Peri-insular hemispherotomy in paediatric epilepsy

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

PURPOSE

Since it was first described in the 1970s, functional hemispherotomy has been an essential tool in treating disabling, medically refractory epilepsy resulting from diffuse unilateral hemispheric disease. We report our experience with 23 patients who underwent hemispherotomy, both using the functional hemispherotomy (FH) as well as a modified peri-insular hemispherotomy (PIH) technique. We present the surgical technique for the latter, review outcomes following disconnection surgery and discuss the differences between the techniques when it comes to complications and postoperative results.

METHODS

A retrospective study of 23 patients with refractory seizures who underwent cerebral hemispherectomy. A thorough analysis of the clinical, imaging, surgical features and postoperative results was performed. We also present the surgical technique for a modified PIH technique.

RESULTS

Between 2000 and 2020, 23 pediatric patients with refractory seizures underwent hemispherotomy (12 FHs, 11 modified PIHs). 91.3% of patients were seizure free at 6 months, 87% at 1 year, and 78.3% at last follow-up. None of the 23 patients presented Engel IV outcome. FH was found to have statistically longer surgical duration (5 ± 1.5 vs 3.83 ± 0.5 hours; p = <0.001). Neurocognition was improved in two thirds of the patients (66.9%). Our study also shows improvement of motor activity in the majority of the patients, regardless of the pathology and surgical technique. In the present report we modified the Cook et al. technique by implementing an amygdalohippocampectomy with resection of the tail of the hippocampus posteriorly and medially, to achieve temporo-occipital disconnection, instead of a complete temporal lobectomy.

CONCLUSION

When patients are wisely selected, the hemispherectomy procedure should be considered as a most attractive and curative treatment for children with refractory seizures, not only giving the patient a high chance of seizure freedom but also providing an improvement in motor and cognitive skills. In our particular case and based on the present study, the modified PIH proves to be a highly effective technique. It not only has a shorter surgical time but also a very low complication rate.

Hippocampal resection during hemispherotomy: is it needed?

PURPOSE

Hemispherotomy is an effective surgery for intractable pediatric hemispheric epilepsy. Over the years, the surgical goal has shifted from a complete hemispheric resection (anatomical hemispherectomy) to a disconnective hemispherotomy (DH). Multiple techniques for DH have been described, and often, anterior temporal lobectomy (ATL, with hippocampal resection) is performed. The goal of the current study is to assess the role of hippocampal resection in DH.

METHODS

We retrospectively collected all clinical data of children (< 18 years old) who underwent DH between 2001 and 2022 at two tertiary large centers. Epilepsy status and surgical outcome were compared, based on whether the hippocampus was resected (as part of an ATL) or disconnected at the amygdala and atrial segment of the fornix (with no ATL).

RESULTS

A total of 86 patients (32 females) were included. The most common epilepsy etiologies were stroke (31), Rasmussen's encephalitis (16), cortical dysplasia (10), and hemimegaloencephaly (9). The mean age at surgery was 7 (± 4.9) years. The average number of anti-seizure medications (ASMs) at surgery was 3 (± 1.2). Hemispherotomy techniques included peri-insular (54), vertical (23 [19 endoscopic + 4 parasagittal]), and trans-sylvian (9). The mean follow-up was 41.5 (± 38) months. Forty-three patients had hippocampal resection, and 43 patients had a hippocampal disconnection. Both groups had similar Engel outcome scores (p = 0.53).

CONCLUSIONS

Disconnective hemispherotomy is highly effective for pediatric intractable hemispheric epilepsy. Our data suggest that the inclusion of hippocampal resection does not provide additional benefit.

Surgical Anatomy and Technique of Peri-Insular Hemispherotomy in Pediatric Epilepsy

BACKGROUND AND OBJECTIVES

Hemispherotomy is a highly complex procedure that demands a steep learning curve. An incomplete brain disconnection often results in failure of seizure control. The purpose of this article was to present a step-by-step guide to the surgical anatomy of this procedure. It is composed of a 7-stage approach, enhancing access to and improving visualization of deep structures.

METHODS

A retrospective analysis of 39 pediatric patients with refractory epilepsy who underwent this technique was conducted. Engel scores were assessed 1 year postsurgery. Cadaveric dissections were performed to illustrate the procedure.

RESULTS

Between 2015 and 2022, 39 patients were surgically treated using the peri-insular technique. The technique involved 7 stages: patient positioning, operative approach, opercular resection, transventricular callosotomy, fronto-orbital disconnection, anterior temporal disconnection, and posterior temporal disconnection. Most of the patients (92.30%) were seizure-free (Engel class I) at 1 year postoperative, 5.13% were nearly seizure-free (Engel II), and 2.56% showed significant improvement (Engel III). Complications occurred in 8% of cases, including 1 infection, 2 cases of aseptic meningitis, and 1 non-shunt-requiring acute hydrocephalus.

CONCLUSION

The peri-insular hemispherotomy technique offers excellent seizure control with a low complication rate. Our visual documentation of surgical anatomy, complemented by detailed descriptions of surgical nuances, significantly contributes to a comprehensive understanding of this technique.

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.

