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

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.

Epilepsy in tuberous sclerosis complex: Findings from the TOSCA Study

OBJECTIVE

To present the baseline data of the international TuberOus SClerosis registry to increase disease Awareness (TOSCA) with emphasis on the characteristics of epilepsies associated with tuberous sclerosis complex (TSC).

METHODS

Retrospective and prospective patients' data on all aspects of TSC were collected from multiple countries worldwide. Epilepsy variables included seizure type, age at onset, type of treatment, and treatment outcomes and association with genotype, seizures control, and intellectual disability. As for noninterventional registries, the study protocol did not specify any particular clinical instruments, laboratory investigations, or intervention. Evaluations included those required for diagnosis and management following local best practice.

RESULTS

Epilepsy was reported in 83.6% of patients (1852/2216) at baseline; 38.9% presented with infantile spasms and 67.5% with focal seizures. The mean age at diagnosis of infantile spasms was 0.4 year (median <1 year; range <1-30 years) and at diagnosis of focal seizures was 2.7 years (median 1 year; range <1-66 years). A total of 1469 patients (79.3%) were diagnosed with epilepsy <2 years. The rate of infantile spasms was higher in patients with a TSC 2 mutation than in patients with a TSC1 mutation (47.3% vs 23%). ɣ-aminobutyric acid (GABA)ergic drugs were the most common treatment modality for both infantile spasms (78.7%) and focal seizures (65.5%). Infantile spasms and focal seizures were controlled in 76.3% and 58.2% of patients, respectively. Control of seizures was associated with lower rates of intellectual disability in both groups.

SIGNIFICANCE

This registry reports the largest international cohort of patients with TSC. Findings confirmed the typical onset pattern of infantile spasms and other focal seizures in the first 2 years of life, and the high rates of infantile spasms in patients with TSC2 mutation. Our results underscored the occurrence of focal seizures at all ages, including an onset that preceded emergence of infantile spasms. Seizure control was shown to be associated with lower rates of intellectual disability but did not preclude the presence of intellectual disability.

The role of mTOR inhibitors in preventing epileptogenesis in patients with TSC: Current evidence and future perspectives

Tuberous sclerosis complex (TSC) is one of the most common genetic causes of epilepsy. Mutations in the TSC1 or TSC2 genes lead to the dysregulation of the mechanistic target of rapamycin (mTOR) pathway. This mTOR pathway hyperactivation is associated with several processes resulting in epileptic conditions. The occurrence of seizures and their treatment outcomes seem to play a crucial role in cognitive and behavioral developments in patients with TSC. Mechanistic target of rapamycin inhibitors have been proven to be effective in epilepsy treatment in individuals with TSC. Specifically, because of their disease-modifying mechanism of action, they have the capability to prevent epileptogenesis in patients with TSC. This article will provide an overview of the current evidence of and delineate future perspectives for mTOR inhibitors and their role in preventing epileptogenesis.

mTOR inhibitor therapy as a disease modifying therapy for tuberous sclerosis complex

Between 1993 and 2003, through experiments involving Drosophila sp., cancer biologists identified the protein kinase known as the mammalian target of rapamycin, its pathway, and its relationship to the genes responsible for tuberous sclerosis. Thereafter, clinical research has resulted in regulatory approval of mTOR inhibitors for four distinct manifestations of the disease: giant cell astrocytoma, angiomyolipoma, lymphangioleiomyomatosis, and epilepsy. These developments are summarized and the practical use of mTOR inhibitors to improve the lives of patients with tuberous sclerosis reviewed.

Current concepts on epilepsy management in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous disease affecting approximately 1 in 6,000 people, and represents one of the most common genetic causes of epilepsy. Epilepsy affects 90% of the patients and appears in the first 2 years of life in the majority of them. Early onset of epilepsy in the first 12 months of life is associated with high risk of cognitive decline and neuropsychiatric problems including autism. Prenatal or early infantile diagnosis of TSC, before the onset of epilepsy, provides a unique opportunity to monitor EEG before the onset of clinical seizures, thus enabling early intervention in the process of epileptogenesis. In this review, we discuss the current status of knowledge on epileptogenesis in TSC, and present recommendations of American and European experts in the field of epilepsy.

