Interhemispheric Vertical Hemispherotomy: A Single Center Experience

Interhemispheric Vertical Hemispherotomy: Technique, Outcome, and Pitfalls-A Bicentric Retrospective Case Series of 39 Cases

BACKGROUND AND OBJECTIVES

When seizure onset affects a whole hemisphere, hemispheric disconnections are efficient and safe procedures. However, both lateral peri-insular hemispherotomy and vertical paramedian hemispherotomy approaches report a failure rate around 20%, which can be explained by residual connections giving rise to persistent seizures. In this study, we present the interhemispheric vertical hemispherotomy (IVH), a technical variation of the vertical paramedian hemispherotomy approach, that aims to increase seizure control avoiding residual connections while exposing the corpus callosum.

METHODS

This is a retrospective study of IVH in two centers, with analysis of clinical and MRI data and outcomes. A detailed description of the technique is provided with a video.

RESULTS

IVH was performed in 39 children. The mean age at surgery was 7.2 years, and etiologies were as follows: malformations of cortical development (n = 14), Rasmussen's encephalitis (n = 10), stroke (n = 10), post-traumatic (3), and Sturge-Weber Syndrome (2). Hemispheric disconnection was complete on postoperative MRI in 34 cases. There was no mortality, hydrocephalus occurred in one case, and subdural collection occurred in four cases. A second surgery was performed in four cases because of seizure relapse (n = 3) and/or incomplete disconnection on MRI (n = 4). With a mean follow-up of 3.2 years, International League Against Epilepsy class I epilepsy outcome was obtained for 37/39 patients.

CONCLUSION

IVH is a safe and effective variation of the vertical approaches for hemispheric disconnection. It allows a good exposure and anatomic control of the corpus callosum, which is a frequent site of incomplete disconnection. IVH may be limited by the thalamic volume and the ventricular size, notably in hemimegalencephaly cases.

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

Introduction

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

Research question

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

Material and methods

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

Results

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

Discussion and conclusion

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

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

Introduction

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

Research question

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

Material & methods

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

Results

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

Discussion and conclusion

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

Surgical Treatments for Epilepsies in Children Aged 1-36 Months: A Systematic Review

BACKGROUND AND OBJECTIVES

Early life epilepsies (epilepsies in children 1-36 months old) are common and may be refractory to antiseizure medications. We summarize findings of a systematic review commissioned by the American Epilepsy Society to assess evidence and identify evidence gaps for surgical treatments for epilepsy in children aged 1-36 months without infantile spasms.

METHODS

EMBASE, MEDLINE, PubMed, and the Cochrane Library were searched for studies published from 1/1/1999 to 8/19/21. We included studies reporting data on children aged 1 month to ≤36 months undergoing surgical interventions or neurostimulation for epilepsy and enrolling ≥10 patients per procedure. We excluded studies of infants with infantile spasms or status epilepticus. For effectiveness outcomes (seizure freedom, seizure frequency), studies were required to report follow-up at ≥ 12 weeks. For harm outcomes, no minimum follow-up was required. Outcomes for all epilepsy types, regardless of etiology, were reported together.

RESULTS

Eighteen studies (in 19 articles) met the inclusion criteria. Sixteen prestudies/poststudies reported on efficacy, and 12 studies addressed harms. Surgeries were performed from 1979 to 2020. Seizure freedom for infants undergoing hemispherectomy/hemispherotomy ranged from 7% to 76% at 1 year after surgery. For nonhemispheric surgeries, seizure freedom ranged from 40% to 70%. For efficacy, we concluded low strength of evidence (SOE) suggests some infants achieve seizure freedom after epilepsy surgery. Over half of infants undergoing hemispherectomy/hemispherotomy achieved a favorable outcome (Engel I or II, International League Against Epilepsy I to IV, or >50% seizure reduction) at follow-up of >1 year, although studies had key limitations. Surgical mortality was rare for functional hemispherectomy/hemispherotomy and nonhemispheric resections. Low SOE suggests postoperative hydrocephalus is uncommon for infants undergoing nonhemispheric procedures for epilepsy.

DISCUSSION

Although existing evidence remains sparse and low quality, some infants achieve seizure freedom after surgery and ≥50% achieve favorable outcomes. Future prospective studies in this age group are needed. In addition to seizure outcomes, studies should evaluate other important outcomes (developmental outcomes, quality of life [QOL], sleep, functional performance, and caregiver QOL).

TRIAL REGISTRATION INFORMATION

This systematic review was registered in PROSPERO (CRD42021220352) on March 5, 2021.

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.

