Infantile spasms in tuberous sclerosis complex: prognostic utility of EEG

Does the absence or presence of sleep spindles on EEG have prognostic value for cognitive outcome in children with infantile epileptic spasms syndrome? A systematic literature review

Infantile Epileptic Spasms Syndrome (IESS) is an epileptic encephalopathy in childhood that affects infants under the age of two years. When spasm series occur, prognosis for cognitive outcome is poor in the majority of cases. The encephalopathy in IESS includes delayed maturation of normal sleep phenomena in the EEG, such as sleep spindles. Children with intellectual disabilities often have abnormal sleep, and children with sleep problems have difficulties learning at school. We examined whether there is evidence of prognostic value of detection of sleep spindles in the EEG of children with IESS on their future cognitive development. A systematic literature search yielded five studies touching this question. They were evaluated by two scorers independently. The lack of normal sleep patterns including lack of sleep spindles was used as a biomarker of poor cognitive outcome. Positive (PPV) and Negative (NPV) prognostic values were calculated. A summary of all five studies indicates a PPV of 82% and an NPV of 45%. Given the small amount of data, the retrospective quality of most studies, and the differences in the outcome parameters reported, it is prudent to say that currently available data do not allow us to conclude whether spindles have a specific and independent role in the cognitive prognosis of affected children. Since sleep spindles are needed for memory consolidation and demonstrate the active role of sleep for learning and memory, the hypothesis remains that their absence in the EEG may indicate an increased risk of cognitive delay, but more supporting data are needed to reach such a firm conclusion.

Neurofibromatosis type1, type 2, tuberous sclerosis and Von Hippel-Lindau disease

Neurocutaneous syndromes (also known as phakomatoses) are heterogenous group of disorders that involve derivatives of the neuroectoderm. Each disease has diagnostic and pathognomonic criteria, once identified, thorough clinical examination to the patient and the family members should be done. Magnetic resonance imaging (MRI) is used to study the pathognomonic findings withing the CNS (Evans et al. in Am J Med Genet A 152A:327-332, 2010). This chapter includes the 4 most common syndromes faced by neurosurgeons and neurologists; neurofibromatosis types 1 and 2, tuberous sclerosis and Von Hippel-Lindau disease. Each syndrome has specific genetic anomaly that involves a tumor suppressor gene and the loss of inhibition of specific pathways. The result is a spectrum of cutaneous manifestations and neoplasms.

Sleep architecture in neonatal and infantile onset epilepsies in the first six months of life: A scoping review

AIM

Epilepsy occurs in approximately 80 per 100,000 infants in the first year of life, ranging in severity from self-limited and likely to spontaneously resolve, to severe developmental and epileptic encephalopathies. Sleep plays a key role in early brain development and the reciprocal relationship between sleep and seizures is not yet fully understood, particularly in young children. We conducted a Scoping Review to synthesise current knowledge of sleep architecture in neonates and infants with epilepsy.

METHOD

Peer-reviewed publications from 2005 to 2022 describing sleep architecture in infants up to six months of age with unprovoked seizures were included. The analysis set was derived from EMBASE, Web of Science and PubMED using key terms "sleep, epilepsy and infant" and related descriptors. Inclusion criteria were prospectively described in a Scoping Review protocol. Sleep architecture was assessed as macro- and micro-structural elements.

RESULTS

21 publications were included in the qualitative analysis. In self-limited familial and genetic epilepsy, sleep macrostructure was generally preserved. In DEEs and in epileptic encephalopathies of genetic or structural aetiology, sleep architecture was significantly disrupted.

INTERPRETATION

Early identification of infants with epilepsy is important to ensure early and effective treatment. In the DEE spectrum, sleep architecture is significantly impacted, and abnormal sleep architecture may be associated with compromised developmental outcome. Further research is needed to identify the sequence of events in abnormal brain development, epilepsy and sleep disruption and potentially help to predict the course of epilepsy towards a self-limited epilepsy versus a DEE.

GluN2C selective inhibition is a target to develop new antiepileptic compounds

OBJECTIVE

Many early-onset epilepsies present as developmental and epileptic encephalopathy associated with refractory seizures, altered psychomotor development, and disorganized interictal cortical activity. Abnormal upregulation of specific N-methyl-d-aspartate receptor (NMDA-R) subunits is being disentangled as one of the mechanisms of severe early-onset epilepsies. In tuberous sclerosis complex (TSC), upregulation of the GluN2C subunit of the NMDA-R with slow deactivation kinetic results in increased neuronal excitation and synchronization.

METHODS

Starting from an available GluN2C/D antagonist, NMDA-R-modulating compounds were developed and screened using a patch clamp on neuronal culture to select those with the strongest inhibitory effect on glutamatergic NMDA currents. For these selected compounds, blood pharmacokinetics and passage through the blood-brain barrier were studied. We tested the effect of the most promising compounds on epileptic activity in Tsc1^+/- mice brain slices with multielectrode array, and then in vivo at postnatal ages P14-P17, comparable with the usual age at epilepsy onset in human TSC.

RESULTS

Using a double-electrode voltage clamp on isolated NMDA currents, we identified the most prominent antagonists of the GluN2C subunit with no effect on GluN2A as a means of preventing side effects. The best compound passing through the blood-brain barrier was selected. Applied in vivo in six Tsc1^+/- mice at P14-P17, this compound reduced or completely stopped spontaneous seizures in four of them, and decreased the background activity disorganization. Furthermore, ictal-like discharges stopped on a human brain sample from an infant with epilepsy due to TSC.

INTERPRETATION

Subunit-selective inhibition is a valuable target for developing drugs for severe epilepsies resulting from an upregulation of NMDA-R subunit-mediated transmission.

