Unveiling the cognitive network organization through cognitive performance.

The evaluation of cognitive functions interactions has become increasingly implemented in the cognition exploration. In the present study, we propose to examine the organization of the cognitive network in healthy participants through the analysis of behavioral performances in several cognitive domains. Specifically, we aim to explore cognitive interactions profiles, in terms of cognitive network, and as a function of participants' handedness. To this end, we proposed several behavioral tasks evaluating language, memory, executive functions, and social cognition performances in 175 young healthy right-handed and left-handed participants and we analyzed cognitive scores, from a network perspective, using graph theory. Our results highlight the existence of intricate interactions between cognitive functions both within and beyond the same cognitive domain. Language functions are interrelated with executive functions and memory in healthy cognitive functioning and assume a central role in the cognitive network. Interestingly, for similar high performance, our findings unveiled differential organizations within the cognitive network between right-handed and left-handed participants, with variations observed both at a global and nodal level. This original integrative network approach to the study of cognition provides new insights into cognitive interactions and modulations. It allows a more global understanding and consideration of cognitive functioning, from which complex behaviors emerge.

Neuropsychological assessment in pediatric epilepsy surgery: A French procedure consensus.

Neuropsychological assessment is a mandatory part of the pre- and post-operative evaluation in pediatric epilepsy surgery. The neuropsychology task force of the ILAE - French Chapter aims to define a neuropsychological procedure consensus based on literature review and adapted for French practice. They performed a systematic review of the literature published between 1950 and 2023 on cognitive evaluation of individuals undergoing presurgical work-up and post-surgery follow-up and focused on the pediatric population aged 6-16. They classified publications listed in the PubMed database according to their level of scientific evidence. The systematic literature review revealed no study with high statistical power and only four studies using neuropsychological scales in their French version. Afterwards, the experts defined a neuropsychological consensus strategy in pediatric epilepsy surgery according to the psychometric determinants of cognitive tests, specificity of epilepsy, surgery context, French culture and literature reports. A common French neuropsychological procedure dedicated to pediatric epilepsy surgery is now available. This procedure could serve as a guide for the pre- and post-surgical work-up in French centers with pediatric epilepsy surgery programs. The main goal is to anticipate the functional risks of surgery, to support the postoperative outcome beyond the seizure-related one, while taking into consideration the plasticity and vulnerability of the immature brain and allowing the possibility of collaborative studies.

Surgical treatment of hypothalamic hamartomas.

Hypothalamic hamartomas are aberrant masses, composed of abnormally distributed neurons and glia. Along endocrine and cognitive symptoms, they may cause epileptic seizures, including the specific gelastic and dacrystic seizures. Surgery is the treatment of drug-resistant hamartoma epilepsy, with associated positive results on endocrine, psychiatric, and cognitive symptoms. Recently, alternatives to open microsurgical treatment have been proposed. We review these techniques and compare their efficacy and safety. Open resection or disconnection of the hamartoma, either through pterional, transcallosal, or transventricular approach, leads to good epileptological control, but its high complication rate, up to 30%, limits its indications. The purely cisternal peduncular forms remain the only indication of open, pterional approach, while other strategies have been developed to overcome the neurological, endocrine, behavioral, or cognitive complications. Laser and radiofrequency thermocoagulation-based disconnection through robot-guided stereo-endoscopy has been proposed as an alternative to open microsurgical resection and stereotactic destruction. The goal is to allow safe and complete disconnection of a possibly complex attachment zone, through a single intraparenchymal trajectory which allows multiple laser or radiofrequency probe trajectory inside the ventricle. The efficacy was high, with 78% of favorable outcome, and the overall complication rate was 8%. It was especially effective in patients with isolated gelastic seizures and pure intraventricular hamartomas. Stereotactic radiosurgery has proved as efficacious and safer than open microsurgery, with around 60% of seizure control and a very low complication rate. Multiple stereotactic thermocoagulation showed very interesting results with 71% of seizure freedom and 2% of permanent complications. Stereotactic laser interstitial thermotherapy (LiTT) seems as effective as open microsurgery (from 76 to 81% of seizure freedom) but causes up to 20% of permanent complications. This technique has however been highly improved by targeting only the epileptogenic onset zone in the hamartoma, as shown on preoperative functional MRI, leading to an improvement of epilepsy control by 45% (92% of seizure freedom) with no postoperative morbidity. All these results suggest that the impact of the surgical procedure does not depend on purely technical matters (laser vs radiofrequency thermocoagulation or stereotactic vs robot-guided stereo-endoscopy) but relies on the understanding of the epileptic network, including inside the hamartoma, the aim being to plan an effective disconnection or lesion of the epileptogenic part while sparing the adjacent functional structures.

