Neonatal seizures and syndromes

The role of molecular chaperones in the mechanisms of epileptogenesis

Epilepsy is a group of neurological diseases which requires significant economic costs for the treatment and care of patients. The central point of epileptogenesis stems from the failure of synaptic signal transmission mechanisms, leading to excessive synchronous excitation of neurons and characteristic epileptic electroencephalogram activity, in typical cases being manifested as seizures and loss of consciousness. The causes of epilepsy are extremely diverse, which is one of the reasons for the complexity of selecting a treatment regimen for each individual case and the high frequency of pharmacoresistant cases. Therefore, the search for new drugs and methods of epilepsy treatment requires an advanced study of the molecular mechanisms of epileptogenesis. In this regard, the investigation of molecular chaperones as potential mediators of epileptogenesis seems promising because the chaperones are involved in the processing and regulation of the activity of many key proteins directly responsible for the generation of abnormal neuronal excitation in epilepsy. In this review, we try to systematize current data on the role of molecular chaperones in epileptogenesis and discuss the prospects for the use of chemical modulators of various chaperone groups' activity as promising antiepileptic drugs.

Genomic analyses of glycine decarboxylase neurogenic mutations yield a large-scale prediction model for prenatal disease

Hundreds of mutations in a single gene result in rare diseases, but why mutations induce severe or attenuated states remains poorly understood. Defect in glycine decarboxylase (GLDC) causes Non-ketotic Hyperglycinemia (NKH), a neurological disease associated with elevation of plasma glycine. We unified a human multiparametric NKH mutation scale that separates severe from attenuated neurological disease with new in silico tools for murine and human genome level-analyses, gathered in vivo evidence from mice engineered with top-ranking attenuated and a highly pathogenic mutation, and integrated the data in a model of pre- and post-natal disease outcomes, relevant for over a hundred major and minor neurogenic mutations. Our findings suggest that highly severe neurogenic mutations predict fatal, prenatal disease that can be remedied by metabolic supplementation of dams, without amelioration of persistent plasma glycine. The work also provides a systems approach to identify functional consequences of mutations across hundreds of genetic diseases. Our studies provide a new framework for a large scale understanding of mutation functions and the prediction that severity of a neurogenic mutation is a direct measure of pre-natal disease in neurometabolic NKH mouse models. This framework can be extended to analyses of hundreds of monogenetic rare disorders where the underlying genes are known but understanding of the vast majority of mutations and why and how they cause disease, has yet to be realized.

Building models of human genetic disease, both computational and animal, is an essential part of understanding the disease, designing treatments, and testing therapies. Here, we have developed new in silico tools to build models for the rare neurological disorder non-ketotic hyperglycinemia (NKH), which is caused by mutations in glycine decarboxylase (GLDC), a protein that degrades glycine. We first applied a mutation scoring tool to GLDC in both the human and mouse genomes, and then used this data to develop a computational model for predicting which mutations would be well-modeled in mice, and how severe their disease would be. We then validated this computational model by genetically-engineering a mutation predicted to cause mild disease and another predicted to cause severe disease. Our predictions were correct and we used them to develop a model relevant for over a hundred major and minor neurogenic mutations that suggests that the more severe the mutation, the greater chance it will cause disease that starts before birth and is likely to be fatal unless rescued by modifying diet. This study also demonstrates the power of in silico analyses for guiding the development of genetic disease models and incorporating them into scalable models that can be applied to understand hundreds of mutations that cause disease.

Basics of modern epilepsy classification and terminology

BACKGROUND

The terminology and classification of seizures and epilepsy has undergone multiple revisions in the last several decades, which can lead to confusion and miscommunication amongst physicians and researchers. In 2017, the International League Against Epilepsy (ILAE) revised the classification of both seizures and epilepsy types in an effort to use less ambiguous terminology. Over time, definitions for status epilepticus, febrile seizures, and neonatal seizures have also evolved, as has the delineation of various epilepsy syndromes by age.

METHODS

Review of the literature for old and new terminology and various epilepsy syndromes was accomplished using the PubMed database system.

RESULTS

In the following article, we review old terminology for classifying seizures and epilepsy as compared to the new (2017) ILAE guidelines. We discuss neonatal seizures, status epilepticus, febrile seizures, autoimmune epilepsy and various epilepsy syndromes by age of onset.

CONCLUSION

Adopting a classification system that uses plain language allows for more effective and efficient communication between individuals and across specialties. Definitions of various syndromes and seizure types have evolved over time and are reviewed.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

Large scale analyses of genotype-phenotype relationships of glycine decarboxylase mutations and neurological disease severity

Monogenetic diseases provide unique opportunity for studying complex, clinical states that underlie neurological severity. Loss of glycine decarboxylase (GLDC) can severely impact neurological development as seen in non-ketotic hyperglycinemia (NKH). NKH is a neuro-metabolic disorder lacking quantitative predictors of disease states. It is characterized by elevation of glycine, seizures and failure to thrive, but glycine reduction often fails to confer neurological benefit, suggesting need for alternate tools to distinguish severe from attenuated disease. A major challenge has been that there are 255 unique disease-causing missense mutations in GLDC, of which 206 remain entirely uncharacterized. Here we report a Multiparametric Mutation Score (MMS) developed by combining in silico predictions of stability, evolutionary conservation and protein interaction models and suitable to assess 251 of 255 mutations. In addition, we created a quantitative scale of clinical disease severity comprising of four major disease domains (seizure, cognitive failure, muscular and motor control and brain-malformation) to comprehensively score patient symptoms identified in 131 clinical reports published over the last 15 years. The resulting patient Clinical Outcomes Scores (COS) were used to optimize the MMS for biological and clinical relevance and yield a patient Weighted Multiparametric Mutation Score (WMMS) that separates severe from attenuated neurological disease (p = 1.2 e-5). Our study provides understanding for developing quantitative tools to predict clinical severity of neurological disease and a clinical scale that advances monitoring disease progression needed to evaluate new treatments for NKH.

