Identification of infants at risk for infantile spasms by neonatal polygraphy

Could prevention of infantile spasms have been possible in a historical cohort of 31 tuberous sclerosis patients?

Efforts to prevent epilepsy in infants with tuberous sclerosis complex (TSC) has been the focus of EPISTOP.

PURPOSE

The present study was carried out to evaluate whether prevention could have been realistic.

METHODS

A retrospective analysis by hospital chart review of 31 patients with TSC and infantile spasms (practically all patients) admitted to two tertiary hospitals, Children's Hospital, University of Helsinki and Kuopio in 1980-2000. Clinical history, early cognitive development, early clinical signs of TSC, clinical signs of suspicious seizures, first seizures and EEG, response to adrenocorticotropic hormone (ACTH) therapy, EEG and brain imaging were evaluated.

RESULTS

Early development prior the spasms was apparently normal in 25 (80%). The first EEG ever performed for a child showed hypsarrhythmia in 16 (51%) or modified hypsarrhythmia in 10 (32%). Treatment lag was short (0-4, mean 2 weeks) and the primary response to ACTH favorable in 19 (64%). Etiological diagnostic workup of IS revealed TSC. In one single case (3%) the diagnosis of TSC could be made at birth due to a congenital cardiac rhabdomyoma. Three other rhabomyomas were diagnosed later. In brain imaging, subependymal periventricular calcifications or hypodense areas were seen in every patient at onset of IS. Other organ manifestations of TSC were retinal phakomas (6), polycystic kidneys (2), and renal angiolipomatosis (1).

CONCLUSIONS

Preventive treatment of epileptic discharges could have been possible in a single case of neonatal rhabdomyoma suggesting that preventive treatment is challenging in everyday practice. The main obstacle is the delay of TSC diagnosis.

Modifying genetic epilepsies - Results from studies on tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous disorder affecting approximately 1 in 6,000 in general population and represents one of the most common genetic causes of epilepsy. Epilepsy affects 90% of the patients and appears in the first 2 years of life in the majority of them. Early onset of epilepsy in the first year of life is associated with high risk of cognitive decline and neuropsychiatric problems including autism. Recently TSC has been recognized as a model of genetic epilepsies. TSC is a genetic condition with known dysregulated mTOR pathway and is increasingly viewed as a model for human epileptogenesis. Moreover, TSC is characterized by a hyperactivation of mTOR (mammalian target of rapamycin) pathway, and mTOR activation was showed to be implicated in epileptogenesis in many animal models and human epilepsies. Recently published studies documented positive effect of preventive or disease modifying treatment of epilepsy in infants with high risk of epilepsy with significantly lower incidence of epilepsy and better cognitive outcome. Further studies on preventive treatment of epilepsy in other genetic epilepsies of early childhood are considered. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

WONOEP appraisal: Development of epilepsy biomarkers-What we can learn from our patients?

OBJECTIVE

Current medications for patients with epilepsy work in only two of three patients. For those medications that do work, they only suppress seizures. They treat the symptoms, but do not modify the underlying disease, forcing patients to take these drugs with significant side effects, often for the rest of their lives. A major limitation in our ability to advance new therapeutics that permanently prevent, reduce the frequency of, or cure epilepsy comes from a lack of understanding of the disease coupled with a lack of reliable biomarkers that can predict who has or who will get epilepsy.

METHODS

The main goal of this report is to present a number of approaches for identifying reliable biomarkers from observing patients with brain disorders that have a high probability of producing epilepsy.

RESULTS

A given biomarker, or more likely a profile of biomarkers, will have both a quantity and a time course during epileptogenesis that can be used to predict who will get the disease, to confirm epilepsy as a diagnosis, to identify coexisting pathologies, and to monitor the course of treatments.

SIGNIFICANCE

Additional studies in patients and animal models could identify common and clinically valuable biomarkers to successfully translate animal studies into new and effective clinical trials.

Tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that affects multiple organ systems and is caused by loss-of-function mutations in one of two genes: TSC1 or TSC2. The disorder can affect both adults and children. First described in depth by Bourneville in 1880, it is now estimated that nearly 2 million people are affected by the disease worldwide. The clinical features of TSC are distinctive and can vary widely between individuals, even within one family. Major features of the disease include tumours of the brain, skin, heart, lungs and kidneys, seizures and TSC-associated neuropsychiatric disorders, which can include autism spectrum disorder and cognitive disability. TSC1 (also known as hamartin) and TSC2 (also known as tuberin) form the TSC protein complex that acts as an inhibitor of the mechanistic target of rapamycin (mTOR) signalling pathway, which in turn plays a pivotal part in regulating cell growth, proliferation, autophagy and protein and lipid synthesis. Remarkable progress in basic and translational research, in addition to several randomized controlled trials worldwide, has led to regulatory approval of the use of mTOR inhibitors for the treatment of renal angiomyolipomas, brain subependymal giant cell astrocytomas and pulmonary lymphangioleiomyomatosis, but further research is needed to establish full indications of therapeutic treatment. In this Primer, we review the state-of-the-art knowledge in the TSC field, including the molecular and cellular basis of the disease, medical management, major knowledge gaps and ongoing research towards a cure.