French neuropsychological procedure consensus in epilepsy surgery.

INTRODUCTION: Neuropsychological assessment is an integral component of the surgical procedure in patients with epilepsy. As no French consensus for neuropsychological assessment was available, the main goal of this work was to define French neuropsychological procedure consensus in regard to literature review. METHOD: A panel of expert in neuropsychology was created within the framework of the French League Against Epilepsy. A systematic search of publications from 1950 to 2017 listed in PubMed database was conducted leading to a classification of articles according to their level of scientific evidence. French neuropsychological procedure consensus was then carried out with an expert panel of expert. RESULTS: Low scientific evidence of neuropsychological data was reported. A panel of expert proposed a comprehensive neuropsychological assessment procedure including the exploration of intellectual efficiency, long-term memory, short-term and working memory, attention, executive functions, processing speed and motor skills, language, visual processing, praxis, psychobehavioral, and social cognition. DISCUSSION: A common procedure for assessing cognitive and psychobehavioral function is now available in patients with epilepsy undergoing surgical evaluation have been established, they may help to improve the quality of care and the patient experience. This work highlights the need of furthers investigations and the necessity to develop specific tools with normative data.

Temporal lobe epilepsy in infants and children.

Clinical expression of temporal lobe seizures is different with a more diverse and more extensive etiology in infants and children than it is in adults. It is dominated by cortical dysplasia, low-grade tumors and perinatal damage. Hippocampal sclerosis, although less frequent, exists in children usually as a dual pathology associated with ipsilateral neocortical lesions. The clinical semiology of temporal seizures is more varied, and sometimes misleading. Motor features including tonic, clonic or myoclonic behaviors, and infantile spasms predominate in infants. Classical complex partial seizures with behavioral arrest and automatisms, as well as lateralizing signs are rare and occur mostly with onset after the age of two years. Interestingly, aura, emotional, and autonomic signs seem to be independent on the brain maturation process. Moreover, the neuropsychological profile varies according to age of onset and duration, lateralization of the focus and etiology. Quality of care benefits from individual cognitive assessment for memory and emotional processes.

Outcome of surgery in children with focal cortical dysplasia younger than 5 years explored by stereo-electroencephalography.

PURPOSE: Focal cortical dysplasia (FCD) is the most frequent etiology for drug-resistant epilepsy in young children. Complete removal of the lesion is mandatory to cure the epilepsy. Stereo-EEG (SEEG) is an excellent method to delimitate the zone to be resected in older children and adults. We studied its feasibility in younger children. METHODS: We retrospectively studied 19 children under 5 years of age who underwent SEEG between January 2009 and December 2012 and were subsequently operated on. FCD was diagnosed in all. We reviewed magnetic resonance imaging (MRI), electrophysiological and clinical data, as well as postoperative seizure outcome. We also included fluoro-deoxyglucose positron emission tomography (FDG-PET) studies, which had been systematically performed before invasive recording in 16 of the 19 children. RESULTS: The mean patient's age at the time of SEEG was 38.6 months, and the mean age at seizure onset was 8 months. Three patients had normal MRI. No SEEG-associated complications occurred. We were able to delineate the epileptogenic zone in all children, and electrode stimulation localized the motor area when necessary (12 patients). Hypometabolic areas on FDG-PET included the epileptogenic zone in 13 of the 16 children, with a lobar concordance in 9 (56 %) and the same anatomical extent in 6 (38 %). Twelve children subsequently underwent focal or sublobar resection, six had multilobar resection, and one had hemispherotomy. The etiology was FCD type 2 in 15 and FCD type 1 or type 3 in three children. Eighty-four percent of our population have remained seizure-free at a mean follow-up of 29 months (12-48 months). CONCLUSION: Although children with FCD can successfully undergo resective surgery without invasive EEG, poor seizure semiology at this age inclines to perform SEEG when the dysplastic lesion is ill-defined and/or the electroclinical correlation is unclear. In cases with normal imaging as well as with suspected huge malformations, as was the case in 52 % of our patients, we consider it to be indispensable.