Neurodegenerative disorders frequently have diverse, severe symptoms and health outcomes that can be difficult to predict. The rare disease non-ketotic hyperglycinemia (NKH) additionally has a wide range of disease-causing mutations in glycine decarboxylase (GLDC), a protein that breaks down glycine. But measuring glycine is not sufficient to foretell disease outcome. A method to predict whether a mutation will cause severe or more mild forms of NKH would be very helpful to both understanding the disease as well as developing treatments for it. We used computation-based approaches to develop a mutation score that comprehensively predicts how mutations decrease GLDC function. After training against clinical data, the score was able to predict whether a mutation will cause severe or attenuated disease. This study utilizes the power of computational and multidisciplinary analyses to advance understanding and treatment of genetically caused neurodegenerative diseases.

Pediatric Compounding Pharmacy: Taking on the Responsibility of Providing Quality Customized Prescriptions

Compounding pharmacy has an important role to play in the field of pediatric medicine. These specialized pharmacies can offer solutions to the unique patient needs that arise in the pediatric population. Medication can be tailored to the child to allow better compliance in cases when the commercial product is unable to meet the needs of the patient. For example, a suspension, suppository, or lozenge formulation is sometimes needed when the manufactured products are only offered as solid oral dosage forms. Sensory processing disorder (SPD), patients with food allergies, and specific dietary needs can also be a big challenge for caregivers and practitioners who need alternatives to the commercially available forms. Three example cases are presented to help describe the process of collaboration between the pharmacist, patient, and doctor to solve the patient’s needs.

Video and audio processing in paediatrics: a review

OBJECTIVE

Video and sound acquisition and processing technologies have seen great improvements in recent decades, with many applications in the biomedical area. The aim of this paper is to review the overall state of the art of advances within these topics in paediatrics and to evaluate their potential application for monitoring in the neonatal intensive care unit (NICU).

APPROACH

For this purpose, more than 150 papers dealing with video and audio processing were reviewed. For both topics, clinical applications are described according to the considered cohorts-full-term newborns, infants and toddlers or preterm newborns. Then, processing methods are presented, in terms of data acquisition, feature extraction and characterization.

MAIN RESULTS

The paper first focuses on the exploitation of video recordings; these began to be automatically processed in the 2000s and we show that they have mainly been used to characterize infant motion. Other applications, including respiration and heart rate estimation and facial analysis, are also presented. Audio processing is then reviewed, with a focus on the analysis of crying. The first studies in this field focused on induced-pain cries and the newest ones deal with spontaneous cries; the analyses are mainly based on frequency features. Then, some papers dealing with non-cry signals are also discussed.

SIGNIFICANCE

Finally, we show that even if recent improvements in digital video and signal processing allow for increased automation of processing, the context of the NICU makes a fully automated analysis of long recordings problematic. A few proposals for overcoming some of the limitations are given.

Management of seizures in children

Seizures are common events in children and up to 10% of all children experience at least one seizure during their childhood. They can be triggered by many conditions such as fever, medications or injury. Febrile seizures are the most common types of seizures, affecting 3-4% of children. While epilepsy is typically recurrent and unprovoked, a single, isolated seizure is not epilepsy. Taking a detailed history of the seizure description helps establish the diagnosis. A video recording of the event can also support the diagnosis and rule out non-epileptic seizures that resemble seizures, such as pseudo-seizure. Seeing a child having a seizure, particularly if it is the first one, is usually frightening and distressing for the parents. First seizure should always be evaluated by health professionals because of a possible serious underlying cause. If the seizure occurs at home, the child should be placed in the recovery side position to prevent the swallowing of any vomit. The care of a child who does have epilepsy is best achieved by a community or hospital epilepsy specialist nurse. These nurses play a pivotal role in providing a close link between the epileptic children and their families. Such a nurse is also in an ideal position to establish a link between the doctor and affected families, offering valuable advice and support, and visiting the epileptic child at home.