Central nervous system manifestations of tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a neurocutaneous autosomal-dominant genetic syndrome marked by development of hamartomatous lesions arising from dysfunction of the mammalian target of rapamycin (mTOR) pathway. Although TSC remains a heterogeneous clinical entity, the recent inclusion of genetic diagnostic criteria reflects advancement in our understanding of its underlying etiopathogenesis. Abnormal cellular growth, differentiation, and migration result in multisystem sequelae, with neurologic manifestations of TSC representing the primary cause of morbidity and mortality for the majority of individuals. Modern imaging techniques aid in the diagnosis of TSC and guide treatment strategies by revealing central nervous system findings. Cortical tubers are the namesake lesion of the disorder and occur in up to 90% of cases, often exerting significant epileptogenic potential. Subependymal nodules are found in 80% of patients as calcified tumors lining the ependyma of the lateral ventricles. In some cases, these nodules are thought to progress to subependymal giant cell astrocytomas and may present with obstructive hydrocephalus. Retinal astrocytic hamartomas are also common, present in 50% of patients. Surgery remains the treatment of choice for large or symptomatic lesions, though clinical trials have highlighted a potential role for mTOR pathway antagonism. A multidisciplinary approach is necessary for achieving optimal patient outcomes.

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.

Ictal signs in tuberous sclerosis complex: Clinical and video-EEG features in a large series of recorded seizures

Epilepsy is the most common neurological symptom in tuberous sclerosis complex (TSC), occurring in 72-85% of affected individuals. Despite the large number of patients reported, their electroclinical phenotype has been rarely described. We analyzed seizure semiology through ictal video-electroencephalography (V-EEG) recordings in a large series of patients. In this multicenter study, we reviewed V-EEGs of 51 patients: ictal recordings were analyzed in correlation with their clinical variables. The median age of epilepsy onset was six months (one day-16 years), with onset in the first year of life in 71% patients (36/51), in 10 of them during the neonatal period. Sixty-five percent of patients (33/51) experienced epileptic spasms in their life, with late-onset (>two years) in five; 42% of the epileptic spasms persisted after age two years, despite the onset in the first year of life. We identified four different electroclinical subsets: focal epilepsy (35%, 18/51), Lennox-Gastaut Syndrome evolution (27%, 14/51), focal seizures with persisting spasms (33%, 17/51), and spasms only (4%, 2/51). We reviewed 45 focal seizures, 13 clusters of epileptic spasms, and seven generalized seizures. In 12 patients, we recorded different seizure types. In 71% of the focal seizures (32/45), the ictal pattern was focal without diffusion. In 38% of the patients (5/13) epileptic spasms were related to typical diffuse slow wave pattern associated with superimposed fast activity, with focal predominance. Focal seizures and focal spasms resulted as the most frequent seizure types in TSC. Seizure onset was variable but showing a predominant involvement of the frontocentral regions (40%). Discrete clinical signs characterized the seizures, and behavioral arrest was the predominant first clinical objective sign. Epileptic spasms were a typical presentation at all ages, frequently asymmetrical and associated with lateralizing features, especially in older patients.

Early predictors of clinical and mental outcome in tuberous sclerosis complex: A prospective study

AIM

We aimed to identify early predictors of intractable epilepsy, intellectual disability (ID) and autism spectrum disorders (ASD) in the cohort of TSC patients initially diagnosed with cardiac rhabdomyomas (CR).

METHOD

Over the period of twelve years we prospectively obtained clinical, neuropsychological, electrophysiological and neuroimaging data in a group of 22 TSC patients (9 females, 13 males) with the pre/perinatal diagnosis of CR, included to the study at the time of diagnosis. Afterwards, we statistically determined variables associated with ID, ASD and intractable epilepsy.

RESULTS

Development of ID was predicted by severe epilepsy (a higher number of anti-epileptic drugs used), a higher number of dysplastic lesions on MRI, and abnormal background activity on EEG (p < 0.05). Predictors of ASD included early developmental delay, abnormal background activity on EEG at the end of follow-up and a higher number of areas with dysplastic features on MRI (p < 0.05). Intractable epilepsy was associated with a higher number of areas with dysplastic features on MRI, ID and with TSC2 genotype.

