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

OBJECTIVES: Although hemispheric surgeries are among the most effective procedures for drug-resistant epilepsy (DRE) in the pediatric population, there is a large variability in seizure outcomes at the group level. A recently developed HOPS score provides individualized estimation of likelihood of seizure freedom to complement clinical judgement. The objective of this study was to develop a freely accessible online calculator that accurately predicts the probability of seizure freedom for any patient at 1-, 2-, and 5-years post-hemispherectomy. METHODS: Retrospective data of all pediatric patients with DRE and seizure outcome data from the original Hemispherectomy Outcome Prediction Scale (HOPS) study were included. The primary outcome of interest was time-to-seizure recurrence. A multivariate Cox proportional-hazards regression model was developed to predict the likelihood of post-hemispheric surgery seizure freedom at three time points (1-, 2- and 5- years) based on a combination of variables identified by clinical judgment and inferential statistics predictive of the primary outcome. The final model from this study was encoded in a publicly accessible online calculator on the International Network for Epilepsy Surgery and Treatment (iNEST) website (https://hops-calculator.com/). RESULTS: The selected variables for inclusion in the final model included the five original HOPS variables (age at seizure onset, etiologic substrate, seizure semiology, prior non-hemispheric resective surgery, and contralateral fluorodeoxyglucose-positron emission tomography [FDG-PET] hypometabolism) and three additional variables (age at surgery, history of infantile spasms, and magnetic resonance imaging [MRI] lesion). Predictors of shorter time-to-seizure recurrence included younger age at seizure onset, prior resective surgery, generalized seizure semiology, FDG-PET hypometabolism contralateral to the side of surgery, contralateral MRI lesion, non-lesional MRI, non-stroke etiologies, and a history of infantile spasms. The area under the curve (AUC) of the final model was 73.0%. SIGNIFICANCE: Online calculators are useful, cost-free tools that can assist physicians in risk estimation and inform joint decision-making processes with patients and families, potentially leading to greater satisfaction. Although the HOPS data was validated in the original analysis, the authors encourage external validation of this new calculator.

Added value of corpus callosotomy following vagus nerve stimulation in children with Lennox-Gastaut syndrome: A multicenter, multinational study.

OBJECTIVE: Lennox-Gastaut syndrome (LGS) is a severe form of epileptic encephalopathy, presenting during the first years of life, and is very resistant to treatment. Once medical therapy has failed, palliative surgeries such as vagus nerve stimulation (VNS) or corpus callosotomy (CC) are considered. Although CC is more effective than VNS as the primary neurosurgical treatment for LGS-associated drop attacks, there are limited data regarding the added value of CC following VNS. This study aimed to assess the effectiveness of CC preceded by VNS. METHODS: This multinational, multicenter retrospective study focuses on LGS children who underwent CC before the age of 18 years, following prior VNS, which failed to achieve satisfactory seizure control. Collected data included epilepsy characteristics, surgical details, epilepsy outcomes, and complications. The primary outcome of this study was a 50% reduction in drop attacks. RESULTS: A total of 127 cases were reviewed (80 males). The median age at epilepsy onset was 6 months (interquartile range [IQR] = 3.12-22.75). The median age at VNS surgery was 7 years (IQR = 4-10), and CC was performed at a median age of 11 years (IQR = 8.76-15). The dominant seizure type was drop attacks (tonic or atonic) in 102 patients. Eighty-six patients underwent a single-stage complete CC, and 41 an anterior callosotomy. Ten patients who did not initially have a complete CC underwent a second surgery for completion of CC due to seizure persistence. Overall, there was at least a 50% reduction in drop attacks and other seizures in 83% and 60%, respectively. Permanent morbidity occurred in 1.5%, with no mortality. SIGNIFICANCE: CC is vital in seizure control in children with LGS in whom VNS has failed. Surgical risks are low. A complete CC has a tendency toward better effectiveness than anterior CC for some seizure types.

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.

