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

Seizure freedom but not epilepsy surgery is associated with fewer neuropsychiatric difficulties in patients with tuberous sclerosis

BACKGROUND

Drug-resistant epilepsy (DRE) in selected individuals with the rare tuberous sclerosis complex (TSC) may benefit from resective epilepsy surgery. Furthermore, associated neuropsychiatric disorders (TAND) are common in patients with TSC; however, long-term data on how surgery affects neuropsychiatric comorbidities are sparse.

MATERIALS AND METHODS

Two retrospective approaches were used to identify children with TSC and DRE with onset at < 18 years of age. The study group (surgical) was identified through the Swedish National Epilepsy Surgery Registry (n = 17), a registry with complete national coverage since 1990 and prospective patient enrolment since 1995. The reference group (non-surgical) was identified by searching medical records retrieved from the tertiary hospital of Southern Sweden (n = 52). Eligible participants were invited to complete the validated TAND lifetime checklist. Those who did not complete the checklist, never had DRE, or were aged < 7 years old were excluded from the study. The reference group was balanced with the study group for putative confounders, in the following hierarchical order: DRE at the survey, age at seizure onset, age at follow-up, and sex.

RESULTS

After the balancing procedure, both groups comprised 13 participants. The median time from epilepsy onset to the survey was 18.5 (range: 7.75-40.25) and 16.0 (7.33-33.5) years in the study and reference groups, respectively. The median time from surgery to the survey was 13 years (range: 4-22). No significant differences were found in behavioural problems, autism spectrum disorder diagnosis or symptoms, or intellectual disability between the groups, regardless of surgery. Seizure-free individuals (n = 11) performed better in social skills (p = 0.016), intellectual skills (p = 0.029), and overall TAND scores (p = 0.005) than the non-seizure-free group (n = 15).

CONCLUSION

This is the first study to evaluate TAND comorbidities during the long-term follow-up after epilepsy surgery in patients with TSC. We found no evidence of the adverse effects of TAND comorbidities after tuberectomy. However, a larger study that allows for a better adjustment for confounders is needed. Following previous studies, seizure-free individuals had fewer symptoms within most TAND domains compared with the group with uncontrolled epilepsy, indicating less severe symptomatology.

A Cost-Utility Analysis of Add-On Cannabidiol Versus Usual Care Alone for the Treatment of Seizures Associated with Tuberous Sclerosis Complex in England and Wales

OBJECTIVES

The aim of this study was to evaluate the cost effectiveness of plant-derived highly purified cannabidiol (Epidyolex® in the UK; 100 mg/mL oral solution) as an add-on treatment to usual care for the management of treatment-refractory seizures associated with tuberous sclerosis complex (TSC) in patients aged ≥ 2 years.

METHODS

A cohort-based model was developed using a National Health Service perspective and lifetime horizon. Health states were based on weekly seizure frequency and seizure-free days, utilizing patient-level data from the GWPCARE6 trial (ClinicalTrials.gov identifier: NCT02544763). Two independent regression models were applied to individual patient-level data to predict seizure-free days and seizure frequency. Healthcare resource utilization data were sourced from a Delphi panel, and patient and caregiver health-related quality of life values were elicited using vignettes valued by the general public. Outcomes relating to TSC-associated neuropsychiatric disorders were modeled with costs and quality-adjusted life-years sourced from published literature.

RESULTS

In the base case, compared with usual care alone, 12 mg/kg/day cannabidiol was associated with an incremental cost-effectiveness ratio (ICER) of £23,797. The National Institute for Health and Care Excellence disease severity modifier reduced the ICER to £19,831. Probabilities of cost effectiveness at willingness-to-pay thresholds of £20,000 and £30,000 were 30% and 52%, respectively, for the base case and 39% and 66%, respectively, for the disease severity modifier. Results were robust to sensitivity and scenario analyses.

CONCLUSIONS

At 12 mg/kg/day and an ICER threshold of £20,000-£30,000, we provide evidence for the cost effectiveness of add-on cannabidiol treatment for patients with TSC-associated seizures aged ≥ 2 years who are refractory to current treatment.

Neuropsychiatric comorbidities in tuberous sclerosis complex patients with epilepsy: results of the TAND checklist survey

PURPOSE

In addition to epilepsy, individuals with tuberous sclerosis complex (TSC) experience a wide range of behavioral, psychiatric, intellectual, academic, and psychosocial problems. They usually exert a large psychological burden on individuals with these illnesses.

METHODS

This cross-sectional study used TSC-associated neuropsychiatric disorders (TAND) checklist interviews conducted at a single medical center. The enrollment of all subjects was > 6 years, and the comorbidities of neurodevelopmental disorders were assessed by clinical psychologists before enrollment. To assess the spectrum of TAND, the TAND checklist was applied as stated in the protocol, and the responses to the TAND checklist were evaluated by clinical psychologists.

RESULTS

In the behavioral concerns of patients with TSC without epilepsy, those with epilepsy had excessive shyness, language delay, lack of eye contact, rigid behavior, inattentiveness, and restlessness. In psychiatric disorders, autism spectrum disorder and attention-deficit/hyperactivity disorder are significantly correlated with epilepsy history. Diminished academic skills, including reading, writing, and mathematics skills, are significantly associated with epilepsy history. For intellectual ability, TSC patients without epilepsy is associated normal intelligence level. Among neuropsychological skills, deficits in attention, dual tasking/multi-tasking, visuospatial tasking, and executive skills are significantly associated with epilepsy history.

