Surgical treatment of epilepsy in children

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.

Planning stereoelectroencephalography using automated lesion detection: Retrospective feasibility study

Objective

This retrospective, cross‐sectional study evaluated the feasibility and potential benefits of incorporating deep‐learning on structural magnetic resonance imaging (MRI) into planning stereoelectroencephalography (sEEG) implantation in pediatric patients with diagnostically complex drug‐resistant epilepsy. This study aimed to assess the degree of colocalization between automated lesion detection and the seizure onset zone (SOZ) as assessed by sEEG.

Methods

A neural network classifier was applied to cortical features from MRI data from three cohorts. (1) The network was trained and cross‐validated using 34 patients with visible focal cortical dysplasias (FCDs). (2) Specificity was assessed in 20 pediatric healthy controls. (3) Feasibility of incorporation into sEEG implantation plans was evaluated in 34 sEEG patients. Coordinates of sEEG contacts were coregistered with classifier‐predicted lesions. sEEG contacts in seizure onset and irritative tissue were identified by clinical neurophysiologists. A distance of <10 mm between SOZ contacts and classifier‐predicted lesions was considered colocalization.

Results

In patients with radiologically defined lesions, classifier sensitivity was 74% (25/34 lesions detected). No clusters were detected in the controls (specificity = 100%). Of the total 34 sEEG patients, 21 patients had a focal cortical SOZ, of whom eight were histopathologically confirmed as having an FCD. The algorithm correctly detected seven of eight of these FCDs (86%). In patients with histopathologically heterogeneous focal cortical lesions, there was colocalization between classifier output and SOZ contacts in 62%. In three patients, the electroclinical profile was indicative of focal epilepsy, but no SOZ was localized on sEEG. In these patients, the classifier identified additional abnormalities that had not been implanted.

Significance

There was a high degree of colocalization between automated lesion detection and sEEG. We have created a framework for incorporation of deep‐learning–based MRI lesion detection into sEEG implantation planning. Our findings support the prospective evaluation of automated MRI analysis to plan optimal electrode trajectories.

Neuroimaging of Early Life Epilepsy

OBJECTIVES

We assessed the adherence to neuroimaging guidelines and the diagnostically relevant yield of neuroimaging in newly presenting early life epilepsy (ELE).

METHODS

There were 775 children with a new diagnosis of epilepsy (<3 years old at onset) who were recruited through the ELE study at 17 US pediatric epilepsy centers (2012-2015) and managed prospectively for 1 year. The data were analyzed to assess the proportion of children who underwent neuroimaging, the type of neuroimaging, and abnormalities.

RESULTS

Of 725 children (93.5%) with neuroimaging, 714 had an MRI (87% with seizure protocols) and 11 had computed tomography or ultrasound only. Etiologically relevant abnormalities were present in 290 individuals (40%) and included: an acquired injury in 97 (13.4%), malformations of cortical development in 56 (7.7%), and other diffuse disorders of brain development in 51 (7.0%). Neuroimaging was abnormal in 160 of 262 (61%) children with abnormal development at diagnosis versus 113 of 463 (24%) children with typical development. Neuroimaging abnormalities were most common in association with focal seizure semiology (40%), spasms (47%), or unclear semiology (42%). In children without spasms or focal semiology with typical development, 29 of 185 (16%) had imaging abnormalities. Pathogenic genetic variants were identified in 53 of 121 (44%) children with abnormal neuroimaging in whom genetic testing was performed.

CONCLUSIONS

Structural abnormalities occur commonly in ELE, and adherence to neuroimaging guidelines is high at US pediatric epilepsy centers. These data support the universal adoption of imaging guidelines because the yield is substantially high, even in the lowest risk group.

Surgical outcomes in two different age groups with Focal Cortical Dysplasia type II: Any real difference?

OBJECTIVE

Focal Cortical Dysplasias (FCDs) represent a common architectural cortical disorder underlying drug-resistant focal epilepsy. So far, studies aimed at evaluating whether age at surgery is a factor influencing surgical outcome are lacking, so that data on the comparison between patients harboring Type II FCD operated at younger age and those operated at adult age are still scarce. We compared presurgical clinical features and surgical outcomes of patients with histopathologically diagnosed Type II FCD undergoing surgery at an earlier age with those operated after 20 years of age.

METHODS

We retrospectively analyzed 1660 consecutive patients operated at the "Claudio Munari" Epilepsy Surgery Centre. There were 289 patients (17.4%) with a neuropathological diagnosis of Type II FCD. We included two different groups of patients, the first one including patients operated on at less than 6years, the second sharing the same seizure onset age but with delayed surgery, carried out after the age of 20. Seizure characteristics and, neuropsychological and postoperative seizure outcomes were evaluated by study group.

RESULTS

Forty patients underwent surgery before the age of 6 and 66 patients after the age of 20. Surgical outcome was favorable in the whole population (72.6% were classified in Engel's Class Ia+Ic), independently from age at surgery. In the children group, 32 patients were classified in Class I, including 30 (75%) children in classes Ia and Ic. In the adult group, 53 belonged to Class I of whom 47 (71%) were in classes Ia and Ic. The percentage of permanent complications, the surgical outcomes, and AED withdrawal did not significantly differ by study group.

CONCLUSION

Our results indicate that there is no difference between the groups, suggesting that outcome depends mainly on the histological findings and not on timing of surgery.

Yield and Predictors of Epilepsy Surgery Candidacy in Children Admitted for Surgical Evaluation

OBJECTIVE

The aim of this study was to identify preadmission variables that are prognostic of epilepsy surgical candidacy for children admitted into an epilepsy-monitoring unit.

METHODS

This study is a retrospective review of patients 0-18 years who were admitted into the pediatric epilepsy-monitoring unit at Mayo Clinic between November 2010 and December 2013 to assess for surgery candidacy for medically intractable epilepsy. Demographic data, epilepsy details, treatments, electroencephalograph and imaging results, and the consensus notes of the epilepsy surgery conferences were collected.