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

OBJECTIVE: To develop and validate a model to predict seizure freedom in children undergoing cerebral hemispheric surgery for the treatment of drug-resistant epilepsy. METHODS: We analyzed 1267 hemispheric surgeries performed in pediatric participants across 32 centers and 12 countries to identify predictors of seizure freedom at 3 months after surgery. A multivariate logistic regression model was developed based on 70% of the dataset (training set) and validated on 30% of the dataset (validation set). Missing data were handled using multiple imputation techniques. RESULTS: Overall, 817 of 1237 (66%) hemispheric surgeries led to seizure freedom (median follow-up = 24 months), and 1050 of 1237 (85%) were seizure-free at 12 months after surgery. A simple regression model containing age at seizure onset, presence of generalized seizure semiology, presence of contralateral 18-fluoro-2-deoxyglucose-positron emission tomography hypometabolism, etiologic substrate, and previous nonhemispheric resective surgery is predictive of seizure freedom (area under the curve = .72). A Hemispheric Surgery Outcome Prediction Scale (HOPS) score was devised that can be used to predict seizure freedom. SIGNIFICANCE: Children most likely to benefit from hemispheric surgery can be selected and counseled through the implementation of a scale derived from a multiple regression model. Importantly, children who are unlikely to experience seizure control can be spared from the complications and deficits associated with this surgery. The HOPS score is likely to help physicians in clinical decision-making.

Cognitive and behavioral profiles of pediatric surgical candidates with frontal and temporal lobe epilepsy.

BACKGROUND: We aimed to prospectively analyze memory and executive and social cognitive functioning in patients with drug-resistant frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE) with focal lesions and isolate the impact of intellectual ability on specific deficits. METHODS: A neuropsychological evaluation was performed in 23 children with FLE, 22 children with TLE, and 36 healthy pediatric controls (HCs). Patients in the epilepsy groups had a range of lesions, including low-grade epilepsy-associated tumors (LEAT), focal cortical dysplasia (FCD) type II, and mesial temporal sclerosis (MS). RESULTS: There were no significant differences between children with FLE and TLE regarding memory, executive, or social cognitive functioning. General Ability Index (GAI) was a predictor of memory, executive function, and social cognition scores and was influenced by age at onset, duration of epilepsy, and number of antiepileptic drugs (AEDs) prescribed at the time of assessment. Working Memory Index scores of patients with TLE, which measure verbal mnesic processing, were significantly lower than those of HCs and patients with TLE. The greatest differences in both clinical groups compared to HCs were recorded in cognitive executive functions, and patients with FLE had lower scores in this domain. Regarding behavioral executive functions, patients with TLE presented impaired emotional control and impulse inhibition and patients with FLE exhibited decreased flexibility. CONCLUSION: Consistent with previous research, our findings provide further detailed evidence of small differences in cognitive performance among children with FLE and TLE. These differences emerge on analysis of the factors with which deficits are associated.

Neuropsychological Profile in Children with Posterior Fossa Tumors with or Without Postoperative Cerebellar Mutism Syndrome (CMS).

Cerebellar mutism syndrome (CMS) is a common surgical sequela in children following posterior fossa tumor (PFT) resection. Here, we analyze the neuropsychological features associated with PFT in children, focusing particularly on the differential profiles associated with the presence or absence of CMS after surgery. We further examine the effect of post-resection treatments, tumor type, and presence/absence of hydrocephalus on surgical outcome. Thirty-six patients diagnosed with PFT (19 with and 17 without CMS) and 34 age- and gender-matched healthy controls (HCs) were recruited. A comprehensive neuropsychological evaluation was conducted in all patients postoperatively and in HCs, including an assessment of general cognitive ability, motor skills, perception, language, memory, attention, executive functions, and academic competence. CMS was found to be a clinical marker of lower neuropsychological profile scores across all cognitive domains except auditory-verbal processing and visual memory tasks. PFT patients not presenting CMS exhibited milder impairment in intellectual functioning, motor tasks, reasoning, language, verbal learning and recall, attention, cognitive executive functions, and academic competence. High-grade tumors were associated with slower processing speed and verbal delayed recall as well as alterations in selective and sustained attention. Hydrocephalus was detrimental to motor functioning and nonverbal reasoning. Patients who had undergone surgery, chemotherapy, and radiotherapy presented impaired processing speed, verbal learning, and reading. In addition to the deleterious effects of PFT, post-resection PFT treatments have a negative cognitive impact. These undesired consequences and the associated tumor-related damage can be assessed using standardized, long-term neuropsychological evaluation when planning rehabilitation.

Trends in pediatric epilepsy surgery in Europe between 2008 and 2015: Country-, center-, and age-specific variation.

