Preventive Antiepileptic Treatment in Tuberous Sclerosis Complex: A Long-Term, Prospective Trial

An update on the novel methods for the discovery of antiseizure and antiepileptogenic medications: where are we in 2024?

INTRODUCTION

Despite the availability of around 30 antiseizure medications, 1/3 of patients with epilepsy fail to become seizure-free upon pharmacological treatment. Available medications provide adequate symptomatic control in two-thirds of patients, but disease-modifying drugs are still scarce. Recently, though, new paradigms have been explored.

AREAS COVERED

Three areas are reviewed in which a high degree of innovation in the search for novel antiseizure and antiepileptogenic medications has been implemented: development of novel screening approaches, search for novel therapeutic targets, and adoption of new drug discovery paradigms aligned with a systems pharmacology perspective.

EXPERT OPINION

In the past, worldwide leaders in epilepsy have reiteratively stated that the lack of progress in the field may be explained by the recurrent use of the same molecular targets and screening procedures to identify novel medications. This landscape has changed recently, as reflected by the new Epilepsy Therapy Screening Program and the introduction of many in vitro and in vivo models that could possibly improve our chances of identifying first-in-class medications that may control drug-resistant epilepsy or modify the course of disease. Other milestones include the study of new molecular targets for disease-modifying drugs and exploration of a systems pharmacology perspective to design new drugs.

Early Subclinical Status Epilepticus May Contribute to Developmental Delays in Infants With Tuberous Sclerosis Complex

We present a case of a newborn with a prenatally discovered cardiac rhabdomyoma leading to early genetic diagnosis of tuberous sclerosis complex (TSC). This early diagnosis prompted a presymptomatic electroencephalography (EEG) that revealed subclinical seizures meeting the definition for status epilepticus on day 1 of life. Antiseizure medications (ASMs), including vigabatrin, were started. The EPISTOP and PREVeNT trials demonstrated that early life initiation of vigabatrin may reduce the degree of refractory epilepsy and epileptic spasms (ES) in this population (TSC). Although neonatal seizures are a known entity in TSC, continuous neonatal EEG monitoring is not standard at birth. This case supports early consideration for neonatal EEG monitoring to identify and treat neonatal seizures, reduce risk for infantile spasms, and potentially improve neurodevelopmental outcomes.

Diagnosis of tuberous sclerosis in the prenatal period: a retrospective study of 240 cases and review of the literature

Tuberous sclerosis complex (TSC) is a rare multisystemic disorder caused by a pathogenic variant in the TSC1 or TSC2 gene. A great phenotypic variability characterises TSC. The condition predisposes to the formation of hamartomas in various tissues, neurologic and neurodevelopmental disorders such as epilepsy, psychiatric disorders, as well as intellectual disability in 50%. TSC may be responsible for cardiac rhabdomyomas (CRs), cortical tubers, or subependymal nodules during foetal life. Detecting multiple CRs is associated with a very high risk of TSC, but the CR could be single and isolated. Few data exist to estimate the risk of TSC in these cases. We report the largest series of prenatal genetic tests for TSC with a retrospective study of 240 foetuses presenting with suggestive antenatal signs. We also provide a review of the literature to specify the probability of clinical or genetic diagnosis of TSC in case of detection of single or multiple CRs. Indeed, an early diagnosis is crucial for the counselling of the couple and their families. In this series, a definite diagnosis was assessed in 50% (41/82) of foetuses who initially presented with a single CR and 80.3% (127/158) in cases of multiple CRs. The prevalence of parental germinal mosaicism was 2.6% (3/115).

Prenatal diagnosis of tuberous sclerosis complex: Echocardiography, cranial magnetic resonance, and genetic testing of 40 cases with fetal cardiac tumors

Objective

To explore the relationship between Tuberous sclerosis complex (TSC) and cardiac tumors at our institution over the past five years and to evaluate the value of imaging technologies and genetic testing in the prenatal diagnosis of TSC.

Methods

Fetal echocardiography (FE) was performed in the whole population between 2016 and 2020. Fetuses detected with cardiac tumor(s) were included. Fetal cranial magnetic resonance imaging (MRI) and gene mutation tests were further examined. Those who declined genetic testing were excluded in the final analysis.

Results

A total of 40 fetuses were included in our study. There were 27 cases performed cranial magnetic resonance imaging (MRI) and the rest of 13 cases refused. Among 10 fetuses with cranial lesions detected by MRI, all of them were eventually diagnosed with TSC. And for 17 fetuses without cranial lesions, none of them were identified with a pathogenic variation in gene TSC1/2. The prevalence of TSC was significantly higher in the multiple tumors group than in the solitary group (9/20 vs. 2/20, P = 0.034). 11 fetuses had TSC1 (n = 3) or TSC2 (n = 8) causative or suspected causative mutations, of which 9 were sporadic mutations and 2 were familial mutations.

Conclusion

Fetal cranial MRI should be recommended to evaluate brain lesions, and genetic mutation should be examined, if possible, especially for those with multiple heart tumors. When typical cardiac tumors and cranial lesions are detected, the diagnosis of TSC can almost be made even without genetic mutation results.

Effect of mTOR Inhibitors in Epilepsy Treatment in Children with Tuberous Sclerosis Complex Under 2 Years of Age

INTRODUCTION

Mechanistic target of rapamycin (mTOR) inhibitors sirolimus and everolimus are an effective therapy for subependymal giant cell astrocytomas, cardiac rhabdomyomas, renal angiomyolipomas, and lymphangioleiomyomatosis associated with tuberous sclerosis complex (TSC). Everolimus was recently approved in the EU and the USA for the treatment of refractory focal-onset seizures. Despite frequent use of mTOR inhibitors, there are only a few studies on their effect on epilepsy control in children under 2 years of age. This study aims to assess the effect of adjunctive mTOR inhibitor treatment on seizure frequency in this age group.

METHODS

We performed retrospective data analysis of medical records of patients with TSC who initiated sirolimus or everolimus under the age of 2 years. Participants' antiseizure medication was adjusted according to their epilepsy control independently from mTOR inhibitor administration. The data was assessed separately for patients treated with mTOR inhibitors before and after the onset of seizures. We also compared the treatment group with a matched control group. The follow-up duration was up to 24 months.

RESULTS

Twenty-one patients with TSC from two clinical centers were included in the study. Nine participants had no history of seizures before mTOR inhibitor initiation. Twelve reported active epilepsy in the month prior to treatment initiation. Most patients treated preventively with mTOR inhibitors did not report active epilepsy at the end of their follow-up. In the second group, the mean frequency of seizures decreased with time. According to the comparative analysis, seizure control was better in the groups treated with mTOR inhibitors.