Tailored Hemispherotomy Using Tractography-Guided Laser Interstitial Thermal Therapy

BACKGROUND

Medically refractory hemispheric epilepsy is a devastating disease with significant lifetime costs and social burden. Functional hemispherotomy is a highly effective treatment for hemispheric epilepsy but is associated with significant complication rates. Percutaneous hemispherotomy through laser interstitial thermal therapy (LITT) based on morphological MRI has been recently described in a single patient but not replicated in the literature.

OBJECTIVE

To describe the first 2 cases of tractography-guided interstitial laser hemispherotomy and their short-term outcomes.

METHODS

Two 11-year-old male patients with medically refractory epilepsy secondary to perinatal large vessel infarcts were referred for hemispherotomy. Both patients underwent multitrajectory LITT to disconnect the remaining pathological hemisphere, using tractography to define targets and assess structural outcomes.

RESULTS

Both cases had minor complication of small intraventricular/subarachnoid hemorrhage not requiring additional intervention. Both patients remain seizure-free at all follow-up visits.

CONCLUSION

LITT hemispherotomy can produce seizure freedom with short hospitalization and recovery. Tractography allows surgical planning to be tailored according to individual patient anatomy, which often is distorted in perinatal stroke. Minimally invasive procedures offer the greatest potential for seizure freedom without the risks of an open hemispherotomy.

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

OBJECTIVE

We aimed to assess determinants of seizure outcome following pediatric hemispherotomy in a contemporary cohort.

METHODS

We retrospectively analyzed the seizure outcomes of 457 children who underwent hemispheric surgery in five European epilepsy centers between 2000 and 2016. We identified variables related to seizure outcome through multivariable regression modeling with missing data imputation and optimal group matching, and we further investigated the role of surgical technique by Bayes factor (BF) analysis.

RESULTS

One hundred seventy seven children (39%) underwent vertical and 280 children (61%) underwent lateral hemispherotomy. Three hundred forty-four children (75%) achieved seizure freedom at a mean follow-up of 5.1 years (range 1 to 17.1). We identified acquired etiology other than stroke (odds ratio [OR] 4.4, 95% confidence interval (CI) 1.1-18.0), hemimegalencephaly (OR 2.8, 95% CI 1.1-7.3), contralateral magnetic resonance imaging (MRI) findings (OR 5.5, 95% CI 2.7-11.1), prior resective surgery (OR 5.0, 95% CI 1.8-14.0), and left hemispherotomy (OR 2.3, 95% CI 1.3-3.9) as significant determinants of seizure recurrence. We found no evidence of an impact of the hemispherotomy technique on seizure outcome (the BF for a model including the hemispherotomy technique over the null model was 1.1), with comparable overall major complication rates for different approaches.

SIGNIFICANCE

Knowledge about the independent determinants of seizure outcome following pediatric hemispherotomy will improve the counseling of patients and families. In contrast to previous reports, we found no statistically relevant difference in seizure-freedom rates between the vertical and horizontal hemispherotomy techniques when accounting for different clinical features between groups.

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.

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.

Endoscopic Anatomy of Transcallosal Hemispherotomy: Laboratory Study with Advanced Three-Dimensional Modeling

BACKGROUND

Epilepsy surgery has an important role in the treatment of patients with medically intractable seizures. Various authors have proposed an endoscopic technique to perform disconnective procedures. A detailed description of intracerebral anatomy seen through an endoscopic transcallosal corridor has not been reported. The aim of this study was to present a cadaveric step-by-step anatomical demonstration of endoscopic transcallosal hemispherotomy using a dedicated three-dimensional model.

METHODS

Anatomical dissections were performed on 6 cadaveric heads (12 hemispheres), and the disconnective procedure was performed using an endoscopic transcallosal approach. A dedicated three-dimensional model was used to better illustrate each step. A simulation of the disconnective procedure was performed by recreating the surgical steps on a subject from the Human Connectome Project dataset, and a calculation of the fiber tracts intersected was performed.

RESULTS

Analyzing data extracted from the three-dimensional model and tractography simulation, 100% of the fibers (streamlines) of corpus callosum, corticopontine tracts, corticospinal tract, and inferior fronto-occipital fascicle were transected. Moreover, a satisfactory number of fibers (>95%) of the thalamocortical tracts, corticostriatal tracts, corona radiata, fornix, and uncinate fascicle were disconnected.

CONCLUSIONS

This anatomical study described the relevant neurovascular structures to enable prediction of feasibility and control of the surgical procedure using the endoscopic transcallosal approach. The quantitative analysis permitted estimation of the theoretical efficacy of the procedure, confirming its relevant role in disconnective surgery.