Pharmacotherapy for Seizures in Tuberous Sclerosis Complex

Epilepsy is one of the main symptoms affecting the lives of individuals with tuberous sclerosis complex (TSC), causing a high rate of morbidity. Individuals with TSC can present with various types of seizures, epilepsies, and epilepsy syndromes that can coexist or appear in relation to age. Focal epilepsy is the most frequent epilepsy type with two developmental and epileptic encephalopathies: infantile spasms syndrome and Lennox-Gastaut syndrome. Active screening and early management of epilepsy is recommended in individuals with TSC to limit its consequences and its impact on quality of life, cognitive outcome and the economic burden of the disease. The progress in the knowledge of the mechanisms underlying epilepsy in TSC has paved the way for new concepts in the management of epilepsy related to TSC. In addition, we are moving from traditional "reactive" and therapeutic choices with current antiseizure medications used after the onset of seizures, to a proactive approach, aimed at predicting and preventing epileptogenesis and the onset of epilepsy with vigabatrin, and to personalized treatments with mechanistic therapies, namely mechanistic/mammalian target of rapamycin inhibitors. Indeed, epilepsy linked to TSC is one of the only epilepsies for which a predictive and preventive approach can delay seizure onset and improve seizure response. However, the efficacy of such interventions on long-term cognitive and psychiatric outcomes is still under investigation.

Factors associated with autism spectrum disorder in children with tuberous sclerosis complex: a systematic review and meta-analysis

AIM

To investigate associations between clinical factors and the development of autism spectrum disorder (ASD) in children with tuberous sclerosis complex (TSC), specifically seizures, electroencephalogram abnormalities, tubers and other neurostructural abnormalities, and genetic factors.

METHOD

MEDLINE, Embase, PubMed, the Cochrane Library, and Web of Science were searched until January 2019. Studies that considered the predefined factors for development of ASD in children with TSC were included, following PRISMA-P guidelines. Two authors independently reviewed titles, abstracts, and full texts, extracted data, and assessed risk of bias.

RESULTS

Forty-two studies with 3542 children with TSC were included. ASD was associated with a history of seizures (odds ratio [OR] 3.79, 95% confidence interval [CI] 1.77-8.14), infantile spasms compared with other seizure types (OR 3.04, 95% CI 2.17-4.27), onset of any seizure type during infancy (OR 2.65, 95% CI 1.08-6.54), and male sex (OR 1.62, 95% CI 1.23-2.14). There was no association with tuber number, tuber location, or genotype.

INTERPRETATION

While a causal link between seizures and ASD in children with TSC cannot be inferred, a strong association between seizures and ASD in children with TSC, particularly with seizure onset during infancy and specifically infantile spasms, is present. Children with TSC and infant-onset seizures should be monitored for emerging features of ASD. What this paper adds Seizures and autism spectrum disorder (ASD) strongly associate in children with tuberous sclerosis complex (TSC). Infant-onset seizures and infantile spasms are particularly strongly associated with ASD in TSC.

Epilepsy Risk Prediction Model for Patients With Tuberous Sclerosis Complex

BACKGROUND

Individuals with tuberous sclerosis complex are at increased risk of epilepsy. Early seizure control improves developmental outcomes, making identifying at-risk patients critically important. Despite several identified risk factors, it remains difficult to predict. The purpose of the study was to evaluate the combined risk prediction of previously identified risk factors for epilepsy in individuals with tuberous sclerosis complex.

METHODS

The study group (n = 333) consisted of individuals with tuberous sclerosis complex who were enrolled in the Tuberous Sclerosis Complex Autism Center of Excellence Research Network and UT TSC Biobank. The outcome was defined as having an epilepsy diagnosis. Potential risk factors included sex, TSC genotype, and tuber presence. Logistic regression was used to calculate the odds ratio and P value for the association between each variable and epilepsy. A clinical risk prediction model incorporating all risk factors was built. Area under the curve was calculated to characterize the full model's ability to discriminate individuals with tuberous sclerosis complex with and without epilepsy.

RESULTS

The strongest risk for epilepsy was presence of tubers (95% confidence interval: 2.39 to 10.89). Individuals with pathogenic TSC2 variants were three times more likely (95% confidence interval: 1.55 to 6.36) to develop seizures compared with those with tuberous sclerosis complex from other causes. The combination of risk factors resulted in an area under the curve 0.73.

CONCLUSIONS

Simple characteristics of patients with tuberous sclerosis complex can be combined to successfully predict epilepsy risk. A risk assessment model that incorporates sex, TSC genotype, protective TSC2 missense variant, and tuber presence correctly predicts epilepsy in 73% of patients with tuberous sclerosis complex.

Treatment of Epilepsy Associated with Common Chromosomal Developmental Diseases

Chromosomal diseases are heterogeneous conditions with complex phenotypes, which include also epileptic seizures. Each chromosomal syndrome has a range of specific characteristics regarding the type of seizures, EEG findings and specific response to antiepileptic drugs, significant in the context of the respective genetic etiology. Therefore, it is very important to know these particularities, in order to avoid an exacerbation of seizures or some side effects. In this paper we will present a review of the epileptic seizures and antiepileptic treatment in some of the most common chromosomal syndromes.

Prognostic utility of hypsarrhythmia scoring in children with West syndrome after ketogenic diet

OBJECTIVE

The aim of this study was to evaluate the clinical efficacy and electroencephalographic (EEG) changes of West syndrome after ketogenic diet (KD) therapy and to explore the correlation of EEG features and clinical efficacy.

PATIENTS AND METHODS

We retrospectively studied 39 patients with West syndrome who accepted KD therapy from May 2011 to October 2017. Outcomes including clinical efficacy and EEG features with hypsarrhythmia severity scores were analyzed.

RESULTS

After 3 months of treatment, 20 patients (51.3%) had ≥50% seizure reduction, including 4 patients (10.3%) who became seizure-free. After 6 months of treatment, 4 patients remained seizure free, 12 (30.8%) had 90-99% seizure reduction, 8 (20.5%) had a reduction of 50-89%, and 15 (38.5%) had <50% reduction. Hypsarrhythmia scores were significantly decreased at 3 months of KD. They were associated with seizure outcomes at 6 months independent of gender, the course of disease and etiologies. Patients with a hypsarrhythmia score ≥8 at 3 months of therapy may not be benefited from KD.