CONCLUSION

Patients with TSC treated with mTOR inhibitors demonstrated better seizure control than individuals without this treatment. Adjunctive pharmacotherapy with mTOR inhibitors appears to have a beneficial effect on epilepsy outcome in young children. Further prospective clinical trials should be conducted to determine the efficacy of mTOR inhibitors on epilepsy in patients with TSC under the age of 2 years.

Recent advances in pharmacotherapy for epilepsy

PURPOSE OF REVIEW

Epilepsy affects 70 million people worldwide and is a significant cause of morbidity and early mortality. The mainstay of therapy is oral medications. Epilepsy drug development is escalating, driven by continued drug resistance in up to a third of epilepsy patients. Treatment development now focuses on discovery of novel mechanisms of action and syndrome-specific therapies.

RECENT FINDINGS

Difficult-to-treat epilepsy related to conditions including tuberous sclerosis complex (TSC), Lennox Gastaut syndrome (LGS) and Dravet syndrome (DS) have been the target of recent developments. Disease-modifying therapy for epilepsy related to TSC with vigabatrin at onset of first electroencephalographic epileptiform changes, rather than after first clinical seizure, has demonstrated strongly positive seizure and developmental outcomes. Fenfluramine, approved for DS and, more recently, LGS, has robust data supporting efficacy, safety/tolerability, as well as mortality, quality of life and cognitive function. Rescue therapy has expanded to include better tolerated benzodiazepines in the form of nasal midazolam and valium. Cenobamate, a first-in-class inactivator of the persistent voltage-gated sodium channel and approved for adult partial onset epilepsy, has exceptional efficacy and tolerability and will be expanded to children and to generalized onset epilepsy in adults.

SUMMARY

The repertoire of available and developmental therapies for epilepsy is rapidly expanding, and now includes disease-modifying vigabatrin in TSC and agents with extraordinary efficacy, fenfluramine and cenobamate.

Safety of Sirolimus in Patients with Tuberous Sclerosis Complex under Two Years of Age-A Bicenter Retrospective Study

BACKGROUND

mTOR inhibitors are a novel pharmacotherapy recommended for subependymal giant astrocytomas, refractory epilepsy, and the treatment of the other clinical manifestations of tuberous sclerosis complex (TSC). Clinical trials on everolimus proved it to be effective and safe in children. Despite its common use in clinical practice, the research on sirolimus is limited. This study is the first to determine and assess the severity of the adverse effects (AEs) of sirolimus administered to children with TSC under two years of age.

METHODS

We performed a bicenter retrospective data analysis of medical records of individuals with TSC who initiated therapy with sirolimus under the age of two.

RESULTS

Twenty-one patients were included in the study. At least one AE was reported in all participants. The most prevalent AEs were anemia, thrombocytosis, and hyperlipidemia. Infections and mouth ulcerations, often reported in the studies on older patients, were infrequent and of mild or moderate grade.

CONCLUSIONS

Adverse effects associated with sirolimus use in infants and young children with TSC are frequent yet not life- or health-threatening. Further multicenter prospective clinical trials should determine the long-term safety of sirolimus.

The state of pediatric tuberous sclerosis complex epilepsy care: Results from a national survey

OBJECTIVE

Epilepsy associated with tuberous sclerosis complex (TSC) can be challenging to treat and is associated with significant disease burden. Our objective was to better understand the state of epilepsy care of TSC amongst pediatric neurologists in Canada, identify gaps in care and determine whether access to a dedicated TSC clinic has an impact on epilepsy management.

METHODS

A survey was developed after a literature review and discussion amongst two pediatric epileptologists and one nurse practitioner with expertise in TSC about the state of epilepsy care of TSC patients in Canada. Canadian pediatric neurologists were asked to participate in sharing their experiences via an anonymous web-based survey through the Canadian League Against Epilepsy (CLAE) and the Canadian Neurological Sciences Federation (CNSF).

RESULTS

Fifty-seven responses were received. Access to a dedicated TSC clinic was reported by 25% (n = 14). Sixty percent (n = 34) reported performing serial EEG monitoring in infants with TSC and 57% (n = 33) started prophylactic antiseizure therapy when EEG abnormalities were detected, regardless of whether there was access to a TSC clinic (P = .06 and P = .29, respectively). While 52% (n = 29) did not feel comfortable prescribing mTORi for epilepsy, 65% (n = 36) indicated they would consider it with additional training. Epilepsy surgery was offered in 93% (n = 13) of centers with a dedicated TSC clinic but only 45% of centers without a TSC clinic (n = 19) (P = .002).

SIGNIFICANCE

Our findings demonstrate the variability in neurological care of pediatric patients with TSC as it pertains to epilepsy management. There is a need for the establishment of epilepsy practice guidelines and a national network to support clinical practice, research, and education.

Limited utility of structural MRI to identify the epileptogenic zone in young children with tuberous sclerosis

BACKGROUND AND PURPOSE

The success of epilepsy surgery in children with tuberous sclerosis complex (TSC) hinges on identification of the epileptogenic zone (EZ). We studied structural MRI markers of epileptogenic lesions in young children with TSC.

METHODS

We included 26 children with TSC who underwent epilepsy surgery before the age of 3 years at five sites, with 12 months or more follow-up. Two neuroradiologists, blinded to surgical outcome data, reviewed 10 candidate lesions on preoperative MRI for characteristics of the tuber (large affected area, calcification, cyst-like properties) and of focal cortical dysplasia (FCD) features (cortical malformation, gray-white matter junction blurring, transmantle sign). They selected lesions suspect for the EZ based on structural MRI, and reselected after unblinding to seizure onset location on electroencephalography (EEG).

RESULTS

None of the tuber characteristics and FCD features were distinctive for the EZ, indicated by resected lesions in seizure-free children. With structural MRI alone, the EZ was identified out of 10 lesions in 31%, and with addition of EEG data, this increased to 48%. However, rates of identification of resected lesions in non-seizure-free children were similar. Across 251 lesions, interrater agreement was moderate for large size (κ = .60), and fair (κ = .24) for all other features.

CONCLUSIONS

In young children with TSC, the utility of structural MRI features is limited in the identification of the epileptogenic tuber, but improves when combined with EEG data.