Cadaveric White Matter Dissection Study of the Telencephalic Flexure: Surgical Implications

Neurosurgery has traditionally been overtly focused on the study of anatomy and functions of cortical areas with microsurgical techniques aimed at preserving eloquent cortices. In the last two decades, there has been ever-increasing data emerging from advances in neuroimaging (principally diffusion tensor imaging) and clinical studies (principally from awake surgeries) that point to the important contribution of white matter tracts (WMT) that influence neurological function as part of a brain network. Major scientific consortiums worldwide, currently working on this human brain connectome, are providing evidence that is dramatically altering the manner in which we view neurosurgical procedures. The development of the telencephalic flexure, a major landmark during the human embryogenesis of the central nervous system (CNS), severely affects the cortical/subcortical anatomy in and around the sylvian fissure and thus the different interacting brain networks. Indeed, the telencephalic flexure modifies the anatomy of the human brain with the more posterior areas becoming ventral and lateral and associative fibers connecting the anterior areas with the previous posterior ones follow the flexure, thus becoming semicircular. In these areas, the projection, association, and commissural fibers intermingle with some WMT remaining curved and others longitudinal. Essentially the ultimate shape and location of these tracts are determined by the development of the telencephalic flexure. Five adult human brains were dissected (medial to lateral and lateral to medial) with a view to describing this intricate anatomy. To better understand the 3D orientation of the WMT of the region we have correlated the cadaveric data with the anatomy presented in the literature of the flexure during human neuro-embryogenesis in addition to cross-species comparisons of the flexure. The precise definition of the connectome of the telencephalic flexure is primordial during glioma surgery and for disconnective epilepsy surgery in this region.

Surgery for Intractable Epilepsy in Pediatrics, a Systematic Review of Outcomes other than Seizure Freedom

To perform a systematic review evaluating reported outcomes for epilepsy surgery in pediatric patients with pharmacoresistant epilepsy beyond seizure control, including impact on quality of life, behavioral, neurocognitive outcomes as well as complications, and death. We reviewed articles from both EMBASE and MEDLINE/PubMed articles that met formal criteria (patients ≤18 years, those with intractable epilepsy, at least 5 patients in the case series, published in peer-reviewed journal). Each reviewer independently reviewed the articles and those with discrepancies were discussed and consensus was reached. Out of a total of 536 abstracts obtained from EMBASE and MEDLINE/PubMed searches combined with additional cross-referencing, a total of 98 manuscripts ultimately met all inclusion criteria. The manuscripts were divided into 3 outcomes categories: Quality of Life (16), Cognitive Outcomes (60), and Deficits and Complications (50). Several papers fell into more than 1 category. These were separated by surgical types and evaluated. We found that overall reporting in all domains was variable and inconsistent amongst the different studies. This systematic review highlights the lack of completeness in reporting outcomes and complications involving pediatric epilepsy surgery and discordant results. This underscores the importance of multicenter systematic prospective data collection in pediatric patients who undergo pediatric epilepsy surgery.

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

Objective

This study was undertaken to determine whether the vertical parasagittal approach or the lateral peri‐insular/peri‐Sylvian approach to hemispheric surgery is the superior technique in achieving long‐term seizure freedom.

Methods

We conducted a post hoc subgroup analysis of the HOPS (Hemispheric Surgery Outcome Prediction Scale) study, an international, multicenter, retrospective cohort study that identified predictors of seizure freedom through logistic regression modeling. Only patients undergoing vertical parasagittal, lateral peri‐insular/peri‐Sylvian, or lateral trans‐Sylvian hemispherotomy were included in this post hoc analysis. Differences in seizure freedom rates were assessed using a time‐to‐event method and calculated using the Kaplan–Meier survival method.

Results

Data for 672 participants across 23 centers were collected on the specific hemispherotomy approach. Of these, 72 (10.7%) underwent vertical parasagittal hemispherotomy and 600 (89.3%) underwent lateral peri‐insular/peri‐Sylvian or trans‐Sylvian hemispherotomy. Seizure freedom was obtained in 62.4% (95% confidence interval [CI] = 53.5%–70.2%) of the entire cohort at 10‐year follow‐up. Seizure freedom was 88.8% (95% CI = 78.9%–94.3%) at 1‐year follow‐up and persisted at 85.5% (95% CI = 74.7%–92.0%) across 5‐ and 10‐year follow‐up in the vertical subgroup. In contrast, seizure freedom decreased from 89.2% (95% CI = 86.3%–91.5%) at 1‐year to 72.1% (95% CI = 66.9%–76.7%) at 5‐year to 57.2% (95% CI = 46.6%–66.4%) at 10‐year follow‐up for the lateral subgroup. Log‐rank test found that vertical hemispherotomy was associated with durable seizure‐free progression compared to the lateral approach (p = .01). Patients undergoing the lateral hemispherotomy technique had a shorter time‐to‐seizure recurrence (hazard ratio = 2.56, 95% CI = 1.08–6.04, p = .03) and increased seizure recurrence odds (odds ratio = 3.67, 95% CI = 1.05–12.86, p = .04) compared to those undergoing the vertical hemispherotomy technique.

Significance

This pilot study demonstrated more durable seizure freedom of the vertical technique compared to lateral hemispherotomy techniques. Further studies, such as prospective expertise‐based observational studies or a randomized clinical trial, are required to determine whether a vertical approach to hemispheric surgery provides superior long‐term seizure outcomes.

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.

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.

Aventricular hemispherotomy: technical note

Hemispheric disconnection in the form of hemispherectomy or hemispherotomy is the most effective way of treating intractable hemispheric epilepsy. Anatomical hemispherectomy approaches have largely been abandoned in most cases due to a higher risk of superficial hemosiderosis, intraoperative blood loss, hydrocephalus, prolonged hospital stay, and mortality compared to the variety of tissue-sparing hemispherotomy techniques. Disconnective hemispherotomy approaches utilize the lateral ventricle as a key component of the surgical corridor. Without a lateral ventricle, disconnective surgery becomes significantly challenging, typically leading to a hemispherectomy. The authors present the case of a patient with severe hemispheric dysplasia without a lateral ventricle on the pathologic side and detail a novel surgical technique for a prone, occipital interhemispheric, tissue-sparing, purely disconnective aventricular hemispherotomy with an excellent surgical outcome.