Epilepsy surgery in children under 3 years of age: surgical and developmental outcomes

OBJECTIVE

Pediatric epilepsy surgery is known to be effective, but early surgery in infancy is not well characterized. Extensive cortical dysplasia, such as hemimegalencephaly, can cause refractory epilepsy shortly after birth, and early surgical intervention is indicated. However, the complication rate of early pediatric surgery is significant. In this study, the authors assessed the risk-benefit balance of early pediatric epilepsy surgery as relates to developmental outcomes.

METHODS

This is a retrospective descriptive study of 75 patients who underwent their first curative epilepsy surgery at an age under 3 years at the authors' institution between 2006 and 2019 and had a minimum 1-year follow-up of seizure and developmental outcomes. Clinical information including surgical complications, seizure outcomes, and developmental quotient (DQ) was collected from medical records. The effects of clinical factors on DQ at 1 year after surgery were evaluated.

RESULTS

The median age at surgery was 6 months, peaking at between 3 and 4 months. Operative procedures included 27 cases of hemispherotomy, 19 cases of multilobar surgery, and 29 cases of unilobar surgery. Seizure freedom was achieved in 82.7% of patients at 1 year and in 71.0% of patients at a mean follow-up of 62.8 months. The number of antiseizure medications (ASMs) decreased significantly after surgery, and 19 patients (30.6%) had discontinued their ASMs by the last follow-up. Postoperative complications requiring cerebrospinal fluid (CSF) diversion surgery, such as hydrocephalus and cyst formation, were observed in 13 patients (17.3%). The mean DQ values were 74.2 ± 34.3 preoperatively, 60.3 ± 23.3 at 1 year after surgery, and 53.4 ± 25.1 at the last follow-up. Multiple regression analysis revealed that the 1-year postoperative DQ was significantly influenced by preoperative DQ and postoperative seizure freedom but not by the occurrence of any surgical complication requiring CSF diversion surgery.

CONCLUSIONS

Early pediatric epilepsy surgery has an acceptable risk-benefit balance. Seizure control after surgery is important for postoperative development.

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.

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.

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.

Dramatic response after functional hemispherectomy in a patient with epileptic encephalopathy carrying a de novo COL4A1 mutation

We describe the first case of a successful functional hemispherectomy in a patient with epileptic encephalopathy and a de novo collagen type IV alpha 1 (COL4A1) mutation. A 4-year-old girl was COL4A1 mutation-positive and suffered from drug-resistant epilepsy, hemiplegia, and developmental delay. Magnetic resonance imaging detected no porencephaly, and she had no cataract or renal abnormality. Following a presurgical evaluation for epilepsy, she underwent a functional hemispherectomy. She has been seizure free with no intracranial hemorrhage or other perioperative complications. Patients with a COL4A1 mutation have an increased risk for intracranial hemorrhage because of disrupted integrity in the vascular basement membrane due to the mutation. After weighing the risks and benefits to these patients, epilepsy surgery may not be absolutely contraindicated. Furthermore, pediatric neurologists should be aware of an undiagnosed COL4A1 mutation when a patient presents with an unexplained neurological phenotype, such as mild hemiparesis, even in the absence of porencephaly.

Anatomic Understanding of Vertical Hemispherotomy With Cadaveric Brains and Intraoperative Photographs

BACKGROUND

Vertical hemispherotomy is performed in hemispheric epilepsy to disconnect commissural fibers, projecting fibers, and limbic system from the affected side of the brain with minimal parenchyma removal. However, anatomic understanding of this surgery is generally difficult.

OBJECTIVE

To present the vertical hemispherotomy procedures using cadaveric brains and intraoperative photographs.

METHODS

Two formalin-fixed adult cadaveric brains were used to demonstrate vertical hemispherotomy. Intraoperative photographs were taken of a 19-year-old man with intractable epilepsy due to head trauma in infancy.

RESULTS

After coronal skin incision along the coronal suture, bifrontal craniotomy and a C-shaped dural incision from lateral to medial to the midline are performed. The interhemispheric fissure is dissected from anterior to posterior. Interhemispheric total corpus callosotomy is performed to disconnect commissural fibers. Corticotomy on the cingulate gyrus is performed to approach the lateral ventricle. The lateral border of the thalamus is cut from posterior to anterior until exposing the inferior horn of the lateral ventricle and hippocampal head to disconnect projecting fibers. At the anteromedial side of the hippocampus, the inferior part of the amygdala and uncal gyrus is removed, exposing the basal cistern to disconnect the hippocampus and amygdala. The posterior column of the fornix at the trigone of the lateral ventricle is resected to disconnect the limbic system. Projecting fibers from the anterior frontal lobe are disconnected.

CONCLUSION

A step-by-step procedure using cadaveric brains and intraoperative photographs provide a better anatomic understanding of vertical hemispherotomy.