Seizures and EEG features in 74 patients with genetic-dysmorphic syndromes

Epilepsy is one of the most common findings in chromosome aberrations. Types of seizures and severity may significantly vary both between different conditions and within the same aberration. Hitherto specific seizures and EEG patterns are identified for only few syndromes. We studied 74 patients with defined genetic-dysmorphic syndromes with and without epilepsy in order to assess clinical and electroencephalographic features, to compare our observation with already described electro-clinical phenotypes, and to identify putative electroencephalographic and/or seizure characteristics useful to address the diagnosis. In our population, 10 patients had chromosomal disorders, 19 microdeletion or microduplication syndromes, and 32 monogenic syndromes. In the remaining 13, syndrome diagnosis was assessed on clinical grounds. Our study confirmed the high incidence of epilepsy in genetic-dysmorphic syndromes. Moreover, febrile seizures and neonatal seizures had a higher incidence compared to general population. In addition, more than one third of epileptic patients had drug-resistant epilepsy. EEG study revealed poor background organization in 42 patients, an excess of diffuse rhythmic activities in beta, alpha or theta frequency bands in 34, and epileptiform patterns in 36. EEG was completely normal only in 20 patients. No specific electro-clinical pattern was identified, except for inv-dup15, Angelman, and Rett syndromes. Nevertheless some specific conditions are described in detail, because of notable differences from what previously reported. Regarding the diagnostic role of EEG, we found that--even without any epileptiform pattern--the generation of excessive rhythmic activities in different frequency bandwidths might support the diagnosis of a genetic syndrome.

Recent advances in neonatal seizures

Neonatal seizures are the most important indicators of underlying brain injury. Seizures in a neonate are different from seizures in older children in many aspects including clinical presentation and etiology. The neonatal brain is immature and tends to have a decreased seizure threshold. Neonatal seizures are classified, based on their presentation as, clinical seizures, electroclinical seizures and electroencephalographic seizures; based on the pathophysiology as epileptic and nonepileptic seizures; and also on the basis of the etiology. Hypoxic ischemic encephalopathy is the leading cause of neonatal seizures, followed by intracranial hemorrhage, metabolic causes such as hypoglycemia and hypocalcemia, intracranial infections and strokes. Neonatal epilepsy syndromes are rare. Electroencephalography (EEG) is the gold standard for diagnosis. Amplitude integrated EEG (aEEG) is also used for continuous monitoring. The approach to management consists of initial stabilization of the neonate followed by treatment of potentially correctable injurious processes such as hypocalcemia, hypoglycemia and electrolyte disturbances, etiology specific therapies and antiepileptic drug (AED) therapy. Phenobarbital remains the first line AED therapy. Pharmacokinetic data on newer drugs is limited. Prognosis depends on the etiology, seizure type, neurological examination at discharge and EEG. Long term neurodevelopmental follow up is essential for babies with neonatal seizures.

Diagnosing neonatal seizures and status epilepticus

Continuous electroencephalographic (CEEG) monitoring is often applied in the Neonatal Intensive Care Unit to aid in the diagnosis and management of seizures. Neonatal seizures are particularly difficult to identify on the basis of clinical observation alone; diagnosis is greatly facilitated by CEEG monitoring. There is building evidence to suggest which neonates are at highest risk for seizures, and how CEEG can aid diagnosis. For the neurophysiologist, the unique features of neonatal seizures can distinguish them from nonictal patterns. These features include duration, location, morphology, and evolution. At the extreme, very frequent or prolonged neonatal seizures constitute status epilepticus. There is no consensus definition for neonatal status epilepticus, although the proposed criteria share some features. This article reviews available evidence to guide the application and interpretation of CEEG in the diagnosis of neonatal seizures and status epilepticus.

Clinical and ictal characteristics of infantile seizures: EEG correlation via long-term video EEG monitoring

PURPOSE

The semiology of infantile seizures often shows different characteristics from that of adults. We performed this study to describe clinical and ictal characteristics of infantile seizures at less than two years of age.

METHODS

A retrospective study was done for infants with epilepsy (ages: 1-24months) who underwent long-term video electroencephalography (EEG) monitoring at Samsung medical center between November 1994 and February 2012. We analyzed the clinical and ictal characteristics of the 56 cases from 51 patients.

RESULTS

In 69% of the patients, the seizure onset was before six months of age and the etiology was symptomatic in one third of the patients. Twelve seizure types were identified; spasms (24%), unilateral motor seizures (18%), and generalized tonic seizures (15%) were the three frequent types of seizure. All partial seizures were well correlated with the partial-onset ictal EEG, however 19.4% (7/36) of clinically generalized seizures revealed partial-onset ictal EEG. About one-thirds (4/11) of generalized tonic seizures had its ictal onset on unilateral or bilateral frontal areas and two out of seven generalized myoclonic seizures showed unilateral frontal rhythmic activities. Hypomotor seizures mainly arose from the temporal areas and hypermotor seizures from the frontal regions.

CONCLUSIONS

Even though most of the seizure semiology of infants is well correlated with ictal EEG, some of the generalized tonic seizures or myoclonic seizures revealed partial-onset ictal EEG suggesting localized epileptic focus. Accurate definition of seizures via video EEG monitoring is necessary for proper management of seizures in infancy, especially in some clinically generalized seizures.

Epidemiology and aetiology of neonatal seizures

Neonatal seizures constitute the most frequent and distinctive neurological symptom in the neonatal period. Seizures in the neonatal period differ considerably from those observed later in life with respect to their aetiological profile and clinical presentation. In addition, the aetiological profile in preterm infants is different from that seen in term infants. Hypoxic-ischaemic encephalopathy is the most frequent cause of neonatal seizures in term babies followed by focal ischaemia (stroke), cerebral malformations and metabolic disturbances. In preterm neonates, intraventricular haemorrhage and infections cause most of the seizures reported in this group. Better neuroimaging techniques have reduced the number of undiagnosed cases, and the institution of newer neuroprotective strategies has influenced the outcome.