Postoperative persistent fever may be a risk factor for hydrocephalus in hemispherical disconnection surgery

INTRODUCTION

Hemispherical disconnection surgery such as hemispherotomy or posterior quadrant disconnection (PQD) surgery sometimes induces hydrocephalus. We postulated that some risk factors for postoperative hydrocephalus can be managed perioperatively. The purpose of this study was to clarify and statistically analyze perioperative risk factors for postoperative progressive hydrocephalus.

METHODS

We reviewed patients who underwent hemispherotomy or PQD. We compared patients with and without progressive hydrocephalus with multivariate and univariate logistic regression analysis to identify risk factors for hydrocephalus.

RESULTS

Twenty-four patients underwent hemispherectomy or PQD (age: 25 days-45 years old, mean: 13.3 years, median: 8 years, standard deviation: 13.9 years, 14 males). Among them, five patients (21%) required hydrocephalus treatment. Persistent fever was a risk factor for progressive hydrocephalus (multivariate analysis: p = 0.024, univariate analysis: p < 0.001).

CONCLUSION

Postoperative persistent fever may be a manageable risk factor for postoperative hydrocephalus in hemispherotomy and PQD surgery.

An immunotherapy effect analysis in Rasmussen encephalitis

Background

Immune-mediated mechanisms substantially contribute to the Rasmussen encephalitis (RE) pathology, but for unknown reasons, immunotherapy is generally ineffective in patients who have already developed intractable epilepsy; overall laboratory data regarding the effect of immunotherapy on patients with RE are limited. We analyzed multiple samples from seven differently treated children with RE and evaluated the effects of immunotherapies on neuroinflammation. Immunotherapy was introduced to all patients at the time of intractable epilepsy and they all had to undergo hemispherothomy.

Methods

Immunohistochemistry, flow cytometry, Luminex multiplex bead and enzyme-linked immunosorbent assay techniques were combined to determine: 1) inflammatory changes and lymphocyte subpopulations in 45 brain tissues; 2) lymphocyte subpopulations and the levels of 12 chemokines/cytokines in 24 cerebrospinal fluid (CSF) samples and 30 blood samples; and 3) the dynamics of these parameters in four RE patients from whom multiple samples were collected.

Results

Sustained T cell-targeted therapy with cyclophosphamide, natalizumab, alemtuzumab, and intrathecal methotrexate (ITMTX), but not with azathioprine, substantially reduced inflammation in brain tissues. Despite the therapy, the distributions of CD8⁺ T cells and the levels of C-X-C motif ligand (CXCL) 10, CXCL13, and B cell activating factor (BAFF) in patients’ CSF remained increased compared to controls. A therapeutic approach combining alemtuzumab and ITMTX was the most effective in producing simultaneous reductions in histopathological inflammatory findings and in the numbers of activated CD8⁺ T cells in the brain tissue, as well as in the overall CD8⁺ T cell population and chemokine/cytokine production in the CSF.

Conclusions

We provide evidence that various T cell-targeted immunotherapies reduced inflammation in the brains of RE patients. The observation that intractable epilepsy persisted in all of the patients suggests a relative independence of seizure activity on the presence of T cells in the brain later in the disease course. Thus, new therapeutic targets must be identified. CXCL10, CXCL13 and BAFF levels were substantially increased in CSF from all patients and their significance in RE pathology remains to be addressed.

Surgical Anatomy of Vertical Perithalamic Hemispherotomy

BACKGROUND

Vertical perithalamic hemispherotomy was introduced by Olivier Delalande in 1992 as an alternative concept of functional hemispherectomy.

OBJECTIVE

To provide a step-by-step illustration of the surgical anatomy of this procedure.

METHODS

The descriptions in this manuscript are based on an experience of 52 hemispherotomies performed with the same technique by a single surgeon.

RESULTS

Our illustrations of the surgical anatomy and the descriptions of the surgical nuances facilitate a deep understanding for the surgical concept of Delalande's vertical hemispherotomy technique. They highlight the advantages (ie, reduced risk of inadvertent damage to the contralateral hemisphere and a clear orientation by defined anatomical landmarks) over the recently suggested modifications to this original technique.

CONCLUSION

Olivier Delalande's original technique remains the most appealing concept of vertical hemispherotomy to us.

Pediatric functional hemispherectomy: operative techniques and complication avoidance

Functional hemispherectomy/hemispherotomy is a disconnection procedure for severe medically refractory epilepsy where the seizure foci diffusely localize to one hemisphere. It is an improvement on anatomical hemispherectomy and was first performed by Rasmussen in 1974. Less invasive surgical approaches and refinements have been made to improve seizure freedom and minimize surgical morbidity and complications. Key anatomical structures that are disconnected include the 1) internal capsule and corona radiata, 2) mesial temporal structures, 3) insula, 4) corpus callosum, 5) parietooccipital connection, and 6) frontobasal connection. A stepwise approach is indicated to ensure adequate disconnection and prevent seizure persistence or recurrence. In young pediatric patients, careful patient selection and modern surgical techniques have resulted in > 80% seizure freedom and very good functional outcome. In this report, the authors summarize the history of hemispherectomy and its development and present a graphical guide for this anatomically challenging procedure. The use of the osteoplastic flap to improve outcome and the management of hydrocephalus are discussed.