CONCLUSION

Adverse mental and clinical outcome was associated with intractable epilepsy and the severe anatomical brain involvement; therefore, our centre developed a tailored protocol for early identification of TSC patients at a higher risk of developing intractable epilepsy with its deleterious effect on cognitive outcome.

Spikes might precede seizures and predict epilepsy in children with Sturge-Weber syndrome: A pilot study

PURPOSE

Sturge-Weber syndrome (SWS) is a neurocutaneous disorder characterized by a facial port-wine stain, a glaucoma, and a leptomeningeal angioma. Epilepsy occurs in more than 75% of affected children, and seizures occurring in the first year of life are associated with a poor neurological prognosis. The aim of this study was to identify possible predictive markers of epilepsy on electroencephalogram (EEG) performed prior to seizure onset in children with SWS.

METHODS

This study included children with a diagnosis of SWS who had an EEG performed prior to seizure onset. Patients who did not develop epilepsy had a minimum follow-up of 3-years. We compared EEG characteristics of patients who developed epilepsy with patients who did not develop epilepsy by the time of their follow-up.

RESULTS

Eleven children were included in this study. EEG was performed at the median age of 2.1 months (range 1.0-22.1). Six children developed seizures with a time interval between EEG and seizure onset ranging from 2 days to 21 months. EEG background activity was asymmetric in 8 patients, 5 of whom later developed epilepsy. Focal interictal spikes or sharp waves were exclusively recorded in patients who developed later epilepsy (4 out of 6). One of these patients had a supposed false positive EEG as he did not developed epilepsy until 21 months later and one patient had a false negative EEG with seizures occurring 2 days after a normal EEG.

CONCLUSION

Spikes on EEG might be a useful marker to identify patients with SWS at risk of developing epilepsy. Their predictive value should be assessed in larger prospective studies.

Secular changes in severity of intellectual disability in tuberous sclerosis complex: A reflection of improved identification and treatment of epileptic spasms?

Tuberous sclerosis complex (TSC) is a multisystem genetic disorder caused by mutations in TSC1 or TSC2. Epilepsy occurs in 80%-90% of affected individuals during their lifetime, and up to one-third of children with TSC will develop epileptic (infantile) spasms, for which vigabatrin has been shown to be particularly effective. Epilepsy severity and epileptic spasms are consistent markers of risk for the development of intellectual impairment in TSC. Although previous studies demonstrate a bimodal distribution of intellectual ability in TSC, recent findings suggest a unimodal distribution, which may reflect a change in IQ distribution over time. We compared 3 large historical UK cohorts of TSC (n = 331) that show varied distributions of intellectual ability, first ruling out differences in study methodology. Later-born individuals had a higher frequency of reported spasms and higher likelihood of vigabatrin administration, but were less likely to have profound intellectual impairment, compared to the earlier-born individuals. Our findings suggest that epileptic spasms went undetected in the older patients and therefore were not treated, leading to a higher occurrence of profound impairment, whereas the later born cohort had better access to treatment. These findings support the importance of early identification and treatment of seizures in TSC.

Cognitive and motor outcomes in children with unilateral Sturge-Weber syndrome: Effect of age at seizure onset and side of brain involvement

PURPOSE

Most children with Sturge-Weber syndrome (SWS) develop seizures that may contribute to neurocognitive status. In this study, we tested the hypothesis that very early seizure onset has a particularly detrimental effect on the cognitive and/or motor outcomes of children with unilateral SWS. We also tested whether side of SWS brain involvement modulates the effect of seizure variables on the pattern of cognitive abnormalities.

METHODS

Thirty-four children (22 girls; mean age 6.1years) with unilateral SWS and history of epilepsy in a longitudinal cohort underwent neurological and cognitive evaluations. Global intelligent quotient (GIQ), verbal intelligent quotient (VIQ), nonverbal intelligent quotient (IQ), and motor function were correlated with epilepsy variables, side and extent of brain involvement on magnetic resonance imaging (MRI).