CONCLUSIONS

Epilepsy in patients with TSC contributes to comorbid neuropsychiatric disorders. In addition to epilepsy evaluation, it is crucial to evaluate the heterogeneous spectrum of neuropsychiatric disorders using a standard checklist during the annual clinical follow-up of patients with TSC.

Congenital single kidney in tuberous sclerosis complex (Bourneville disease)

Introduction

Bournevile disease is a rare global condition that presents a diagnostic challenge due to its diverse multisystemic involvement.

Case presentation

This report presents the case of a 14-year-old male with a medical history of congenital single kidney, heart rate abnormalities, Bournevile disease with cognitive deficits, brain lesions, and dermatological features. The patient presented with sudden onset renal angiolipomatosis, and the diagnosis was based on specific computed tomography (CT) findings. Despite having these complex medical conditions, the patient had never been admitted to the hospital since infancy, and treatment was limited to surveillance only.

Clinical discussion

Bourneville disease is a multisystemic disease that affects several organ systems within the human body and thus demands multidisciplinary approach in the treatment and follow-up options.

Conclusion

This case report highlights Bournevile disease in a patient with a congenital single kidney, a rare finding that further complicates the disease. It emphasises the importance of recognising and managing this condition to ensure appropriate care for affected individuals.

Tuberous sclerosis complex in adulthood: focus on epilepsy prognosis

OBJECTIVE

Typically diagnosed in early childhood or adolescence, TSC is a chronic, multisystemic disorder with age-dependent manifestations posing a challenge for transition and for specific surveillance throughout the lifetime. Data on the clinical features and severity of TSC in adults and on the prognosis of epilepsy are scarce. We analyzed the clinical and genetic features of a cohort of adult patients with TSC, to identify the prognostic predictors of seizure remission after a long follow-up.

METHOD

We conducted a retrospective analysis of patients diagnosed with TSC according to the updated international diagnostic criteria. Pearson's chi-square or Fisher's exact test and Mann Whitney U test were used to compare variables among the Remission (R) and Non-Remission (NR) group. Univariate and multivariate logistic regression analyses were performed.

RESULTS

We selected 43 patients with TSC and neurological involvement in terms of epilepsy and/or brain lesions, attending the Epilepsy Center of our Institute: of them, 16 (37.2%) were transitioning from the pediatric care and 6 (13.9%) were referred by other specialists. Multiorgan involvement includes cutaneous (86.0%), nephrological (70.7%), hepatic (40.0%), ocular (34.3%), pneumological (28.6%) and cardiac (26.3%) manifestations. Thirty-nine patients (90.7 %) had epilepsy. The mean age at seizure onset was 4 ± 7.3 years: most patients (29, 76.3 %) presented with focal seizures or spasms by age 3 years; only 2 (5.3 %) had seizure onset in adulthood. Twenty-seven patients (69.2 %) experienced multiple seizure types overtime, 23 (59.0 %) had intellectual disability (ID). At last assessment, 14 (35.9 %) were seizure free (R group) and 25 (64.1 %) had drug-resistant seizures (NR group). At logistic regression univariate analysis, ID (OR 7.9, 95 % CI 1.8--34.7), multiple seizure types lifelong (OR 13.2, 95 % CI 2.6- 67.2), spasms/tonic seizures at presentation (OR 6.5, 95 % CI 1.2--35.2), a higher seizure frequency at onset (OR 5.4, 95 % CI 1.2--24.3), abnormal neurological examination (OR 9.8, 95 % CI 1.1--90.6) and pathogenic variants in TSC2 (OR 5.4, 95 % CI 1.2--24.5) were significantly associated with non-remission. In the multivariate analysis, both ID and multiple seizure types lifelong were confirmed as independent predictors of poor seizure outcome.

CONCLUSIONS

In our cohort of adult patients with TSC, epilepsy remains one of the main neurological challenges with only 5.3% of cases manifesting in adulthood. Approximately 64% of these patients failed to achieve seizure remission. ID and multiple seizure types were the main predictors of poor outcome. Nephrological manifestations require continuous specific follow-up in adults.

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

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

How have the recent updated epilepsy classifications impacted on diagnosis and treatment?

INTRODUCTION

Epilepsies are a diverse group of disorders which differ regarding prognosis for seizure control and associated comorbidities. Accurate classification is critical to choose the highest yield investigations and best therapeutic options and to provide the most accurate prognoses regarding the expected degree of seizure control, possible remission, and risk of associated comorbidities to patients and their families. This article reviews the recent updates in epilepsy classification to illustrate how accurate classification impacts care for persons with epilepsy.

AREAS COVERED

The authors discuss the ILAE 2017 Classification of the Epilepsies along with the modification of the classification for neonatal seizures and epilepsies. They also discuss the ILAE position papers on Epilepsy syndromes in neonates and infants and children of variable age and the Idiopathic Generalized Epilepsies.

EXPERT OPINION

Accurate epilepsy classification allows selection of the highest yield investigations, choice of optimal therapies, and accurate prognostication of seizures (likelihood of response to antiseizure treatments and likelihood of remission with age), as well as comorbidities (likelihood, type, and severity). As we move into the era of disease modifying therapy, early accurate identification of underlying causes with timely introduction of specific treatments will be crucial to lessen the severity of epilepsy, with improved seizure control and attenuation of associated comorbidities.