RESULTS

One hundred and forty eight children underwent inpatient, prolonged video-electroencephalograph monitoring for presurgical evaluation, of which 136 had their typical events recorded. Five recommended for callosotomy alone were excluded and 131 composed the study group. Of these 131, the epilepsy surgery conference consensus deemed that 69 were surgical candidates, of which 45 (65%) underwent resective surgery. Chi-square analysis found seven preadmission predictors of surgical candidacy: single semiology at seizure onset (P < 0.001), structural etiology (P < 0.001), one or more interictal foci all in the same hemisphere (P < 0.004), focal background electroencephalograph slowing (P < 0.001), focal or hemispheric abnormality on magnetic resonance imaging (P < 0.001), male sex (P = 0.02), and normal development (P = 0.04).

CONCLUSIONS

The presence of fewer than four predictors was suggestive of low likelihood of candidacy (<31%), whereas if more than four factors were present, 91% were found to be surgical candidates. These findings facilitate clinical decision-making for providers in a cost-effective manner and provide realistic expectations for families.

Long-term EEG in children

Long-term video-EEG corresponds to a recording ranging from 1 to 24 h or even longer. It is indicated in the following situations: diagnosis of epileptic syndromes or unclassified epilepsy, pre-surgical evaluation for drug-resistant epilepsy, follow-up of epilepsy or in cases of paroxysmal symptoms whose etiology remains uncertain. There are some specificities related to paediatric care: a dedicated pediatric unit; continuous monitoring covering at least a full 24-hour period, especially in the context of pre-surgical evaluation; the requirement of presence by the parents, technician or nurse; and stronger attachment of electrodes (cup electrodes), the number of which is adapted to the age of the child. The chosen duration of the monitoring also depends on the frequency of seizures or paroxysmal events. The polygraphy must be adapted to the type and topography of movements. It is essential to have at least an electrocardiography (ECG) channel, respiratory sensor and electromyography (EMG) on both deltoids. There is no age limit for performing long-term video-EEG even in newborns and infants; nevertheless because of scalp fragility, strict surveillance of the baby's skin condition is required. In the specific context of pre-surgical evaluation, long-term video-EEG must record all types of seizures observed in the child. This monitoring is essential in order to develop hypotheses regarding the seizure onset zone, based on electroclinical correlations, which should be adapted to the child's age and the psychomotor development.

Diagnosis and management of childhood epilepsy

Epilepsy is a relatively common neurologic disorder in children that has important implications for development, parents, and society. Making the correct diagnosis starts with an accurate and complete history that consequently leads to a directed diagnostic workup. This article outlines a diagnostic and management approach to pediatric seizures and epilepsy syndromes. Making the correct diagnosis of epilepsy or nonepileptic imitators allows the practitioner to prescribe appropriate therapy. Initial management for typical epileptic syndromes and seizures and potential adverse effects are discussed. Alternative treatment options for pharmacologically resistant patients such as ketogenic diet, vagal nerve stimulation, and surgery are also discussed. While most children favorably respond to antiepileptic medications, early identification of medication failure is important to ensure optimal neurodevelopment.

[French guidelines on electroencephalogram]

Electroencephalography allows the functional analysis of electrical brain cortical activity and is the gold standard for analyzing electrophysiological processes involved in epilepsy but also in several other dysfunctions of the central nervous system. Morphological imaging yields complementary data, yet it cannot replace the essential functional analysis tool that is EEG. Furthermore, EEG has the great advantage of being non-invasive, easy to perform and allows control tests when follow-up is necessary, even at the patient's bedside. Faced with the advances in knowledge, techniques and indications, the Société de Neurophysiologie Clinique de Langue Française (SNCLF) and the Ligue Française Contre l'Épilepsie (LFCE) found it necessary to provide an update on EEG recommendations. This article will review the methodology applied to this work, refine the various topics detailed in the following chapters. It will go over the summary of recommendations for each of these chapters and underline proposals for writing an EEG report. Some questions could not be answered by the review of the literature; in those cases, an expert advice was given by the working and reading groups in addition to the guidelines.

Epilepsies associated with focal cortical dysplasias (FCDs)

Focal cortical dysplasias (FCDs) are increasingly recognized as one of the most common causes of pharmaco-resistant epilepsies. FCDs were recently divided into various clinico-pathological subtypes due to distinct imaging, electrophysiological, and outcome characteristics. In this review, we will overview the international consensus classification of FCDs in light of more recently reported clinical, electrical, imaging and functional observations, and will also address areas of ongoing debate. In addition, we will summarize our current knowledge on pathobiology and epileptogenicity of FCDs as well as its underlying molecular and cellular mechanisms. The clinical (electroencephalographic, imaging, and functional) characteristics of major FCD subtypes and their implications on the presurgical evaluation and surgical management will be discussed in light of studies describing these characteristics and postoperative seizure outcomes in patients with medically intractable focal epilepsy due to histopathologically confirmed FCDs.

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.

Cognitive disorders in pediatric epilepsy

Childhood epilepsy may cause cognitive disorders and the intellectual quotient is indeed not normally distributed in epileptic children, a fair proportion of whom show an IQ in the deficient range. Some epileptic syndromes happen during vulnerability periods of brain maturation and interfere with the development of specific cognitive functions. This is the case for the Landau-Kleffner syndrome, which generally appears during speech development and affects language. Similarly, West syndrome - or infantile spasms - is an epileptogenic encephalopathy appearing during the first years of life and induces a major delay in social and oculo-motor development. Specific impairments can also be identified in partial childhood epilepsies in relation with seizure focus localization. For instance, left temporal and frontal epilepsies are frequently associated with verbal impairments. Moreover, episodic memory disorders have been described in children suffering from temporal lobe epilepsy whereas executive deficits (planning, self-control, problem solving) have been reported in frontal lobe epilepsy. In most cases, including its mildest forms, childhood epilepsy induces attention deficits, which may affect academic achievement. These observations militate in favor of individual neuropsychological assessments as well as early interventions in order to provide the child with an optimal individualized treatment program.