Risk factors and results of hemispherotomy reoperations in children

OBJECTIVE

The goal of this study was to perform an analysis of a single-center experience with hemispherotomy reoperations for refractory hemispheric pediatric epilepsy due to persistence of seizures after initial surgery. The authors also identify possible anatomical and neurophysiological reasons for hemispherotomy failure, as well as risk factors and surgical options for this subgroup of patients.

METHODS

A review was performed of the medical records in 18 consecutive cases in which candidates for redo hemispherotomy were treated between 2003 and 2018 at the authors’ epilepsy surgery center. Fourteen patients underwent reoperation due to seizure recurrence and were studied herein, whereas in 3 the initial surgical procedure was stopped because of uncontrollable bleeding, and the remaining patient refused to undergo a reoperation in spite of seizure recurrence and went on to have a vagus nerve stimulation device placed.

RESULTS

Among the 14 patients whose seizures recurred and in whom reoperations were done, the etiology of epilepsy consisted of 7 cases with malformations of cortical development (50%), 5 cases of Rasmussen encephalitis (35.8%), 1 case of porencephaly (7.1%), and 1 case of Sturge-Weber syndrome (7.1%). Eleven patients had radiological evidence of incomplete disconnection. After reoperation, 6 patients were Engel class IA, 1 was Engel II, 5 were Engel III, and 2 were Engel IV, within a mean follow-up of 48.4 months.

CONCLUSIONS

Patients with malformations of cortical development have a higher risk of seizure recurrence, and these malformations comprised the main etiology in the reoperation series. Failure of an initial hemispherotomy usually occurs due to incomplete disconnection and needs to be extensively assessed. Outcomes of reoperation are most often favorable, with acceptable complication rates.

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

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.

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.

Endoscope-assisted (with robotic guidance and using a hybrid technique) interhemispheric transcallosal hemispherotomy: a comparative study with open hemispherotomy to evaluate efficacy, complications, and outcome

OBJECTIVEEndoscope-assisted hemispherotomy (EH) has emerged as a good alternative option for hemispheric pathologies with drug-resistant epilepsy.METHODSThis was a prospective observational study. Parameters measured included primary outcome measures (frequency, severity of seizures) and secondary outcomes (cognition, behavior, and quality of life). Blood loss, operating time, complications, and hospital stay were also taken into account. A comparison was made between the open hemispherotomy (OH) and endoscopic techniques performed by the senior author.RESULTSOf 59 cases (42 males), 27 underwent OH (8 periinsular, the rest vertical) and 32 received EH. The mean age was 8.65 ± 5.41 years (EH: 8.6 ± 5.3 years; OH: 8.6 ± 5.7 years). Seizure frequency per day was 7 ± 5.9 (EH: 7.3 ± 4.6; OH: 15.0 ± 6.2). Duration of disease (years since first episode) was 3.92 ± 1.24 years (EH: 5.2 ± 4.3; OH: 5.8 ± 4.5 years). Number of antiepileptic drugs per patient was 3.9 ± 1.2 (EH: 4.2 ± 1.2; OH: 3.8 ± 0.98). Values for the foregoing variables are expressed as the mean ± SD. Pathologies included the following: postinfarct encephalomalacia in 19 (EH: 11); Rasmussen's syndrome in 14 (EH: 7); hemimegalencephaly in 12 (EH: 7); hemispheric cortical dysplasia in 7 (EH: 4); postencephalitis sequelae in 6 (EH: 2); and Sturge-Weber syndrome in 1 (EH: 1). The mean follow-up was 40.16 ± 17.3 months. Thirty-nine of 49 (79.6%) had favorable outcomes (International League Against Epilepsy class I and II): in EH the total was 19/23 (82.6%) and in OH it was 20/26 (76.9%). There was no difference in the primary outcome between EH and OH (p = 0.15). Significant improvement was seen in the behavioral/quality of life performance, but not in IQ scores in both EH and OH (p < 0.01, no intergroup difference). Blood loss (p = 0.02) and hospital stay (p = 0.049) were less in EH.CONCLUSIONSEH was as effective as the open procedure in terms of primary and secondary outcomes. It also resulted in less blood loss and a shorter postoperative hospital stay.

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.

Periinsular anterior quadrantotomy: technical note

Refractory frontal lobe epilepsy has been traditionally treated through a frontal lobectomy. A disconnective technique may allow similar seizure outcomes while avoiding the complications associated with large brain resections. The aim of this study was to describe a new technique of selective disconnection of the frontal lobe that can be performed in cases of refractory epilepsy due to epileptogenic foci involving 1 frontal lobe (anterior to the motor cortex), with preservation of motor function. In addition to the description of the technique, an illustrative case is also presented. This disconnective procedure is divided into 4 steps: the suprainsular window, the anterior callosotomy, the intrafrontal disconnection, and the frontobasal disconnection. The functional neuroanatomy is analyzed in detail for each step of the surgery. It is important to perform cortical and subcortical electrophysiological mapping to guide this disconnective procedure and identify eloquent cortices and intact neural pathways. The authors describe the case of a 9-year-old boy who presented with refractory epilepsy due to epileptogenic foci localized to the right frontal lobe. MRI confirmed the presence of a focal cortical dysplasia of the right frontal lobe. A periinsular anterior quadrant disconnection (quadrantotomy) was performed. The postoperative period was uneventful, and the patient was in Engel seizure outcome Class I at the 3-year follow-up. A significant cognitive gain was observed during follow-up. Periinsular anterior quadrantotomy may thus represent a safe technique to efficiently treat refractory epilepsy when epileptogenic foci are localized to 1 frontal lobe while preserving residual motor functions.