Selective suppression of excessive GluN2C expression rescues early epilepsy in a tuberous sclerosis murine model.

Tuberous sclerosis complex (TSC), caused by dominant mutations in either TSC1 or TSC2 tumour suppressor genes is characterized by the presence of brain malformations, the cortical tubers that are thought to contribute to the generation of pharmacoresistant epilepsy. Here we report that tuberless heterozygote Tsc1(+/-) mice show functional upregulation of cortical GluN2C-containing N-methyl-D-aspartate receptors (NMDARs) in an mTOR-dependent manner and exhibit recurrent, unprovoked seizures during early postnatal life (

Insular and insulo-opercular epilepsy in childhood: an SEEG study.

PURPOSE: In recent years, there have been series analysing the electro-clinical correlations of insular epilepsy in adult populations. In contrast, the ictal semiology in children with insular epilepsy is poorly described. Considering that early and successful surgery may greatly improve the cognitive outcome and quality of life, it is worthwhile to deepen our knowledge of insular epilepsy in children. METHODS: We retrospectively evaluated ten children with drug-resistant focal insular epilepsy who had been consecutively explored with stereoelectroencephalography (SEEG), followed by individually tailored resective surgery that included part of the insula in all cases. A detailed anatomo-electro-clinical analysis of non-invasive EEG and SEEG data was performed. At least one of the electrodes explored the insular cortex. SEEG analysis confirmed that the insular cortex was included in the ictal onset zone. RESULTS: Epilepsy onset was mostly during the first year of life, characterized by subtle seizures as well as spasms and myoclonic seizures. Later on, neurovegetative signs and asymmetric tonic and hypermotor seizures (HMS) dominated the ictal semiology. The epileptogenic zone was frequently wider than insular with frontal and central predominance. In eight patients, the tailored resection included a lesion. In seven patients, an Engel class 1 outcome as well as neuropsychological and behavioural improvement was obtained. CONCLUSIONS: SEEG is feasible and useful in children with drug-resistant insular epilepsy which is often characterized by autonomic symptoms as the initial symptoms and should be suspected in cases with HMS, asymmetric tonic seizures and even asymmetric spasms. Early propagation is mostly frontal and central. Analysis of a larger population is required to refine these findings.

Spatiotemporal source analysis in scalp EEG vs. intracerebral EEG and SPECT: a case study in a 2-year-old child.