CONCLUSION

Our findings suggest a potential benefit of KD for patients with drug-resistant West syndrome. Early change of EEG after KD may be a predictor of a patient's response to the therapy.

Increased electroencephalography connectivity precedes epileptic spasm onset in infants with tuberous sclerosis complex

OBJECTIVE

To identify whether abnormal electroencephalography (EEG) connectivity is present before the onset of epileptic spasms (ES) in infants with tuberous sclerosis complex (TSC).

METHODS

Scalp EEG recordings were collected prospectively in infants diagnosed with TSC in the first year of life. This study compared the earliest recorded EEG from infants prior to ES onset (n = 16) and from infants who did not develop ES (n = 28). Five minutes of stage II or quiet sleep was clipped and filtered into canonical EEG frequency bands. Mutual information values between each pair of EEG channels were compared directly and used as a weighted graph to calculate graph measures of global efficiency, characteristic path length, average clustering coefficient, and modularity.

RESULTS

At the group level, infants who later developed ES had increased EEG connectivity in sleep. They had higher mutual information values between most EEG channels in all frequency bands adjusted for age. Infants who later developed ES had higher global efficiency and average clustering coefficients, shorter characteristic path lengths, and lower modularity across most frequency bands adjusted for age. This suggests that infants who went on to develop ES had increased local and long-range EEG connectivity with less segregation of graph regions into distinct modules.

SIGNIFICANCE

This study suggests that increased neural connectivity precedes clinical ES onset in a cohort of infants with TSC. Overconnectivity may reflect progressive pathologic network synchronization culminating in generalized ES. Further research is needed before scalp EEG connectivity measures can be used as a potential biomarker of ES risk and treatment response in pre-symptomatic infants with TSC.

Management of epilepsy associated with tuberous sclerosis complex: Updated clinical recommendations

Patients with tuberous sclerosis complex (TSC) are at very high risk for developing epilepsy, and the majority experience seizure onset during the first year of life. Early targeted interventions increase the probability of seizure-freedom and may protect neurodevelopment. In 2012, clinical recommendations for the management of epilepsy in patients with TSC were published by a panel of European experts. Since that time novel studies, reports, and expert opinions in preclinical and clinical TSC-related sciences prompted the need for updated recommendations, including epileptogenesis in TSC, the potential role of predictive biomarkers, the possible benefits of presymptomatic diagnosis and preventive treatment, and new treatment options including mTOR inhibitors. A reconvened panel reviewed the current literature to answer specific questions and five panelists discussed the findings, followed by a general discussion during which all issues were debated to achieve consensus regarding recommendations. A draft manuscript based on these discussions and recommendations was then circulated several times among the panelists, who added their own comments. All the panelists/authors agreed with the final manuscript, which was then submitted for publication. The panel concluded that the need for early diagnosis of TSC-associated seizures is now established, electroencephalographic monitoring has good predictive value for epilepsy before seizure onset in TSC, and, until conclusive data from the EPISTOP trial are available, administration of vigabatrin may be considered in children with subclinical epileptiform EEG discharges. The panel also supported the role of adjunctive everolimus for TSC-associated drug-refractory seizures and emphasized the necessity of early surgical evaluation.

Epilepsy genetics: Current knowledge, applications, and future directions

The rapid pace of disease gene discovery has resulted in tremendous advances in the field of epilepsy genetics. Clinical testing with comprehensive gene panels, exomes, and genomes are now available and have led to higher diagnostic rates and insights into the underlying disease processes. As such, the contribution to the care of patients by medical geneticists, neurogeneticists and genetic counselors are significant; the dysmorphic examination, the necessary pre- and post-test counseling, the selection of the appropriate next-generation sequencing-based test(s), and the interpretation of sequencing results require a care provider to have a comprehensive working knowledge of the strengths and limitations of the available testing technologies. As the underlying mechanisms of the encephalopathies and epilepsies are better understood, there may be opportunities for the development of novel therapies based on an individual's own specific genotype. Drug screening with in vitro and in vivo models of epilepsy can potentially facilitate new treatment strategies. The future of epilepsy genetics will also probably include other-omic approaches such as transcriptomes, metabolomes, and the expanded use of whole genome sequencing to further improve our understanding of epilepsy and provide better care for those with the disease.

Early diagnosis of tuberous sclerosis complex: a race against time. How to make the diagnosis before seizures?

BACKGROUND

Tuberous sclerosis complex (TSC) is a genetic disorder with an incidence of 1:6000 live births and associated with the development of benign tumors in several organs. It is also characterized by high rates of neurological and neuropsychiatric abnormalities, including epilepsy affecting 70-90% of patients and being one of the major risk factors of intellectual disability. The first seizures in TSC patients appear usually between the 4th and the 6th months of life. Recent studies have shown the beneficial role of preventative antiepileptic treatment in TSC patients, with the possibility for improvement of cognitive outcome. Moreover, European recommendations suggest early introduction of Vigabatrin if ictal discharges occur on EEG recordings, with or without clinical manifestation. The aim of this study was to define the most useful approach to make the diagnosis of TSC before seizure onset (before age 4th months), in order to start early EEG monitoring with possible preventative treatment intervention.

METHODS

We performed a retrospective review of children who were suspected of having TSC due to single or multiple cardiac tumors as the first sign of the disease. We analyzed the medical records in terms of conducted clinical tests and TSC signs, which were observed until the end of the 4th month of age. Subsequently, we described the different clinical scenarios and recommendations for early diagnosis.

RESULTS

82/100 children were diagnosed with TSC within the first 4 months of life. Apart from cardiac tumors, the most frequently observed early TSC signs were subependymal nodules (71/100, 71%), cortical dysplasia (66/100, 66%), and hypomelanotic macules (35/100, 35%). The most useful clinical studies for early TSC diagnosis were brain magnetic resonance imaging (MRI), skin examination and echocardiography. Genetic testing was performed in 49/100 of the patients, but the results were obtained within the first 4 months of life in only 3 children.

CONCLUSIONS

Early diagnosis of TSC, before seizure onset, is feasible and it is becoming pivotal for epilepsy management and improvement of cognitive outcome. Early TSC diagnosis is mostly based on clinical signs. Brain MRI, echocardiography, skin examination and genetic testing should be performed early in every patient suspected of having TSC.