The Burden of Caring for Individuals with Tuberous Sclerosis Complex (TSC) Who Experience Epileptic Seizures: A Descriptive UK Survey

INTRODUCTION

Tuberous sclerosis complex (TSC) is a rare multisystem genetic condition characterised by benign tumours; prevalent manifestations include epilepsy and neuropsychiatric disorders. This study examined the burden of TSC for primary caregivers and families, exploring the impact of characteristics such as seizures.

METHODS

Primary caregivers of individuals with TSC in the United Kingdom participated in an online survey, comprising the Pediatric Quality of Life Inventory™ Family Impact Module, Hospital Anxiety and Depression Scale (HADS), and TSC-specific items. Responses were analysed using descriptive and regression analysis statistics (closed-ended) or qualitative content analysis (open-ended).

RESULTS

Seventy-three participants partially completed and 59 fully completed the survey; 95% were female, and 90% were parents of an individual with TSC. A median (range) of 2 (1-11) household members were carers. Primary caregivers spent a mean (standard deviation [SD]) of 104.3 (51.7) hours caring in the previous week, reporting high mean (SD) HADS scores of 11.2 (4.8) (anxiety) and 7.9 (4.4) (depression) and considerable family burden. Increased seizure frequency increased hours spent caring by primary caregivers (p = 0.01) and was associated with a decreased mean (SD) family functioning score of 46.2 (23.0) and parent health-related quality of life (HRQL) score of 45.4 (20.3) (both p = 0.03). Multivariable models predicted intellectual disability increased hours spent caring by primary caregivers (p = 0.01-0.04), and neuropsychiatric comorbidities decreased family functioning (p = 0.02) and caregiver HRQL (p < 0.01).

CONCLUSION

These findings highlight the role of epileptic seizures and neuropsychiatric disorders in the considerable burden of TSC on primary caregivers and families.

Epilepsy severity mediates association between mutation type and ADHD symptoms in tuberous sclerosis complex

The association between attention-deficit/hyperactivity disorder (ADHD) and tuberous sclerosis complex (TSC) is widely reported, with support for the role of epilepsy, yet the mechanisms underlying the association across development are unclear. The Tuberous Sclerosis 2000 Study is a prospective longitudinal study of TSC. In Phase 1 of the study, baseline measures of epilepsy, cortical tuber load, and mutation were obtained with 125 children ages 0-16 years. In Phase 2, at an average of 8 years later, ADHD symptoms were measured for 81 of the participants. Structural equation modeling revealed an indirect pathway from genetic mutation, to cortical tuber load, to epileptic spasm severity in infancy, to ADHD symptoms in middle childhood and adolescence, in addition to a pathway linking current seizure severity to ADHD symptoms. Findings were retained when intelligence quotient (IQ) was entered as a correlated factor. The findings support a cascading developmental pathway to ADHD symptoms mediated by early-onset and severe epilepsy in the first 2 years of life. This warrants detailed investigation of seizure characteristics and cognitive and behavioral sequelae associated with ADHD from early in life, to further the understanding of the association between ADHD and early-onset epilepsy across syndromic and non-syndromic populations.

Treatment-Resistant Epilepsy and Tuberous Sclerosis Complex: Treatment, Maintenance, and Future Directions

Tuberous sclerosis complex (TSC) is a neurogenetic disorder that affects multiple organ systems, including the heart, kidneys, eyes, skin, and central nervous system. The neurologic manifestations have the highest morbidity and mortality, in particular in children. Clinically, patients with TSC often present with new-onset seizures within the first year of life. TSC-associated epilepsy is often difficult to treat and refractory to multiple antiseizure medications. Refractory TSC-associated epilepsy is associated with increased risk of neurodevelopmental comorbidities, including developmental delay, intellectual disability, autism spectrum disorder, and attention hyperactivity disorder. An increasing body of research suggests that early, effective treatment of TSC-associated epilepsy during critical neurodevelopmental periods can potentially improve cognitive outcomes. Therefore, it is important to treat TSC-associated epilepsy aggressively, whether it be with pharmacological therapy, surgical intervention, and/or neuromodulation. This review discusses current and future pharmacological treatments for TSC-associated epilepsy, as well as the importance of early surgical evaluation for refractory epilepsy in children with TSC and consideration of neuromodulatory interventions in young adults.

The autism spectrum disorder phenotype in children with tuberous sclerosis complex: A systematic review and meta-analysis

AIM

To investigate the phenotype in autistic children with tuberous sclerosis complex (TSC), specifically autism spectrum disorder (ASD) severity and characteristics, intellectual ability, adaptive and executive function, language skills, attention-deficit/hyperactivity disorder features, and internalizing and externalizing behaviours.

METHOD

MEDLINE, Embase, and the Cochrane Library were searched up to March 2021. Studies that investigated predefined phenotypic factors in children with TSC-ASD were included according to the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) guidelines. Two authors independently reviewed titles, abstracts, full texts, and extracted the data. Risk of bias and GRADE assessments were completed.