OBJECTIVE: To profile European trends in pediatric epilepsy surgery (<16 years of age) between 2008 and 2015. METHODS: We collected information on volumes and types of surgery, pathology, and seizure outcome from 20 recognized epilepsy surgery reference centers in 10 European countries. RESULTS: We analyzed retrospective aggregate data on 1859 operations. The proportion of surgeries significantly increased over time (P < .0001). Engel class I outcome was achieved in 69.3% of children, with no significant improvement between 2008 and 2015. The proportion of histopathological findings consistent with glial scars significantly increased between the ages of 7 and 16 years (P for trend = .0033), whereas that of the remaining pathologies did not vary across ages. A significant increase in unilobar extratemporal surgeries (P for trend = .0047) and a significant decrease in unilobar temporal surgeries (P for trend = .0030) were observed between 2008 and 2015. Conversely, the proportion of multilobar surgeries and unrevealing magnetic resonance imaging cases remained unchanged. Invasive investigations significantly increased, especially stereo-electroencephalography. We found different trends comparing centers starting their activity in the 1990s to those whose programs were developed in the past decade. Multivariate analysis revealed a significant variability of the proportion of the different pathologies and surgical approaches across countries, centers, and age groups between 2008 and 2015. SIGNIFICANCE: Between 2008 and 2015, we observed a significant increase in the volume of pediatric epilepsy surgeries, stability in the proportion of Engel class I outcomes, and a modest increment in complexity of the procedures.

An Adolescent Presenting With Seizures as a Symptom of Gliomatosis Cerebri.

Gliomatosis cerebri is a diffuse infiltrating glioma of neuroepithelial origin that affects more than 2 cerebral lobes. This is rarely seen in pediatric patients. The clinical presentation and imaging are very unspecific, and a biopsy is typically needed for the diagnosis. Given the widespread nature of the disease, surgical treatment is not possible and has a poor overall prognosis. A pediatric patient presented with elevated intracranial pressure. All initial studies were negative, and the imaging showed a symmetrical affection involving the supratentorial and infratentorial regions. A biopsy ultimately confirmed gliomatosis cerebri. This case describes a unique clinical presentation of gliomatosis cerebri in a pediatric patient.

Pediatric cerebellar giant cavernous malformation: case report and review of literature.

BACKGROUND AND IMPORTANCE: Giant cavernous malformations (GCM) are low flow, angiographically occult vascular lesions, with a diameter >4 cm. Cerebellar GCMs are extremely rare, with only seven cases reported based on English literature. These lesions are most commonly seen in the pediatric age group, which is known to have an increased risk of hemorrhage, being surgery clearly recommended. CLINICAL PRESENTATION: An 18-month-old girl presented with a 6-month history of cervical torticollis and upper extremities clumsiness. An MRI revealed a 57 × 46 × 42 mm multi-cystic, left cerebellar hemisphere mass, showing areas of hemorrhages and cysts with various stages of thrombus. There was no enhancement with contrast. Cerebral angiography ruled out an arteriovenous malformation. She underwent a left paramedian occipital craniotomy, and macroscopic gross total resection was accomplished. Histopathologic examination was consistent with a cavernous malformation. After surgery, the patient had no new neurological deficit and an uneventful postoperative recovery. Follow-up MRI confirmed total removal of the lesion. CONCLUSION: Cerebellar GCMs in children are symptomatic lesions, which prompt immediate surgical treatment. These are rare lesions, which can radiologically and clinically mimic a tumor with bleed, having to be considered in the differential diagnosis of neoplastic lesions. Cerebellar GCMs might be suspected in the presence of large hemorrhagic intra-axial mass with "bubbles of blood," multi-cystic appearance, surrounded by hemosiderin ring, fluid-fluid levels, and accompanying edema-mass effect. Careful radiological study provides a preoperative diagnosis, but its confirmation requires histopathological examination. Complete surgical removal should be attempted when possible.

[Choroid plexus tumour treatment at Hospital Infantil Niño Jesús in Madrid: Our experience over the last three decades]. / Tratamiento de los tumores de plexos coroideos en el Hospital Infantil Niño Jesús de Madrid: nuestra experiencia en las últimas tres décadas.