Prognostic Utility of Clinical Epilepsy Severity Score Versus Pretreatment Hypsarrhythmia Scoring in Children With West Syndrome

This cross-sectional study assessed the impact of clinical epilepsy severity and pretreatment hypsarrhythmia severity on epilepsy and cognitive outcomes in treated children with West syndrome. Thirty-three children, aged 1 to 5 years, with infantile spasms were enrolled if pretreatment EEG records were available, after completion of ≥1 year of onset of spasms. Neurodevelopment was assessed by Development Profile 3 and Gross Motor Function Classification System. Epilepsy severity in the past 1 year was determined by the Early Childhood Epilepsy Severity Score (E-Chess). Kramer Global Score of hypsarrhythmia severity was computed. Kramer Global Score (≤8) and E-Chess (≤9) in the past 1 year were associated with favorable epilepsy outcome but not neurodevelopmental or motor outcome.

Clinical and Electroencephalographic Characteristics of Infantile-Onset Epilepsies Caused by Genetic Mutations

OBJECTIVES

To determine whether certain characteristic electroencephalography (EEG) features are indicative of a genetic cause in early-life epilepsy.

STUDY DESIGN

We enrolled a total of 100 patients with infantile-onset (<3 years) epilepsy due to known genetic cause (n = 50) and nongenetic cause (acquired, structural, or unknown, n = 50). The genetic group was classified into synaptopathies, channelopathies, mTOR (mammalian target of rapamycin)-opathies, and chromosomal abnormalities. The nongenetic group included epilepsy of unknown cause and structural abnormalities such as brain tumor, focal cortical dysplasia and encephalomalacia. The clinical features, magnetic resonance imaging, and video EEG obtained before 3 years of age and again at follow-up were reviewed. Specifically, the background rhythms and patterns of interictal epileptiform discharges were analyzed to define the EEG characteristics.

RESULTS

The genetic group was more likely to have seizure recurrence beyond infancy and significant developmental delay (P <.01). The genetic and nongenetic groups showed different EEG patterns in the initial EEGs that persisted in follow-up EEGs. Diffuse slowing with pleomorphic focal/multifocal epileptiform discharges were present more often in the genetic (86%) compared with the nongenetic group (20%) in the initial EEGs (P <.01). The last available follow-up EEG features were similar (81% in genetic versus 17% in nongenetic) to the EEG performed prior to 3 years of age.

CONCLUSIONS

Our findings suggest a simple guide for genetic screening in children with early-onset epilepsy. Genetic testing may be indicated and useful in infants with delayed development, no obvious cause, and significant EEG background slowing with pleomorphic focal or multifocal epileptiform discharges.

An Overview of Autosomal Dominant Tumour Syndromes with Prominent Features in the Oral and Maxillofacial Region

Several autosomal dominant inherited tumour syndromes demonstrate prominent features in the oral and maxillofacial region. Although multiple organ systems are frequently involved, the target organs more frequently affected are the skin (nevoid basal cell carcinoma syndrome, Brooke-Spiegler syndrome, Birt-Hogg-Dube syndrome and Muir-Torre syndrome), gastrointestinal tract (Peutz-Jegher syndrome and Gardner syndrome) or endocrine system (multiple endocrine neoplasia type 2b and hyperparathyroidism-jaw tumour syndrome). In some syndromes, the disease is multisystem with skin index lesions presenting in the head and neck (Cowden syndrome and tuberous sclerosis complex). The pertinent features of these syndromes are reviewed with a systems-based approach, emphasising their clinical impact and diagnosis.

Long-term weekly ACTH therapy for relapsed West syndrome in tuberous sclerosis complex: A case report

BACKGROUND

In Japan, adrenocorticotropic hormone (ACTH) therapy has been the mainstay of treatment of West syndrome. Conventional ACTH therapy is administered short-term with efficacy, yet the relapse rate is high. Relapse after initial ACTH therapy is a poor prognostic factor for long-term seizure control and outcome of cognitive function. Here, we report successful long-term weekly ACTH therapy for relapsed WS in a tuberous sclerosis complex (TSC) child after conventional ACTH therapy.

PATIENT

The patient had a series of epileptic spasms (ES) and hypsarrhythmia at age 3 months. She was diagnosed with WS associated with TSC, and was treated with conventional ACTH therapy at age 4 months, and a second course of ACTH therapy at age 8 months. Both courses of therapy were transiently effective. A third course of ACTH therapy was started at age 1 year and 2 months, and long-term weekly ACTH therapy was continued thereafter. During this therapy, both ES and hypsarrhythmia remained completely resolved. Therapy was continued, and dose reduction was started when the patient was 2 years and 10 months old. No serious adverse events had occurred during this therapy.

CONCLUSION

This case demonstrated that long-term weekly ACTH may be safe and effective. Although at present, this therapy may only be considered for relapsed symptomatic WS patients, it may be a good alternative therapy when frequent relapses occur after favorable response to conventional ACTH therapy.

Clinical Electroencephalographic Biomarker for Impending Epilepsy in Asymptomatic Tuberous Sclerosis Complex Infants

BACKGROUND

We assessed the clinical utility of routine electroencephalography (EEG) in the prediction of epilepsy onset in asymptomatic infants with tuberous sclerosis complex.

METHODS

This multicenter prospective observational study recruited infants younger than 7 months, seizure-free and on no antiepileptic drugs at enrollment, who all underwent serial physical examinations and video EEGs throughout the study. Parental education on seizure recognition was completed at the time of initial enrollment. Once seizure onset occurred, standard of care was applied, and subjects were followed up until 24 months.