RESULTS

Thirty-four studies with 3160 children with TSC, 30% with ASD, were included. Meta-analysis found that 90% (95% confidence interval 86%-94%) of children with TSC-ASD have an intellectual disability. There was some evidence to suggest that young children with TSC-ASD and idiopathic ASD have a similar pattern of severity and behaviour. Overall, data about phenotypic characteristics were limited.

INTERPRETATION

A greater proportion of children with TSC-ASD are reported to have an intellectual disability than children with idiopathic ASD. Early intervention should consider the needs of children with a high likelihood of intellectual disability. Research is needed to better understand the impacts of intellectual disability and other co-occurring difficulties on adaptive function, participation, and quality of life in TSC-ASD.

WHAT THIS PAPER ADDS

Most children with tuberous sclerosis complex (TSC) and autism spectrum disorder (ASD) have an intellectual disability. TSC-ASD early intervention planning should consider the high likelihood of intellectual disability. Quality of life and the functional impact of intellectual disability in TSC-ASD are not understood. Little is known about co-occurring difficulties in TSC-ASD.

The longitudinal evolution of cerebral blood flow in children with tuberous sclerosis assessed by arterial spin labeling magnetic resonance imaging may be related to cognitive performance

OBJECTIVE

To study longitudinal changes in tuber and whole-brain perfusion in children with tuberous sclerosis complex (TSC) using arterial spin labeling (ASL) perfusion MRI and correlate them with pathological EEG slow wave activity and neurodevelopmental outcomes.

METHODS

Retrospective longitudinal cohort study of 13 children with TSC, 3 to 6 serial ASL-MRI scans between 2 months and 7 years of age (53 scans in total), and an EEG examination performed within 2 months of the last MRI. Tuber cerebral blood flow (CBF) values were calculated in tuber segmentation masks, and tuber:cortical CBF ratios were used to study tuber perfusion. Logistic regression analysis was performed to identify which initial tuber characteristics (CBF value, volume, location) in the first MRI predicted tubers subsequently associated with EEG slow waves. Whole-brain and lobar CBF values were extracted for all patient scans and age-matched controls. CBF ratios were compared in patients and controls to study longitudinal changes in whole-brain CBF.

RESULTS

Perfusion was reduced in tubers associated with EEG slow waves compared with other tubers. Low tuber CBF values around 6 months of age and large tuber volumes were predictive of tubers subsequently associated with EEG slow waves. Patients with severe developmental delay had more severe whole-brain hypoperfusion than those with no/mild delay, which became apparent after 2 years of age and were not associated with a higher tuber load.

CONCLUSIONS

Dynamic changes in tuber and brain perfusion occur over time. Perfusion is significantly reduced in tubers associated with EEG slow waves. Whole-brain perfusion is significantly reduced in patients with severe delay.

KEY POINTS

• Tubers associated with EEG slow wave activity were significantly more hypoperfused than other tubers, especially after 1 year of age. • Larger and more hypoperfused tubers at 6 months of age were more likely to subsequently be associated with pathological EEG slow wave activity. • Patients with severe developmental delay had more extensive and severe global hypoperfusion than those without developmental delay.

Epidemiology and disease burden of tuberous sclerosis complex in France: A population-based study based on national health insurance data

OBJECTIVE

Tuberous sclerosis complex (TSC) is a rare multisystem disorder, often associated with epilepsy. This retrospective study aimed to identify patients with TSC, including those with epilepsy, from a French healthcare claims database, and to report incidence, prevalence, and healthcare costs and resource utilization.

METHODS

The anonymized French health insurance database (SNDS) covers almost the entire French population. Patients with TSC were identified as having ≥1 International Classification of Diseases, Tenth Revision (ICD-10) diagnosis code Q85.1 or a long-term disease (LTD) registration over the inclusion period (2006-2017). Patients with an ICD-10 epilepsy code or who were dispensed ≥1 antiseizure medication (ASM) in the same year or after their TSC diagnosis were identified as having TSC with epilepsy. Newly diagnosed patients over the inclusion period constituted the incident cohort. Healthcare costs (patients with recorded costs only), healthcare resource use, and ASM dispensation are reported for patients with 2018 data.

RESULTS

In 2018, 3139 prevalent patients with TSC were identified (crude prevalence, 4.69 per 100 000); the incident cohort comprised 2988 patients (crude incidence, 0.44 per 100 000). Among patients with TSC, 67% (2101/3139) had epilepsy (mean [standard deviation, SD] age: 28.8 [18.8] years; male: 48%). Among patients with epilepsy, total mean (SD) annual healthcare costs were €11 413 (27 620) per capita (outpatient, 63%; inpatient, 37%), 46% were hospitalized during 2018 (mean [SD]: 1.8 [10.9] acute care visits per patient), and 65% visited a hospital specialist. Among patients with epilepsy, medication (mean [SD]: €4518 [12 102] per capita) was the greatest contributor (63%) to outpatient costs, and in 2018, 74% were dispensed ≥1 different ASM and 9% were dispensed ≥4 ASMs.

SIGNIFICANCE

TSC with epilepsy was associated with substantial healthcare costs and resource utilization, particularly outpatient and medication costs. Many patients with TSC with epilepsy were prescribed multiple ASMs, suggesting refractory epilepsy.