RESULTS

Mean age at seizure onset was 1.3years (0.1-6years) and mean IQ at follow-up was 86 (45-118). Age at seizure onset showed a logarithmic association with IQ, with maximum impact of seizures starting before age 1year, both in uni- and multivariate regression analyses. In the left SWS group (N=20), age at seizure onset was a strong predictor of nonverbal IQ (p=0.001); while early seizure onset in the right-hemispheric group had a more global effect on cognitive functions (p=0.02). High seizure frequency and long epilepsy duration also contributed to poor outcome IQ independently in multivariate correlations. Children with motor involvement started to have seizures at/before 7months of age, while frontal lobe involvement was the strongest predictor of motor deficit in a multivariate analysis (p=0.017).

CONCLUSION

These findings suggest that seizure onset prior to age 1year has a profound effect on severity of cognitive and motor dysfunction in children with SWS; however, the effect of seizures on the type of cognitive deficit is influenced by laterality of brain involvement.

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.

Targeting the Mammalian Target of Rapamycin for Epileptic Encephalopathies and Malformations of Cortical Development

Malformations of cortical development represent a common cause of epileptic encephalopathies and drug-resistant epilepsy in children. As current treatments are often ineffective, new therapeutic targets are needed for epileptic encephalopathies associated with cortical malformations. The mechanistic/mammalian target of rapamycin (mTOR) pathway constitutes a signaling pathway that drives cellular and molecular mechanisms of epileptogenesis in a variety of focal cortical malformations. mTOR inhibitors prevent epilepsy and associated pathogenic mechanisms of epileptogenesis in mouse models of tuberous sclerosis complex and are currently in clinical trials for drug-resistant seizures in these patients. A recent explosion of genetic studies has linked mutations in various genes regulating the mTOR pathway to other cortical malformations, such as focal cortical dysplasia and hemimegalencephaly. Thus, mTOR inhibitors represent promising candidates as novel antiseizure and antiepileptogenic therapies for epilepsy associated with a spectrum of cortical malformations.

Presentation and Diagnosis of Tuberous Sclerosis Complex in Infants

OBJECTIVES

Tuberous sclerosis complex (TSC) is a neurocutaneous genetic disorder with a high prevalence of epilepsy and neurodevelopmental disorders. TSC can be challenging to diagnose in infants because they often do not show many clinical signs early in life. In this study, we describe the timing and pattern of presenting and diagnostic features in a prospective longitudinal study of infants with TSC.

METHODS

Two multicenter, prospective studies enrolled 130 infants with definite TSC by clinical or genetic criteria and followed them longitudinally up to 36 months of age. Periodic study visits included medical and seizure histories, physical and neurologic examinations, and developmental assessments. Ages at which major and minor features of TSC and seizures were first identified were analyzed.

RESULTS

The most common initial presenting features of TSC were cardiac rhabdomyomas (59%) and hypomelanotic macules or other skin findings (39%), and 85% of infants presented with either or both. Ultimately, the most prevalent diagnostic TSC features were hypomelanotic macules (94%), tubers or other cortical dysplasias (94%), subependymal nodules (90%), and cardiac rhabdomyomas (82%). Thirty-five percent of infants presented prenatally, 41% presented at birth or within the first month of life, and 74% met criteria for TSC diagnosis at or within 30 days of presentation. Seizure onset occurred before or at initial presentation in only 15% of infants, but 73% developed epilepsy within the first year of life.

CONCLUSIONS

Infants with TSC can often be identified early, before the onset of neurologic sequelae, enabling earlier diagnosis, surveillance, and possibly disease-modifying treatment.