RESULTS

Forty patients were enrolled, 28 older than 12 months with completed EEG evaluation at the time of this interim analysis. Of those, 19 (67.8%) developed seizures. Epileptic spasms occurred in 10 (52.6%), focal seizures in five (26.3%), generalized tonic-clonic seizure in one (5.3%), and a combination of epileptic spasms and focal seizures in three (15.7%). Fourteen infants (73.6%) had the first emergence of epileptiform abnormalities on EEG at an average age 4.2 months, preceding seizure onset by a median of 1.9 months. Hypsarrhythmia or modified hypsarrhythmia was not found in any infant before onset of epileptic spasms. All children with epileptiform discharges subsequently developed epilepsy (100% positive predictive value), and the negative predictive value for not developing epilepsy after a normal EEG was 64%.

CONCLUSIONS

Serial routine EEGs in infants with tuberous sclerosis complex is a feasible strategy to identify individuals at high risk for epilepsy. The most frequent clinical presentation was epileptic spasms followed by focal seizures, and then a combination of both seizure types.

Genotype/Phenotype Correlations in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the development of widespread hamartomatous lesions in various organs, including brain, skin, kidneys, heart, and eyes. Central nervous system is almost invariably involved, with up to 85% of patients presenting with epilepsy, and at least half of patients having intellectual disability or other neuropsychiatric disorders including autism spectrum disorder. TSC is caused by the mutation in one of the 2 genes TSC1, at 9q34, and TSC2, at 16p13.3. They respectively encode for hamartin and tuberin, which form an intracellular complex inhibiting the mammalian target of rapamycin. Mammalian target of rapamycin overactivation following the genetic defect determines the cell growth and proliferation responsible for TSC-related lesions, as well as the alterations in neuronal excitability and synaptogenesis leading to epilepsy and neuropsychiatric disorders. A causative mutation for the disorder is identified in about 85% of patients with a clinical diagnosis of TSC. Mosaicism and technology limits likely explain most of the no mutation identified cases. This review confirms that patients with TSC2 mutations considered as a group usually present a more severe phenotype, characterized by higher number of tubers, earlier age at seizure onset and higher prevalence of intellectual disability. However, the clinical phenotype of the disease presents a high variability, thus making the prediction of the phenotype on an individual basis still challenging. The increasing application of new molecular techniques to subjects with TSC has the potential to significantly reduce the rate of patients with no mutation demonstrated and to identify an increasing higher number of mutations. This would hopefully allow a better characterization of higher risk mutations, which might help clinicians to plan individualized surveillance plans. Furthermore, the increasing availability of disease registries to collect clinical and genetics data of patients help to define more valid and clinically oriented genotype or phenotype correlations.

Tuberous Sclerosis: A New Frontier in Targeted Treatment of Autism

Tuberous sclerosis complex (TSC) is a genetic disorder with a high prevalence of autism spectrum disorder (ASD). Tremendous progress in understanding the pathogenesis of TSC has been made in recent years, along with initial trials of medical treatment aimed specifically at the underlying mechanism of the disorder. At the cellular level, loss of TSC1 or TSC2 results in upregulation of the mechanistic target of rapamycin (mTOR) pathway. At the circuitry level, TSC and mTOR play crucial roles in axonal, dendritic, and synaptic development and function. In this review, we discuss the molecular mechanism underlying TSC, and how this disease results in aberrant neural connectivity at multiple levels in the central nervous system, leading to ASD symptoms. We then review recent advances in mechanism-based treatments of TSC, and the promise that these treatments provide for future mechanism-based treatment of ASD. Because of these recent advances, TSC represents an ideal model for how to make progress in understanding and treating the mechanisms that underlie ASD in general.

Autism spectrum disorder and epilepsy: Disorders with a shared biology

There is an increasing recognition of clinical overlap in patients presenting with epilepsy and autism spectrum disorder (ASD), and a great deal of new information regarding the genetic causes of both disorders is available. Several biological pathways appear to be involved in both disease processes, including gene transcription regulation, cellular growth, synaptic channel function, and maintenance of synaptic structure. We review several genetic disorders where ASD and epilepsy frequently co-occur, and we discuss the screening tools available for practicing neurologists and epileptologists to help determine which patients should be referred for formal ASD diagnostic evaluation. Finally, we make recommendations regarding the workflow of genetic diagnostic testing available for children with both ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".

Seizure patterns in childhood

Seizures are alarming and can be life-threatening. It is essential that pediatric providers be able to identify those paroxysmal events most likely to be seizures and to know which require immediate evaluation. Severity can range from childhood syndromes that are controlled relatively easily and usually outgrown to epileptic encephalopathies that are associated with severe developmental delay and sometimes death. Familiarity with seizure semiology can guide early diagnosis and treatment.

Early neurodevelopmental screening in tuberous sclerosis complex: a potential window of opportunity

BACKGROUND

Infants born with tuberous sclerosis complex, a genetic condition resulting from a mutation in TSC1 or TSC2, are at increased risk for intellectual disability and/or autism. Features of epilepsy, neuropathology, genetics, as well as timing and type of mechanism-based medications have been proposed as risk factors. Neurodevelopmental outcomes have been reported among these studies; however, few include data about the individuals' early neurodevelopmental profile, a factor that may contribute significantly to these outcomes. Further, there is no clinical standard for the neurodevelopmental assessment of these infants. The paucity of data regarding the natural history of neurodevelopment in infants with tuberous sclerosis complex and the lack of a gold standard for neurodevelopmental evaluation present a significant challenge for clinicians and researchers.

METHOD

During the first year of life, we tracked the onset of infantile spasms, the type and timing of antiepileptic treatments, and the associated response of two age-matched infants with tuberous sclerosis complex. We also employed Capute Scales as a part of a structured neurodevelopmental evaluation to characterize and compare their neurodevelopmental profiles.

RESULTS

Infant 1 developed infantile spasms with confirmed hypsarrhythmia at 4 months of age. Treatment with vigabatrin was initiated within 24 hours with near immediate cessation of seizures and no further seizures to date. Expressive language delay was detected at 12 months and treated with speech and/or language therapy. Infant 2 developed complex partial seizures at 1 month. Treatment included levetiracetam, oxcarbazepine, and the ketogenic diet. Vigabatrin was initiated on detection of hypsarrhythmia after 4 months. Intractable epilepsy persists to date. Global developmental delay was evident by 8 months and treated with physical, occupational, and speech and/or language therapy.