Epilepsy and Language Development in 8–36-Month-Old Toddlers with Tuberous Sclerosis Complex

This paper aimed to assess language development in infants and toddlers with tuberous sclerosis complex (TSC) and epilepsy, which increase the risk of autism spectrum disorder. We assessed language development in 61 patients with TSC at 8–36 months using a standardized Speech Development and Communication Inventory tool. The results showed differences in outcomes due to the duration of the seizures and the number of drugs (pFDR = 0.007 **—pFDR = 0.037 *). Children with TSC with longer epilepsy duration and receiving more antiepileptic drugs have a greater risk of language development delay.

miRNAs and isomiRs: Serum-Based Biomarkers for the Development of Intellectual Disability and Autism Spectrum Disorder in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a rare multi-system genetic disorder characterized by a high incidence of epilepsy and neuropsychiatric manifestations known as tuberous-sclerosis-associated neuropsychiatric disorders (TANDs), including autism spectrum disorder (ASD) and intellectual disability (ID). MicroRNAs (miRNAs) are small regulatory non-coding RNAs that regulate the expression of more than 60% of all protein-coding genes in humans and have been reported to be dysregulated in several diseases, including TSC. In the current study, RNA sequencing analysis was performed to define the miRNA and isoform (isomiR) expression patterns in serum. A Receiver Operating Characteristic (ROC) curve analysis was used to identify circulating molecular biomarkers, miRNAs, and isomiRs, able to discriminate the development of neuropsychiatric comorbidity, either ASD, ID, or ASD + ID, in patients with TSC. Part of our bioinformatics predictions was verified with RT-qPCR performed on RNA isolated from patients’ serum. Our results support the notion that circulating miRNAs and isomiRs have the potential to aid standard clinical testing in the early risk assessment of ASD and ID development in TSC patients.

Genetic pathogenesis of the epileptogenic lesions in Tuberous Sclerosis Complex: Therapeutic targeting of the mTOR pathway

Tuberous sclerosis complex (TSC) is a genetic multisystem disease due to the mutation in one of the two genes TSC1 and TSC2, affecting several organs and systems and carrying a significant risk of early onset and refractory seizures. The pathogenesis of this complex disorder is now well known, with most of TSC-related manifestations being a consequence of the overactivation of the mammalian Target of Rapamycin (mTOR) complex. The discovery of this underlying mechanism paved the way for the use of a class of drugs called mTOR inhibitors including rapamycin and everolimus and specifically targeting this pathway. Rapamycin has been widely used in different animal models of TSC-related epilepsy and proved to be able not only to suppress seizures but also to prevent the development of epilepsy, thus demonstrating an antiepileptogenic potential. In some models, it also showed some benefit on neuropsychiatric manifestations associated with TSC. Everolimus has recently been approved by the US Food and Drug Administration and the European Medical Agency for the treatment of refractory seizures associated with TSC starting from the age of 2 years. It demonstrated a clear benefit when compared to placebo on reducing the frequency of different seizure types and exerting a higher effect in younger children. In conclusion, mTOR cascade can be a potentially major cause of TSC-associated epilepsy and neurodevelopmental disability, and additional research should investigate if early suppression of abnormal mTOR signal with mTOR inhibitors before seizure onset can be a more efficient approach and an effective antiepileptogenic and disease-modifying strategy in infants with TSC.

The clinical and paraclinical manifestations of tuberous sclerosis complex in children

Tuberous sclerosis complex (TSC) is an autosomal-dominant, multi-system, neurocutaneous disorder characterized by hamartomas in multiple organs. This study aimed to evaluate the clinical and paraclinical manifestations of children with TSC. The clinical and paraclinical characteristics of 79 children with TSC were evaluated and the possible correlations between the factors were calculated. Among the studied children which composed of 41 females (51.9%) and 38 males (48.1%), skin manifestations as hypopigmented macules as well as the brain involvement as cortical tubers in all (100%) cases, seizure in 74 (93.7%), and sub-ependymal nodules in 73 (92.4%) patients were the most common findings. The renal angiomyolipoma was diagnosed in 36 (70.6%) out of 51 patients. Subependymal giant cell astrocytoma in 25 (3/54%) out of 46 patients, retinal hamartoma in 15 (42.9%) out of 35 patients, and cardiac rhabdomyoma in 17 (41.3%) out of 46 patients were diagnosed. Furthermore, 50 (63.3%) out of 79 patients had psychological disorders that had a significant correlation with the prevalence of seizures (p = 0.002). Given the multi-systemic involvement of TSC, it is necessary that all organs of the patients even without any related clinical symptom or sign be examined regularly for proper therapeutic intervention and prevent disease progression. The growth of hamartomas in the brain and kidneys can be life-threatening; therefore, these organs have more importance to be regularly followed up and examined.

A scoping review on cannabidiol therapy in tuberous sclerosis: Current evidence and perspectives for future development

Cannabidiol (CBD) has recently been approved as an add-on therapy by various regulatory agencies for tuberous sclerosis complex (TSC)-associated seizures based on its short-term efficacy and safety in a pivotal randomized controlled trial. However, critical information about which patients with TSC and seizure types respond best to CBD (clinical, electrophysiological, and genetic predictors of responsiveness), when to use CBD in the treatment algorithm, and how CBD can be combined with other antiseizure medications (ASMs) in the form of a rational polypharmacy therapy is still lacking. In general, there is a limited in-depth critical review of CBD for the treatment of TSC to facilitate its optimal use in a clinical context. Here, we utilized a scoping review approach to report the current evidence of efficacy and safety of pharmaceutical-grade CBD in patients with TSC, including relevant mechanism of action and drug-drug interactions with other ASMs. We also discussed emerging information about CBD's long-term efficacy and safety data in patients with TSC. Finally, we discussed some critical unanswered questions in several domains related to effective clinical management of TSC using CBD, including barriers to early and aggressive treatment in infants, difficulty with universal access to CBD, a lack of studies to understand CBD's impact on seizure severity and specific seizure types, insufficient exploration of CBD in TSC-related cognitive and behavioral issues, and the need for more research into CBD's effects on various biomarkers.

Emerging therapeutic targets for epilepsy: Preclinical insights

INTRODUCTION

Around 30% of patients with epilepsy suffer from drug-resistant seizures. Drug-resistant seizures may have significant consequences such as sudden death in epilepsy, injuries, memory disturbances, and childhood learning and developmental problems. Conventional and newer available antiepileptic drugs (AEDs) work via numerous mechanisms - mainly through inhibition of voltage-operated Na⁺ and/or Ca²⁺ channels, excitation of K⁺ channels, enhancement of GABA-mediated inhibition and/or blockade of glutamate-produced excitation. However, the discovery and development of novel brain targets may improve the future pharmacological management of epilepsy and hence is of pivotal importance.

AREAS COVERED

This article examines novel drug targets such as brain multidrug efflux transporters and inflammatory pathways; it progresses to discuss possible strategies for the management of drug-resistant seizures. Reduction of the consequences of blood brain barrier dysfunction and enhancement of anti-oxidative defense are discussed.

EXPERT OPINION

Novel drug targets comprise brain multidrug efflux transporters, TGF-β, Nrf2-ARE or m-TOR signaling and inflammatory pathways. Gene therapy and antagomirs seem the most promising targets. Epileptic foci may be significantly suppressed by viral-vector-mediated gene transfer, leading to an increased in situ concentration of inhibitory factors (for instance, galanin). Also, antagomirs offer a promising possibility of seizure inhibition by silencing micro-RNAs involved in epileptogenesis and possibly in seizure generation.