EEG abnormalities preceding the epilepsy onset in tuberous sclerosis complex patients - a prospective study of 5 patients

Tuberous sclerosis complex (TSC) is a multisystem, autosomal dominant disorder characterized by multiple hamartomas development. Epilepsy is the most common symptom appearing in 80-90% of the patients mainly in the first year of life. A prompt and early seizure control is crucial and can prevent development of an epileptic encephalopathy and secondary mental retardation. Therefore the very early identification of seizures seems to be of a great importance. We present the cases of 5 patients diagnosed with TSC prenatally or perinatally and regularly monitored (at 4-6 weeks intervals) with EEG before the epilepsy onset. The patients' age at baseline varied from 9 days to 9 weeks. In all of the patients epileptiform discharges preceded the epilepsy onset. The time interval between abnormality detection on EEG and the epilepsy onset varied from 1 to 8 days. The patient's age at the epilepsy onset ranged from the 17th day to the 5th month of life. In one patient the EEG was abnormal from the beginning and in this patient the epileptic seizures started from the neonatal period. In the rest of the patients (4/5) the EEG remained normal throughout the first months of life. In all of the children epilepsy started with focal motor seizures. Our study is the first prospective one showing the results of the EEG monitoring in TSC patients and the natural evolution of the EEG patterns in patients with the seizures types other than infantile spasms.

Prolonged EEG depression in term and near-term infants with hypoxic ischemic encephalopathy and later development of West syndrome

PURPOSE

This study was performed to clarify the relationship between prolonged depression of electroencephalography (EEG) in term and near-term infants with hypoxic ischemic encephalopathy (HIE) and the later development of West syndrome (WS).

METHODS

We investigated 17 term and near-term infants with HIE. Inclusion criteria were as follows: ≥35 weeks of gestation, clinical signs of HIE, magnetic resonance imaging (MRI) lesions corresponding to HIE, assessment of outcome at >18 months of age, depression of EEG, and serial EEG examinations. The 17 infants were divided into the following two groups: Group A (n = 4) with prolonged EEG depression over 21 days of age, and group B (n = 13) with disappearance of EEG depression by 21 days of age.

RESULTS

WS developed in all four infants in group A, but in only one of 13 infants in group B. WS occurred significantly more frequently in group A than in group B. For the prediction of subsequent development of WS, prolonged EEG depression over 21 days of age showed sensitivity of 0.80 and specificity of 1.0. In both groups, abnormal irregular faster waves with or without EEG depression were seen in 11 infants between 2 and 28 days of age. They had no significant relationship with WS, but were significantly related to an adverse developmental outcome.

CONCLUSIONS

Prolonged depression of EEG over 21 days of age in term or near-term infants with HIE is a valuable predictor of the later development of WS.

Electroencephalographic evolution of hypsarrhythmia: toward an early treatment option

PURPOSE

A retrospective study for a classification of prehypsarrhythmic elecroencephalographies (EEGs) was carried out to enable an early treatment option for West syndrome.

METHODS

Out of 39 infants with symptomatic West syndrome, 18 infants (age 3-14 months) with 61 serial non-REM sleep EEG records of the prehypsarrhythmic phase were identified. The prehypsarrhythmic phase encompassed 2 to 13 months (mean 4.5 months) after an initial insult. A classification system of three EEG types corresponding to the clinical states prior to West syndrome occurrence was developed. In addition, follow-up of all patients presenting with type 2 EEGs (n = 22) was evaluated.

RESULTS

Three clinical states and corresponding EEG types were classified. Clinical state 1 (weeks to months, silent phase) presented with (multi-)focal epileptic discharges <50% of the non-REM EEG recording time (type 1 EEG). Clinical state 2 (several weeks, beginning mental deterioration) was accompanied by type 2 EEG with bihemispheric epileptic discharges >50% of the non-REM EEG recording time within abnormal background activity (imminent hypsarrhythmia). Clinical state 3 (mental deterioration) was characterized by hypsarryhthmia. Interrater reliability of seven blinded raters was good (median weighted kappa 0.67). Out of 22 patients presenting with type 2 EEGs, two were lost for follow-up, and 16 developed West syndrome, whereas four were treated early with anti-epileptic drugs and remained stable.

CONCLUSIONS

Infants with West syndrome could be reliably identified several weeks before the occurrence of hypsarrhythmia by a typical EEG pattern (type 2), thereby opening the way for early intervention studies.