CONCLUSION

Many risk factors have been associated with intellectual disability and/or autism in individuals with tuberous sclerosis complex; however, few data are available regarding practical clinical tools for early identification. In our case series, inclusion of the Capute Scales as a part of routine medical care led to the identification of developmental delays in the first 12 months of life and selection of targeted neurodevelopmental interventions. Development of a risk-based assessment using this approach will be the focus of future studies as it may provide a potential window of opportunity for both research and clinical purposes. In research, it may serve as an objective outcome measure. Clinically, this type of assessment has potential for informing clinical treatment decisions and serving as a prognostic indicator of long-term cognitive and psychiatric outcomes.

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.

Diffusion tensor imaging and related techniques in tuberous sclerosis complex: review and future directions

In this article, the authors aim to introduce the nonradiologist to diffusion tensor imaging (DTI) and its applications to both clinical and research aspects of tuberous sclerosis complex. Tuberous sclerosis complex is a genetic neurocutaneous syndrome with variable and unpredictable neurological comorbidity that includes refractory epilepsy, intellectual disability, behavioral abnormalities and autism spectrum disorder. DTI is a method for modeling water diffusion in tissue and can noninvasively characterize microstructural properties of the brain. In tuberous sclerosis complex, DTI measures reflect well-known pathological changes. Clinically, DTI can assist with detecting the epileptogenic tuber. For research, DTI has a putative role in identifying potential disease biomarkers, as DTI abnormalities of the white matter are associated with neurocognitive morbidity including autism. If indeed DTI changes parallel phenotypical changes related to the investigational treatment of epilepsy, cognition and behavior with mTOR inhibitors, it will facilitate future clinical trials.

Prognostic factors of infantile spasms: role of treatment options including a ketogenic diet

OBJECTIVES

The aim of this study was to provide additional evidences on prognostic factors for infantile spasms and the possible role of a ketogenic diet.

METHODS

A retrospective analysis was performed for patients with infantile spasms who had been followed up for more than 6months between January 2000 and July 2012 at Samsung Medical Center (Seoul, Republic of Korea). We analyzed the association between possible prognostic factors and seizure/developmental outcomes.

RESULTS

Sixty-nine patients were included in this study and their mean follow-up duration was 52.5 (9-147) months. In the patients who had been followed up for more than 2years, 53.6% (n=30/57) remained seizure-free at the last visit. Sixty patients (86.9%) showed developmental delay at last follow-up. Forty-two patients (60.9%) became spasm-free with one or two antiepileptic drugs, one patient with epilepsy surgery for a tumor, and seven patients with a ketogenic diet after the failure of two or more antiepileptic drugs. The etiology and age of seizure onset were the significant prognostic factors.

CONCLUSIONS

In this study, about 60% of the patients became spasm-free with vigabatrin and topiramate. Ketogenic diet increased the rate by 10% in the remaining antiepileptic drug resistant patients. However, 86.9% of the patients showed developmental delay, mostly a severe degree. Early diagnosis and prompt application of treatment options such as antiepileptic drugs, a ketogenic diet or epilepsy surgery can improve outcomes in patients with infantile spasms.

Towards early diagnosis and treatment to save children from catastrophic epilepsy -- focus on epilepsy surgery

OBJECTIVE

To analyze and to discuss whether by paying attention to the many recent advancements in the field of pediatric epilepsy surgery catastrophic childhood epilepsies caused by definitive or suspected structural lesions can be prevented more often these days in comparison to the past.

METHODS

Based on data from the literature and supplemented by the authors own experience, risks for children suffering from structural focal epilepsies that the epilepsy becomes catastrophic and ways how such evolutions can possibly be prevented are discussed for the different lesion-types separately - in the order of their frequency as they are seen at pediatric epilepsy surgery centers. Special emphasis is put on data regarding attempts to prevent permanent severe mental retardations.

RESULTS

There are common factors predisposing to catastrophic courses in all structural focal epilepsies, such as early onset and a longer duration of epilepsy (with respect to cognitive outcome not with respect to seizure outcome), but there are also differences. Moreover the better perspectives now in comparison to the past for children with conditions like MRI-negative focal epilepsies, subtle focal cortical dysplasias, epilepsies post hypoxic-ischemic events, tuberous sclerosis etc. are not well recognized yet. While there is agreement that "early" (and successful) surgery is essential in many instances to prevent permanent mental retardations there is insufficient data regarding the issue that "early surgery "might not be early enough under certain circumstances and there is also only little data regarding variables which would allow to keep calm when a child is presenting with early onset difficult to control seizures. One of the biggest changes seen over the last decade is the fact that children with very severe epilepsies, who have unilateral lesions, but "generalized" seizures and/or "generalized" EEGs, are not excluded anymore from considerations for epilepsy surgery. Even children with bilateral lesions can be surgical candidates.

CONCLUSION

The gradually widening spectrum of indications for epilepsy surgery in children is resulting in an increasing number of preventions of catastrophic epilepsies. Insufficient data regarding timing of surgery in order to prevent permanent mental retardations are calling for prospective multi-center studies.

Potential for treatment of severe autism in tuberous sclerosis complex

The Food and Drug Administration (FDA) has approved two mechanism-based treatments for tuberous sclerosis complex (TSC)-everolimus and vigabatrin. However, these treatments have not been systematically studied in individuals with TSC and severe autism. The aim of this review is to identify the clinical features of severe autism in TSC, applicable preclinical models, and potential barriers that may warrant strategic planning in the design phase of clinical trial development. A comprehensive search strategy was formed and searched across PubMed, Embase and SCOPUS from their inception to 2/21/12, 3/16/12, and 3/12/12 respectively. After the final search date, relevant, updated articles were selected from PubMed abstracts generated electronically and emailed daily from PubMed. The references of selected articles were searched, and relevant articles were selected. A search of clinicaltrials.gov was completed using the search term “TSC” and “tuberous sclerosis complex”. Autism has been reported in as many as 60% of individuals with TSC; however, review of the literature revealed few data to support clear classification of the severity of autism in TSC. Variability was identified in the diagnostic approach, assessment of cognition, and functional outcome among the reviewed studies and case reports. Objective outcome measures were not used in many early studies; however, diffusion tensor imaging of white matter, neurophysiologic variability in infantile spasms, and cortical tuber subcategories were examined in recent studies and may be useful for objective classification of TSC in future studies. Mechanism-based treatments for TSC are currently available. However, this literature review revealed two potential barriers to successful design and implementation of clinical trials in individuals with severe autism-an unclear definition of the population and lack of validated outcome measures. Recent studies of objective outcome measures in TSC and further study of applicable preclinical models present an opportunity to overcome these barriers.