Neonatal seizures and status epilepticus

Neonatal seizures are common, often require EEG monitoring for diagnosis and management, may be associated with worse neurodevelopmental outcome, and can often be treated with existing anticonvulsants. A neonatal electrographic seizure is defined as a sudden, repetitive, evolving, and stereotyped event of abnormal electrographic pattern with amplitude of at least 2 μV and a minimum duration of 10 seconds. The diagnosis of neonatal seizures relies heavily on the neurophysiologist's interpretation of EEG. Consideration of specific criteria for the definition of a neonatal seizure, including seizure duration, location, morphology, evolution, semiology, and overall seizure burden, has utility for both the clinician and the researcher. The importance of EEG in the diagnosis and management of neonatal seizures, the electrographic characteristics of neonatal seizures, the impact of neonatal seizures on outcome, and tools to aid in the identification of neonatal seizures are reviewed.

Classification of clinical semiology in epileptic seizures in neonates

The clinical semiology of 61 neonatal seizures with EEG correlates, in 24 babies was analysed. Most seizures (89%) had multiple features during the EEG discharge. The seizures were classified using the prominent clinical feature at onset, and all features seen during the seizure, using an extended classification scheme. Orolingual features occurred most frequently at onset (30%), whereas ocular phenomena occurred most often during the seizure (70%). Orolingual, ocular and autonomic features were seen at onset in 55% of the seizures. Seizure onsets with clonic, tonic and hypomotor features were seen in 20%, 8% and 18% respectively. Clinico-electrical correlations were as follows. The EEG discharge involved both hemispheres in 54% of all seizures, in clonic seizures this was 93%. Focal clonic seizures were associated with EEG seizure onset from the contralateral hemisphere. Majority of the clonic and hypomotor seizures had a left hemisphere ictal EEG onset. Orolingual seizures frequently started from the right hemisphere, whereas ocular and autonomic seizures arose from either hemisphere. There was no significant difference in mortality, morbidity, abnormal neuroimaging and EEG background abnormalities in babies with or without clonic seizures. This study provides insights into neuronal networks that underpin electroclinical seizures, by analysing and classifying the obvious initial clinical features and those during the seizure.

Ictal electroencephalograms in neonatal seizures: characteristics and associations

The characteristics of ictal electroencephalograms in 160 neonatal seizures of 43 babies were correlated with mortality and neurodevelopmental outcomes. Neonatal seizures are focal at onset, most frequently temporal, and often occur during sleep. Twenty-one percent of babies with seizures died, and 76% of survivors manifested neurodevelopmental impairment during 2-6-year follow-up. A low-amplitude ictal electroencephalogram discharge was associated with increased mortality, and a frequency of <2 Hz with increased morbidity. Status epilepticus, ictal fractions, multiple foci, and bihemispheric involvement did not influence outcomes. Of 160 seizures, 99 exhibited no associated clinical features (electrographic seizures). Neonatal seizures with clinical correlates (electroclinical seizures) exhibited a higher amplitude and frequency of ictal electroencephalogram discharge than electrographic seizures. During electroclinical seizures, the ictal electroencephalogram was more likely to involve larger areas of the brain and to cross the midline. Mortality and morbidity were similar in babies with electroclinical and electrographic seizures, emphasizing the need to diagnose and treat both types. Ictal electroencephalogram topography has implications for electrode application during limited-channel, amplitude-integrated electroencephalograms. We recommend temporal and paracentral electrodes. Video electroencephalograms are important in diagnosing neonatal seizures and providing useful information regarding ictal electroencephalogram characteristics.

Neonatal Seizures: When to Consider and How to Investigate for an Inborn Error of Metabolism

Seizures occur more frequently in the neonatal period than in the remainder of childhood. Neonatal seizures can have different aetiologies. Inborn errors of metabolism are rare causes of seizures in the newborn. However, they are an important cause of intractable neonatal seizures, accounting for 30% of cases. Diagnosis is necessary for timely institution of appropriate treatment and is important in determining clinical outcome. As these are genetic conditions, it allows for appropriate genetic counselling. We describe the clinical presentation of neonatal seizures and the investigation findings in symptomatic neonatal seizures and epilepsy syndromes that arise in the neonatal period. The approach in diagnosis and investigation of an underlying inborn error of metabolism is described and inborn errors of metabolism that are important causes of neonatal seizures are reviewed.

[Ohtahara syndrome--early infantile epileptic encephalopathy]

DEFINITION

Ohtahara syndrome (early infantile epileptic encephalopathy with suppression bursts), is the earliest developing form of epileptic encephalopathy. ETHIOLOGY: It considered to be a result of static structural developing brain damage.

CLINICAL PICTURE

Variable seizures develop mostly within the first 10 days of life, but may occur during the first hour after delivery. The most frequently observed seizure type are epileptic spasms, which may be either generalized and symmetrical or lateralized .The tonic spasms may occur in clusters or singly, while awake and during sleep alike. The duration of spasms is up to 10 seconds, and the interval between spasms within cluster ranges from 9 to 15 seconds. In one third of cases, other seizure types include partial motor seizures or hemiconvulsions The disorder takes a progressively deteriorating course with increasing frequency of seizures and severe retardation of psychomotor development.