White matter disruptions related to inattention and autism spectrum symptoms in tuberous sclerosis complex

Tuberous sclerosis complex is a rare genetic multisystem condition that is associated with a high prevalence of neurodevelopmental disorders such as autism and attention-deficit/hyperactivity disorder. The underlying neural mechanisms of the emergence of these symptom domains in tuberous sclerosis complex remain unclear. Here, we use fixel-based analysis of diffusion-weighted imaging, which allows for the differentiation between multiple fibre populations within a voxel, to compare white matter properties in 16 participants with tuberous sclerosis complex (aged 11-19) and 12 age and sex matched control participants. We further tested associations between white matter alterations and autism and inattention symptoms as well as cognitive ability in participants with tuberous sclerosis complex. Compared to controls, participants with tuberous sclerosis complex showed reduced fibre density cross-section (FDC) in the dorsal branch of right superior longitudinal fasciculus and bilateral inferior longitudinal fasciculus, reduced fibre density (FD) in bilateral tapetum, and reduced fibre cross-section (FC) in the ventral branch of right superior longitudinal fasciculus. In participants with tuberous sclerosis complex, the extent of FDC reductions in right superior longitudinal fasciculus was significantly associated with autism traits (social communication difficulties and restricted, repetitive behaviours), whereas FDC reductions in right inferior longitudinal fasciculus were associated with inattention. The observed white matter alterations were unrelated to cognitive ability. Our findings shed light on the fibre-specific biophysical properties of white matter alterations in tuberous sclerosis complex and suggest that these regional changes are selectively associated with the severity of neurodevelopmental symptoms.

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.

Interictal Discharge Pattern in Preschool-Aged Children With Tuberous Sclerosis Complex Before and After Resective Epilepsy Surgery

Objective

To analyze the interictal discharge (IID) patterns on pre-operative scalp electroencephalogram (EEG) and compare the changes in IID patterns after removal of epileptogenic tubers in preschool children with tuberous sclerosis complex (TSC)-related epilepsy.

Methods

Thirty-five preschool children who underwent resective surgery for TSC-related epilepsy were enrolled retrospectively, and their EEG data collected before surgery to 3 years after surgery were analyzed.

Results

Twenty-three (65.7%) patients were seizure-free post-operatively at 1-year follow-up, and 37–40% of post-operative patients rendered non-IID on scalp EEGs, and patients with focal IIDs or generalized IID patterns on pre-operative EEG presented a high percentage of normal post-operative scalp EEGs. IID patterns on pre-operative scalp EEGs did not influence the outcomes of post-operative seizure controls, while patients with non-IID and focal IID on post-operative EEGs were likely to achieve post-operative seizure freedom. Patients with new focal IIDs presented a significantly lower percentage of seizure freedom than those without new focal IIDs on post-operative EEGs at 3-year follow-up.

Conclusion

Over 1/3 children with TSC presented normal scalp EEGs after resective epileptsy surgery. Patients with post-operative seizure freedom were more likely to have non-IIDs on post-operative EEGs. New focal IIDs were negative factors for seizure freedom at the 3-year follow-up.

The role of astrocytes in epileptic disorders

Epilepsy affects about 1% of the population and approximately 30% of epileptic patients are resistant to current antiepileptic drugs. As a hallmark in epileptic tissue, many of the epileptic patients show changes in glia morphology and function. There are characteristic changes in different types of glia in different epilepsy models. Some of these changes such as astrogliosis are enough to provoke epileptic seizures. Astrogliosis is well known in mesial temporal lobe epilepsy (MTLE), the most common form of refractory epilepsy. A better understanding of astrocytes alterations could lead to novel and efficient pharmacological approaches for epilepsy. In this review, we present the alterations of astrocyte morphology and function and present some instances of targeting astrocytes in seizure and epilepsy.

Abnormal activation of Yap/Taz contributes to the pathogenesis of tuberous sclerosis complex

The multi-systemic genetic disorder tuberous sclerosis complex (TSC) impacts multiple neurodevelopmental processes including neuronal morphogenesis, neuronal migration, myelination and gliogenesis. These alterations contribute to the development of cerebral cortex abnormalities and malformations. Although TSC is caused by mTORC1 hyperactivation, cognitive and behavioral impairments are not improved through mTORC1 targeting, making the study of the downstream effectors of this complex important for understanding the mechanisms underlying TSC. As mTORC1 has been shown to promote the activity of the transcriptional co-activator Yap, we hypothesized that altered Yap/Taz signaling contributes to the pathogenesis of TSC. We first observed that the levels of Yap/Taz are increased in human cortical tuber samples and in embryonic cortices of Tsc2 conditional knockout (cKO) mice. Next, to determine how abnormal upregulation of Yap/Taz impacts the neuropathology of TSC, we deleted Yap/Taz in Tsc2 cKO mice. Importantly, Yap/Taz/Tsc2 triple conditional knockout (tcKO) animals show reduced cortical thickness and cortical neuron cell size, despite the persistence of high mTORC1 activity, suggesting that Yap/Taz play a downstream role in cytomegaly. Furthermore, Yap/Taz/Tsc2 tcKO significantly restored cortical and hippocampal lamination defects and reduced hippocampal heterotopia formation. Finally, the loss of Yap/Taz increased the distribution of myelin basic protein in Tsc2 cKO animals, consistent with an improvement in myelination. Overall, our results indicate that targeting Yap/Taz lessens the severity of neuropathology in a TSC animal model. This study is the first to implicate Yap/Taz as contributors to cortical pathogenesis in TSC and therefore as potential novel targets in the treatment of this disorder.