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.

Epileptic spikes in Rasmussen's encephalitis: Migratory pattern and short-term evolution. A MEG study

OBJECTIVE

We aimed this study at identifying cortical areas involved in the generation of interictal spikes in Rasmussen's Encephalitis (RE) patients using magnetoencephalography (MEG), at comparing spike localization with the degree of cortical atrophy detected by MRI, and at identifying short-term changes during the follow-up.

METHODS

Five patients with RE underwent two MEG and magnetic resonance imaging (MRI) (six months interval). The sources of visually detected spikes were estimated using equivalent current dipoles technique; these were then superimposed on individual MRI and clustered; the locations of the clusters were related to the MRI stage of cortical atrophy.

RESULTS

All patients showed spikes and clusters located in different cortical areas in both recordings; the locations had a limited correspondence with cortical atrophy. The second recordings showed changes in the localisation of spikes and clusters, and confirmed the dissimilarities with neuroradiological abnormalities.

CONCLUSIONS

The presence of clusters of spikes of variable localisation suggests that RE progresses in a multifocal and fluctuating manner. The cortical areas most involved in epileptogenesis did not completely coincide with the most atrophic areas.

SIGNIFICANCE

MEG can contribute to evaluating multifocal hemispheric spikes in RE and to better understand the time course of epileptogenic process.

Outcomes after hemispherectomy in adult patients with intractable epilepsy: institutional experience and systematic review of the literature

OBJECTIVE Hemispherectomy is a surgical technique that is established as a standard treatment in appropriately selected patients with drug-resistant epilepsy. It has proven to be successful in pediatric patients with unilateral hemispheric lesions but is underutilized in adults. This study retrospectively evaluated the clinical outcomes after hemispherectomy in adult patients with refractory epilepsy. METHODS This study examined 6 cases of hemispherectomy in adult patients at Barrow Neurological Institute. In addition, all case series of hemispherectomy in adult patients were identified through a literature review using MEDLINE and PubMed. Case series of patients older than 18 years were included; reports of patients without clear follow-up duration or method of validated seizure outcome quantification were excluded. Seizure outcome was based on the Engel classification. RESULTS A total of 90 cases of adult hemispherectomy were identified, including 6 newly added by Barrow Neurological Institute. Sixty-five patients underwent functional hemispherectomy; 25 patients had anatomical hemispherectomy. Length of follow-up ranged from 9 to 456 months. Seizure freedom was achieved in 80% of patients. The overall morbidity rate was low, with 9 patients (10%) having new or additional postoperative speech or language dysfunction, and 19 patients (21%) reporting some worsening of hemiparesis. No patients lost ambulatory or significant functional ability, and 2 patients had objective ambulatory improvement. Among the 41 patients who underwent additional formal neuropsychological testing postoperatively, overall stability or improvement was seen. CONCLUSIONS Hemispherectomy is a valuable surgical tool for properly selected adult patients with pre-existing hemiparesis and intractable epilepsy. In published cases, as well as in this series, the procedure has overall been well tolerated without significant morbidity, and the majority of patients have been rendered free of seizures.

Posterior Quadrant Disconnection: A Fiber Dissection Study

BACKGROUND

Posterior quadrant disconnection can be highly effective in the surgical treatment of selected cases of refractory epilepsy. The technique aims to deafferent extensive areas of epileptogenic posterior cortex from the rest of the brain by isolating the temporoparietooccipital cortex.

OBJECTIVE

To describe this procedure and relevant white matter tracts with a specific emphasis on the extent of callosotomy in an anatomic study.

METHODS

Twenty hemispheres were dissected according to Klingler's fiber dissection technique illustrating the peri-insular (temporal stem, superior longitudinal fasciculus, corona radiata) and mesial disconnection (mesiotemporal cortex, cingulum, and corpus callosum).

RESULTS

Extensive white matter tract disconnection is obtained after posterior quadrant disconnection. Callosal fibers connecting the anterior most part of the parietal cortex invariably ran through the isthmus of the corpus callosum and need to be disconnected, while frontal lobe connections including the corticospinal tract and the anterior two-thirds of the corpus callosum are spared during the procedure.

CONCLUSION

Our findings suggest the involvement of both the splenium and the isthmus in interhemispheric propagation in posterior cortex epilepsies. Sectioning the total extent of the posterior one-third of the corpus callosum might therefore be necessary to achieve optimal outcomes in posterior quadrant epilepsy surgery.