Epilepsy Management in Tuberous Sclerosis Complex: Existing and Evolving Therapies and Future Considerations

Tuberous sclerosis complex (TSC) is a rare autosomal dominant condition that affects multiple body systems. Disruption of the mammalian target of rapamycin (mTOR) pathway results in abnormal cell growth, proliferation, protein synthesis, and cell differentiation and migration in TSC. In the central nervous system, mTOR disruption is also believed to influence neuronal excitability and promote epileptogenesis. Epilepsy is the most common neurological manifestation of TSC and affects 80% to 90% of individuals with high rates of treatment resistance (up to 75%). The onset of epilepsy in the majority of individuals with TSC occurs before the age of two years, which is a critical time in neurodevelopment. Both medically refractory epilepsy and early-onset epilepsy are associated with intellectual disability in TSC, while seizure control and remission are associated with lower rates of cognitive impairment. Our current knowledge of the treatment of epilepsy in TSC has expanded immensely over the last decade. Several new therapies such as preemptive vigabatrin therapy in infants, cannabidiol, and mTOR inhibitors have emerged in recent years for the treatment of epilepsy in TSC. This review will provide clinicians with a comprehensive overview of the pharmacological and nonpharmacological therapies available for the treatment of epilepsy related to TSC.

Risk Factors Associated with Refractory Epilepsy in Patients with Tuberous Sclerosis Complex: A Systematic Review

BACKGROUND

Epilepsy affects 70-90% of patients with tuberous sclerosis complex (TSC). In one-third of them, the seizures become refractory to treatment. Drug-resistant epilepsy (DRE) carries a significant educational, social, cognitive, and economic burden. Therefore, determining risk factors that increase the odds of refractory seizures is needed. We reviewed current data on risk factors associated with DRE in patients with tuberous sclerosis.

METHODS

The review was performed according to the PRISMA guidelines. Embase, Cochrane Library, MEDLINE, and ClinicalTrial.gov databases were searched. Only full-text journal articles on patients with TSC which defined risk factors related to DRE were included.

RESULTS

Twenty articles were identified, with a cohort size between 6 and 1546. Seven studies were prospective. Three factors appear to significantly increase DRE risk: TSC2 mutation, infantile spasms, and a high number of cortical tubers.

CONCLUSIONS

A proper MRI and EEG monitoring, along with genetic testing, and close observation of individuals with early onset of seizures, allow identification of the patients at risk of DRE.

Prevention of infantile spasms in tuberous sclerosis complex

Since the ground-breaking work of Gomez in the 1970s and the later epidemiological studies of Webb and Osborne [1], the link between early onset epilepsy, especially infantile spasms (IS), and intellectual disability in tuberous sclerosis complex (TSC) has been accepted. This association raises the question of whether prevention of epilepsy in early life in TSC patients may improve the longer-term cognitive outcome.

Historical Patterns of Diagnosis, Treatments, and Outcome of Epilepsy Associated With Tuberous Sclerosis Complex: Results From TOSCA Registry

Background: Epilepsy is the most common neurological manifestation in individuals with tuberous sclerosis complex (TSC). However, real-world evidence on diagnosis and treatment patterns is limited. Here, we present data from TuberOus Sclerosis registry to increase disease Awareness (TOSCA) on changes in patterns of epilepsy diagnosis, treatments, and outcomes over time, and detailed epilepsy characteristics from the epilepsy substudy.

Methods: TuberOus Sclerosis registry to increase disease Awareness (TOSCA) was a multicentre, international disease registry, consisting of a main study that collected data on overall diagnostic characteristics and associated clinical features, and six substudies focusing on specific TSC manifestations. The epilepsy substudy investigated detailed epilepsy characteristics and their correlation to genotype and intelligence quotient (IQ).

Results: Epilepsy was reported in 85% of participants, more commonly in younger individuals (67.8% in 1970s to 91.8% in last decade), while rate of treatments was similar across ages (>93% for both infantile spasms and focal seizures, except prior to 1960). Vigabatrin (VGB) was the most commonly used antiepileptic drugs (AEDs). Individuals with infantile spasms showed a higher treatment response over time with lower usage of steroids. Individuals with focal seizures reported similar rates of drug resistance (32.5–43.3%). Use of vagus nerve stimulation (VNS), ketogenic diet, and surgery remained low.

Discussion: The epilepsy substudy included 162 individuals from nine countries. At epilepsy onset, most individuals with infantile spasms (73.2%) and focal seizures (74.5%) received monotherapies. Vigabatrin was first-line treatment in 45% of individuals with infantile spasms. Changes in initial AEDs were commonly reported due to inadequate efficacy. TSC1 mutations were associated with less severe epilepsy phenotypes and more individuals with normal IQ. In individuals with TSC diagnosis before seizure onset, electroencephalogram (EEG) was performed prior to seizures in only 12.5 and 25% of subsequent infantile spasms and focal seizures, respectively.

Conclusions: Our study confirms the high prevalence of epilepsy in TSC individuals and less severe phenotypes with TSC1 mutations. Vigabatrin improved the outcome of infantile spasms and should be used as first-line treatment. There is, however, still a need for improving therapies in focal seizures. Electroencephalogram follow-up prior to seizure-onset should be promoted for all infants with TSC in order to facilitate preventive or early treatment.

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.

Antiepileptogenesis and disease modification: Clinical and regulatory issues

This is a summary report of clinical and regulatory issues discussed at the 2018 NINDS workshop, entitled “Accelerating Therapies for Antiepileptogenesis and Disease Modification.” The intent of the workshop was to optimize and accelerate development of therapies for antiepileptogenesis (AEG) and disease modification in the epilepsies. The working group discussed nomenclature for antiepileptogenic therapies, subdividing them into “antiepileptogenic therapies” and “disease modifying therapies,” both of which are urgently needed. We use the example of traumatic brain injury to explain issues and complexities in designing a trial for disease‐preventing antiepileptogenic therapies, including identifying timing of intervention, selecting the appropriate dose, and the need for biomarkers. We discuss the recent trials of vigabatrin to prevent onset and modify epilepsy outcome in children with tuberous sclerosis (Epistop and PreVeNT). We describe a potential approach to a disease modification trial in adults, using patients with temporal lobe epilepsy. Finally, we discuss regulatory hurdles for antiepileptogenesis and disease‐modifying trials.