Predictors of Drug-Resistant Epilepsy in Tuberous Sclerosis Complex

Utilizing the multicenter TSC (tuberous sclerosis complex) Natural History Database including 2034 subjects, this study aimed to identify predictors of drug-resistant epilepsy in TSC. Basic epilepsy data were available for 1965 individuals in the database. Supplemental data were further collected from 1546 of these subjects through directed site queries, addressing additional epilepsy characteristics including the presence of drug-resistant epilepsy, therapies trialed, and outcomes of specific therapies. Epilepsy was reported in 86.4% of individuals with TSC. Infantile spasms were reported in 45.2% of individuals and focal seizures were reported in 84.4% of individuals. In those with focal epilepsy, drug resistance was reported in 59.6%, with focal seizure onset prior to age 1 year (odds ratio [OR] 1.9, confidence interval [CI] 1.4-2.5, P < .001), infantile spasms (OR 2.0, CI 1.5-2.5, P < 0.001), and infantile spasms incompletely responsive to therapy (OR 47.6, CI 6.7-333.3, P < 0.001) being associated with an increased likelihood of drug resistance.

Everolimus for treatment of tuberous sclerosis complex-associated neuropsychiatric disorders

Objective

To evaluate if short-term treatment with everolimus was safe and could improve neurocognition and behavior in children with TSC.

Methods

This was a prospective, double-blind randomized, placebo-controlled two-center phase II study. Participants diagnosed with TSC and age 6-21 years were treated with 4.5 mg/m² per day of oral everolimus (n = 32) or matching placebo (n = 15) taken once daily for 6 months. For efficacy, a comprehensive neurocognitive and behavioral evaluation battery was performed at baseline, 3 months, and 6 months. For safety, adverse events recorded continuously via patient diary were categorized and graded per NCI Common Toxicity Criteria for Adverse Events, version 3.0 (CTCAE 3.0). Analyses were performed on the intention-to-treat population (n = 47).

Results

Nearly all assessment measures failed to demonstrate significant differences between the two groups at the end of 6 months. Only one measure each of executive function (Cambridge Neuropsychological Test Automated Battery Stockings of Cambridge) favoring placebo (P = 0.025) and social cognition (Social Responsiveness Scale Social Cognition Subscale) favoring everolimus (P = 0.011) was observed. A total of 473 adverse events (AE) were reported. The average number of total AE per subject was similar for both placebo and everolimus. Most were mild or moderate in severity and serious AE were rare.

Interpretation

While safe, oral everolimus administered once daily for 6 months did not significantly improve neurocognitive functioning or behavior in children with TSC.

Early Detection of Tuberous Sclerosis Complex: An Opportunity for Improved Neurodevelopmental Outcome

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant condition associated with epilepsy, benign tumors, and variable neurodevelopmental outcomes. The diagnosis is most commonly made after epilepsy onset, although a proportion are diagnosed prenatally. Presymptomatic or early treatment with agents such as vigabatrin offers the hope of improved neurodevelopmental outcome. Therefore early diagnosis, before the onset of seizures, is important. In a cohort of children with TSC, we evaluated the age and mode of initial presentation, assessed the neurocognitive and epilepsy outcome, and analyzed whether those diagnosed before the onset of seizures have a different outcome compared with those diagnosed postseizures.

METHODS

We reviewed patients at the TSC clinic at Sydney Children's Hospital who were born between 2001 and 2015.

RESULTS

A total of 74 patients were identified: 34 (46%) diagnosed preseizure (21 prenatally) and 40 (54%) postseizure. In the preseizure cohort, 77% presented with cardiac rhabdomyoma(s) and 72% developed seizures. The postseizure cohort had more severe epilepsy, requiring more antiepileptic drugs for seizure control (median five, compared with three in the preseizure cohort [P = 0.01]). Developmental disability occurred in 65% of the preseizure cohort compared with 72% of the postseizure cohort. Severe developmental disability most often occurred in children who had their first seizure before age 12 months.

CONCLUSION

Children who are diagnosed with TSC before the onset of seizures have less severe epilepsy and better developmental outcome.

The Utility of Surveillance Electroencephalography to Guide Early Antiepileptic Drug Therapy in Infants With Tuberous Sclerosis Complex

BACKGROUND

Seizures are a common early presentation in infants with tuberous sclerosis complex (TSC) and can be preceded by electrographic changes on electroencephalography (EEG) before clinical seizure onset. A limited number of studies have addressed the initial EEG findings in TSC and the outcome of early treatment with antiepileptic medication prior to clinical seizure onset.