Delayed diagnosis of shunt overdrainage following functional hemispherotomy and ventriculoperitoneal shunt placement in a hemimegalencephaly patient

Shunt overdrainage represents a nebulous condition of variable clinical and imaging presentations, where the diagnosis is primarily clinical. The condition presents a diagnostic challenge particularly in patients with cognitive impairment and developmental delays. Here we present a 3-year-old boy with drug-resistant focal onset seizures due to hemimegalencephaly who previously underwent functional hemispherotomy followed by ventriculoperitoneal shunt placement for postoperative hydrocephalus. The subsequent clinical course was complicated by delayed diagnosis of shunt overdrainage in the absence of significant image findings. Maintaining a high index of suspicion for the possibility of shunt overdrainage is critical even in the face of unremarkable imaging findings.

Functional hemispherotomy in Rasmussen syndrome in the absence of classic MRI findings

A 7-year-old previously healthy girl presented with a left-sided focal seizure without impaired consciousness and subsequently developed epilepsia partialis continua. Initial MRI was normal, and the subsequent images only showed a focal T2/FLAIR hyperintense area without cortical atrophy. She was diagnosed with Rasmussen syndrome by pathology and promptly treated with functional hemispherotomy. Rasmussen syndrome is a rare progressive neurological disorder, the only definitive cure for which is hemispheric disconnection. The disease presents a management dilemma, especially early in disease course without characteristic neuroimaging features. A high index of suspicion, multidisciplinary approach, and clear timely communication with the family are critical.

Use of a contoured bioresorbable plate with a hemostatic plug to control life-threatening bleeding from the superior sagittal sinus during hemispherotomy: technical note

Profuse bleeding originating from an injured cerebral sinus can be a harrowing experience for any surgeon, particularly during an operation on a young child. Common surgical remedies include sinus ligation, primary repair, placement of a hemostatic plug, and patch or venous grafting that may require temporary stenting. In this paper the authors describe the use of a contoured bioresorbable plate to hold a hemostatic plug in place along a tear in the inferomedial portion of a relatively inaccessible part of the posterior segment of the superior sagittal sinus in an 11-kg infant undergoing hemispherotomy for epilepsy. This variation on previously described hemostatic techniques proved to be easy, effective, and ultimately lifesaving. Surgeons may find this technique useful in similar dire circumstances when previously described techniques are ineffective or impractical.

Predicting hand function after hemidisconnection

Hemidisconnections (i.e. hemispherectomies or hemispherotomies) invariably lead to contralateral hemiparesis. Many patients with a pre-existing hemiparesis, however, experience no deterioration in motor functions, and some can still grasp with their paretic hand after hemidisconnection. The scope of our study was to predict this phenomenon. Hypothesizing that preserved contralateral grasping ability after hemidisconnection can only occur in patients controlling their paretic hands via ipsilateral corticospinal projections already in the preoperative situation, we analysed the asymmetries of the brainstem (by manual magnetic resonance imaging volumetry) and of the structural connectivity of the corticospinal tracts within the brainstem (by magnetic resonance imaging diffusion tractography), assuming that marked hypoplasia or Wallerian degeneration on the lesioned side in patients who can grasp with their paretic hands indicate ipsilateral control. One hundred and two patients who underwent hemidisconnections between 0.8 and 36 years of age were included. Before the operation, contralateral hand function was normal in 3/102 patients, 47/102 patients showed hemiparetic grasping ability and 52/102 patients could not grasp with their paretic hands. After hemidisconnection, 20/102 patients showed a preserved grasping ability, and 5/102 patients began to grasp with their paretic hands only after the operation. All these 25 patients suffered from pre- or perinatal brain lesions. Thirty of 102 patients lost their grasping ability. This group included all seven patients with a post-neonatally acquired or progressive brain lesion who could grasp before the operation, and also all three patients with a preoperatively normal hand function. The remaining 52/102 patients were unable to grasp pre- and postoperatively. On magnetic resonance imaging, the patients with preserved grasping showed significantly more asymmetric brainstem volumes than the patients who lost their grasping ability. Similarly, these patients showed striking asymmetries in the structural connectivity of the corticospinal tracts. In summary, normal preoperative hand function and a post-neonatally acquired or progressive lesion predict a loss of grasping ability after hemidisconnection. A postoperatively preserved grasping ability is possible in hemiparetic patients with pre- or perinatal lesions, and this is highly likely when the brainstem is asymmetric and especially when the structural connectivity of the corticospinal tracts within the brainstem is asymmetric.

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.

Vertical extraventricular functional hemispherotomy: a new variant for hemispheric disconnection. Technical notes and results in three patients

PURPOSE

Hemispherectomy and disconnective hemispherotomy are the most effective epilepsy surgical procedures for the treatment of epilepsy due to hemispheric pathologies such as Sturge-Weber syndrome, diffuse hemispheric cortical dysplasia, and posttraumatic and postischemic focal lesions. Disconnective hemispherotomy is nowadays preferred to reduce surgical morbidity in term of early and late complications (i.e., cerebral superficial hemosiderosis). Despite the number of existing technical variants conceived to further reduce the amount of brain tissue to be removed, postoperative hydrocephalus still persists and may account for an average incidence of 15-41% according to different series and reviews. A new variant of disconnective vertical hemispherotomy we termed vertical extraventricular parasagittal hemispherotomy is described aiming to further reduce the amount of removed brain tissue and so the risk of postoperative hydrocephalus in favor of a pure hemispheric disconnection.