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.

Adults with tuberous sclerosis complex: A distinct patient population

OBJECTIVES

There are few data on adults living with tuberous sclerosis complex (TSC), with most studies focusing on pediatric populations. The objective of our study was to examine a large national cohort of adults with TSC, and to describe the clinical characteristics of these adults and the nature of the multidisciplinary care that they receive.

METHODS

Six Canadian medical centers collaborated in this study. Data were collected using a standardized form, and descriptive statistics were used for the analyses.

RESULTS

Our study included 181 adults with definite TSC (mean age = 33.6 years [SD = 13.7]). More than 40% (n = 75) had family members affected by TSC. Forty-six percent (n = 83) of individuals had intellectual disability. Nearly 30% (n = 52) of individuals reported living alone or with a partner/spouse. Seventy-six percent (n = 138) of people had epilepsy, 43% (n = 59) of whom had drug-resistant epilepsy, and 21% (n = 29) had undergone epilepsy surgery. Neuropsychiatric disease (n = 128) and renal angiomyolipomas (n = 130) were both present in approximately 70% of people. Renal imaging was performed in 75.7% (n = 137) of participants within the past 3 years. Renal and pulmonary function tests, as well as electrocardiograms, were recently performed in a minority of individuals.

SIGNIFICANCE

Our cohort of adults with TSC showed that an important proportion have a milder phenotype, and are more frequently familial, as compared to children with TSC (and differing from prior reports in adult cohorts). Drug-resistant epilepsy, neuropsychiatric comorbidities, and renal angiomyolipoma are challenging factors in adults with TSC. Our participating medical centers generally followed recommended screening strategies, but there remain important gaps in care. Multidisciplinary and structured TSC care centers offering service to adults may help to improve the health of this important patient population.

Oscillatory neural network alterations in young people with tuberous sclerosis complex and associations with co-occurring symptoms of autism spectrum disorder and attention-deficit/hyperactivity disorder

Tuberous sclerosis complex (TSC) is a genetic disorder caused by mutations on the TSC1/TSC2 genes, which result in alterations in molecular signalling pathways involved in neurogenesis and hamartomas in the brain and other organs. TSC carries a high risk for autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), although the reasons for this are unclear. One proposal is that TSC-related alterations in molecular signalling during neurogenesis lead to atypical development of neural networks, which are involved in the occurrence of ASD and ADHD in TSC. We investigated this proposal in young people with TSC who have been studied longitudinally since their diagnosis in childhood. Electroencephalography (EEG) was used to examine oscillatory connectivity in functional neural networks and local and global network organisation during three tasks (resting-state, attentional and inhibitory control Go/Nogo task, upright and inverted face processing task) in participants with TSC (n = 48) compared to an age- and sex-matched group of typically developing Controls (n = 20). Compared to Controls, the TSC group showed hypoconnected neural networks in the alpha frequency during the resting-state and in the theta and alpha frequencies during the Go/Nogo task (P ≤ .008), as well as reduced local network organisation in the theta and alpha frequencies during the Go/Nogo task (F = 3.95, P = .010). There were no significant group differences in network metrics during the face processing task. Increased connectivity in the hypoconnected alpha-range resting-state network was associated with greater ASD and inattentive ADHD symptoms (rho≥.40, P ≤ .036). Reduced local network organisation in the theta-range during the Go/Nogo task was significantly associated with higher hyperactive/impulsive ADHD symptoms (rho = -.43, P = .041). These findings suggest that TSC is associated with widespread hypoconnectivity in neural networks and support the proposal that altered network function may be involved in the co-occurrence of ASD and ADHD in TSC.

Neurologic and developmental considerations in children with medical complexity

Children with medical complexity are at increased risk of neurodevelopmental conditions. Signs or symptoms of neurodevelopmental conditions may be more apparent in the context of a medical illness or hospitalization. Thus, primary care, front-line subspecialty and hospital-based pediatricians are encouraged to be on the alert for these conditions from infancy through adolescence. Medical and mental health issues must be considered in the differential diagnoses when children with neurodevelopmental conditions present with a change or regression in their behavior. Management of maladaptive behaviors includes managing the underlying medical and mental health conditions that are contributing to the behavior, environmental supports, behavior therapy interventions, communication and other skills building support for the child, as well as judicious use of medication when necessary.

Epilepsy in adult patients with tuberous sclerosis complex

OBJECTIVES

Little is known about the evolution of epilepsy in individuals with tuberous sclerosis complex (TSC) in adulthood. This study aims at describing the characteristics of epilepsy in adult TSC patients attending a single multidisciplinary clinic.

MATERIALS AND METHODS

We collected data about epilepsy (age at onset, seizure types, history of infantile spasms (IS), epilepsy diagnosis and outcome), genetic and neuroradiological findings, cognitive outcome and psychiatric comorbidities.