Review of the treatment options for epilepsy in tuberous sclerosis complex: towards precision medicine

Tuberous sclerosis complex (TSC) is a rare genetic disorder caused by mutations in the TSC1 or TSC2 genes, which encode proteins that antagonise the mammalian isoform of the target of rapamycin complex 1 (mTORC1) - a key mediator of cell growth and metabolism. TSC is characterised by the development of benign tumours in multiple organs, together with neurological manifestations including epilepsy and TSC-associated neuropsychiatric disorders (TAND). Epilepsy occurs frequently and is associated with significant morbidity and mortality; however, the management is challenging due to the intractable nature of the seizures. Preventative epilepsy treatment is a key aim, especially as patients with epilepsy may be at a higher risk of developing severe cognitive and behavioural impairment. Vigabatrin given preventatively reduces the risk and severity of epilepsy although the benefits for TAND are inconclusive. These promising results could pave the way for evaluating other treatments in a preventative capacity, especially those that may address the underlying pathophysiology of TSC, including everolimus, cannabidiol and the ketogenic diet (KD). Everolimus is an mTOR inhibitor approved for the adjunctive treatment of refractory TSC-associated seizures that has demonstrated significant reductions in seizure frequency compared with placebo, improvements that were sustained after 2 years of treatment. Highly purified cannabidiol, recently approved in the US as Epidiolex® for TSC-associated seizures in patients ⩾1 years of age, and the KD, may also participate in the regulation of the mTOR pathway. This review focusses on the pivotal clinical evidence surrounding these potential targeted therapies that may form the foundation of precision medicine for TSC-associated epilepsy, as well as other current treatments including anti-seizure drugs, vagus nerve stimulation and surgery. New future therapies are also discussed, together with the potential for preventative treatment with targeted therapies. Due to advances in understanding the molecular genetics and pathophysiology, TSC represents a prototypic clinical syndrome for studying epileptogenesis and the impact of precision medicine.

Effects of Mutations in TSC Genes on Neurodevelopment and Synaptic Transmission

Mutations in TSC1 or TSC2 genes are linked to alterations in neuronal function which ultimately lead to the development of a complex neurological phenotype. Here we review current research on the effects that reduction in TSC1 or TSC2 can produce on the developing neural network. A crucial feature of the disease pathophysiology appears to be an early deviation from typical neurodevelopment, in the form of structural abnormalities. Epileptic seizures are one of the primary early manifestation of the disease in the CNS, followed by intellectual deficits and autism spectrum disorders (ASD). Research using mouse models suggests that morphological brain alterations might arise from the interaction of different cellular types, and hyperexcitability in the early postnatal period might be transient. Moreover, the increased excitation-to-inhibition ratio might represent a transient compensatory adjustment to stabilize the developing network rather than a primary factor for the development of ASD symptoms. The inhomogeneous results suggest region-specificity as well as an evolving picture of functional alterations along development. Furthermore, ASD symptoms and epilepsy might originate from different but potentially overlapping mechanisms, which can explain recent observations obtained in patients. Potential treatment is determined not only by the type of medicament, but also by the time point of treatment.

Brain Symptoms of Tuberous Sclerosis Complex: Pathogenesis and Treatment

The mammalian target of the rapamycin (mTOR) system plays multiple, important roles in the brain, regulating both morphology, such as cellular size, shape, and position, and function, such as learning, memory, and social interaction. Tuberous sclerosis complex (TSC) is a congenital disorder caused by a defective suppressor of the mTOR system, the TSC1/TSC2 complex. Almost all brain symptoms of TSC are manifestations of an excessive activity of the mTOR system. Many children with TSC are afflicted by intractable epilepsy, intellectual disability, and/or autism. In the brains of infants with TSC, a vicious cycle of epileptic encephalopathy is formed by mTOR hyperactivity, abnormal synaptic structure/function, and excessive epileptic discharges, further worsening epilepsy and intellectual/behavioral disorders. Molecular target therapy with mTOR inhibitors has recently been proved to be efficacious for epilepsy in human TSC patients, and for autism in TSC model mice, indicating the possibility for pharmacological treatment of developmental synaptic disorders.

How to Find Candidate Drug-targets for Antiepileptogenic Therapy?

Although over 25 antiepileptic drugs (AEDs) have become currently available for clinical use, the incidence of epilepsy worldwide and the proportions of drug-resistant epilepsy among them are not significantly reduced during the past decades. Traditional screens for AEDs have been mainly focused on their anti-ictogenic roles, and their efficacies primarily depend on suppressing neuronal excitability or enhancing inhibitory neuronal activity, almost without the influence on the epileptogenesis or with inconsistent results from different studies. Epileptogenesis refers to the pathological process of a brain from its normal status to the alterations with the continuous prone of unprovoked spontaneous seizures after brain insults, such as stroke, traumatic brain injury, CNS infectious, and autoimmune disorders, and even some specific inherited conditions. Recently growing experimental and clinical studies have discovered the underlying mechanisms for epileptogenesis, which are multi-aspect and multistep. These findings provide us a number of interesting sites for antiepileptogenic drugs (AEGDs). AEGDs have been evidenced as significantly roles of postponing or completely blocking the development of epilepsy in experimental models. The present review will introduce potential novel candidate drug-targets for AEGDs based on the published studies.

Tuberous Sclerosis Complex

Affecting approximately 1 per 6000-10,000 individuals, tuberous sclerosis complex (TSC) is a neurocutaneous disorder that is not only uncommon but at risk to go underrecognized. Similar to other phakomatoses, TSC is a disorder of cellular proliferation and migration producing hamartomas-benign tumors or malignant cancers affecting the skin and brain-and also involving the heart, kidneys, lungs and eyes in ways that can vary across the lifetime. It also occurs and varies across generations. Among medical subspecialists, the pediatric neurologist is often responsible for making the initial diagnosis when the affected individual presents with infantile spasms or another early-onset epilepsy syndrome. In recent decades, the identification of the responsible genes and gene products forming the mechanistic target of rapamycin complex, previously termed the mammalian target of rapamycin, not only has expanded our understanding of tuberous sclerosis pathophysiology, but has also inspired the search for targeted interventions.

Early epileptiform EEG activity in infants with tuberous sclerosis complex predicts epilepsy and neurodevelopmental outcomes

OBJECTIVE

To study the association between timing and characteristics of the first electroencephalography (EEG) with epileptiform discharges (ED-EEG) and epilepsy and neurodevelopment at 24 months in infants with tuberous sclerosis complex (TSC).

METHODS

Patients enrolled in the prospective Epileptogenesis in a genetic model of epilepsy - Tuberous sclerosis complex (EPISTOP) trial, had serial EEG monitoring until the age of 24 months. The timing and characteristics of the first ED-EEG were studied in relation to clinical outcome. Epilepsy-related outcomes were analyzed separately in a conventionally followed group (initiation of vigabatrin after seizure onset) and a preventive group (initiation of vigabatrin before seizures, but after appearance of interictal epileptiform discharges [IEDs]).