Noninvasive approach to focal cortical dysplasias: clinical, EEG, and neuroimaging features

Purpose. The main purpose is to define more accurately the epileptogenic zone (EZ) with noninvasive methods in those patients with MRI diagnosis of focal cortical dysplasia (FCD) and epilepsy who are candidates of epilepsy surgery. Methods. Twenty patients were evaluated prospectively between 2007 and 2010 with comprehensive clinical evaluation, video-electroencephalography, diffusion tensor imaging (DTI), and high-resolution EEG to localize the equivalent current dipole (ECD). Key Findings. In 11 cases with white matter asymmetries in DTI the ECDs were located next to lesion on MRI with mean distance of 14.63 millimeters with topographical correlation with the EZ. Significance. We could establish a hypothesis of EZ based on Video-EEG, high-resolution EEG, ECD method, MRI, and DTI. These results are consistent with the hypothesis that the EZ in the FCD is complex and is often larger than visible lesion in MRI.

Rhythmic intrinsic bursting neurons in human neocortex obtained from pediatric patients with epilepsy

Neocortical oscillations result from synchronized activity of a synaptically coupled network and can be strongly influenced by the intrinsic firing properties of individual neurons. As such, the intrinsic electroresponsive properties of individual neurons may have important implications for overall network function. Rhythmic intrinsic bursting (rIB) neurons are of particular interest, as they are poised to initiate and/or strongly influence network oscillations. Although neocortical rIB neurons have been recognized in multiple species, the current study is the first to identify and characterize rIB neurons in the human neocortex. Using whole-cell current-clamp recordings, rIB neurons (n = 12) are identified in human neocortical tissue resected from pediatric patients with intractable epilepsy. In contrast to human regular spiking neurons (n = 12), human rIB neurons exhibit rhythmic bursts of action potentials at frequencies of 0.1-4 Hz. These bursts persist after blockade of fast excitatory neurotransmission and voltage-gated calcium channels. However, bursting is eliminated by subsequent application of the persistent sodium current (I(NaP)) blocker, riluzole. In the presence of riluzole (either 10 or 20 μm), human rIB neurons no longer burst, but fire tonically like regular spiking neurons. These data demonstrate that I(NaP) plays a critical role in intrinsic oscillatory activity observed in rIB neurons in the human neocortex. It is hypothesized that aberrant changes in I(NaP) expression and/or function may ultimately contribute to neurological diseases that are linked to abnormal network activity, such as epilepsy.

Diffusion tensor imaging assessment of the epileptogenic zone in children with localization-related epilepsy

BACKGROUND AND PURPOSE

Patients with MR imaging-negative epilepsy could have subtle FCD. Our aim was to determine if structural changes could be identified by using DTI in children with intractable epilepsy, from MR imaging-visible FCD and MR imaging-negative localization-related epilepsy, that were concordant with the epileptogenic zone as defined by using the MEG dipole cluster.

MATERIALS AND METHODS

Eight children with MR imaging-visible FCD and 16 with MR imaging-negative epilepsy underwent DTI and MEG. Twenty-six age-matched healthy children underwent DTI. Analysis was performed on controls across individual patients. Agreement between the location of DTI abnormalities and FCD and MEG dipole clusters was assessed.

RESULTS

In patients with MR imaging-visible FCD, abnormal FA, MD, λ(1), λ(2), and λ(3) were lobar concordant with the MEG dipole cluster in 4/8 (50.0%), 5/8 (62.5%), 3/8 (37.5%), 6/8 (75.0%), and 5/8 (62.5%), respectively. In patients with MR imaging-visible FCD, abnormal FA, MD, λ(1), λ(2), and λ(3) overlapped the x-, y-, and z-axes of the MEG dipole cluster in 1/8 (12.5%), 4/8 (50%), 4/8 (50%), 6/8 (75%), and 4/8 (50%), respectively, and with FCD in 1/8 (12.5%), 3/8 (37.5%), 0/8 (0%), 3/8 (37.5%), and 1/8 (12.5%), respectively. In patients with MR imaging-negative epilepsy, abnormal FA, MD, λ(1), λ(2), and λ(3) were lobar-concordant with the MEG dipole cluster in 11/16 (68.8%), 11/16 (68.8%), 8/16 (50.0%), 10/16 (62.5%), and 10/16 (62.5%), respectively, and overlapped the x-, y-, and z-axes of the MEG dipole cluster in 9/16 (56.3%), 10/16 (62.5%), 8/16 (50%), 8/16 (50%), and 8/16 (50%), respectively. There was no significant difference between abnormal DTI lobar concordance with the MEG dipole cluster in patients with MR imaging-visible FCD and MR imaging-negative epilepsy.

CONCLUSIONS

White matter changes can be detected with DTI in children with MR imaging-visible FCD and MR imaging-negative epilepsy, which were concordant with the epileptogenic zone in more than half of the patients.

Neuronal bursting properties in focal and parafocal regions in pediatric neocortical epilepsy stratified by histology

To test the hypothesis that focal and parafocal neocortical tissue from pediatric patients with intractable epilepsy exhibits cellular and synaptic differences, the authors characterized the propensity of these neurons to generate (a) voltage-dependent bursting and (b) synaptically driven paroxysmal depolarization shifts. Neocortical slices were prepared from tissue resected from patients with intractable epilepsy. Multiunit network activity and simultaneous whole-cell patch recordings were made from neurons from three patient groups: (1) those with normal histology; (2) those with mild and severe cortical dysplasia; and (3) those with abnormal pathology but without cortical dysplasia. Seizure-like activity was characterized by population bursting with concomitant bursting in intracellularly recorded cortical neurons (n = 59). The authors found significantly more N-methyl-D-aspartic acid-driven voltage-dependent bursting neurons in focal versus parafocal tissue in patients with severe cortical dysplasia (P < 0.01). Occurrence of paroxysmal depolarization shifts and burst amplitude and burst duration were significantly related to tissue type: focal or parafocal (P < 0.05). The authors show that functional differences between focal and parafocal tissue in patients with severe cortical dysplasia exist. There are functional differences between patient groups with different histology, and bursting properties can be significantly associated with the distinction between focal and parafocal tissue.

Decreased relative efficacy of the ketogenic diet for children with surgically approachable epilepsy

PURPOSE

In children with intractable, surgically approachable epilepsy, the ketogenic diet is often perceived as less efficacious than surgery.

METHODS

A retrospective chart review was performed of 554 children started on the ketogenic diet since 1994. Forty-five children were identified as surgical candidates, with at least 2 focal routine EEGs, ictal video-EEG, and corresponding focal neuroimaging findings, of whom 24 eventually had resective surgery and were followed subsequently. A comparison cohort group was also created of 45 children matched for age and seizure frequency that received the diet but were not surgical candidates (multifocal or generalized seizures).