RESULTS

Out of 257 adults with TSC, 183 (71.2%) had epilepsy: 121 (67.2%) were drug-resistant; 59 (32.8%) seizure-free, at a median age of 18 years. 22% of the seizure-free patients (13/59) discontinued medication. Median age at seizure onset was 9 months. Seventy-six patients (41.5%) had a history of IS. TSC2 pathogenic variants (p = 0.018), cortical tubers (p < 0.001) and subependymal nodules (SENs) (p < 0.001) were more frequent in those who developed epilepsy. Cognitive functioning was lower (p < 0.001) and psychiatric disorders more frequent (p = 0.001). We did not find significant differences regarding age, gender, mutation and tubers/SENs in seizure-free vs drug-resistant individuals. Intellectual disability (p < 0.001) and psychiatric disorders (p = 0.004) were more common among drug-resistant patients.

CONCLUSIONS

Epilepsy in TSC can be a lifelong disorder, but one-third of individuals reach seizure freedom by early adulthood. In the long term, age at epilepsy onset has a crucial role in drug resistance and in developing intellectual disability, both in drug-resistant and drug-sensible patients. Patients with drug-refractory seizures tend to develop psychiatric issues, which should be recognized and adequately treated.

You Snooze You Seize: GABAergic Potentiation of Genetic Generalized Seizures During NREM

Impaired State-Dependent Potentiation of GABAergic Synaptic Currents Triggers Seizures in a Genetic Generalized Epilepsy Model Zhang C-Q, Catron MA, Ding L, Hanna CM, Gallagher MJ, Macdonald RL, Zhou C. Cereb Cortex . 2021;31(2):768-784. doi:10.1093/cercor/bhaa256. https://pubmed.ncbi.nlm.nih.gov/32930324/ Epileptic activity in genetic generalized epilepsy (GGE) patients preferentially appears during sleep and its mechanism remains unknown. Here, we found that sleep-like slow-wave oscillations (0.5 Hz SWOs) potentiated excitatory and inhibitory synaptic currents in layer V cortical pyramidal neurons from wild-type (wt) mouse brain slices. In contrast, SWOs potentiated excitatory, but not inhibitory, currents in cortical neurons from a heterozygous (het) knock-in (KI) Gabrg2+Q/390X model of Dravet epilepsy syndrome. This created an imbalance between evoked excitatory and inhibitory currents to effectively prompt neuronal action potential firings. Similarly, physiologically similar up-/down-state induction (present during slow-wave sleep) in cortical neurons also potentiated excitatory synaptic currents within brain slices from wt and het KI mice. Moreover, this state-dependent potentiation of excitatory synaptic currents entailed some signaling pathways of homeostatic synaptic plasticity. Consequently, in het KI mice, in vivo SWO induction (using optogenetic methods) triggered generalized epileptic spike-wave discharges (SWDs), being accompanied by sudden immobility, facial myoclonus, and vibrissa twitching. In contrast, in wt littermates, SWO induction did not cause epileptic SWDs and motor behaviors. To our knowledge, this is the first mechanism to explain why epileptic SWDs preferentially happen during non-rapid eye-movement sleep and quiet-wakefulness in human GGE patients.

Precision Therapy for Epilepsy Related to Brain Malformations

Malformations of cortical development (MCDs) represent a range of neurodevelopmental disorders that are collectively common causes of developmental delay and epilepsy, especially refractory childhood epilepsy. Initial treatment with antiseizure medications is empiric, and consideration of surgery is the standard of care for eligible patients with medically refractory epilepsy. In the past decade, advances in next generation sequencing technologies have accelerated progress in understanding the genetic etiologies of MCDs, and precision therapies for focal MCDs are emerging. Notably, mutations that lead to abnormal activation of the mammalian target of rapamycin (mTOR) pathway, which provides critical control of cell growth and proliferation, have emerged as a common cause of malformations. These include tuberous sclerosis complex (TSC), hemimegalencephaly (HME), and some types of focal cortical dysplasia (FCD). TSC currently represents the best example for the pathway from gene discovery to relatively safe and efficacious targeted therapy for epilepsy related to MCDs. Based on extensive pre-clinical and clinical data, the mTOR inhibitor everolimus is currently approved for the treatment of focal refractory seizures in patients with TSC. Although clinical studies are just emerging for FCD and HME, we believe the next decade will bring significant advancements in precision therapies for epilepsy related to these and other MCDs.

Sub-genic intolerance, ClinVar, and the epilepsies: A whole-exome sequencing study of 29,165 individuals

Both mild and severe epilepsies are influenced by variants in the same genes, yet an explanation for the resulting phenotypic variation is unknown. As part of the ongoing Epi25 Collaboration, we performed a whole-exome sequencing analysis of 13,487 epilepsy-affected individuals and 15,678 control individuals. While prior Epi25 studies focused on gene-based collapsing analyses, we asked how the pattern of variation within genes differs by epilepsy type. Specifically, we compared the genetic architectures of severe developmental and epileptic encephalopathies (DEEs) and two generally less severe epilepsies, genetic generalized epilepsy and non-acquired focal epilepsy (NAFE). Our gene-based rare variant collapsing analysis used geographic ancestry-based clustering that included broader ancestries than previously possible and revealed novel associations. Using the missense intolerance ratio (MTR), we found that variants in DEE-affected individuals are in significantly more intolerant genic sub-regions than those in NAFE-affected individuals. Only previously reported pathogenic variants absent in available genomic datasets showed a significant burden in epilepsy-affected individuals compared with control individuals, and the ultra-rare pathogenic variants associated with DEE were located in more intolerant genic sub-regions than variants associated with non-DEE epilepsies. MTR filtering improved the yield of ultra-rare pathogenic variants in affected individuals compared with control individuals. Finally, analysis of variants in genes without a disease association revealed a significant burden of loss-of-function variants in the genes most intolerant to such variation, indicating additional epilepsy-risk genes yet to be discovered. Taken together, our study suggests that genic and sub-genic intolerance are critical characteristics for interpreting the effects of variation in genes that influence epilepsy.

