cortexes, which failed to alter the course of the illness, was followed by high-dose prednisone (about 2 weeks worth), without improvement. Both functional hemispherectomies and anatomical hemispherectomies failed to halt the course of the illness, and contralateral seizures developed and became apparent after the operation, suggesting bilateral RE.

Contralateral MRI abnormalities in candidates for hemispherectomy for refractory epilepsy

PURPOSE

To assess the impact of contralateral magnetic resonance imaging (MRI) findings on seizure outcome after hemispherectomy for refractory epilepsy.

METHODS

We retrospectively reviewed 110 children, 0.4-18 (median 5.9) years of age, who underwent hemispherectomy for severe refractory epilepsy at Cleveland Clinic Children's Hospital. In children with contralateral (as well as ipsilateral) MRI findings appreciated preoperatively, the decision to proceed to surgery was based on other features concordant with the side with the most severe MRI abnormality, including ipsilateral epileptiform discharges, lateralizing seizure semiology, and side of hemiparesis.

RESULTS

We retrospectively observed contralateral MRI abnormalities (predominantly small hemisphere, white matter loss or abnormal signal, or sulcation abnormalities) in 81 patients (74%), including 31 of 43 (72%) with malformations of cortical development (MCD), 31 of 42 (73%) with perinatal injury from infarction or hypoxia, and 15 of 25 (60%) with Rasmussen's encephalitis, Sturge-Weber syndrome, or posttraumatic encephalomalacia. Among 84 children (76%) with lesions that were congenital or acquired pre- or perinatally, 67 (83%) had contralateral MRI abnormalities (p = 0.02). Contralateral findings were subjectively judged to be mild or moderate in 70 (86%). At follow-up 12-84 (median 24) months after surgery, 79% of patients with contralateral MRI abnormalities were seizure-free compared to 83% of patients without contralateral MRI findings, with no differences based on etiology group or type or severity of contralateral MRI abnormality.

DISCUSSION

MRI abnormalities, usually mild to moderate in severity, were seen in the contralateral hemisphere in the majority of children who underwent hemispherectomy for refractory epilepsy due to various etiologies, especially those that were congenital or early acquired. The contralateral MRI findings, always much less prominent than those in the ipsilateral hemisphere, did not correlate with seizure outcome and may not contraindicate hemispherectomy in otherwise favorable candidates.

Comparative role of neuropsychological testing in the presurgical evaluation of children with medically intractable epilepsies

PURPOSE

In the present study, we evaluated the preoperative demographic, clinical, and neuropsychological variables that could predict postoperative seizure outcome in a group of pediatric epileptic patients.

MATERIALS AND METHODS

We studied 40 consecutive pediatric patients, ages ranging from 6 to 16 years, that underwent resective surgery for the treatment of medically intractable epilepsy at the Clinical Hospital of Ribeirão Preto School of Medicine. We performed ictal electroencephalography (EEG), interictal EEG, magnetic resonance imaging (MRI), and a preoperative neuropsychological assessment in the presurgical workup.

RESULTS

The following factors were correlated with seizure outcome: (1) duration of epilepsy, (2) surgery localization, (3) localized Neuropsychological (NPS) Evaluation, (4) ictal EEG, (5) interictal EEG, and (6) MRI. Mental retardation, NPS tests, and the other demographic variables failed to correlate with seizure reduction.

CONCLUSIONS

The identification of predictor variables of epilepsy surgery outcome could improve the epileptic prognosis and guarantee the children's full potential development.

Outcomes of epilepsy surgery in adults and children

Surgery is widely accepted as an effective therapy for selected individuals with medically refractory epilepsy. Numerous studies in the past 20 years have reported seizure freedom for at least 1 year in 53-84% of patients after anteromesial temporal lobe resections for mesial temporal lobe sclerosis, in 66-100% of patients with dual pathology, in 36-76% of patients with localised neocortical epilepsy, and in 43-79% of patients after hemispherectomies. Reported rates for non-resective surgery have been less impressive in terms of seizure freedom; however, the benefit is more apparent when reported in terms of significant seizure reductions. In this Review, we consider the outcomes of surgery in adults and children with epilepsy and review studies of neurological and cognitive sequelae, psychiatric and behavioural outcomes, and overall health-related quality of life.