RESULTS

Of the 24 children who received both dietary and surgical therapies, there was a higher likelihood after 6 months of both >90% seizure reduction (71% versus 17%) and seizure freedom (63% versus 0%) following surgery, both p < 0.0001. Similarly, the 45 cohort children who were not surgical candidates were more likely to be seizure-free (29% versus 13%, p = 0.041) and remained on the diet for shorter duration (10 months versus 18 months, p = 0.035) compared to the surgical group.

CONCLUSION

Children with surgically approachable epilepsy do respond to the diet, but are more likely to be seizure-free following surgery.

Memory functions following surgery for temporal lobe epilepsy in children

Surgical treatment appears to improve the cognitive prognosis in children undergoing surgery for temporal lobe epilepsy (TLE). The beneficial effects of surgery on memory functions, particularly on material-specific memory, are more difficult to assess because of potentially interacting factors such as age range, intellectual level, left-handedness, type of surgery and seizure outcome. This study investigated memory functions in 20 right-handed children who had left or right-temporal lobe surgery - including hippocampectomy - and became seizure-free. The neuropsychological evaluation included tests measuring verbally and visually mediated episodic memory, everyday memory as well as attention/working memory and language/semantic memory. We also assessed the relationships between age of seizure onset, general cognitive ability and memory functions. Children with TLE showed poor memory efficiency before surgery that tended to improve about 1 year after surgery. We found a material-specific memory effect, especially after surgery-9 (out of 12) children with left TLE had worse verbal memory results while 5 (out of 8) with right TLE had worse visual memory results. Post-operatively, most children had poor everyday memory performance on the Rivermead Behavioural Memory Test. No significant relationship was observed between episodic memory scores and age of epilepsy onset but children with early onset remained with lower Performance IQ values, Rey's figure copy scores and naming performances after surgery. Surgery significantly improved all the attention/working memory scores, some verbal episodic memory tasks and naming test performances. A different pattern of episodic and semantic memory limitations related to left or right TLE was observed.

Stereo-EEG in children

BACKGROUND

Stereotactic placement of intracerebral multilead electrodes for chronic EEG recording of seizures or stereoelectroencephalography (SEEG) was introduced 50 years ago at Saint Anne Hospital in Paris, France for the presurgical evaluation of patients with drug-resistant focal epilepsy. SEEG explorations are indicated whenever the noninvasive tests fail to adequately localize the epileptogenic zone (EZ).

INDICATIONS

Currently, approximately 35% of our operated-on children require a SEEG evaluation. Arrangement of electrodes is individualized according to the peculiar needs of each child, to verify a predetermined hypothesis of localization of the EZ based on pre-SEEG anatomo-electro-clinical findings. Multilead intracerebral electrodes are designed to sample cortical structures on the lateral, intermediate, and mesial aspect of the hemisphere, as well as deep-seated lesions. Stereotactic stereoscopic teleangiograms and coregistered 3-D MRI are employed to plan avascular trajectories and to accurately target the desired structures. Pre-SEEG stereotactic neuroradiology and electrode implantation are usually performed in separate procedures. Electrodes are removed once video-SEEG monitoring is completed.

INTRACEREBRAL ELECTRICAL STIMULATIONS

Intracerebral electrical stimulations are used to better define the EZ and to obtain a detailed functional mapping of critical cortical and subcortical regions.

MORBIDITY

Surgical morbidity of SEEG is definitely low in children. SEEG-GUIDED RESECTIVE SURGERY: In 90% of evaluated children, SEEG provides a guide for extratemporal or multilobar resections. SEEG-guided resective surgery may yield excellent results on seizures with 60% of patients in Engel's Class I.

Hemimegalencephaly: clinical implications and surgical treatment

INTRODUCTION

Hemimegalencephaly (HME) is a quite rare malformation of the cortical development arising from an abnormal proliferation of anomalous neuronal and glial cells that generally leads to the hypertrophy of the whole affected cerebral hemisphere. The pathogenesis of such a complex malformation is still unknown even though several hypotheses are reported in literature.

BACKGROUND

HME can occur alone or associated with neurocutaneous disorders, such as neurofibromatosis, epidermal nevus syndrome, Ito's hypomelanosis, and Klippel-Trenonay-Weber syndrome. The clinical picture is usually dominated by a severe and drug-resistant epilepsy. Other common findings are represented by macrocrania, mean/severe mental retardation, unilateral motor deficit, and hemianopia. The EEG shows different abnormal patterns, mainly characterized by suppression burst and/or hemihypsarrhythmia. Although neuroimaging and histologic investigations often show typical findings (enlarged hemisphere, malformed ventricular system, alteration of the normal gyration), the differential diagnosis with other disorders of the neuronal and glial proliferation may be difficult to obtain. Hemispherectomy/hemispherotomy is the most effective treatment to control seizure, and it also seems to provide good results on the psychomotor development when performed early, as demonstrated by the literature review and by the reported personal series reported here (20 children). The surgical therapy of HME, however, is still burdened by a quite high complication rate and mortality risk.

Pediatric Magnetoencephalography and Magnetic Source Imaging

Magnetoencephalography (MEG) and magnetic source imaging (MSI) together represent a uniquely powerful functional imaging modality because of their capabilities of directly observing the electrophysiologic activity of neurons with exquisite temporal detail and accurately localizing corresponding neuromagnetic field sources onto high-resolution MR images. These features have and should continue to advance our understanding of the complex spatiotemporal basis of normal and abnormal brain function and development in children. By more clearly delineating and characterizing epileptogenic foci and their relation to eloquent cortex, MSI enables earlier and more effective neurosurgery to be performed, thus resulting in improved seizure outcomes. Although MEG and MSI cannot replace scalp electroencephalography, neuropsychologic testing, and the need for meticulous intraoperative cortical mapping in patients undergoing excision of epileptogenic lesions, their increasing availability should ultimately persuade many clinicians of their key, if not essential, role in the evaluation and treatment of children with epilepsy.

Hemispherectomy for catastrophic epilepsy in infants

PURPOSE

To report our experience with hemispherectomy in the treatment of catastrophic epilepsy in children younger than 2 years.