DIAGNOSTIC WORKUP

In the initial stage of Ohtahara syndrome, interictal EEG shows a pattern of suppression-burst with high-voltage paroxysmal discharges separated by prolonged periods of nearly flat tracing that last for up to 18 seconds.

PROGNOSIS AND TREATMENT

Half of the reported children having Ohtahara syndrome die in infancy. Anticonvulsant helps little in controlling the seizures and halting the deterioration of psychomotor development. Severe psychomotor retardation is the rule. With time, the disorder may evolve into West syndrome or partial epilepsy. Psychomotor development may be slightly better if the infants do not develop West and later Lennox-Gastaut syndrome.

Long-term consequences of drugs on the paediatric cardiovascular system

Many pharmacological and toxicological actions of drugs in children cannot be fully predicted from adult clinical experience or from standard non-clinical toxicology studies. Numerous drugs have direct or indirect pharmacological effects on the heart and are prescribed for children of all ages. Toxicity or secondary effects may be immediate or delayed for years after drug exposure has ceased. Originally, the aim of this review was to compile information on the effect of specific drugs on the post-natal development of the cardiovascular system and to examine long-term follow-up of the use of cardio-active drugs in children. The limited database of published information caused the original question to evolve into an examination of the medical literature for three areas of information: (i) whether vulnerable developmental windows have been identified that reflect the substantial functional development that the cardiovascular system undergoes after birth; (ii) what is known about pharmacological perturbation of development; and (iii) what the likelihood is of drug exposure during childhood. We examined different scenarios for exposure including random, isolated exposure, conditions historically associated with adults, primary or secondary cardiac disease, psychiatric and neurological conditions, asthma, cancer and HIV. Except for random, isolated drug exposures, each category of possible exposure contained numerous drugs known to have either primary or secondary effects on the cardiovascular system or to influence factors associated with atherosclerosis. It is likely that a significant number of children will be prescribed drugs having either direct or indirect effects upon the immature cardiovascular system. A confounding factor is the simultaneous use of over-the-counter medications and herbal or nutraceutical preparations that a patient, parent or guardian does not mention to a prescribing physician. Metabolism is also important in assessing drug effects in children. Differences in body water : body fat ratio, age-related gastrointestinal absorption, distribution, excretion, renal function and drug metabolizing capabilities make it possible for children to have a different metabolite profile for a drug compared with adults. There is little examination of drug effects on the interdependent processes of cardiac maturation and less examination of metabolite effects. It is difficult to identify delayed toxicities in children as these adverse events may take years to manifest with many patients lost to follow-up. Clearly this is an area of study where intermediate endpoints and surrogate markers would be of great benefit. Pharmacogenomics may be useful in providing markers of increased risk or susceptibility. A perspective must be kept in balancing the possibility of a problem with the very real benefits that many children experience from the use of these pharmaceuticals.

Pharmacologically intractable epilepsy in children: diagnosis and preoperative evaluation

It is important to correctly diagnose medically intractable epilepsy in children and to identify those children whose medically refractory, localization-related seizures may be surgically remediable as soon as possible to optimize the surgical outcome. In this paper the authors review the definition of medically intractable seizures and discuss the various causes and risk factors for this disorder in children. They also outline the presurgical diagnostic evaluation process for pharmacologically intractable epilepsy in children who may be candidates for surgical treatment of localization-related seizures. The treatment of children with medically intractable epilepsy is both challenging and rewarding. Surgery has the potential of altering the natural history of epilepsy by improving or eliminating seizures in carefully selected patients.

Layer-specific generation and propagation of seizures in slices of developing neocortex: role of excitatory GABAergic synapses

The neonatal period is critical for seizure susceptibility, and neocortical networks are central in infantile epilepsies. We report that application of 4-aminopyridine (4-AP) to immature (P6-P9) neocortical slices generates layer-specific interictal seizures (IISs) that transform after recurrent seizures to ictal seizures (ISs). During IISs, cell-attached recordings show action potentials in interneurons and pyramidal cells in L5/6 and interneurons but not pyramidal neurons in L2/3. However, L2/3 pyramidal neurons also fire during ISs. Using single N-methyl-d-aspartate (NMDA) channel recordings for measuring the cell resting potential (Em), we show that transition from IISs to ISs is associated with a gradual Em depolarization of L2/3 and L5/6 pyramidal neurons that enhances their excitability. Bumetanide, a NKCC1 co-transporter antagonist, inhibits generation of IISs and prevents their transformation to ISs, indicating the role excitatory GABA in epilepsies. Therefore deep layer neurons are more susceptible to seizures than superficial ones. The initiating phase of seizures is characterized by IISs generated in L5/6 and supported by activation of both L5/6 interneurons and pyramidal cells. IISs propagate to L2/3 via activation of L2/3 interneurons but not pyramidal cells, which are mostly quiescent at this phase. In superficial layers, a persistent increase in excitability of pyramidal neurons caused by Em depolarization is associated with a transition from largely confined GABAergic IIS to ictal events that entrain the entire neocortex.