METHODS

We describe two infants with tuberous sclerosis complex whose surveillance EEG showed focal seizures that were not previously recognized by caregivers. We review previously reported patients with TSC with early EEG findings. Our patients were started on vigabatrin after the onset of focal seizures with the aim of preventing seizure recurrence, halting the possible progression to infantile spasms or focal seizures, and preventing neurodevelopmental decline.

RESULTS

Both patients remain seizure free and have reached appropriate developmental milestones.

CONCLUSIONS

We recommend early serial EEG monitoring once a diagnosis of TSC is suspected or confirmed in infants. Additional prospective studies are needed to assess the long-term outcome of early antiepileptic drug initiation as soon as electrographic seizure activity is detected.

Autism spectrum disorder and epileptic encephalopathy: common causes, many questions

Epileptic encephalopathies represent a particularly severe form of epilepsy, associated with cognitive and behavioral deficits, including impaired social-communication and restricted, repetitive behaviors that are the hallmarks of autism spectrum disorder (ASD). With the advent of next-generation sequencing, the genetic landscape of epileptic encephalopathies is growing and demonstrates overlap with genes separately implicated in ASD. However, many questions remain about this connection, including whether epileptiform activity itself contributes to the development of ASD symptomatology. In this review, we compiled a database of genes associated with both epileptic encephalopathy and ASD, limiting our purview to Mendelian disorders not including inborn errors of metabolism, and we focused on the connection between ASD and epileptic encephalopathy rather than epilepsy broadly. Our review has four goals: to (1) discuss the overlapping presentations of ASD and monogenic epileptic encephalopathies; (2) examine the impact of the epilepsy itself on neurocognitive features, including ASD, in monogenic epileptic encephalopathies; (3) outline many of the genetic causes responsible for both ASD and epileptic encephalopathy; (4) provide an illustrative example of a final common pathway that may be implicated in both ASD and epileptic encephalopathy. We demonstrate that autistic features are a common association with monogenic epileptic encephalopathies. Certain epileptic encephalopathy syndromes, like infantile spasms, are especially linked to the development of ASD. The connection between seizures themselves and neurobehavioral deficits in these monogenic encephalopathies remains open to debate. Finally, advances in genetics have revealed many genes that overlap in ties to both ASD and epileptic encephalopathy and that play a role in diverse central nervous system processes. Increased attention to the autistic features of monogenic epileptic encephalopathies is warranted for both researchers and clinicians alike.

New insights into the pathogenesis and prevention of tuberous sclerosis-associated neuropsychiatric disorders (TAND)

Tuberous sclerosis complex (TSC) is a multi-system disorder resulting from mutations in either the TSC1 or TSC2 genes leading to hyperactivation of mechanistic target of rapamycin (mTOR) signaling. TSC is commonly associated with autism (61%), intellectual disability (45%), and behavioral, psychiatric, intellectual, academic, neuropsychological, and psychosocial difficulties that are collectively referred to as TSC-associated neuropsychiatric disorders (TAND). More than 90% of children with TSC have epilepsy, including infantile spasms, and early onset of seizures, especially infantile spasms, is associated with greater impairment in intellectual development compared with individuals with TSC without seizures. Development of the mTOR inhibitors everolimus and sirolimus has led to considerable progress in the treatment of renal angiomyolipomata, pulmonary lymphangioleiomyomatosis, and subependymal giant cell astrocytomas in the brain. However, similar therapeutic progress is needed in the treatment of TAND.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

SIGNIFICANCE

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

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.

Long-term treatment of epilepsy with everolimus in tuberous sclerosis

OBJECTIVE

To evaluate the long-term benefit and safety of everolimus for the treatment of medically refractory epilepsy in patients with tuberous sclerosis complex (TSC).

METHODS

Everolimus was titrated over 4 weeks and continued an additional 8 weeks in a prospective, open-label, phase I/II clinical trial design. Participants demonstrating initial benefit continued treatment until study completion (48 months). The primary endpoint was percentage of patients with a ≥50% reduction in seizure frequency compared to baseline. Secondary endpoints assessed absolute seizure frequency, adverse events (AEs), behavior, and quality of life.