METHODS

In a single-surgeon series, we performed a retrospective analysis of 18 patients with refractory epilepsy undergoing hemispherectomy (22 procedures). Three different surgical techniques were performed: anatomic hemispherectomy, functional hemispherectomy, and modified anatomic hemispherectomy. Pre- and postoperative evaluations included extensive video-EEG monitoring, magnetic resonance imaging, and positron emission tomography scanning. Seizure outcome was correlated with possible variables associated with persistent postoperative seizures. The Generalized Estimation Equation (GEE) and the Barnard's exact test were used as statistical methods.

RESULTS

The follow-up was 12-74 months (mean, 34.8 months). Mean weight was 9.3 kg (6-12.3 kg). The population age was 3-22 months (mean, 11.7 months). Thirteen (66%) patients were seizure free, and four patients had >90% reduction of the seizure frequency and intensity. The overall complication rate was 16.7%. No deaths occurred. Twelve (54.5%) of 22 procedures resulted in incomplete disconnection, evidenced on postoperative images. Type of surgical procedure, diagnosis categories, persistence of insular cortex, and bilateral interictal epileptiform activity were not associated with persistent seizures after surgery. Incomplete disconnection was the only variable statistically associated with persistent seizures after surgery (p<0.05).

CONCLUSIONS

Hemispherectomy for seizure control provides excellent and dramatic results with a satisfactory complication rate. Our results support the concept that early surgery should be indicated in highly selected patients with catastrophic epilepsy. Safety factors such as an expert team in the pediatric intensive care unit, neuroanesthesia, and a pediatric epilepsy surgeon familiar with the procedure are mandatory.

Surgically amenable epilepsies in children and adolescents: clinical, imaging, electrophysiological, and post-surgical outcome data

BACKGROUND AND PURPOSE

A large number of patients with epilepsy in the pediatric population have medically intractable epilepsy. In this age group seizures are usually daily or weekly, and response to antiepileptic therapy is poor, especially for those with neurological abnormalities and symptomatic epilepsies. However, several authors have already demonstrated similarly favorable long-term post-surgical seizure control when comparing pediatric and adult populations. In this article we aim to report the experience of the Ribeirão Preto Epilepsy Surgery Program in pediatric epilepsy surgery.

PATIENTS AND METHODS

We analyzed 107 patients with medically intractable epilepsy operated on between July 1994 and December 2002, considering age at surgery, seizure type, pathological findings, and seizure outcome. All data were prospectively collected according to protocols previously approved by the institution ethics committee.

RESULTS

We analyzed a total of 115 operations performed in 107 patients. There was no difference in sex distribution. Complex partial seizures occurred in 31.4% of the patients, followed by tonic seizures (25.9%), focal motor seizures (15.4%), and infantile spasms (13.3%). The most common etiologies were cortical developmental abnormalities (25.2%), tumors (16.8%), mesial temporal sclerosis (15.9%), Rasmussen syndrome (6.5%), and tuberous sclerosis (6.5%). Overall post-surgical seizure outcome showed 67.2% of the patients within Engel classes I and II, reaching 75.0% when patients with callosotomies were excluded.

CONCLUSIONS

Post-surgical seizure control in the pediatric population is similar to that in adult patients, despite the fact that epilepsies in this age group are more frequently of extratemporal origin, suggesting that surgery should be considered in children as soon as intractability is determined.

Source analysis of interictal spikes in polymicrogyria: Loss of relevant cortical fissures requires simultaneous EEG to avoid MEG misinterpretation

PURPOSE

Multiple source analysis of interictal EEG and MEG spikes was used to identify irritative zones in polymicrogyria (PMG). Spike onset times and source localization were compared between both modalities. PMG is characterized by a marked loss of deep cortical fissures. Hence, differences between EEG and MEG were expected since MEG signals are predominantly generated from tangentially orientated neurons in fissures.

PATIENTS

We studied 7 children and young adults (age 7.5 to 19 years) with localization-related epilepsy and unilateral polymicrogyria (PMG) as defined from anatomical MRI.

METHODS

122-channel whole-head MEG and 32-channel EEG were recorded simultaneously for 25 to 40 min. Using the BESA program, interictal spikes were identified visually and used as templates to search for similar spatio-temporal spike patterns throughout the recording. Detected similar spikes (r > 0.85) were averaged, high-pass filtered (5 Hz) to enhance spike onset, and subjected to multiple spatio-temporal source analysis. Source localization was visualized by superposition on T1-weighted MRI and compared to the lesion.

RESULTS

Nine spike types were identified in seven patients (2 types in 2 patients). Eight out of nine EEG sources and seven MEG sources modeling spike onset were localized within the visible lesion. EEG spike onset preceded MEG significantly in two spike types by 19 and 25 ms. This was related to radial onset activity in EEG while MEG localized propagated activity. In one case, the earliest MEG spike activity was localized to the normal hemisphere while the preceding radial EEG onset activity was localized within the lesion. Distances between EEG and MEG onset sources varied markedly between 9 and 51 mm in the eight spike types with concordant lateralization.

CONCLUSION

Interictal irritative zones were localized within the lesion in PMG comparable to other malformations, e.g., FCD. Discrepancies in MEG and EEG were related to the lack of deep fissures in PMG. In two cases, MEG was blind to the onset of radial interictal spike activity and localized propagated spike activity. In two other cases, MEG localized to the more peripheral parts of the irritative zone. Simultaneous EEG recordings with MEG and multiple source analysis are required to avoid problems of MEG interpretation.

Cognitive Function in Preschool Children after Epilepsy Surgery: Rationale for Early Intervention

PURPOSE

The detrimental effect of frequent early seizures on the cognitive potential of children is a significant clinical issue. Epilepsy surgery in childhood offers a good prognosis for seizure control and improved developmental outcome. We studied the postoperative outcome and the developmental velocity after surgery and analyzed risk factors for developmental delay in 50 consecutive preschool children treated surgically for severe epilepsy at ages 3 to 7 years.

METHODS

Pre- and postoperative developmental quotients (DQs) were analyzed with analysis of variance; stepwise linear regressions were performed on preoperative DQs and on a difference score between post- and preoperative DQs to determine risk factors for preoperative development and factors influencing postoperative development.