Treatments with midazolam and lidocaine for status epilepticus in neonates

Status epilepticus (SE) occurs in children of all ages. Recent epidemiologic investigations of SE show heightened morbidity and mortality in newborns and young infants. However, the existing definition of SE in newborns is not precise and not easily applied in clinical investigations or in clinical practice. To evaluate the underlying conditions, clinical features and treatment of SE in neonates in Japan, a retrospective multi-center study was performed. In the initial investigation, questionnaires were sent to pediatric neurologists in 194 neonatal intensive care units of university hospitals, children's hospitals, and general hospitals throughout in Japan. The questionnaires sought information on the background of each case, types of seizures, etiology of SE, treatments, results and adverse effects of treatment for patients less than 1 week old who had prolonged or frequently repeated seizures lasting more than 15 min and who are refractory to treatment with conventional anticonvulsants, such as diazepam (DZP), phenobarbital (PB) or phenytoin (PHT). As a secondary investigation, 65 cases from nine institutes, which completely fulfilled these criteria and were treated with midazolam (MDL) or lidocaine (Lid) to stop seizures were examined more fully. Subtle seizure and generalized tonic-clonic seizure were the most frequent seizure types. Neonatal SE was most frequently associated with hypoxic-ischemic encephalopathy, followed by intraventricular hemorrhage, central nervous system infections, and cerebral infarction. The final treatment outcome was available for 72.7% and 81.3% of MDL- and Lid-treated patients, respectively. Adverse effects of MDL and Lid were identified in 7.3% and 6.3% of patients, respectively. To reveal electroclinical seizures, clinical seizures without ictal discharge or other non-epileptic movements in neonates was important for appropriate treatment. MDL and Lid were useful drugs for the treatment of neonatal SE.

Heart and respiration rate changes in the neonate during electroencephalographic seizure

An investigation of changes in the neonatal electrocardiogram (ECG) and respiration signals from labelled seizure data for five neonatal patient records is reported. A decrease during seizure of 5.70% in the mean RR-interval was found. The mean respiration rate per epoch was found to decrease by a mean 18.44% during seizure. No significant change in the RR-interval standard deviation or in the mean respiration amplitude during seizure was observed. These results raise the possibility of using ECG and respiration based methods instead of existing electrcoenceplogram (EEG) based methods, or in concert with EEG-based neonatal seizure detection methods to improve on previously reported seizure detection methods.

What is epilepsy? Clinical perspectives in the diagnosis and treatment

SUMMARY

The CINNR International Conference, "An Overview of Epilepsy Research: What, Where, When, and Why?," was designed to introduce epilepsy to the nonclinician interested in epilepsy research. This article discusses the clinical aspects of epilepsy, defines clinical terms associated with epilepsy and seizure disorders, and outlines the scope of the clinical problem and the issues that need clarification from a clinical perspective. Most importantly, it is hoped that this article will put a human face on this common disease.

Neonatal Seizures: Gaps Between the Laboratory and the Clinic

Seizures in neonates (NBs) remain the most frequent neurological problem in the nursery. Considerable debate about their consequences exists between data and deductions reached through animal experimentations and those obtained through clinical investigations. The main conflicting issues are whether seizures in NBs can plant the roots for epileptogenesis and cause long-term deficits. The purpose of this chapter is to evaluate both laboratory and clinical results.

METHODS

Clinical data will be presented, including a 20-year-long cohort of NBs. This will be followed by the main seminal discoveries obtained in neonatal models. The phenomenon of transient or persistent dysmaturity following NB seizures will be discussed in relation to etiological factors.

RESULTS

The findings and deductions from animal models support the notions that epileptogenesis and cognitive deficits result from NB seizures. These conclusions contrast with clinical investigations maintaining that NB seizures, per se, are symptomatic markers of preexisting or of ongoing morbidities. The reasons for contrasting views will be discussed. Suggestions will be advanced for more animal models whose seizures are consistent with the etiologies and the phenotypes of human NB seizures.

Electrocardiogram Based Neonatal Seizure Detection

A method for the detection of seizures in the newborn using the electrocardiogram (ECG) signal is presented. Using a database of eight recordings, a method was developed for automatically annotating each 1-min epoch as "nonseizure" or "seizure". The system uses a linear discriminant classifier to process 41 heartbeat timing interval features. Performance assessment of the method showed that on a patient-specific basis an average accuracy of 70.5% was achieved in detecting seizures with associated sensitivity of 62.2% and specificity of 71.8%. On a patient-independent basis the average accuracy was 68.3% with sensitivity of 54.6% and specificity of 77.3%. Shifting the decision threshold for the patient-independent classifier allowed an increase in sensitivity to 78.4% at the expense of decreased specificity (51.6%), leading to increased false detections. The results of our ECG-based method are comparable with those reported for EEG-based neonatal seizure detection systems and offer the benefit of an easier acquisition methodology for seizure detection.