Seizure outcome after epilepsy surgery in tuberous sclerosis complex: Results and analysis of predictors from a multicenter study

Epilepsy surgery is recommended in selected patients with Tuberous Sclerosis Complex (TSC). However, reports on predictive factors of seizure outcome are variable. Here we report on seizure and cognitive outcome of 35 TSC patients who received surgery for refractory epilepsy in 7 Italian centers over a period of 22 years (1997-2019). The rate of seizure-free individuals at last follow-up (mean 7.5 years, range 1-21 years) was 51%. Patients with longer follow-up (≥10 years) had a lower rate of Engel I outcome (11.1%) than those who received surgery in the last 10 years (65.4%, p = 0.003). Factors associated with Engel II, III, IV outcome in our cohort included: high number of cortical tubers (≥5); presence of subependymal nodules (SENs); seizure onset before age 1 year; and multifocal interictal epileptic discharges (IEDs) on electroencephalogram (EEG). A subset of patients evaluated with Vineland Adaptive Behaviour Scales (VABS) showed developmental gains, in line with their developmental trajectories, but no improvement in standard scores after surgery was noted. Our study demonstrates that the rates of successful seizure outcome of epilepsy surgery in TSC have improved in the last 10 years. More than half of the patients achieved seizure freedom, and a high proportion of affected individuals experienced a reduction in seizure burden and in antiseizure medications. A comprehensive assessment after surgery should be performed in TSC patients to evaluate the overall neurodevelopmental outcome, as measures that are based only on seizure control do not adequately identify the benefits of surgery on global functioning in these patients.

Epilepsy and TSC-Associated Neuropsychiatric Disorders

Investigators from multiple institutions (Cleveland Clinic, University Hospital Leuven, ZOL Genk, Kempenhaeghe and Maastricht UMC+, and Children's Hospitals and Clinics of Minnesota) used the Tuberous Sclerosis Complex Natural History Database (TSCNHD) to evaluate the relationship between epilepsy and neuropsychiatric disorders in individuals with TSC, along with any potential influence of genotype.

Epilepsy in NF1: a systematic review of the literature

Epilepsy is one of the possible neurological manifestations of the neurofibromatosis type 1 (NF1) that represents the most common neurocutaneous disorder. We performed a systematic review of the literature on epilepsy associated with NF1 since 1995 in order to better define prevalence and describe type and causes of seizures. Data on type, nature of studies, number of patients, gender, and inheritance of NF1 were recorded as well as data on causes, type, EEGs, brain imaging, intellectual disability (ID), surgical treatment, and outcome of epilepsy. We identified a total of 141 references through the literature search of Pubmed and Embase. After screening, 42 records were identified, including 11617 individuals with NF1 (53% of males). Overall prevalence was estimated at 5.4% lifelong with values that seemed to be slightly lower in children, 3.7% (p 0.0016). Neither gender differences nor correlation with NF1 inheritance was found. Focal with or without bilateral tonic-clonic seizures were the most common seizure type encountered (60.9%). Structural causes were identified in half of cases (114/226). Low-grade gliomas were the most frequent associated lesions followed by mesial temporal sclerosis, malformation of cortical development, dysembryoplastic neuroepithelial tumor, and cerebrovascular lesions. In these cases, the surgical approach improved the epileptic outcome. Prevalence of epilepsy is higher in subjects with NF1 respect of the general population, with values apparently significantly lower in pediatric age. Brain tumors and cytoarchitectural abnormalities are the most frequent causes of epilepsy in this population, although many other brain complications should be taken in account.

Tuberous Sclerosis Complex as Disease Model for Investigating mTOR-Related Gliopathy During Epileptogenesis

Tuberous sclerosis complex (TSC) represents the prototypic monogenic disorder of the mammalian target of rapamycin (mTOR) pathway dysregulation. It provides the rational mechanistic basis of a direct link between gene mutation and brain pathology (structural and functional abnormalities) associated with a complex clinical phenotype including epilepsy, autism, and intellectual disability. So far, research conducted in TSC has been largely neuron-oriented. However, the neuropathological hallmarks of TSC and other malformations of cortical development also include major morphological and functional changes in glial cells involving astrocytes, oligodendrocytes, NG2 glia, and microglia. These cells and their interglial crosstalk may offer new insights into the common neurobiological mechanisms underlying epilepsy and the complex cognitive and behavioral comorbidities that are characteristic of the spectrum of mTOR-associated neurodevelopmental disorders. This review will focus on the role of glial dysfunction, the interaction between glia related to mTOR hyperactivity, and its contribution to epileptogenesis in TSC. Moreover, we will discuss how understanding glial abnormalities in TSC might give valuable insight into the pathophysiological mechanisms that could help to develop novel therapeutic approaches for TSC or other pathologies characterized by glial dysfunction and acquired mTOR hyperactivation.

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.