RESULTS

Of the 50 patients, 70% were retarded, with IQ < 70; 16% were of average intelligence, with IQ ranging from 85 to 115. Age at seizure onset and extent of lesion were predictive variables for preoperative cognitive development. Six to 12 months after surgery (early postoperative phase), 66% were seizure free (Engel outcome class I), 26% had substantial to worthwhile seizure reduction (classes II and III), and 8% were unchanged (class IV). Forty-one (82%) children showed stable velocity of development; three children showed gains of >/=15 IQ points; three had developmental decline (loss of >/=10 IQ points), which was transient in two children; and three children moved from not assessable to assessable. At last follow-up (6 months to 10 years after surgery), 11 children showed IQ/DQ gains of >/=15 IQ points. Gains in IQ were observed only in seizure-free children and were stable over time. Shorter duration of epilepsy was significantly associated with a postoperative increase in DQ.

CONCLUSIONS

(a) Substantial global mental delay is common in young children treated for epilepsy with surgery; (b) In most patients, postoperative development proceeded at a stable velocity; (c) Catch-up development may occur but only in seizure-free patients; (d) Substantial cognitive losses were noted in only one child. and (e) Early seizure control stabilized developmental velocity in this patient cohort.

EEG and MEG source analysis of single and averaged interictal spikes reveals intrinsic epileptogenicity in focal cortical dysplasia

PURPOSE

Simultaneous interictal EEG and magnetoencephalography (MEG) recordings were used for noninvasive analysis of epileptogenicity in focal cortical dysplasia (FCD). The results of two different approach methods (multiple source analysis of averaged spikes and single dipole peak localization of single spikes) were compared with pre- and postoperative anatomic magnetic resonance imaging (MRI).

PATIENTS

We studied nine children and adolescents (age, 3.5-15.9 years) with localization-related epilepsy and FCD diagnosis based on MRI. Five patients underwent epilepsy surgery, two of them after long-term recording with subdural grid electrodes, and one after intraoperative electrocorticography.

METHODS

The 122-channel whole-head MEGs and 33-channel EEGs were recorded simultaneously for 25 to 40 min. Interictal spikes were identified visually and used as templates to search for similar spatiotemporal spike patterns throughout the recording. With the BESA program, similar spikes (r > 0.85) were detected, averaged, high-pass filtered (5 Hz) to enhance spike onset, and subjected to multiple spatiotemporal source analysis with a multishell spherical head model. Peak activity from single spikes was modeled by single dipoles for the same subset of spikes. Source localization was visualized by superposition on T1-weighted MRI and compared with the lesion identified in T1- and T2-weighted MRI. In the five cases undergoing epilepsy surgery, the results were correlated with invasive recordings, postoperative MRI, and outcome.

RESULTS

In all cases, the analysis of averaged spikes showed a localization of onset- and peak-related sources within the visible lesion for both EEG and MEG. Of the single spikes, 128 (45%; total 284) were localizable at the peak in MEG, and 170 (60%) in EEG. Of these, 91% localized within the lesion with MEG, and 93.5% with EEG. In three of five patients operated on, the resected area included the onset zones of averaged EEG and MEG spike activity. These patients had excellent postoperative outcome, whereas the others did not become seizure free.

CONCLUSIONS

Consistent MEG and EEG spike localization in the lesional zone confirmed the hypothesis of intrinsic epileptogenicity in FCD.

Rasmussen syndrome and long-term response to thalidomide

We report a 13-year-old female who experienced symptoms and signs of Rasmussen encephalitis for the first time at the age of 5 years. Various therapeutic procedures, including conventional and new antiepileptic drugs, steroids, immunoglobulin, plasma exchanges, and partial hemispherectomy, were applied, but their results were unsatisfactory. During one of the exacerbations, when the patient's life was endangered, thalidomide was administered. Frequency and intensity of epileptic seizures were reduced significantly, and the quality of her life improved. Except for moderate neutropenia, the other adverse effects were not recognized. In our opinion, thalidomide is not a first-choice drug for Rasmussen encephalitis but is a good alternative only for cases refractory to other well-known and accepted therapeutic procedures.

Epilepsy: habilitation and rehabilitation

Rehabilitation represents not only a distinct field of medicine, but also a philosophical and practical treatment approach that can be applied to a variety of chronic disorders. Neurology encompasses many chronic disorders, making it ideal for the application of rehabilitation principles in daily practice. Epilepsy offers a unique opportunity to incorporate rehabilitation principles into the management of a complex medical disorder. Epilepsy is an evolving disease process that changes with the maturation of the central nervous system. The rehabilitative model provides the framework for a dynamic treatment plan to meet the changing needs of the child with epilepsy through the social and developmental changes of childhood, adolescence, and adulthood. The development of epilepsy may complicate the recovery from many acute and chronic conditions that affect the central nervous system. The rehabilitation process must address these many aspects of the disease process and its sequelae. This makes neurologists uniquely qualified to manage the rehabilitation team. The impact of the therapeutic milieu on the recovery process may be as important as any specific medical or surgical intervention.

Magnetoencephalography in pediatric neurology and in epileptic syndromes

In recent years, great advances in the knowledge of neuromagnetism have permitted the application of Superconducting Quantum Interference Devices to the pathophysiologic study of the human brain. In particular, in pediatric neurology, the integration of biomagnetism with magnetic resonance imaging and other techniques for medical imaging have allowed for precise neuromagnetic measurements of the human brain. The more frequently used technique is magnetoencephalography. Recent data have illustrated the usefulness of magnetoencephalography in mapping activity of sensory and motor areas and in studying the spatiotemporal pattern of brain activation specific to somatosensory function. Moreover, magnetoencephalography is an important tool to localize epileptic activity; magnetic source imaging superimposes magnetoencephalographic localizations on the magnetic resonance imaging and yields improved spatial resolution as compared with surface electroencephalography. The role of magnetoencephalography in evaluating patients with epilepsy continues to evolve; in fact, it seems to be very useful in the localization of the epileptogenic zone in patients with partial epilepsy. This application of magnetoencephalography is essential in the selection of epileptic children candidates to surgical treatment of seizures.