OBJECTIVE: To review childhood patients with choroid plexus tumors (CPT) who underwent surgery at Hospital Infantil Niño Jesús of Madrid since January 1981 to September 2014. MATERIAL AND METHODS: Registered charts were analyzed based on the epidemiology, tumor grade, clinical profile, location, dissemination characteristics, therapy, prognosis and complications. RESULTS: Seventeen childhood patients were recorded with CPT. Cases were distributed so that 9 cases were choroid plexus-papilloma (CPP) (52.9%), 2 cases atypical CPP (11.7%) and 6 cases choroid plexus-carcinoma (CPC) (35.2%). Age at diagnosis was less than 2 years in 14 of the 17 patients (82.3%) and the incidence was higher in males (82.3% of the cases). Gross total resection was performed in 16 patients (94.1%). Adjuvant treatment was used in 6 patients (all this cases with CPC) (35.2%). Two of the 17 patients died (11.7%), showing an incidence density of 0.01 deaths/year. CONCLUSIONS: Our case series is consistent with previous published in scientific literature regarding epidemiology, tumor grade, clinical presentation, radiological features and therapeutic approach. Gross total resection is considered the therapeutic gold standard for choroid plexus tumors. Chemotherapy and radiotherapy should be used as adjuvant treatment in CPC and recurrent or remaining atypical CPP.

[Spinal stenosis at the level of atlas in a boy with Down syndrome. A case report and literature review]. / Estenosis de canal a nivel del atlas en un niño con síndrome de Down. Presentación de un caso y revisión de la literatura.

INTRODUCTION: The appearance of congenital anomalies at the level of atlas is frequent in patients with neural alterations, as well as in the Down syndrome. The presence of clinical stenosis for alteration in the posterior arch of C1 without a previous atlantoaxial subluxation hasn't been described in the literature thus far. CASE REPORT: We report an exceptional case of myelopathy due to compression at the level of the atlas in a 5-year-old boy with Down syndrome provoked by a developmental anomaly of the posterior arch of C1. A posterior laminectomy was achieved at that level with improvement of the previous symptoms. CONCLUSIONS: We have to pay special attention in children with syndromes associated with chondrogenesis alterations, as in the case of those with Down syndrome, to benefit from early treatment, since in most of the time they are diagnosed when symptoms are very severe.

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.

Seizure and developmental outcomes after hemispherectomy in children and adolescents with intractable epilepsy.

PURPOSE: The aim of this study is to describe a series of pediatric hemispherectomies, reviewing pathologic substrate, epilepsy characteristics and seizure outcome as well as developmental profiles, before and after surgery, in different domains. METHODS: Seventeen patients with full pre-surgical work-up, minimum follow-up of 12 months, and at least one post-surgical neuropsychological evaluation were selected. Three had Rasmussen encephalitis (RE), five hemispheric malformations of cortical development (MCD), and nine hemispheric vascular lesions. RESULTS: At latest follow-up, all patients with RE and 66.7 % of those with vascular lesions are in Engel's class I; in the latter group, pre-surgical independent contralateral EEG discharges statistically correlated with a worse seizure outcome. Patients with MCD showed the worst seizure outcome. Pre-surgical language transfer to the right hemisphere was confirmed in a boy with left RE, operated on at 6 years of age. Patients with MCD and vascular lesions already showed severe global developmental delay before surgery, which persists afterwards. A linear correlation was found between earlier age at surgery and better outcome in personal-social, gross motor, and adaptive domains, in the vascular lesions group. The case with highest cognitive improvement had continuous spike and wave during sleep on pre-surgical EEG. CONCLUSIONS: Pathologic substrate was the main factor related with seizure outcome. In children with MCD and vascular lesions, although developmental progression is apparent, significant post-surgical improvements are restricted by the severity of pre-surgical neuropsychological disturbances and a slow maturation. Early surgery assessment is recommended to enhance the possibilities for a better quality of life in terms of seizure control, as well as better autonomy and socialization.

D-galactose Supplementation for the Treatment of Mild Malformation of Cortical Development with Oligodendroglial Hyperplasia in Epilepsy (MOGHE): A Pilot Trial of Precision Medicine After Epilepsy Surgery.