OBJECTIVE: This case study aims to demonstrate that spatiotemporal spike discrimination and source analysis are effective to monitor the development of sources of epileptic activity in time and space. Therefore, they can provide clinically useful information allowing a better understanding of the pathophysiology of individual seizures with time- and space-resolved characteristics of successive epileptic states, including interictal, preictal, postictal, and ictal states. METHODS: High spatial resolution scalp EEGs (HR-EEG) were acquired from a 2-year-old girl with refractory central epilepsy and single-focus seizures as confirmed by intracerebral EEG recordings and ictal single-photon emission computed tomography (SPECT). Evaluation of HR-EEG consists of the following three global steps: (1) creation of the initial head model, (2) automatic spike and seizure detection, and finally (3) source localization. During the source localization phase, epileptic states are determined to allow state-based spike detection and localization of underlying sources for each spike. In a final cluster analysis, localization results are integrated to determine the possible sources of epileptic activity. The results were compared with the cerebral locations identified by intracerebral EEG recordings and SPECT. RESULTS: The results obtained with this approach were concordant with those of MRI, SPECT and distribution of intracerebral potentials. Dipole cluster centres found for spikes in interictal, preictal, ictal and postictal states were situated an average of 6.3mm from the intracerebral contacts with the highest voltage. Both amplitude and shape of spikes change between states. Dispersion of the dipoles was higher in the preictal state than in the postictal state. Two clusters of spikes were identified. The centres of these clusters changed position periodically during the various epileptic states. CONCLUSION: High-resolution surface EEG evaluated by an advanced algorithmic approach can be used to investigate the spatiotemporal characteristics of sources located in the epileptic focus. The results were validated by standard methods, ensuring good spatial resolution by MRI and SPECT and optimal temporal resolution by intracerebral EEG. Surface EEG can be used to identify different spike clusters and sources of the successive epileptic states. The method that was used in this study will provide physicians with a better understanding of the pathophysiological characteristics of epileptic activities. In particular, this method may be useful for more effective positioning of implantable intracerebral electrodes.

Heterotopia associated with hippocampal sclerosis: an under-recognized cause of early onset epilepsy in children operated on for temporal lobe epilepsy.

PURPOSE: The aim of this study is to report on 52 children operated on for pharmacoresistant temporal lobe epilepsy, with special emphasis on histopathology and correlation with clinical features. METHODS: Charts were retrospectively analyzed. All children underwent comprehensive clinical, electrophysiological and radiological investigations before surgery. Surgical procedures were tailored according to scalp, foramen ovale and eventually depth electrode recordings. Histopathology was compared with clinical variables (χ (2) and Fisher's exact tests). Outcome was evaluated using the Engel scale. RESULTS: Developmental tumor was found in 14 cases, malformation of cortical development (MCD) in 26, isolated hippocampal sclerosis (HS) in 5 and gliosis in 7. Dual pathology (DP) affected 18 patients and the main extrahippocampal lesion consisted of microscopic sub-cortical heterotopias (HS-HT) for 15 patients who shared a particular clinical pattern: a history of febrile seizures (FS) and/or brain injury, early onset of epilepsy without latent period from FS to the first temporal seizure, and a particularly good outcome following surgery. CONCLUSION: In our pediatric temporal lobe surgery series, the prevalence for MCD and for DP was higher than in adult series. Age at seizure onset depends on pathology, and is earlier when involving the neocortex rather than only the hippocampus. We identify the association HS-HT (the most frequent DP in this series), with particular clinical features.

[Quality of life in children with epilepsy: a review]. / La qualité de vie chez l'enfant avec épilepsie: revue de la littérature.

Health-related quality of life (HRQOL) is a multidimensional construct, without general agreement on the number of domains and the content of each domain. In children with epilepsy, the HRQOL evaluation includes both nonspecific aspects, such as behavioral, psychological and cognitive difficulties and the impact of a chronic pediatric illness on the child and its family and specific aspects, such as the perception of the severity of the seizures and of the undesirable effects of the antiepileptic treatments, as well as the social impact of a negative attitude toward epilepsy. The present article presents a review of the methods proposed for the assessment of HRQOL in children with epilepsy. Most methods rely on parental reports; however, there is an increasing effort to develop tools taking the child's point of view into account. HRQOL tools have often been used in clinical trials and, especially, to evaluate the surgical treatments of epilepsy. For the clinician, HRQOL tools may be a preliminary approach to the patient's problems to be interpreted in relation to the patient's medical, psychological, cognitive, social and familial context. In France, few large-scale studies on HRQOL in children with epilepsy have been conducted. We present the preliminary results of a French study based on parental reports.

[Surgical disconnection of hypothalamic hamartomas]. / Déconnexion chirurgicale des hamartomes hypothalamiques.