Epilepsy surgery. Presurgical evaluation

The presurgical evaluation should result in a clear understanding of whether surgery can be undertaken and its associated risks and potential for benefit. The results of surgery are best when there is congruence in the seizure semiology, the irritative zone on interictal EEG, and the ictal onset zone with the epileptogenic lesion as defined on MRI and PET, and when there is a clear understanding of the ictal onset zone's relationship to eloquent cortex as defined by neuropsychologic evaluation, the intracarotid amobarbital test, and cortical functional mapping.

Spontaneous long-term remission of intractable partial epilepsy in childhood

Drug-resistant partial epilepsy in children often has a major impact on cognitive development, and early surgical intervention has been advocated to prevent adverse neurobehavioral effects of seizures in such patients. We report a 5-year-old boy who had cryptogenic partial epilepsy of right parietal origin as documented by ictal electroencephalogram (EEG) and glucose metabolism positron emission tomographic (PET) scan. His atonic seizures could not be controlled by multiple antiepilepsy drugs; therefore, cortical resection was scheduled. However, his seizures remitted spontaneously after 1 year of failed medical treatment. The epileptiform abnormality disappeared on the follow-up EEGs, and a glucose PET scan also normalized. This boy has fully retained his cognitive and motor functions and has remained seizure free in the past 4z\x years off medications.

Surgical treatment of medically refractory epilepsy in childhood

Twenty-five percent of children with epilepsy continue to seize despite the best medical management and may be defined as medically refractory. Many children with medically refractory localization-related epilepsy, i.e. seizures which originate in a particular area of the brain and secondarily spread to involve other brain regions, may benefit from a variety of surgical treatments including hemispherectomy, corpus callosotomy, focal cortical resection of the temporal lobe, focal cortical resection of extratemporal regions of the brain, and multiple subpial resections. A successful outcome from epilepsy surgery is generally defined as a seizure-free state with no imposition of neurologic deficit. In order to achieve these twin goals two criteria must be fulfilled. First, precise localization of the epileptogenic zone in the brain is necessary. The epileptogenic zone may be defined as the region of epileptogenic cerebral cortex whose removal will result in a seizure-free state. Second, one must determine the anatomic localization of eloquent cortex in the brain in order to spare these areas during any planned cortical excision of epileptogenic cortex. Several diagnostic measures may be used to achieve a successful surgical outcome. A clinical history to ascertain the earliest symptom in the clinical progression of the seizure (semiology) is imperative as is ictal and interictal scalp EEG, neuropsychological testing, magnetic resonance imaging, positron emission tomography, single photon emission computerized tomography, and interictal magnetoencephalography. In the typical child undergoing evaluation for epilepsy surgery, if the clinical, neuropsychological, EEG, and radiological data are all concordant and point to the same area of epileptogenicity in the brain, cortical excision of the suspected epileptogenic zone is undertaken. However, if the data are discordant, and/or the epileptogenic zone resides wholly or in part within eloquent cortex, invasive intracranial monitoring from depth and/or subdural electrodes during a seizure is required to map out the areas of epileptogenicity in the brain. The assessment of potential risks and benefits for this type of epilepsy surgery in children involves complex age-related issues, including the possible impact of uncontrolled seizures, medication, or surgery on learning and development.

Magnetoencephalography and magnetic source imaging in children

Magnetoencephalography is a technique that detects the magnetic fields associated with the intracellular current flow within neurons, unlike electroencephalography, which measures extracellular volume currents. Superconducting quantum interference devices are used to amplify these very small magnetic field signals. Magnetic source imaging is the combination of functional data derived from magnetoencephalographic recordings coregistered with structural magnetic resonance imaging (MRI). The utility of magnetic source imaging lies in the combination of the submillisecond temporal resolution of magnetoencephalography with the precise anatomic images provided by magnetic resonance imaging. As such, magnetic source imaging is a useful tool for noninvasive localization of the epileptogenic zone in children who are candidates for epilepsy surgery. Similarly, using magnetoencephalographic recordings with evoked and event-related potentials, magnetic source imaging holds great promise as a noninvasive method for precise localization of somatosensory, motor, language, visual, and auditory cortex. Finally, magnetic source imaging is proving a valuable research tool in the investigation of epilepsy, head trauma, brain plasticity, and disorders of language, memory, cognition, and executive function in children.

Surgical indication for refractory childhood epilepsy

Recent progress in surgical intervention for medically refractory epilepsy has helped to shed light on more complex epileptogenic problems in children and infants. Surgical treatment increasingly is being used in pediatric patients, but the indications for surgery in this age group have not been well defined. The developing child with a seizure disorder has several problems that are different from adults, such as neural plasticity, deleterious effects of seizures on developmental status, and spontaneous resolution of epilepsy. The critical age for irreversible brain dysfunction and the timing of surgery are the main issues for the treatment of children. Thus, earlier surgical intervention is generally recommended to prevent further detrimental seizure effects, but we still do not know the optimal age. Until the establishment of guidelines for pediatric epilepsy surgery, surgical indications should be determined by the prognosis and the presence of a resectable epileptogenic focus, which in turn are based on the localization of the epileptic focus, seizure frequency, severity, and cognitive function of each case, rather than just the patient's age.

Predictors and underlying causes of medically intractable localization-related epilepsy in childhood

The goal of this study is to clarify the prognostic factors in childhood localization-related epilepsy in a tertiary medical center. Children (n = 113) with symptomatic and cryptogenic localization-related epilepsy were divided into groups of intractable patients (average seizure frequency: one or more per month during the 6 months before the last follow-up; n = 40) and well-controlled patients (no seizures for at least 1 year before the last follow-up; n = 73). Clinical and electroencephalogram (EEG) factors were examined to elucidate prognostic factors. The subtypes of epilepsies and causes were also investigated. Univariate analyses indicated that the following factors were correlated with seizure outcome: (1) seizure type at the first visit; (2) seizure frequency; (3) underlying cause; (4) age at onset of epilepsy; (5) status epilepticus occurring as the first seizure and before the first visit; and (6) diffuse epileptic discharges on first visit interictal EEGs. Multivariate analyses revealed that seizure type at the first visit, seizure frequency, status epilepticus before the first visit, and underlying causes were significant independent predictive factors. The rate of intractable patients was highest in multilobar epilepsy, followed by frontal-lobe epilepsy. Regarding etiologies, the intractable group contained nine patients with encephalitis of unknown origin and three each with localized cortical malformation and mesial temporal sclerosis.