RESULTS

Eighty-three infants with TSC were enrolled at a median age of 28 days (interquartile range [IQR] 14-54). Seventy-nine of 83 patients (95%) developed epileptiform discharges at a median age of 77 days (IQR 23-111). Patients with a pathogenic TSC2 variant were significantly younger (P-value .009) at first ED-EEG and more frequently had multifocal IED (P-value .042) than patients with a pathogenic TSC1 variant. A younger age at first ED-EEG was significantly associated with lower cognitive (P-value .010), language (P-value .001), and motor (P-value .013) developmental quotients at 24 months. In the conventional group, 48 of 60 developed seizures. In this group, the presence of focal slowing on the first ED-EEG was predictive of earlier seizure onset (P-value .030). Earlier recording of epileptiform discharges (P-value .019), especially when multifocal (P-value .026) was associated with higher risk of drug-resistant epilepsy. In the preventive group, timing, distribution of IED, or focal slowing, was not associated with the epilepsy outcomes. However, when multifocal IEDs were present on the first ED-EEG, preventive treatment delayed the onset of seizures significantly (P-value <.001).

SIGNIFICANCE

Early EEG findings help to identify TSC infants at risk of severe epilepsy and neurodevelopmental delay and those who may benefit from preventive treatment with vigabatrin.

Prevention of Epilepsy in Infants with Tuberous Sclerosis Complex in the EPISTOP Trial

OBJECTIVE

Epilepsy develops in 70 to 90% of children with tuberous sclerosis complex (TSC) and is often resistant to medication. Recently, the concept of preventive antiepileptic treatment to modify the natural history of epilepsy has been proposed. EPISTOP was a clinical trial designed to compare preventive versus conventional antiepileptic treatment in TSC infants.

METHODS

In this multicenter study, 94 infants with TSC without seizure history were followed with monthly video electroencephalography (EEG), and received vigabatrin either as conventional antiepileptic treatment, started after the first electrographic or clinical seizure, or preventively when epileptiform EEG activity before seizures was detected. At 6 sites, subjects were randomly allocated to treatment in a 1:1 ratio in a randomized controlled trial (RCT). At 4 sites, treatment allocation was fixed; this was denoted an open-label trial (OLT). Subjects were followed until 2 years of age. The primary endpoint was the time to first clinical seizure.

RESULTS

In 54 subjects, epileptiform EEG abnormalities were identified before seizures. Twenty-seven were included in the RCT and 27 in the OLT. The time to the first clinical seizure was significantly longer with preventive than conventional treatment [RCT: 364 days (95% confidence interval [CI] = 223-535) vs 124 days (95% CI = 33-149); OLT: 426 days (95% CI = 258-628) vs 106 days (95% CI = 11-149)]. At 24 months, our pooled analysis showed preventive treatment reduced the risk of clinical seizures (odds ratio [OR] = 0.21, p = 0.032), drug-resistant epilepsy (OR = 0.23, p = 0.022), and infantile spasms (OR = 0, p < 0.001). No adverse events related to preventive treatment were noted.

INTERPRETATION

Preventive treatment with vigabatrin was safe and modified the natural history of seizures in TSC, reducing the risk and severity of epilepsy. ANN NEUROL 2021;89:304-314.

Approach to Preventive Epilepsy Treatment in Tuberous Sclerosis Complex and Current Clinical Practice in 23 Countries

Tuberous sclerosis complex (TSC) is associated with a high risk of early-onset epilepsy and developmental delay. Recently, EEG monitoring in infants with TSC and preventive antiepileptogenic treatment have been proposed to improve epilepsy and neurodevelopmental outcome. We explored how recent studies and recommendations regarding EEG monitoring and preventive epilepsy treatment have influenced the clinical practice of epilepsy management among children with TSC.

METHODS

A survey on the epilepsy management approach in infants with TSC was sent by e-mail to 165 clinicians who actively participated in TSC international research conferences in years 2016 - 2019. Additionally, the e-mail addresses of TSC referral centers were collected from national TSC organizations. The survey was also distributed in the American Epilepsy Society newsletter. Only responses from centers providing neurological care for children with TSC were included in the study.

RESULTS

Sixty-one responses from 23 countries were analyzed. Sixty respondents answered questions concerning infants, and 57 of 60 respondents (95%) perform at least one EEG study before epilepsy onset and 42 (70.0%) conduct regular EEG monitoring. Most of the clinicians perform video EEG (42/61, 68.8%). Overall, 51.7% of respondents, mostly from Europe, Australia, and South America, endorse preventive antiepileptic treatment in infants with TSC. Vigabatrin is a preferred drug in patients younger than two years old for both focal (61.7%) and generalized (56.7%) seizures.

CONCLUSIONS

Despite the lack of published results of randomized trials, the concepts of preseizure EEG monitoring and epilepsy prevention are already being implemented in the majority of surveyed centers.

Impact of predictive, preventive and precision medicine strategies in epilepsy

Over the last decade, advances in genetics, neuroimaging and EEG have enabled the aetiology of epilepsy to be identified earlier in the disease course than ever before. At the same time, progress in the study of experimental models of epilepsy has provided a better understanding of the mechanisms underlying the condition and has enabled the identification of therapies that target specific aetiologies. We are now witnessing the impact of these advances in our daily clinical practice. Thus, now is the time for a paradigm shift in epilepsy treatment from a reactive attitude, treating patients after the onset of epilepsy and the initiation of seizures, to a proactive attitude that is more broadly integrated into a 'P4 medicine' approach. This P4 approach, which is personalized, predictive, preventive and participatory, puts patients at the centre of their own care and, ultimately, aims to prevent the onset of epilepsy. This aim will be achieved by adapting epilepsy treatments not only to a given syndrome but also to a given patient and moving from the usual anti-seizure treatments to personalized treatments designed to target specific aetiologies. In this Review, we present the current state of this ongoing revolution, emphasizing the impact on clinical practice.

Prediction of Neurodevelopment in Infants With Tuberous Sclerosis Complex Using Early EEG Characteristics

Tuberous Sclerosis Complex (TSC) is a multisystem genetic disorder with a high risk of early-onset epilepsy and a high prevalence of neurodevelopmental comorbidities, including intellectual disability and autism spectrum disorder (ASD). Therefore, TSC is an interesting disease model to investigate early biomarkers of neurodevelopmental comorbidities when interventions are favourable. We investigated whether early EEG characteristics can be used to predict neurodevelopment in infants with TSC. The first recorded EEG of 64 infants with TSC, enrolled in the international prospective EPISTOP trial (recorded at a median gestational age 42 4/7 weeks) was first visually assessed. EEG characteristics were correlated with ASD risk based on the ADOS-2 score, and cognitive, language, and motor developmental quotients (Bayley Scales of Infant and Toddler Development III) at the age of 24 months. Quantitative EEG analysis was used to validate the relationship between EEG background abnormalities and ASD risk. An abnormal first EEG (OR = 4.1, p-value = 0.027) and more specifically a dysmature EEG background (OR = 4.6, p-value = 0.017) was associated with a higher probability of ASD traits at the age of 24 months. This association between an early abnormal EEG and ASD risk remained significant in a multivariable model, adjusting for mutation and treatment (adjusted OR = 4.2, p-value = 0.029). A dysmature EEG background was also associated with lower cognitive (p-value = 0.029), language (p-value = 0.001), and motor (p-value = 0.017) developmental quotients at the age of 24 months. Our findings suggest that early EEG characteristics in newborns and infants with TSC can be used to predict neurodevelopmental comorbidities.