METHODS

Three patients affected by drug-resistant epilepsy due to different hemispheric pathologies (posttraumatic epilepsy, Sturge-Weber syndrome, diffuse hemispheric cortical dysplasia) were considered to be candidates for vertical extraventricular parasagittal hemispherotomy disconnective based on presurgical evaluation protocol. The oldest patient was 15 years old, the two youngest were both 2 years old.

RESULTS

None of the patients experienced early and late surgical complications. After a mean follow-up of 36 months (range 12-60 months), two patients were seizure free, one relapsed seizures 18 months later. Postoperative hydrocephalus never occurred.

CONCLUSION

Vertical extraventricular parasagittal hemispherotomy may be an efficacious and less invasive technique as it consists in a pure disconnection of the hemisphere with less amount of brain tissue removed and a theoretical reduced risk of postoperative hydrocephalus.

A long-term patient perspective after hemispherotomy--a population based study

PURPOSE

Explore the long-term life situation for Swedish hemispherotomy patients reporting not only seizure outcome but also patients' perspectives on function, quality of life (QoL) and satisfaction with the surgery.

METHODS

This population based study uses prospectively collected data from the Swedish National Epilepsy Surgery Register. An independent researcher interviewed patients or parents, using two patient oriented questionnaires.

RESULTS

Twenty-nine patients underwent hemispherotomy in Sweden after 1995 and had a five- or ten-year follow-up. At the 2-year follow-up 55% (16/29) were seizure-free since surgery, and 11/29 (38%) were seizure-free at the long term follow up. Twenty-six (90%) participated in this study. Median time to interview was 13.5 years; 9/26 (35%) were seizure-free then; 23% were off antiepileptic medication. In those not seizure-free, seizures were considered mild or moderate; 11% attended mainstream school and 3/12 adults lived independently. Most parents both of seizure-free and non seizure-free patients reported QoL and general health to be very good/good; 73% were satisfied/very satisfied with the hemispherotomy.

CONCLUSION

In this series there were more long-term recurrences than previously reported. This might be related to the lower level of function of this cohort and higher percentage of developmental aetiologies compared to other series. However, most hemispherotomy patients have a good QoL in the long run and feel that the operation was worthwhile, even when it did not stop seizures. The majority had persisting impairments. Proxies were not very concerned about seizures, indicating that reduction in seizure frequency and/or severity may be an important gain with hemispherotomy.

Endoscopy-Assisted Interhemispheric Transcallosal Hemispherotomy

BACKGROUND:

Various hemispherotomy techniques have been developed to reduce complication rates and achieve the best possible seizure control.

OBJECTIVE:

To present a novel and minimally invasive endoscopy-assisted approach to perform this procedure.

METHODS:

Endoscopy-assisted interhemispheric transcallosal hemispherotomy was performed in 5 children (April 2013-June 2014). The procedure consisted of performing a small craniotomy (4 × 3 cm) just lateral to midline using a transverse skin incision. After dural opening, the surgery was performed with the assistance of a rigid high-definition endoscope, and bayoneted self-irrigating bipolar forceps and other standard endoscopic instruments. Steps included a complete corpus callosotomy followed by the disconnection of the hemisphere at the level of the basal nuclei and thalamus. The surgeries were performed in a dedicated operating room with intraoperative magnetic resonance imaging and neuronavigation. Intraoperative magnetic resonance imaging confirmed a total disconnection.

RESULTS:

The pathologies for which surgeries were performed included sequelae of middle a cerebral artery infarct (n = 2), Rasmussen syndrome (n = 1), and hemimegalencephaly (2). Four patients had an Engel class I and 1 patient had a class II outcome at a mean follow-up of 10.2 months (range, 3-14 months). The mean blood loss was 80 mL, and mean operating time was 220 minutes. There were no complications in this study.

CONCLUSION:

This study describes a pilot novel technique and the feasibility of performing a minimally invasive, endoscopy-assisted hemispherotomy.

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.

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.

Hemispherotomy in Rasmussen encephalitis: long-term outcome in an Italian series of 16 patients

Surgical disconnection of the affected hemisphere is considered the treatment of choice for Rasmussen encephalitis (RE), however few data on long-term outcomes after disconnective surgery are available. We report on long-term seizure, cognitive and motor outcomes after disconnective surgery in 16 (8 M, 8 F) RE patients. Pre- and post-operative evaluations included long-term video-EEG monitoring, MRI, assessment of motor function, and cognitive evaluation. Hemispherotomy, by various techniques was used to obtain functional disconnection of the affected hemisphere. The patients, of median current age 23.5 years, range 12-33, were operated on between 1993 and 2009. Median age at disease onset was 5.8 years (range 3-11.4). Median time from seizure onset to surgery was 3.8 years, range 8 months to 21 years. Post-surgical follow-up was a median of 9.5 years, range 3-20. At surgery all patients were receiving two or more antiepileptic drugs (AEDs). All but three patients were seizure-free at latest follow-up. AEDs had been stopped in ten patients; in the remaining six AEDs were markedly reduced. Postural control improved in all patients. Gain in cognitive functioning was significantly (p=0.002) related to disease duration. The long-term outcomes, in terms of seizure control, motor improvement, and cognitive improvement provide important support for disconnective surgery as first choice treatment for RE.