Recent advances in candidate selection for pediatric epilepsy surgery

Many patients who were once considered inoperable are candidates for a wide variety of surgical procedures. This trend is particularly striking at pediatric centers that serve patients with diverse forms of epilepsy that compromise development. Newer diagnostic techniques, including structural and functional imaging, EEG monitoring, and surgical technology, can provide a complete representation of the etiology and expression of the epileptic focus, including accurate cortical localization. This review focuses on several forms of epilepsy that, until recently, were not regarded to be surgically amenable. The adverse seizure and neurobehavioral prognosis in patients with these disorders provides the justification to search for innovative treatments. With more sophisticated tools for preoperative evaluation and an expanding knowledge base, it is likely that the number of surgical candidates will continue to increase in the future.

Transparahippocampal selective amygdalohippocampectomy in children and adolescents: efficacy of the procedure and cognitive morbidity in patients

OBJECT

Unilateral resection of the hippocampus and amygdala can be used to treat medically intractable mesial temporal lobe seizures. To date seizure outcome and the extent of cognitive morbidity have been unknown in children following the transparahippocampal variation of selective amygdalohippocampectomy (TSA), which prompted the present prospective study.

METHODS

Preoperative examinations and outcomes in 22 consecutive children and adolescents who underwent TSA were studied. Cognitive and psychological morbidity were assessed using standard neuropsychological instruments. The authors evaluated relationships between seizure control and cognitive morbidity and 13 and nine clinical variables, respectively. Seizure control was achieved in 11 (65%) of 17 patients (>2 years follow up). Among 13 clinical variables, the only preoperative finding that had a significant bearing on seizure control was the presence of unilateral hypometabolism, which could be observed on [18F]fluorodeoxyglucose-positron emission tomography scans (p<0.001). Patients with seizure control showed significant improvements in verbal and full scale intelligence quotients (both p = 0.05). Patients with longer preoperative durations of seizures exhibited more cognitive impairment that persisted postoperatively. Cognitive outcome analysis based on nine clinical factors revealed no significant difference in cognitive parameters postoperatively, except that significant improvement occurred in rote verbal memory scores among patients who underwent right-sided TSA (p = 0.01). Individually, 81% of the children achieved significant improvement in at least one of seven cognitive parameters, and 52% had stable or improved scores in all parameters.

CONCLUSIONS

The results indicate that TSA is a safe effective approach for the treatment of medically intractable mesial temporal lobe seizures in children with minimum effect on cognitive morbidity. Given that the literature suggests that children suffer progressive cognitive morbidity from persistent seizures, the results of this study support early surgical intervention for this group of children.

Intractable pediatric epilepsy: presurgical evaluation

Epilepsy surgery in children requires a multidisciplinary approach. This section examines the role of scalp EEG, video-EEG monitoring, and intracranial EEG in the presurgical evaluation. Concepts central to understanding the basis for surgical treatment, such as the epileptogenic zone, the irritative zone, and the epileptogenic lesion, are discussed. An illustrative case then demonstrates application of the process in clinical practice. Neuroimaging and neuropsychological issues are not discussed herein; rather they are addressed elsewhere in this issue.

Clinicopathological findings in patients who have undergone epilepsy surgery in the first year of life

Epilepsy presenting early in childhood may be associated with a neurologically devastating clinical course and have significant implications for the child's development. There are limited published data regarding the clinicopathological features of patients who have undergone epilepsy surgery in the first year of life and the role such surgery may have in reducing seizure frequency. This study retrospectively reviews the clinicopathologic features of eight patients from a tertiary care setting who underwent surgery for epilepsy in the first year of life. Eight infants, including seven males and one female, underwent surgery for epilepsy at 3-11 months of age (median 7.5 months). Age at the time of seizure onset ranged from birth to 2 months. Epileptogenic foci were localized by electroencephalographic and radiographic studies to the right side in five patients and left side in three patients. Histopathological findings in excised tissues included cortical dysplasia (n = 7), hemimegalencephaly (n = 3), and Sturge-Weber syndrome (n = 1). Dysplasia was marked by abnormalities in cortical lamination and neuronal orientation (n = 7), neuronal cytomegaly (n = 6), increased molecular layer neurons (n = 5) and balloon cells (n = 2). One patient was known to have epidermal nevus syndrome. Two patients required additional surgery for continued seizures. At last known follow up, all but one patient, who died in the postoperative period, were alive with no or decreased seizures at postoperative intervals of 3-60 months (median 13 months). Surgery can potentially ameliorate epilepsy in patients less than 1 year of age. Most of the patients in this series had cortical dysplasia as the underlying pathology of their epilepsy.

Efficacy of five days' barbiturate anesthesia in the treatment of intractable epilepsies in children

PURPOSE

To analyze the efficacy of barbiturate anesthesia in the treatment of intractable epilepsies in childhood.

METHODS

Anesthesia for 4-5 days with thiopentone sodium was used to treat children with intractable epilepsy in the Department of Pediatrics, Oulu, Finland, from November 1980 through December 1995. The number of epileptic seizures, the number and dosage of antiepileptic drugs (AEDs), and psychomotor development before and after anesthesia were compared.

RESULTS

Fifty-four children with intractable epilepsy were treated with barbiturate anesthesia. Twenty-four children had infantile spasms; 22, Lennox-Gastaut syndrome; seven, complex partial epilepsy; and one, myoclonic epilepsy. Twenty-four (44.4%) children had complications during the anesthesia. The seizures recurred in 53 of the 54 patients in a median time of 12 days after the anesthesia. In 42 (78%) children, the seizure frequency returned to a level equal to or higher than that before the anesthesia in a median time of 211 days. The number of AEDs was significantly greater after than before the anesthesia (6.33 vs. 4.8; p < 0.001). Seventeen (32.5%) children were treated surgically after the anesthesia.

CONCLUSIONS

Although the seizures are eliminated or the seizure frequency decreases for a short period after the barbiturate anesthesia, the anesthesia does not change the long-term outcome and is therefore inefficient in the treatment of childhood intractable epilepsies.