Epileptic spasms in tuberous sclerosis complex

PURPOSE

To characterize epileptic spasms (ES) occurring after the age of two years in patients with tuberous sclerosis complex (TSC), particularly treatment response to vigabatrin (VGB), which is extremely effective for infantile spasms (IS) in TSC.

METHODS

The authors retrospectively reviewed 19 patients with TSC and ES. Medical records were assessed for clinical and treatment data, neurocognitive, EEG, MRI data, and genetic analyses.

RESULTS

Of 391 patients with TSC, 19 (4.8%) had ES. Of those with detailed clinical data, six had infantile spasms that persisted after 2 years old, six recurred after an initial remission of infantile spasms (range 2-24 years old), and four occurred de novo over the age of two (range 2-20 years old). All concurrently had other seizure types. One had hypsarrhythmia on EEG. All had brain MRI stigmata typical of TSC. Thirteen had a mutation in TSC2, and one in TSC1. Six patients became spasm-free with medication treatment, including four with VGB, one with VGB in combination with the low glycemic index dietary treatment, and one with felbamate. Five became spasm-free after epilepsy surgery. VGB was not effective for seven patients. The majority continued to have refractory epilepsy.

CONCLUSIONS

ES are not uncommon in patients with TSC, especially those with TSC2 mutations. ES in TSC occur in the setting of other seizure types and refractory epilepsy. Hypsarrhythmia is rare. VGB can be effective, but the success of VGB for ES in TSC is not equivalent to that of IS in TSC.

Infantile spasms (West syndrome): update and resources for pediatricians and providers to share with parents

BACKGROUND

Infantile spasms (IS; West syndrome) is a severe form of encephalopathy that typically affects infants younger than 2 years old. Pediatricians, pediatric neurologists, and other pediatric health care providers are all potentially key early contacts for families who have an infant with IS. The objective of this article is to assist pediatric health care providers in the detection of the disease and in the counseling and guidance of families who have an infant with IS.

METHODS

Treatment guidelines, consensus reports, and original research studies are reviewed to provide an update regarding the diagnosis and treatment of infants with IS. Web sites were searched for educational and supportive resource content relevant to providers and families of patients with IS.

RESULTS

Early detection of IS and pediatrician referral to a pediatric neurologist for further evaluation and initiation of treatment may improve prognosis. Family education and the establishment of a multidisciplinary continuum of care are important components of care for the majority of patients with IS. The focus of the continuum of care varies across diagnosis, initiation of treatment, and short- and long-term needs. Several on-line educational and supportive resources for families and caregivers of patients with IS were identified.

CONCLUSIONS

Given the possibility of poor developmental outcomes in IS, including the emergence of other seizure disorders and cognitive and developmental problems, early recognition, referral, and treatment of IS are important for optimal patient outcomes. Dissemination of and access to educational and supportive resources for families and caregivers across the lifespan of the child with IS is an urgent need. Pediatric health care providers are well positioned to address these needs.

Long-term neurological outcome in children with early-onset epilepsy associated with tuberous sclerosis

In tuberous sclerosis complex, early seizure onset is associated with high risk of intractable epilepsy and cognitive/behavioral impairment. We retrospectively evaluated the long-term outcome of 44 infants presenting with seizures in the first 12 months who received vigabatrin, and were followed up for at least 3.5 years. At the final evaluation 55% of patients were still having seizures, 80% had intellectual disability, and 30% had autism. Sixty-five percent of children who had been treated earlier with vigabatrin after seizure onset achieved seizure freedom, compared with 24% of subjects who received vigabatrin treatment later (P<0.01). Intellectual disability was present in 61% of the children treated early (group A) and in 100% of the children treated later (group B). Nine percent of group A and 52% of group B had autism (P≈0.001). A shorter gap between seizure onset and start of treatment could reduce the risk of epileptic encephalopathy, minimizing the deleterious effect of seizures, but is not able to completely reverse the tuberous sclerosis complex-associated cognitive impairment.

Genetic and biologic classification of infantile spasms

Infantile spasms constitute an age-dependent epilepsy, highly associated with cognitive impairment, autism, and movement disorders. Previous classification systems focused on a distinction between symptomatic and cryptogenic etiologies, and have not kept pace with recent discoveries of mutations in genes in key pathways of central nervous system development in patients with infantile spasms. Children with certain genetic syndromes are much likelier to manifest infantile spasms, and we review the literature to propose a genetic classification of these disorders. Children demonstrating genetic associations with infantile spasms also manifest phenotypes beyond epilepsy that may be explained by recent advances in the understanding of underlying biological mechanisms. Therefore we propose a biologic classification of genes highly associated with infantile spasms, and articulate models for infantile spasms pathogenesis based on those data. The two best described pathways of pathogenesis involve abnormalities in the gene regulatory network of gamma-aminobutyric acidergic forebrain development and abnormalities in molecules expressed at the synapse. These genetic and biologic classifications are flexible, and they should encourage much needed progress in syndrome recognition, clinical genetic testing, and the development of new therapies targeting specific pathways of pathogenesis.

In search of epilepsy biomarkers in the immature brain: goals, challenges and strategies

Epilepsy and seizures are very common in the early years of life and are often associated with significant morbidity and mortality. Identification of biomarkers for the early detection of epileptogenicity, epileptogenesis, comorbidities, disease progression and treatment implementation will be very important in implementing more effective therapies. This article summarizes the current needs in the search for new early life epilepsy-related biomarkers and discusses the candidate biomarkers that are under investigation, as well as the challenges associated with the identification and validation of these biomarkers.