BACKGROUND AND PURPOSE: Surgical resection of hypothalamic hamartomas (HHs) associated with drug-resistant gelastic epilepsy carries a considerable risk of neurological and endocrine morbidity. Alternative surgical routes and techniques have therefore been proposed, especially for broadly attached lesions and for those with a third ventricular location. METHODS: We present an updated series of 43 patients (aged nine months to 34 years), operated on from 1998 through 2005 at our institution. The hamartoma was disconnected using a microsurgical pterional approach of those lesions extending from the hypothalamic floor downward into the interpeduncular cistern. When the HH presented as a paramedian mass, partly or exclusively bulging into the third ventricle, with a rather vertical plane of attachment, we chose a frameless stereotactic endoscopic technique to disconnect the lesion. In several of our patients, both methods were applied subsequently. RESULTS: Surgery-related morbidity was lower with the ventricular endoscopic technique. Twenty-one patients (50%) are seizure-free and two patients (5%) almost seizure-free, while in 17 patients (40%), there was a significant seizure reduction. Two patients (5%) had no postoperative improvement. According to the different topographic features of the HHs, for which we have recently proposed a classification into four subtypes, the intraventricularly located hamartoma had the best prognosis following endoscopic disconnection. Ten of the 12 patients (83%) with this HH location became seizure-free. CONCLUSIONS: Resection of epilepsy-related HHs can be replaced by disconnective procedures. Our results confirm their feasibility and acceptable morbidity, with particularly good seizure outcome in patients with intraventricularly located HHs.

[Epilepsy surgery in France]. / La chirurgie de l'épilepsie en France Evaluation de l'activité

We report here the results of the first survey on epilepsy surgery activity in France. Data from a questionnaire sent to 17 centers practicing epilepsy surgery were analyzed. All centers responded; however, all items were not completely documented. Over 50 years, more than 5000 patients have been operated on for drug-resistant epilepsy and more than 3000 patients underwent some invasive monitoring, most often SEEG. Currently, nearly 400 patients (including more than 100 children) are operated on yearly for epilepsy in France. Over a study period varying among centers (from two to 20 years; mean, 9.5 years), results from more than 2000 patients including one-third children were analyzed. Important differences between adults and children, respectively, were observed in terms of location (temporal: 72% versus 4.3%; frontal: 12% versus 28%; central: 2% versus 11%), etiology (hippocampal sclerosis: 41% versus 2%; tumors 20% versus 61%); and procedures (cortectomy: 50% versus 23%; lesionectomy: 8% versus 59%), although overall results were identical (seizure-free rates following temporal lobe surgery: 80.6% versus 79%; following extratemporal surgery: 65.9% versus 65%). In adults, the best results were observed following temporomesial (TM) resection associated with hippocampal sclerosis or other lesions (class I: 83% and 79%, respectively), temporal neocortical (TNC) lesional (82%), while resections for cryptogenic temporal resections were followed by 69% (TM) and 63% (TNC) class I outcome. Extratemporal lesional resections were associated with 71% class I outcome and cryptogenic 43%. In children, the best results were obtained in tumor-associated epilepsy regardless of location (class I: 80%). A surgical complication occurred in 8% after resective surgery - with only 2.5% permanent morbidity - and 4.3% after invasive monitoring (mostly hemorrhagic). Overall results obtained by epilepsy surgery centers were in the higher range of those reported in the literature, along with a low rate of major surgical complications. Growing interest for epilepsy surgery is clearly demonstrated in this survey and supports further development to better satisfy the population's needs, particularly children. Activity should be further evaluated, while existing epilepsy surgery centers as well as healthcare networks should be expanded.

[Epilepsy surgery during infancy and early childhood in France]. / Chirurgie de l'épilepsie de l'enfant et du nourrisson en France.