Epilepsy development in infancy with epileptic discharges

As a part of the study to prevent West syndrome (WS) by early treatment, we assessed what kind of epilepsy developed in infants who showed epileptic discharges in early infancy. EEG examinations were performed on 116 infants born from 1997 to September 2004, both before and after 3 months of corrected age (CA). We divided 45 infants who showed epileptic discharges in early infancy into two groups according to the existence of periventricular leukomalacia (PVL) and retrospectively performed the course observation at the survey point on April 1 in 2005. Out of 45 infants showing epileptic discharges in early infancy, 26 developed WS. Compared with infants without PVL, infants with PVL were more likely to develop WS than infants without PVL. Furthermore, infants with PVL were more likely to develop WS than other types of epilepsy. Namely, 11 out of 17 infants with PVL developed WS at the survey point. All infants with WS showed initial epileptic discharges before 5 months of corrected age (CA), and most of them (except for five) had initial epileptic discharges before 3 months of CA. There were two infants who once developed hypsarrhythmia on EEG; however, after starting VPA therapy, they did not develop WS with the improvement of EEG findings, and one was presented here in detail. We proposed that preterm infants with PVL who showed epileptic discharges before 3 months of CA should be treated by antiepileptic drugs to prevent the onset of WS syndrome.

The predictive value of electroencephalogram during early infancy for later development of West syndrome in infants with cystic periventricular leukomalacia

PURPOSE

The aim of this study was to elucidate a predictive value of electroencephalogram (EEG) during early infancy for later development of West syndrome (WS) in premature infants with cystic periventricular leukomalacia (PVL).

METHODS

The subjects of this study were 19 infants with cystic PVL born between 1992 and 1996. EEGs were recorded at 3 months of corrected age (CA) in all of them. We divided these 19 infants into the following two groups; group A (n = 9), no paroxysmal discharge was recognized; and group B (n = 10), paroxysmal discharges were recognized.

RESULTS

In none of the infants in group A did WS develop. Subsequent EEGs were normal in all infants in group A. WS developed in seven of 10 infants in group B. The occurrence of WS is significantly higher in group B than in group A. The mean age at the onset of WS was 6 months of CA. Paroxysmal discharges in infants in group B were observed as irregular spikes-and-waves and polyspikes-and-waves, mainly in bilateral parietooccipital areas. In seven of eight patients with severe MRI findings in group B, WS developed.

CONCLUSIONS

Paroxysmal discharges during early infancy were correlated with later development of WS in infants with cystic PVL. The possibility of developing WS had increased in the children with the combination with EEG and MRI findings.

Clinico-electrical evolution in pre-hypsarrhythmic stage: towards prediction and prevention of West syndrome

We investigated serial electroencephalographic (EEG) changes before the onset of spasms in patients with West syndrome (WS) due to perinatal injury in order to determine whether one can predict WS or not. In preterm infants with periventricular leukomalacia (PVL), depression of EEG activities is commonly followed by disorganized pattern during the early neonatal period. Disorganized patterns persist until the late neonatal period, but epileptiform discharges do not appear. Epileptiform discharges usually appear during early infancy in infants who later develop WS. As the onset of WS was relatively later in preterm infants with PVL, it may be possible to select the patients at risk for secondary prevention of WS with sufficient treatment period. In term infants with hypoxic-ischemic encephalopathy, all EEGs during the neonatal period did not reveal epileptiform discharges in the majority of patients. Multifocal spikes were very likely to be observed during early infancy, but hypsarrhythmia was observed immediately after their appearance. It is not always easy to select patients for prevention of WS with sufficient treatment period.

[West syndrome: clinical and electroencephalographic follow up of 70 patients and response to its treatment with adrenocorticotropic hormone, prednisone, vigabatrin, nitrazepam and valproate]

In a retrospective study we assessed the outcome of the criptogenic and symptomatic forms of West syndrome and evaluated the efficacy of adrenocorticotropic hormone, vigabatrin, prednisone, valproate and nitrazepam in the spasms control. Seventy patients were follwed up by 2 years. Twelve (17%) were criptogenics and 58 (83%) symptomatics. In criptogenic group significantly more patients were in regular school classes and with normal motor development, better control of seizure, less tendency to evoluate to Lennox Gastaut syndrome and 83. 3% had control of spasms (72.4% of patients from symptomatic group had control of spasms). Adrenocorticotropic hormone and vigabatrin were the most efective drugs, with 68.75% and 60% of spasms control, respectivelly, when used as first line of therapy and 75% and 50%, respectivelly, as second line of therapy.

EEG background as predictor of electrographic seizures in high-risk neonates

PURPOSE

Experience with continuous EEG monitoring in 29 consecutive infants at risk of neonatal seizures demonstrated that background abnormalities on the initial EEG were strongly associated with electrographic seizures in the subsequent 18-24 h. To test this association prospectively, we examined the relationship between EEG background and the presence of electrographic seizures in the next 22 at-risk infants monitored for seizures.