RESULTS

Of the 20 participants who completed the initial study phase, 18 continued extended treatment. Fourteen of 18 (78%) participants completed the study, all but 1 of whom reported ≥50% reduction in seizure frequency at 48 months. All participants reported at least 1 AE, the vast majority (94%) of which were graded mild or moderate severity. Improvements in behavior and quality of life were also observed, but failed to achieve statistical significance at 48 months.

CONCLUSIONS

Improved seizure control was maintained for 4 years in the majority of patients with TSC with medically refractory epilepsy treated with everolimus. Long-term treatment with everolimus is safe and well-tolerated in this population. Everolimus may be a therapeutic option for refractory epilepsy in TSC.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with TSC with medically refractory epilepsy everolimus improves seizure control.

Applying the Lessons of Tuberous Sclerosis: The 2015 Hower Award Lecture

Tuberous sclerosis complex is a dominantly inherited disorder that variably affects the brain, skin, kidneys, heart, and other organs. Its neurological manifestations include epilepsy, autism, cognitive and behavioral dysfunction, and giant cell tumors. A mutation of either TSC1 or TSC2 can cause tuberous sclerosis complex. Their two gene products, hamartin and tuberin, form a physical complex which normally inhibits protein synthesis mediated through the mechanistic target of rapamycin, so a TSC1 or TSC2 mutation results in overactivation of the mechanistic target of rapamycin cascade. In addition to their tumor suppressor roles, TSC1 and TSC2 help to regulate cell size, neuronal migration, axon formation, and synaptic plasticity. Clinical trials of two different the mechanistic target of rapamycin inhibitors have demonstrated substantial improvement of tuberous sclerosis complex-related tumors, and a recent trial also showed a benefit from the mechanistic target of rapamycin inhibitor everolimus in the treatment of refractory epilepsy due to tuberous sclerosis complex. Effective mechanism-based therapy is now available for some manifestations of tuberous sclerosis complex.

Tuberous Sclerosis Complex: A Roadmap for Future Research

Investigators from the NINDS and the Tuberous Sclerosis Alliance sponsored a workshop in March 2015, which joined basic scientists and clinicians with expertise in various aspects of Tuberous Sclerosis Complex (TSC), in order to assess the current state of TSC research and to set future goals.

Systemic disease manifestations associated with epilepsy in tuberous sclerosis complex

OBJECTIVE

Epilepsy is one of the most disabling symptoms of tuberous sclerosis complex (TSC) and is a leading cause of morbidity and mortality in affected individuals. The relationship between systemic disease manifestations and the presence of epilepsy has not been thoroughly investigated. This study utilizes a multicenter TSC Natural History Database including 1,816 individuals to test the hypothesis that systemic disease manifestations of TSC are associated with epilepsy.

METHODS

Univariate analysis was used to identify patient characteristics (e.g., age, gender, race, and TSC mutation status) associated with the presence of epilepsy. Individual logistic regression models were built to examine the association between epilepsy and each candidate systemic or neurologic disease variable, controlling for the patient characteristics found to be significant on univariate analysis. Finally, a multivariable logistic regression model was constructed, using the variables found to be significant on the individual analyses as well as the patient characteristics that were significant on univariate analysis.

RESULTS

Nearly 88% of our cohort had a history of epilepsy. After adjusting for age, gender, and TSC mutation status, multiple systemic disease manifestations including cardiac rhabdomyomas (odds ratio [OR] 2.3, 95% confidence interval [CI] 1.3-3.9, p = 0.002), retinal hamartomas (OR 2.1, CI 1.0-4.3, p = 0.04), renal cysts (OR 2.1, CI 1.3-3.4, p = 0.002), renal angiomyolipomas (OR 3.0, CI 1.8-5.1, p < 0.001), shagreen patches (OR 1.7, CI 1.0-2.7, p = 0.04), and facial angiofibromas (OR 1.7, CI 1.1-2.9, p = 0.03) were associated with a higher likelihood of epilepsy. In the multivariable logistic regression model, cardiac rhabdomyomas (OR 1.9, CI 1.0-3.5, p = 0.04) remained significantly associated with the presence of epilepsy.