BACKGROUND AND PURPOSE: We present the epilepsy surgery activity in infants and children at the Fondation Rothschild Hospital, the main center dedicated to this activity in France. METHOD: A prospective study was conducted from 2003 to 2007 based on three populations: (1) children selected as candidates for surgery, (2) children undergoing presurgical evaluation and (3) children undergoing surgical procedures for epilepsy. RESULTS: Children selected as candidates for surgery: 304 children were referred and discussed by our multidisciplinary staff. They came from Paris and its suburbs (40%), the provinces (43%) or from other countries (14%). Sixty-one percent of them were included in our surgery program and 24% were excluded. Sixty-one percent of them were under 10 years of age. Children undergoing presurgical evaluation: 296 children were recorded: 140 EEG (47%), 46 with foramen ovale electrodes (16%) and 110 with invasive recording techniques (37%). Seventy percent of these children were under 10 years of age. Children undergoing surgical procedures: 316 children underwent surgery; 68% of them were under 10 years of age. The surgical procedures were focal resection (136 children), vertical parasagittal hemispherotomy (77 children), resection and or disconnection for hypothalamic hamartoma (69 children) and 34 had palliative surgery (callosotomy or vagal nerve stimulation). CONCLUSION: Eighty to 100 children undergo surgery each year in our department for drug-resistant partial epilepsy; 70% of them are less than 10 years of age. This activity is part of a network of pediatric neurologists who are deeply involved in treatment of severe epilepsy in children.

[Electrophysiological investigations in childhood epilepsy surgery]. / Explorations électroencéphalographiques préchirurgicales de l'enfant.

Epilepsy surgery in children is a functional surgery: its goal is to perform the resection of the epileptic brain tissue while sparing the eloquent cortex. Prolonged scalp video-EEGs allow recording of all types of seizures and play a crucial role in localizing the epileptogenic zone. Furthermore, EEG data correlation with clinical and radiological findings provides a guide for the surgical strategy: either resection without further investigations or an invasive recording procedure. In prehemispherotomy evaluation, EEG recordings confirm that limited resections are not indicated and demonstrate that the opposite hemisphere is not involved. If invasive recordings are needed, they consist in foramen ovale electrode insertion, which provides valuable information in mesial temporal lobe epilepsy, stereoelectroencephalography for children older than two years, and subdural grids associated with depth electrodes in infants or when the eloquent areas need to be carefully investigated. Such investigations allow tailoring surgery to each child.

[Long-term outcome after hemispheric disconnection]. / Evaluation à long terme des déconnexions hémisphériques.

Hemispheric disconnection has been largely proposed for patients with severe epilepsy associated with a congenital or acquired hemispheric cerebral pathology. The classical procedure of anatomical hemispherectomy was progressively abandoned by neurosurgeons in order to avoid postoperative complications since then hemispherotomy techniques have been developed. Globally, with hemispheric disconnection, the rate of patients becoming seizure-free has been between 50 and 80%. The factors affecting seizure control have not been completely elucidated, but several authors suggested that differences in etiology as well as the hemispheric disconnection technique used may partially explain this variability. The percentage of seizure-free patients is higher with hemispherotomy techniques and in the group of patients with Rasmussen encephalitis, Sturge-Weber syndrome, and vascular insults. Depending on overall long-term progression, there is an improvement compared to preoperative status even if children exhibit heterogenous abilities. The lowest scores are observed for motor skills but communication and socialization are relatively well-preserved and strongly related to the duration of epilepsy: the longer the duration, the lower the scores were. Neuropsychological outcome following hemispheric disconnection makes it possible to study the development of hemispheric specialization during infancy and to provide information on cognitive recovery. Cerebral reorganization has been proved to exist in motor and language recovery. Ipsilateral corticospinal pathways seem to be involved in the movement of hemiplegic limbs. Everyday language can be supported by both hemispheres, but there is an early hemispheric specialization of the left hemisphere according to metaphonologic abilities.

Long term response to steroid therapy in Rasmussen encephalitis.