Antiepileptic treatment before the onset of seizures reduces epilepsy severity and risk of mental retardation in infants with tuberous sclerosis complex

BACKGROUND

Epilepsy appears in 70-80% of patients with tuberous sclerosis complex, most commonly in the first year of age. Early manifestation of epilepsy is associated with drug-resistant epilepsy and mental retardation in more than 80% of patients. Clinical epileptic seizures are preceded by deterioration of EEG recording thus infants with high risk of epilepsy can be identified.

AIMS

We hypothesized that preventative antiepileptic treatment of infants with multifocal activity on EEG might lower the incidence of drug-resistant epilepsy and mental retardation.

METHODS

Forty-five infants with early diagnosis of tuberous sclerosis complex were included in the open-label study. They were divided in two groups: standard (n=31) and preventative one (n=14). In standard group the antiepileptic treatment was launched early, but after the onset of seizures. In preventative group medication was commenced when active epileptic discharges were seen on EEG, but before the onset of clinical seizures. Children were followed till the end of 2 years of age.

RESULTS

At 24 months of age mental retardation was significantly more frequent and severe in "standard" vs "preventative" group (48% vs 14%; p=0.031; mean IQ score 68.7 vs 92.3; p<0.05). The "preventative" group was characterized by higher ratio of seizure-free patients (93% vs 35%; p=0.004), lower incidence of drug-resistant epilepsy (7% vs 42%; p=0.021) and lower number of patients requiring polytherapy (21% vs 55%; 0.039) than the "standard group.

CONCLUSIONS

Preventative antiepileptic treatment of infants with tuberous sclerosis complex and high risk of epilepsy markedly improves their neurodevelopmental outcome and reduces the incidence of drug-resistant seizures.

SISCOM in children with tuberous sclerosis complex-related epilepsy

Identification of a single epileptogenic focus in patients with tuberous sclerosis complex is a challenge. Noninvasive imaging modalities, including subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance imaging (SISCOM), have been used to determine the dominant epileptogenic focus for surgical resection. We assessed whether complete resection of SISCOM hyperperfusion abnormality correlates with seizure-free outcome in 6 children with tuberous sclerosis complex-related epilepsy. The median seizure onset age was 4 months (range 1 day to 16 months). The age at surgery ranged from 8 months to 13 years. A dominant SISCOM hyperperfusion focus was identified in 5 patients with multiple tubers. SISCOM provided additional localizing information for epilepsy surgery in 3 patients with nonlocalizing or discordant electrophysiologic and neuroimaging findings. At a minimum of 2 years' follow-up, 3 patients were free of seizures overall. Freedom from seizures was associated with complete resection of SISCOM abnormality in 2 patients. These findings demonstrate that SISCOM can be useful in identifying the epileptogenic zone and in guiding the location and extent of epilepsy surgery in children with tuberous sclerosis complex and multifocal abnormalities. In children with tuberous sclerosis complex and intractable epilepsy, complete resection of the SISCOM hyperperfusion abnormality is associated with freedom from seizures.

Targeting mTOR complex 1 to treat neurological and psychiatric manifestations of tuberous sclerosis complex

While tuberous sclerosis complex is a genetic disorder with multiorgan involvement, it is the cerebral lesions and abnormal brain function that are responsible for the highest morbidity in affected individuals and for negatively impacting overall quality of life. Identification and effective treatment of the resultant neurological and psychiatric symptoms can be challenging, and evidence-based management techniques are often lacking to help the clinician provide optimal care for these patients. This article identifies the most significant neurological and psychiatric disorders associated with tuberous sclerosis complex and their current management, as well as exploring recent advances in the use of mTOR complex 1 inhibitors, such as sirolimus or everolimus, to treat these disorders.

Tuberous sclerosis complex: a brave new world?

PURPOSE OF REVIEW

Tuberous sclerosis complex (TSC) is a multiorgan genetic disease caused by mutations in the TSC1 or TSC2 genes. TSC has been recognized for many years as an important cause of severe neurological disease with patients suffering from epilepsy, developmental delay, autism, and psychiatric problems. During the last year, there have been enormous advances in basic and translational research pertaining to TSC.

RECENT FINDINGS

In this review, I discuss the basic science findings that position the TSC1 and TSC2 genes as critical regulators of the mammalian target of rapamycin kinase within mammalian target of rapamycin complex 1. In addition, I will discuss the development of new animal models, translational data, and recent clinical trials using mammalian target of rapamycin complex 1 inhibitors such as rapamycin.

SUMMARY

The past few years have seen spectacular advances that have energized TSC-related research and challenged existing symptomatic treatments. Although it remains to be seen whether use of mammalian target of rapamycin complex 1 inhibitors will revolutionize the care of patients with TSC, the application of basic and translational research towards a specific clinical disorder emphasizes the potential and promise of molecular medicine.

Treatment of infantile spasms in tuberous sclerosis complex: dismal outcomes but future hope?

This commentary discusses a retrospective study by Muzykewicz et al. that details EEG results from children with infantile spasms in the setting of tuberous sclerosis complex (TSC). In this study, several factors were identified as being predictive of poor cognitive outcome, including worsening degree of hypsarrhythmia, abnormalities in EEG background activity, and incomplete response to vigabatrin. Notably, the majority of patients had a poor outcome, experiencing cognitive impairment and intractable epilepsy irrespective of whether they were treated with adrenocorticotropic hormone (corticotropin) or vigabatrin, despite the fact that vigabatrin has shown promise in previous studies. However, among the entire cohort a third of patients enjoyed greater than 1 year of seizure freedom and about a quarter had either mild or no cognitive impairment at follow-up. Overall, these findings underscore the great challenges that are faced in the treatment of infantile spasms in patients with TSC. I suggest that, while vigabatrin has been shown to have impressive short-term efficacy, the intractable seizures and cognitive impairment in many patients with TSC strongly indicate that new therapies and treatment strategies are urgently needed.