SIGNIFICANCE

The identification of systemic disease manifestations such as cardiac rhabdomyomas that confer a higher risk of epilepsy development in TSC could contribute to disease prognostication and assist in the identification of individuals who may receive maximal benefit from potentially novel, targeted, preventative therapies.

Advances and Future Directions for Tuberous Sclerosis Complex Research: Recommendations From the 2015 Strategic Planning Conference

On March 10 to March 12, 2015, the National Institute of Neurological Disorders and Stroke and the Tuberous Sclerosis Alliance sponsored a workshop in Bethesda, Maryland, to assess progress and new opportunities for research in tuberous sclerosis complex with the goal of updating the 2003 Research Plan for Tuberous Sclerosis (http://www.ninds.nih.gov/about_ninds/plans/tscler_research_plan.htm). In addition to the National Institute of Neurological Disorders and Stroke and Tuberous Sclerosis Alliance, participants in the strategic planning effort and workshop included representatives from six other Institutes of the National Institutes of Health, the Department of Defense Tuberous Sclerosis Complex Research Program, and a broad cross-section of basic scientists and clinicians with expertise in tuberous sclerosis complex along with representatives from the pharmaceutical industry. Here we summarize the outcomes from the extensive premeeting deliberations and final workshop recommendations, including (1) progress in the field since publication of the initial 2003 research plan for tuberous sclerosis complex, (2) the key gaps, needs, and challenges that hinder progress in tuberous sclerosis complex research, and (3) a new set of research priorities along with specific recommendations for addressing the major challenges in each priority area. The new research plan is organized around both short-term and long-term goals with the expectation that progress toward specific objectives can be achieved within a five to ten year time frame.

Predictive Power of EEG in Infants with Tuberous Sclerosis

Investigators from University of California- Los Angeles and collaborators from across the country report on the use of prospective EEGs in infants with tuberous sclerosis complex (TSC) to predict evolution to seizures.

Early developmental pathways to autism spectrum disorder in tuberous sclerosis complex

Purpose

– Tuberous sclerosis complex (TSC) is a genetic disorder with a high prevalence of autism spectrum disorder (ASD), yet no single genetic, neurological or neurophysiological risk marker is necessary or sufficient to increase risk for ASD. This paper aims to discuss the utility of adopting a developmental perspective.

Design/methodology/approach

– The increasing number of TSC infants presenting with abnormalities prenatally provides a unique opportunity to study risk pathways to ASD from birth. Here, the authors review findings to date that support the investigation of infants with TSC to further our understanding of typical and atypical development.

Findings

– Evidence has accumulated from studies of infants at familial risk for ASD (“baby siblings”) to suggest that early markers of ASD are present in the first year of life. The early waves of prospective studies of infants with TSC indicate dynamic changes in developmental trajectories to ASD and are likely to provide insight into cascading effects of brain “insult” early in development. Emerging evidence of phenotypic and biological homology between syndromic and idiopathic cases of ASD supports the notion of a convergence of risk factors on a final common pathway in ASD.

Originality/value

– The delineation of brain-based biomarkers of risk, prediction and treatment response in TSC will be critical in aiding the development of targeted intervention and prevention strategies for those infants at high risk of poorer developmental outcomes.

Combined targeted treatment in early onset epilepsy associated with tuberous sclerosis

Tuberous sclerosis is associated with epilepsy in up to 85% of cases, and in 2/3, the onset is within the first year of life. An early antiepileptic treatment is crucial to minimize the consequences of epilepsy on cognition and behavior. We present a case report of a child with tuberous sclerosis who presented with infantile spasms at the age of 6 months, immediately treated with vigabatrin. Because of the presence of a subependymal giant cell astrocytoma, he also received everolimus since 18 months of age. We might wonder if an earlier treatment could have produced a better outcome; in fact, despite a targeted combined treatment, he continues to suffer from sporadic focal motor seizures, and at the age of 40 months, he presents severe developmental delay with autism-like behavior.