Medical treatment of tuberous sclerosis-related epilepsy

Epilepsy is one of the most frequent CNS manifestations of tuberous sclerosis, and for most patients, it is the major debilitating factor. In up to 70% of the cases, the epilepsy is refractory and usually associated with significant behavioral as well as developmental consequences. Therefore, controlling seizures is one of the biggest medical and surgical challenges. Understanding the cellular mechanism involved in the disease empowered targeted research aimed toward early intervention in the epileptogenicity process. In this review, we present an update on the pharmacological treatments in tuberous sclerosis-related epilepsy.

Behavioral problems and family distress in tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC)-associated neuropsychiatric disorders (TAND) have a large impact on patients and their families. Improving intellectual ability outcomes using preventive vigabatrin (VGB) treatment has recently been reported.

AIM

The aim of this study was to investigate the severity of behavioral problems and degree of distress among families of patients with TSC with and without a history of VGB treatment.

METHOD

The study enrolled 21 children and adolescents who were patients with TSC from four hospitals: 14 in the VGB group and 7 in the no-VGB group. To evaluate patients' psychiatric and neurological symptoms, we used the TAND Checklist, Aberrant Behavior Checklist (ABC), Social Communication Questionnaire (SCQ), and Social Responsive Scale-2nd edition (SRS-2).

RESULTS

All VGB-group patients were administered VGB after the onset of epileptic seizures. No obvious differences were observed between the VGB and no-VGB groups in behavioral problem scores on the TAND Checklist, or on the ABC, SCQ, and SRS-2 total scores. Behavioral problem scores were lower in patients with normal intelligence than in those with mild intellectual disability (ID; P = 0.042). Degrees of family distress assessed with the TAND Checklist were not correlated with the intelligence quotient/developmental quotient (IQ/DQ) or seizure frequency but were correlated with the total SRS-2 scores (P = 0.022). For several patients, there were large discrepancies between familial and physician ratings of the TAND impact score.

CONCLUSION

Children and adolescents with TSC may present with significant behavioral difficulties and family distress, regardless of whether they were treated with VGB or not after the onset of seizures. Difficulties in social communication may have the strongest "TAND impact" on families.

An Updated Review of Tuberous Sclerosis Complex-Associated Autism Spectrum Disorder

Tuberous sclerosis complex (TSC) is a neurocutaneous disorder caused by mutations of either the TSC1 or TSC2 gene. Various neuropsychiatric features, including autism, are prevalent in TSC. Recently, significant progress has been possible with the prospective calculation of the prevalence of autism in TSC, identification of early clinical and neurophysiological biomarkers to predict autism, and investigation of different therapies to prevent autism in this high-risk population. The author provides a narrative review of recent findings related to biomarkers for diagnosis of autism in TSC, as well as recent studies related to the management of TSC-associated autism. Further sophisticated modeling and analysis are required to understand the role of different models-tuber models, seizures and related neurophysiological factors models, genotype models, and brain connectivity models-to unravel the neurobiological basis of autism in TSC. Early neuropsychologic assessments may be beneficial in this high-risk group. Targeted intervention to improve visual skill, cognition, and fine motor skills with later addition of social skill training can be helpful. Multicenter, prospective studies are ongoing to identify if presymptomatic treatment with vigabatrin in patients with TSC can improve outcomes, including autism. Several studies indicated reasonable safety of everolimus in young children, and its potential application in high-risk infants with TSC, before the closure of the temporal window of permanent changes, maybe undertaken shortly.

Pilot Study of Neurodevelopmental Impact of Early Epilepsy Surgery in Tuberous Sclerosis Complex

BACKGROUND

To determine if early epilepsy surgery mitigates detrimental effects of refractory epilepsy on development, we investigated surgical and neurodevelopmental outcomes in children with tuberous sclerosis complex who underwent surgery before age two years.

METHODS

Prospective multicenter observational study of 160 children with tuberous sclerosis complex. Surgical outcome was determined for the seizure type targeted by surgery. We obtained Vineland Adaptive Behavior Scales, Second Edition (Vineland-II); Mullen Scales of Early Learning; and Preschool Language Scales, Fifth Edition, at age three, six, nine, 12, 18, 24, and 36 months. Surgical cases were compared with children without seizures, with controlled seizures, and with medically refractory seizures.

RESULTS

Nineteen children underwent surgery (median age 17 months, range 3.7 to 21.3), and mean follow-up was 22.8 months (range 12 to 48). Surgical outcomes were favorable in 12 (63%, Engel I-II) and poor in seven (37%, Engel III-IV). Nine (47%) had new or ongoing seizures distinct from those surgically targeted. All children with seizures demonstrated longitudinal decline or attenuated gains in neurodevelopment, the surgical group scoring the lowest. Favorable surgical outcome was associated with increased Mullen Scales of Early Learning receptive and expressive language subscores compared with the medically refractory seizure group. A nonsignificant but consistent pattern of improvement with surgery was seen in all tested domains.

CONCLUSIONS

These pilot data show neurodevelopmental gains in some domains following epilepsy surgery. A properly powered, prospective multicenter observational study of early epilepsy surgery is needed, using both surgical and developmental outcome metrics.

Is autism driven by epilepsy in infants with Tuberous Sclerosis Complex?

Objective

To evaluate the relationship between age at seizure onset and neurodevelopmental outcome at age 24 months in infants with TSC, as well as the effect on neurodevelopmental outcome of early versus conventional treatment of epileptic seizures with vigabatrin (80–150 mg/kg/day).

Methods

Infants with TSC, aged ≤4 months and without previous seizures were enrolled in a prospective study and closely followed with monthly video EEG and serial standardized neurodevelopmental testing (Bayley Scales of Infant Development and Autism Diagnostic Observation Schedule).

Results

Eighty infants were enrolled. At the age of 24 months testing identified risk of Autism Spectrum Disorder (ASD) in 24/80 children (30.0%), and developmental delay (DD) in 26/80 (32.5%). Children with epilepsy (51/80; 63.8%) had a higher risk of ASD (P = 0.02) and DD (P = 0.001). Overall, no child presented with moderate or severe DD at 24 months (developmental quotient < 55). In 20% of children abnormal developmental trajectories were detected before the onset of seizures. Furthermore, 21% of all children with risk of ASD at 24 months had not developed seizures at that timepoint. There was no significant difference between early and conventional treatment with respect to rate of risk of ASD (P = 0.8) or DD (P = 0.9) at 24 months.

Interpretation

This study confirms a relationship between epilepsy and risk of ASD/DD. However, in this combined randomized/open label study, early treatment with vigabatrin did not alter the risk of ASD or DD at age 2 years.