MOGHE is defined as mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy. Approximately half of the patients with histopathologically confirmed MOGHE carry a brain somatic variant in the SLC35A2 gene encoding a UDP-galactose transporter. Previous research showed that D-galactose supplementation results in clinical improvement in patients with a congenital disorder of glycosylation due to germline variants in SLC35A2. We aimed to evaluate the effects of D-galactose supplementation in patients with histopathologically confirmed MOGHE, with uncontrolled seizures or cognitive impairment and epileptiform activity at the EEG after epilepsy surgery (NCT04833322). Patients were orally supplemented with D-galactose for 6 months in doses up to 1.5 g/kg/day and monitored for seizure frequency including 24-h video-EEG recording, cognition and behavioral scores, i.e., WISC, BRIEF-2, SNAP-IV, and SCQ, and quality of life measures, before and 6 months after treatment. Global response was defined by > 50% improvement of seizure frequency and/or cognition and behavior (clinical global impression of "much improved" or better). Twelve patients (aged 5-28 years) were included from three different centers. Neurosurgical tissue samples were available in all patients and revealed a brain somatic variant in SLC35A2 in six patients (non-present in the blood). After 6 months of supplementation, D-galactose was well tolerated with just two patients presenting abdominal discomfort, solved after dose spacing or reduction. There was a 50% reduction or higher of seizure frequency in 3/6 patients, with an improvement at EEG in 2/5 patients. One patient became seizure-free. An improvement of cognitive/behavioral features encompassing impulsivity (mean SNAP-IV - 3.19 [- 0.84; - 5.6]), social communication (mean SCQ - 2.08 [- 0.63; - 4.90]), and executive function (BRIEF-2 inhibit - 5.2 [- 1.23; - 9.2]) was observed. Global responder rate was 9/12 (6/6 in SLC35A2-positive). Our results suggest that supplementation with D-galactose in patients with MOGHE is safe and well tolerated and, although the efficacy data warrant larger studies, it might build a rationale for precision medicine after epilepsy surgery.

A Simple Technique for Endoscopic Hypothalamic Hamartoma Disconnection in Refractory Epilepsy: 2-Dimensional Operative Video.

Hypothalamic hamartomas often cause refractory epilepsy, best controlled with surgery. A transcallosal interforniceal approach provides good outcomes although it has resulted in some complications including fornix lesions with transitory and permanent memory losses.1-2 Endoscopic disconnection is less invasive, avoids interhemispheric approach, callosotomy and fornix as well as propagation of epileptic discharges.3,4 Laser disconnection does not allow objective measurement of the vaporized tissue and can cause significant hypothalamic edema. We demonstrate a simple hypothalamic disconnection endoscopy technique using the VarioGuide frameless stereotactic system (Brainlab, Germany), bipolar coagulation electrode (Karl Storz, Germany), and 3-French Fogarty catheter (Edwards Lifesciences, USA). We present a 12-yr-old right-handed girl who developed normally until 4 yr old when gelastic seizures began. Antiepileptic drugs and gamma knife radiosurgery did not control the seizures. Magnetic resonance imaging showed a nodular 13 mm left hypothalamic mass protruding into the third ventricle. The patient consented to surgery. We used a rigid 30° 6-mm neuroendoscope (Aesculap, Germany) with VarioGuide to reach the ventricle. After visualizing the foramen of Monro, the bipolar coagulation electrode perforated holes along the hamartoma/hypothalamus interface. The Fogarty balloon catheter was inserted into each hole and gently inflated to connect the holes and disconnect the mass from the hypothalamus. The patient's postsurgical recovery was excellent, presenting intact short- and long-term memory without neurological deficit or endocrine complications. She continues seizure-free 2 yr after surgery. We have successfully used this technique in 4 more cases and, if results continue to be good, will consider it a useful tool for these infrequent malformations.

Implantation of Depth Electrodes in Children Using VarioGuide® Frameless Navigation System: Technical Note.

BACKGROUND: Electrode placement in epilepsy surgery seeks to locate the sites of ictal onset and early propagation. An invasive diagnostic procedure, stereoelectroencephalography (SEEG) is usually implemented with frame-based methods that can be especially problematic in young children. OBJECTIVE: To evaluate the feasibility and accuracy of a new technique for frameless SEEG in children using the VarioGuide® system (Brainlab AG, München, Germany). METHODS: A frameless stereotactic navigation system was used to implant depth electrodes with percutaneous drilling and bolt insertion in pediatric patients with medically refractory epilepsy. Data on general demographic information of electrode implantation, duration, number, and complications were retrospectively collected. To determine the placement accuracy of the VarioGuide® frameless system, the mean Euclidean distances were calculated by comparing the preoperatively planned trajectories with the final electrode position observed on postoperative computed tomography scans. RESULTS: From May 2011 to December 2015, 15 patients (8 males, 7 females; mean age: 8 yr, range: 3-16 yr) underwent SEEG depth electrode implantation of a total of 111 electrodes. The mean error measured by the Euclidean distance from the center of the entry point to the intended entry point was 3.64 ± 1.78 mm (range: 0.58-7.59 mm) and the tip of the electrode to the intended target was 2.96 ± 1.49 mm (range: 0.58-7.82 mm). There were no significant complications. CONCLUSION: Depth electrodes can be placed safely and accurately in children using the VarioGuide® frameless stereotactic navigation system.