Rasmussen encephalitis (RE) is a severe and progressive focal epilepsy of unknown origin that leads to deterioration of motor and cognitive function. In a previous study, we described positive effect of high doses of steroids during the first year after the onset of RE. The objective of this study was to evaluate this therapy at long term. We reviewed 11 patients (7 girls and 4 boys) with RE of the right hemisphere (7) and the left (4) at a follow-up of 9+/-2 years. Age at onset of RE ranged from 2 to 14 years. Six patients had no benefit from steroid therapy and underwent hemispherotomy. Five had significant reduction of seizure frequency with disappearance of epilepsia partialis continua, and improved motor function. Of these, two died of unexpected sudden death 5 and 7 years after seizure control. Two others with initial response experienced progressive recurrence of seizures 1 to 4 years after the end of steroid therapy and required hemispherotomy. Finally, only one patient exhibited total cessation of seizures with steroids for 3 years, but seizures progressively recurred although the frequency was moderate. Our data confirm that although steroid treatment can be useful when given early in the course of RE, long term relapse can occur among the good responders requiring delayed hemispheric disconnection.

[Recent advances in pathogenic concepts and therapeutic strategies in Rasmussen's encephalitis]. / Avancées actuelles sur les concepts pathogéniques et thérapeutiques de l'encéphalite de Rasmussen.

Rasmussen's encephalitis (RE) is a rare inflammatory brain disease mainly affecting children and characterised by intractable epilepsy involving a single hemisphere that undergoes progressive atrophy. RE is characterized by refractory focal seizures, often associated with epilepsia partialis continua, progressive unilateral motor defect, slow EEG activity over the entire contralateral hemisphere, with focal white matter hyperintensity and insular cortical atrophy on neuroimaging. Surgical exclusion of the affected hemisphere is the only treatment that interrupts progression of the disease. Pathogenic concepts have considered viruses, autoimmune antibodies and autoimmune cytotoxic T lymphocytes that might contribute to the initiating or perpetuating events in the central nervous system. Based on these concepts, different therapeutic strategies have been pursued, such as antiviral agents, plasmapheresis, immuno-adsorption, immunosuppression or immunomodulation with intravenous immunoglobulins. However, due to the lack of large studies, to date there is no established therapeutic strategy for this devastating condition. In this review, we give an overview of the current state of immunopathogenic concepts for Rasmussen's encephalitis and discuss the different therapeutic options for future perspectives.

[Surgery for intractable focal epilepsy in children]. / Chirurgie de l'épilepsie chez l'enfant.

Surgery of drug resistant epilepsy in children is a functional surgery which aims at the suppression of the epileptogenic focus. The surgical decision is adopted or rejected as a result of the clinical examination and complementary investigations following a multidisciplinary discussion in which the benefit-risk ratio is being carefully weighed. The objective of the presurgical investigations, dominated by scalp-recorded video-electroencephalography and magnetic resonance imaging, is the localization of the epileptogenic focus. The invasive surgical investigations with intracranial electrode placement are indicated when the limits of a planned resection have to be defined precisely or when the focus is located nearby a functionally eloquent region (sensori-motor and language region). Their identification is possible by means of electrical stimulation. Two methods of exploration are available: The combination of subdural and intracerebral electrode placement through craniotomy and the stereotactic placement of intracerebral depth electrodes (Stereo-EEG). The choice of either of these two methods depends on the child's age and on the topography of the epileptogenic focus. Surgery can be either palliative, with the purpose of reducing the intensity and/or the frequency of a certain seizure type (callosotomy, multiple subpial transsections) or curative, aiming at a suppression of the epileptogenic focus through a resective or a disconnective surgical procedure. We have operated on a population of 148 children and infants between 3 months and 10 years of age during the years 1993 to 2001: In the infant group, dysplastic lesions represented the predominant etiology. In the age group of 3 to 10 years, the underlying pathology was more distributed (dysplastic lesions, epileptogenic tumors, Rasmussen's encephalitis, hypothalamic hamartomas). Extratemporal focal resections required, in the majority of cases, an invasive preoperative exploration and hemispherotomy was frequent in this group (44 p. 100). Sixty-seven percent of the children were seizure-free, with an acceptable morbidity rate, primarily due to shunt placement following hemispherotomy in children with dysplastic lesions. Our preliminary results concerning quality of life and socialization are encouraging and favor surgical treatment at an early stage.