Application of Routine Monitoring Data for Determination of the Population Pharmacokinetics and Enteral Bioavailability of Phenytoin in Neonates and Infants With Seizures

This study investigated the population pharmacokinetics and the enteral bioavailability of phenytoin (PTN) in neonates and infants with seizures. Data from 83 patients were obtained retrospectively from medical records. A 1-compartment model was fitted to the log-transformed concentration data using NONMEM. Between-subject variability and interoccasion variability were modelled exponentially together with a log transform, both-sides exponential residual unexplained variance model. Covariates in nested models were screened for significance. Model robustness was assessed by bootstrapping with replacement (n = 500) from the study data. The parameters of the final pharmacokinetic model were clearance (L/h) = 0.826.[weight (WT, kg) / 70].[1 + 0.0692.(postnatal age (d) - 11)]; volume of distribution (L) = 74.2.[WT (kg) / 70]; absolute enteral bioavailability = 0.76; absorption rate constant (h) = 0.167. The between-subject variability for clearance and volume of distribution was 74.2% and 65.6%, respectively. The interoccasion variability for clearance was 54.4%. The unexplained variability was 51.1%. Final model parameter values deviated from median bootstrap estimates by less than 9%. Phenytoin disposition in neonates and infants can be described satisfactorily by linear pharmacokinetics. The values of allometrically scaled clearance and volume were similar to adult values, suggesting no major kinetic differences between adults and infants on the basis of size alone. Postnatal age independently influenced clearance. Switching from enteral to intravenous routes may require a dosage adjustment. The results of this study provide a basis for more rational prescribing of phenytoin in infants and neonates.

Brain white matter lesions correlated to newborns death and lethality

OBJECTIVES: to describe hospital lethality rates and factors correlated to death in neonates with brain white matter lesions. METHODS: a retrospective study was performed from January 1994 to December 2001. Neonates with white brain matter lesions were divided into survival and death groups and their medical files reviewed through the single blind method to determine evolution. Death certificates provided the cause of death. The groups were compared through correlation coefficients. Hospital lethality rate was calculated. RESULTS: ninety three cases of white brain matter lesions and seven deaths were determined. Hospital lethality rate was of 8.2.% (95%CI: 2.4-14.0) independently from lesion occurrence time, and of 10.3% (95%CI: 3.3-17.3) for deaths occurred during prenatal and perinatal periods. Death was correlated to: Apgar score, non-cephalic presentation, gestational age, hyperglicemia, hypercalcemia, convulsion, respiratory insufficiency and atelectasy. CONCLUSIONS: hospital lethality was of 10.3% generating the following hypothesis: perinatal asphyxia must be the principal direct and indirect etiologic factor (aggravating the expression of prematurity and infection diseases), of prenatal and perinatal mortality among newborns with white brain matter lesions; and <7 Apgar score in the 5th minute associated to brain white matter lesions, are markers for perinatal asphyxia diagnosis.

Seizure detection algorithm for neonates based on wave-sequence analysis

OBJECTIVE

The description and evaluation of the performance of a new real-time seizure detection algorithm in the newborn infant.

METHODS

The algorithm includes parallel fragmentation of EEG signal into waves; wave-feature extraction and averaging; elementary, preliminary and final detection. The algorithm detects EEG waves with heightened regularity, using wave intervals, amplitudes and shapes. The performance of the algorithm was assessed with the use of event-based and liberal and conservative time-based approaches and compared with the performance of Gotman's and Liu's algorithms.

RESULTS

The algorithm was assessed on multi-channel EEG records of 55 neonates including 17 with seizures. The algorithm showed sensitivities ranging 83-95% with positive predictive values (PPV) 48-77%. There were 2.0 false positive detections per hour. In comparison, Gotman's algorithm (with 30s gap-closing procedure) displayed sensitivities of 45-88% and PPV 29-56%; with 7.4 false positives per hour and Liu's algorithm displayed sensitivities of 96-99%, and PPV 10-25%; with 15.7 false positives per hour.

CONCLUSIONS

The wave-sequence analysis based algorithm displayed higher sensitivity, higher PPV and a substantially lower level of false positives than two previously published algorithms.

SIGNIFICANCE

The proposed algorithm provides a basis for major improvements in neonatal seizure detection and monitoring.

Multi-channel EEG based neonatal seizure detection

A multi-channel method for patient specific and patient independent, EEG based neonatal seizure detection is presented. Two classifier configurations are proposed and tested, along with a number of classifier models. Existing methods for neonatal seizure detection have been empirical threshold based or based on a single EEG channel. The optimum patient specific classifier for EEG based neonatal seizure detection was found to be an Early Integration configuration employing a linear discriminant classifier model. This yielded a mean classification accuracy of 74.66% for 11 neonatal records. The optimum patient independent classifier was an Early Integration configuration with a linear discriminant classifier model giving a mean accuracy of 72.81%

Migrating partial seizures in infancy: expanding the phenotype of a rare seizure syndrome

PURPOSE

The constellation of early-onset, unprovoked, alternating electroclinical seizures and neurodevelopmental devastation was first described by Coppola et al. We report six new patients and the prospect of a more optimistic developmental outcome.

METHODS

Retrospective chart reviews were performed on six infants evaluated at the Children's Hospital of Philadelphia (five patients) and at Hershey Medical Center (one patient) who had electroclinically alternating seizures before age 6 months of age. Electroclinical characteristics and long-term follow-up were recorded.

RESULTS

All had unprovoked, early-onset (range, 1 day to 3 months; mean, 25 days) intractable electroclinical seizures that alternated between the two hemispheres. Each patient underwent comprehensive brain imaging and neurometabolic workups, which were unrevealing. In all patients, subsequently intractable partial seizures developed and often a progressive decline of head circumference percentile occurred with age. Three demonstrated severe developmental delay and hypotonia. All survived, and 7-year follow-up on one patient was quite favorable.