METHODS

A standard EEG was recorded for each infant at risk for seizures. Based on specific criteria, the background was graded as normal; immature for age; or mildly, moderately, or severely abnormal. The EEG was then monitored continuously until no electrographic seizures were recorded for 18-24 h.

RESULTS

Findings in the retrospective group of 29 infants and the prospective group of 22 infants did not differ. For the combined 51 infants, a normal or immature initial EEG background predicted the absence of seizures in the subsequent 18-24 h with a sensitivity of 96% [confidence interval (CI) 0.88, 1.0] and specificity of 81% (CI 0.67, 0.96). Administration of antiepileptic drugs (AEDs) before the start of the EEG recording did not affect this association.

CONCLUSIONS

In 51 consecutively monitored infants at risk for neonatal seizures, a normal or immature EEG background strongly predicted the absence of electrographic seizures in the subsequent 18-24 h; background abnormalities strongly predicted the occurrence of electrographic seizures concomitantly or in the subsequent 18-24 h of recording. Screening infants at risk for neonatal seizures with a routine EEG allows identification of infants at highest risk for seizures, thus conserving resources required for continuous EEG monitoring and facilitating early intervention for seizures.

West syndrome following deep hypothermic infant cardiac surgery

Postoperative seizures are among the more common complications of cardiac surgery in children. These seizures have traditionally been considered benign, transient phenomena with little, if any, prognostic significance. We report 4 infants with early postoperative seizures following cardiac surgery who later developed the previously unreported complication of West syndrome, with infantile spasms, hypsarrhythmia, and developmental delay. This group constitutes 6% of 67 infant spasms evaluated over a 5-year period at Boston Children's Hospital. The postoperative seizures in these 4 patients were more difficult than usual to control with antiepileptic therapy; otherwise no intra- or perioperative features distinguished these infants who later developed West syndrome from infants with apparently benign "postpump seizures."

Visual abnormalities and occipital EEG discharges: risk factors for West syndrome

Seventeen infants (7 boys and 10 girls) with visual abnormalities (such as poor tracking and following and nystagmoid eye movement) and occipital slow activities with irregular polyspikes on EEG were studied. Two thirds of the children showed development of West syndrome with hypsarrhythmia on follow-up EEG. In 1 child, hypsarrhythmia was evident on the follow-up EEG, but no clinical seizures occurred. Because most of the children in our series developed West syndrome, patients with visual abnormalities associated with occipital EEG discharges in early infancy may be at high risk for West syndrome. Occipital abnormalities in early infancy may relate to the occurrence of West syndrome.

The epidemiology and natural history of infantile spasms

Few population-based studies of infantile spasms have been done, and most reports have not included comparison groups. In spite of these limitations, this review attempts to summarize what is known about the distribution, etiology, and natural history of infantile spasms in populations; discusses the limitations of current data; and includes suggestions for further population-based research. Most estimates of the incidence of infantile spasms are between 0.25 and 0.42 per 1000 live births per year. Among children less than 10 years of age, the annual prevalence of infantile spasms is 0.14 to 0.19 per 1000. The peak age at onset of spasms is 4 to 6 months, and there appears to be a slight excess of male cases. The etiology of infantile spasms is unknown for 40% to 50% of affected children. Selected syndromes (eg, Aicardi syndrome, Down syndrome, etc) and inherited disorders (eg, tuberous sclerosis) may account for as many as one third of cases. Other factors, such as intrauterine infection, "birth injury," and head trauma have not been systematically evaluated, and thus, their contribution to the etiology of infantile spasms is uncertain. Areas for future etiologic research include controlled studies of immunologic factors and in utero and postnatal infections and further exploration of the interrelationship between infantile spasms and Lennox-Gastaut syndrome.

Preliminary report of a multi-center study on the West syndrome

During a 12-month period, 54 infants with the West syndrome (10 idiopathic, 44 symptomatic) referred to 10 major children's hospitals for initial treatment were evaluated to obtain comprehensive data on clinical findings and current treatment modalities. Prominent features included prevalence of prenatal and perinatal etiologies, severe neurological deficits and disturbed psychomotor development as well as patient-specific spectrum of seizure manifestations. Characteristic behavioural abnormalities before onset of spasms are an early indicator for the West syndrome. Therapeutic management varied considerably. Response to ACTH/steroid regiments was more favourable than to non-ACTH/steroid regimens. The most frequent serious adverse reactions during the initial treatment period were arterial hypertension and infections. Improved therapeutic strategies based on detailed initial patient assessment and systematic monitoring of beneficial effects and adverse reactions are necessary for future trials.