Epilepsy and Neurodevelopmental Comorbidities in Tuberous Sclerosis Complex: A Natural History Study

BACKGROUND

We studied the natural history, genotype influence, and inter-relationship of epilepsy and neuropsychiatric disorders in tuberous sclerosis complex.

METHODS

Patients were identified using the TSC Natural History Database, the largest repository of longitudinally studied patients enrolled by the TSC Clinics Consortium.

RESULTS

A cohort of 1657 TSC Natural History Database patients was analyzed. Eighty-eight percent patients (91% TSC2 vs 82% TSC1; P = 0.002) had epilepsy; TSC2 was more frequent with epilepsy onset at age less than two years (TSC2 82% vs TSC1 54%; P < 0.001) and infantile spasms (TSC2 56% vs TSC1 27%; P < 0.001). Frequency of intellectual disability (intelligence quotient less than 70) was higher when epilepsy coexisted (P < 0.001), but was not impacted by genotype (P = 0.08). Severe intellectual disability (intelligence quotient less than 50) was associated with epilepsy onset at age less than two years (P = 0.007), but not with the epilepsy duration (P = 0.45). Autism was diagnosed in 23% and was associated with epilepsy (P < 0.001), particularly with epilepsy onset at age less than two years (P = 0.02) but not with genotype (P = 0.06). Attention-deficit/hyperactivity disorder (age greater than four years) was diagnosed in 18% and was associated with epilepsy (P < 0.001), but genotype made no difference. Nine percent had anxiety (age greater than seven years) and 6% had depression (age greater than nine years), but neither showed association with epilepsy or genotype.

CONCLUSIONS

Epilepsy is associated with intellectual disability, and when epilepsy begins before age two years the frequency and severity of intellectual disability is much higher. Epilepsy is also associated with autism and attention-deficit/hyperactivity disorder but not with anxiety and depression. Additional trials, blinded, prospective, and adequately powered, will help clarify if early and effective treatment of epilepsy may also mitigate intellectual disability, autism, and attention-deficit/hyperactivity disorder.

Treatment of infantile spasms: why do we know so little?

INTRODUCTION

Infantile spasm (IS) is an epileptic syndrome with typical onset within the first 2 years of life. This condition might be caused by several etiologies. IS is associated with pathological neuronal networks; however, definite hypotheses on neurobiological processes are awaited.

AREAS COVERED

Changes in NMDA and GABA_B receptors and increase of Ca²⁺ conductance are some of the possible pathophysiological mechanisms. Animal models can help, but most have only some features of IS. Outcome is strongly affected by etiology and the timing of treatment, which relies still on ACTH, oral steroids, and vigabatrin. No significant differences in terms of efficacy have been documented, though a combination of ACTH and vigabatrin seems to be associated with better long-term outcomes. Despite the increasing knowledge about the etiology and pathophysiology of IS, in the last years, no new treatment approaches have been recognized to be able to modify the neurobiological process underlying IS. Precision medicine has far to come in IS.

EXPERT OPINION

Recently, no new therapeutic options for IS have emerged, probably due to the lack of reliable animal models and to the extreme variability in etiologies. Consequently, the outlook for patients and families is poor and early recognition and intervention remain research priorities.

Repurposed molecules for antiepileptogenesis: Missing an opportunity to prevent epilepsy?

Prevention of epilepsy is a great unmet need. Acute central nervous system (CNS) insults such as traumatic brain injury (TBI), cerebrovascular accidents (CVA), and CNS infections account for 15%-20% of all epilepsy. Following TBI and CVA, there is a latency of days to years before epilepsy develops. This allows treatment to prevent or modify postinjury epilepsy. No such treatment exists. In animal models of acquired epilepsy, a number of medications in clinical use for diverse indications have been shown to have antiepileptogenic or disease-modifying effects, including medications with excellent side effect profiles. These include atorvastatin, ceftriaxone, losartan, isoflurane, N-acetylcysteine, and the antiseizure medications levetiracetam, brivaracetam, topiramate, gabapentin, pregabalin, vigabatrin, and eslicarbazepine acetate. In addition, there are preclinical antiepileptogenic data for anakinra, rapamycin, fingolimod, and erythropoietin, although these medications have potential for more serious side effects. However, except for vigabatrin, there have been almost no translation studies to prevent or modify epilepsy using these potentially "repurposable" medications. We may be missing an opportunity to develop preventive treatment for epilepsy by not evaluating these medications clinically. One reason for the lack of translation studies is that the preclinical data for most of these medications are disparate in terms of types of injury, models within different injury type, dosing, injury-treatment initiation latencies, treatment duration, and epilepsy outcome evaluation mode and duration. This makes it difficult to compare the relative strength of antiepileptogenic evidence across the molecules, and difficult to determine which drug(s) would be the best to evaluate clinically. Furthermore, most preclinical antiepileptogenic studies lack information needed for translation, such as dose-blood level relationship, brain target engagement, and dose-response, and many use treatment parameters that cannot be applied clinically, for example, treatment initiation before or at the time of injury and dosing higher than tolerated human equivalent dosing. Here, we review animal and human antiepileptogenic evidence for these medications. We highlight the gaps in our knowledge for each molecule that need to be filled in order to consider clinical translation, and we suggest a platform of preclinical antiepileptogenesis evaluation of potentially repurposable molecules or their combinations going forward.

Update on Drug Management of Refractory Epilepsy in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a genetic neurocutaneous disorder with epilepsy as a common and early presenting symptom. The neurological phenotype, however, is variable and unpredictable. Early and refractory seizures, infantile spasms in particular, are associated with a poor neurological outcome. Preliminary data suggests early and aggressive seizure control may mitigate the detrimental neurodevelopmental effects of epilepsy. For infantile spasms, vigabatrin is the first line of treatment, and steroids and classic antiepileptic drugs (AEDs) are suitable for second line. Based on retrospective data, vigabatrin should be considered for other indications, especially in infants with focal seizures, as this may prevent infantile spasms, but also in children and adults with epileptic spasms and tonic seizures. Otherwise, for most seizure types, treatment is similar to that for patients without TSC, including the use of novel AEDs, although limited data are available. Three major developments are changing the field of epilepsy management in TSC. First, final recommendations on preventive treatment with vigabatrin will result from two multicenter trials in the US (PREVeNT, clinicaltrials.gov #NCT02849457) and Europe (EPISTOP, clinicaltrials.gov #NCT02098759). Second, treatment with everolimus, an inhibitor of the mechanistic target of rapamycin (mTOR), reduced seizures when compared to placebo. Further, mTOR inhibitors may have an overall disease-modifying effect. Third, the role of cannabidiol in the treatment of refractory seizures in TSC is yet to be established. With treatment recommendations in TSC, we keep an eye on the prize for the broader field of pediatric epilepsy: the lessons learned from TSC are likely applicable to other epileptic encephalopathies.