CONCLUSIONS

Our patients satisfied the seven major diagnostic criteria first described by Coppola et al. The prognosis of this rare neonatal-onset epilepsy syndrome from the original description and subsequent case reports was very poor, with 28% mortality, and the majority of survivors were profoundly retarded and nonambulatory. Our patient data validate the diagnostic criteria of this syndrome and further quantify a previously described observation of progressive decline of head circumference percentiles with age. Our data also suggest that the prognosis of this syndrome, although poor, is not as uniformly grim as the cases reported previously in the literature.

Indications de l'électroencéphalogramme en période néonatale

The electroencephalogram (EEG), an easy-to-use and non invasive cerebral investigation, is a useful tool for diagnosis and early prognosis in newborn babies. In newborn full term babies manifesting abnormal clinical signs, EEG can point focal lesions or specific aetiology. EEG background activity and sleep organization have a high prognostic value. Tracings recorded over long period can detect seizures, with or without clinical manifestations, and differentiate them from paroxysmal non epileptic movements. The EEG should therefore be recorded at the beginning of the first symptoms, and if possible before any seizure treatment. When used as a neonatal prognostic tool, EEG background activity is classified as normal, abnormal (type A and type B discontinuous and hyperactive rapid tracing) or highly abnormal (inactive, paroxysmal, low voltage plus theta tracing). In such cases, the initial recording must be made between 12 and 48 h after birth, and then between 4 and 8 days of life. Severe EEG abnormalities before 12 h of life have no reliable prognostic value but may help in the choice of early neuroprotective treatment of acute cerebral hypoxia-ischemia. During presumed hypoxic-ischemic encephalopathy, unusual EEG patterns may indicate another diagnosis. In premature newborn babies (29-32 w GA) with neurological abnormalities, EEG use is the same as in term newborns. Without any neurological abnormal sign, EEG requirements depend on GA and the mother's or child's risk factors. Before 28 w GA, when looking for positive rolandic sharp waves (PRSW), EEG records are to be acquired systematically at D2-D3, D7-D8, 31-32 and 36 w GA. It is well known that numerous and persistent PRSW are related to periventricular leukomalacia (PVL) and indicate a bad prognosis. In babies born after 32 GA with clinically severe symptoms, an EEG should be performed before D7. Background activity, organization and maturation of the tracing are valuable diagnosis and prognosis indicators. These recommendations are designed (1) to get a maximum of precise informations from a limited number of tracings and (2) to standardize practices and thus facilitate comparisons and multicenter studies.

Wavelet analysis for neonatal electroencephalographic seizures

Electroencepholographs (EEGs) of neonatal seizures differ from those of children and adults. This study evaluated whether wavelet transform analysis, a nonstationary frequency analysis of EEG, can recognize and characterize neonatal seizures. Twenty-second segments were analyzed from 69 EEG seizures in 15 neonatal patients whose seizures lasted 10 seconds or longer. The wavelet transform results were examined, as were EEG seizure durations and dominant frequencies. The wavelet transform results were correlated with the occurrence, after an 18-month follow-up, of postneonatal seizures. Wavelet transform analysis identified 40 seizures (58%) with a "sustained dominant frequency component" that lasted 10 seconds or longer and 29 seizures without a sustained dominant frequency component. The mean seizure duration of the 40 seizures with sustained dominant frequency components was 63.3 seconds, longer than the mean duration (33.6 seconds) of the seizures without sustained dominant frequency components, P < 0.01. Eleven patients manifested postneonatal epileptic seizures. Fifty-two EEG seizures in these 11 patients revealed more sustained dominant frequency components (74%) than 17 seizures in the 4 patients without postneonatal seizures (only 12%), P < 0.05. Wavelet transform analysis can identify neonatal EEG seizures and characterize their epileptic components. The presence of sustained dominant frequency components may predict postneonatal epileptic seizures.

Neonatal seizures: the overlap between diagnosis of metabolic disorders and structural abnormalities. Case report

Inborn metabolic errors (IME) and cortical developmental malformations are uncommon etiologies of neonatal seizures, however they may represent treatable causes of refractory epilepsy and for this reason must be considered as possible etiological factors. This case report aims to demonstrate the importance of neuroimaging studies in one patient with neonatal seizures, even when there are clues pointing to a metabolic disorder.

CASE REPORT

A previously healthy 14 day-old child started presenting reiterated focal motor seizures (FMS) which evolved to status epilepticus. Exams showed high serum levels of ammonia and no other abnormalities. A metabolic investigation was conducted with normal results. During follow-up, the patient presented developmental delay and left side hemiparesia. Seizures remained controlled with anti-epileptic drugs for four months, followed by relapse with repetitive FMS on the left side. Temporary improvement was obtained with anti-epileptic drug adjustment. At the age of 6 months, during a new episode of status epilepticus, high ammonia levels were detected. Other metabolic exams remained normal. The child was referred to a video-electroencephalographic monitoring and continuous epileptiform discharges were recorded over the right parasagittal and midline regions, with predominance over the posterior quadrant. A new neuroimaging study was performed and displayed a malformation of cortical development. Our case illustrates that because newborns are prone to present metabolic disarrangement, an unbalance such as hyperammonemia may be a consequence of acute events and conduct to a misdiagnosis of IME.