Neuroendoscopic Intraventricular Biopsy in Children with Small Ventricles Using Frameless VarioGuide System.

Endoscopic biopsy for intraventricular tumors in pediatric patients with small ventricles is a challenging procedure because of the risk of morbidity during the intraventricular approach. We describe the use of the VarioGuide system for intraventricular endoscopic biopsy in 9 consecutive pediatric patients with intraventricular lesions and small ventricular size. All patients had lesions in the anterior part of the third ventricle with a median frontal and occipital horn ratio of 0.33. Patients presented with growth failure (n = 4), visual disturbances (n = 4), and seizures (n = 1). The VarioGuide system consists of an ergonomic arm with 3 joints for gross adjustment. The 3 rotational joints on the distal side of the system are adjusted according to the angles of the planned trajectory. The endoscope is adjusted to the distal side of the VarioGuide and inserted through the ring, previously set for the diameter of the endoscope and for the planned trajectory. The accuracy of the trajectory and correct ventricular cannulation are confirmed under endoscopic guidance. The biopsy is carried out according to the standard technique. In all cases, the biopsy sample provided the definitive diagnosis. Diagnoses included germinomas in 4 patients, hamartoma in 1 patient, hypothalamic astrocytoma in 2 patients, and craniopharyngioma in 2 patients. The use of the VarioGuide system for intraventricular endoscopic biopsy is highly recommended for pediatric patients with small ventricle size. This technique may help minimize the risk of unnecessary brain damage during the entrance to small ventricles.

[Reversible neuropsychological deterioration associated to zonisamide in a paediatric patient with tuberous sclerosis]. / Deterioro neuropsicologico reversible asociado a zonisamida en un paciente pediatrico con esclerosis tuberosa.

AIM: To document reversible cognitive deterioration associated to high doses of zonisamide, using the Reliable Change Index to control practice effects derived from repetitive neuropsychological assessments. CASE REPORT: A 11 year-old boy with tuberous sclerosis complex and left frontal refractory epilepsy, evaluated within a paediatric epilepsy surgery program. The epileptogenic zone was found to be related with a tuber situated on the left inferior frontal gyrus. The effects of high doses of zonisamide simulate a disturbance of eloquent cortex within the epileptogenic zone and the impact of uncontrolled seizures on cognitive functioning over the language-dominant hemisphere. Drug withdrawal significantly improved total intelligence index, verbal comprehension intellectual index and specific language-sustained cognitive abilities, beyond practice effects. CONCLUSIONS: The differentiation between cognitive effects of drugs and functional deficits resulting from eloquent cortex involvement within the epileptogenic zone can be of crucial importance in the decision-making process for epilepsy surgery.

TITLE: Deterioro neuropsicologico reversible asociado a zonisamida en un paciente pediatrico con esclerosis tuberosa.Objetivo. Documentar el deterioro cognitivo reversible asociado a altas dosis de zonisamida, utilizando indices de cambio fiable para controlar los efectos de practica derivados de evaluaciones neuropsicologicas repetidas. Caso clinico. Niño de 11 años con complejo esclerosis tuberosa y epilepsia refractaria del lobulo frontal izquierdo, evaluado en el contexto de un programa de cirugia de la epilepsia pediatrica. La zona epileptogena se relaciono con un tuber epileptogeno localizado en el giro frontal inferior del hemisferio izquierdo. Los efectos de altas dosis de zonisamida mimetizaron una afectacion de la corteza elocuente en la zona epileptogena y un impacto de las crisis no controladas en el funcionamiento cognitivo asociado al hemisferio dominante para el lenguaje. La retirada del farmaco mejoro significativamente, mas alla de los efectos de practica, el cociente intelectual total, el indice intelectual de comprension verbal y habilidades cognitivas especificas sustentadas en el lenguaje. Conclusiones. La diferenciacion entre los efectos cognitivos de los farmacos y la existencia de un deficit funcional por afectacion de la corteza elocuente en el area epileptogena puede ser crucial para la toma de decisiones en cirugia de la epilepsia.