Association of Early MRI Characteristics With Subsequent Epilepsy and Neurodevelopmental Outcomes in Children With Tuberous Sclerosis Complex

Neuropsychiatric disorders in Chinese pediatric tuberous sclerosis complex patients associated with drug-resistant epilepsy: A TAND checklist-based survey

Tuberous sclerosis complex (TSC) is an autosomal-dominant genetic disorder frequently accompanied by neuropsychiatric disorders, especially in patients who have drug-resistant epilepsy (DRE). This study aimed to evaluate the distribution of neuropsychiatric disorders in Chinese children with TSC-related epilepsy using the TAND (Tuberous Sclerosis Complex Associated Neuropsychiatric Disorders) checklist, comparing those with DRE to those achieving seizure freedom. A total of 47 children, aged 6 to 18 years, diagnosed with TSC at Peking University People's Hospital, participated in this cross-sectional study. All participants met the latest diagnostic criteria for TSC. Based on the definition of drug-resistant epilepsy, participants were categorized into DRE group and seizure-free group. Neurodevelopmental disorders were evaluated using the TAND checklist. The study found that 66 % of participants exhibited varying degrees of intellectual disability, with the DRE group demonstrating significantly poorer performance in intelligence, behavior, neuropsychological, and learning skills compared to the seizure-free group. The DRE group also had higher rates of attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), alongside greater impairments in psychosocial functioning. This study indicates that DRE is strongly associated with neuropsychiatric development in children with TSC, but also that all children with TSC are at increased risk of TAND. Our findings highlight the importance of regular assessment and intervention to support TAND and improve quality of life in this vulnerable group.

Intellectual disability and autistic behavior and their modifying factors in children with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is classified among developmental epileptic encephalopathies, where epilepsy is often associated with comorbidities such as intellectual disability and autistic behavior. The recently introduced term TAND (TSC-associated neuropsychiatric disorders) encompasses the wide range of cognitive, behavioral, psychiatric, and psychosocial manifestations seen in TSC. The severity of these comorbidities is influenced by several factors, including the TSC1/TSC2 genotype, the age of epilepsy onset, the number, volume and type of cortical tubers, the interval between epilepsy onset and treatment initiation, and the presence of infantile spasms, hypsarrhythmia, or drug-resistant epilepsy. Clinical, genetic, EEG, and neuroimaging biomarkers enable the early identification of infants at high risk of developing intellectual disability or autism spectrum disorder. Early preventive intervention targeting seizures and tailored strategies during a sensitive developmental window may modify these contributing factors, leading to improved neurodevelopmental outcomes in infants with TSC.

Multi-parametric diffusion spectrum imaging in tuberous sclerosis complex: Identifying cortical tubers and predicting genotypes

OBJECTIVES

This study employed advanced MRI diffusion imaging techniques to identify cortical tubers in Tuberous Sclerosis Complex (TSC) patients and compared the diagnostic efficacy of various diffusion model parameters in predicting TSC genotypes.

METHODS

From July 2019 to April 2024, a prospective study was conducted at our Hospital. Participants meeting specific criteria underwent genetic testing and Diffusion Spectrum Imaging (DSI) data collection. The Dipy toolbox calculated parameters for Diffusion Tensor Imaging (DTI), Diffusion Kurtosis Imaging (DKI), Neurite Orientation Dispersion and Density Imaging (NODDI), and Mean Apparent Propagator (MAP) models. Lesion visibility and contrast were scored by two neuroradiologists. Significant parameters were identified through univariate logistic regression, and predictive models were developed using multivariate logistic regression and backward stepwise regression, resulting in a nomogram.

RESULTS

Eighty-three TSC patients were included (49 females, median age 5 years, IQR 3-9 years). Significant differences were found in lesion visibility and contrast among different diffusion model parameter maps (p < 0.001), with NODDI-ICVF and MAP-QIV showing clear advantages. The DTI, DKI, and MAP models struggled to distinguish small lesions near cerebral sulci from cerebrospinal fluid, while NODDI-ICVF performed well. The combined model using ICVF, QIV, and RTOP parameters demonstrated potentially better diagnostic performance compared to single diffusion models, with the nomogram indicating strong discrimination (AUC of 0.89, 95 % CI: 0.86-0.92). Clinical decision curves indicated significant net benefits at probability thresholds of 15 %-95 %.

CONCLUSION

NODDI and MAP models reveal cortical tubers more clearly. The combined model based on advanced diffusion parameters offers the best predictive efficiency for TSC genotypes.

Accumulated seizure burden predicts neurodevelopmental outcome at 36 months of age in patients with tuberous sclerosis complex

OBJECTIVE

Epilepsy and intellectual disability are common in tuberous sclerosis complex (TSC). Although early life seizures and intellectual disability are known to be correlated in TSC, the differential effects of age at seizure onset and accumulated seizure burden on development remain unclear.

METHODS

Daily seizure diaries, serial neurodevelopmental testing, and brain magnetic resonance imaging were analyzed for 129 TSC patients followed from 0 to 36 months. We used machine learning to identify subgroups of patients based on neurodevelopmental test scores at 36 months of age and assessed the stability of those subgroups at 12 months. We tested the ability of candidate biomarkers to predict 36-month neurodevelopmental subgroup using univariable and multivariable logistic regression. Candidate biomarkers included age at seizure onset, accumulated seizure burden, tuber volume, sex, and earlier neurodevelopmental test scores.

RESULTS

Patients clustered into two neurodevelopmental subgroups at 36 months of age, higher and lower scoring. Subgroup was mostly (75%) the same at 12 months. Significant univariable effects on subgroup were seen only for accumulated seizure burden (largest effect), earlier test scores, and tuber volume. Neither age at seizure onset nor sex significantly distinguished 36-month subgroups, although for girls but not boys there was a significant effect of age at seizure onset. In the multivariable model, accumulated seizure burden and earlier test scores together predicted 36-month neurodevelopmental group with 82% accuracy and an area under the curve of .86.

SIGNIFICANCE

These results untangle the contributions of age at seizure onset and accumulated seizure burden to neurodevelopmental outcomes in young children with TSC. Accumulated seizure burden, rather than the age at seizure onset, most accurately predicts neurodevelopmental outcome at 36 months of age. These results emphasize the need to manage seizures aggressively during the first 3 years of life for patients with TSC, not only to promote seizure control but to optimize cognitive function.

Radiomic detection of abnormal brain regions in tuberous sclerosis complex

BACKGROUND

Radiomics refers to the extraction of quantitative information from medical images and is most commonly utilized in oncology to provide ancillary information for solid tumor diagnosis, prognosis, and treatment response. The traditional radiomic pipeline involves segmentation of volumes of interest with comparison to normal brain. In other neurologic disorders, such as epilepsy, lesion delineation may be difficult or impossible due to poor anatomic definition, small size, and multifocal or diffuse distribution. Tuberous sclerosis complex (TSC) is a rare genetic disease in which brain magnetic resonance imaging (MRI) demonstrates multifocal abnormalities with variable imaging and epileptogenic features.

PURPOSE

The purpose of this study was to develop a radiomic workflow for identification of abnormal brain regions in TSC, using a whole-brain atlas-based approach with generation of heatmaps based on signal deviation from normal controls.

METHODS

This was a retrospective pilot study utilizing high-resolution whole-brain 3D FLAIR MRI datasets from retrospective enrollment of tuberous sclerosis complex (TSC) patients and normal controls. Subjects underwent MRI including high-resolution 3D FLAIR sequences. Preprocessing included skull stripping, coregistration, and intensity normalization. Using the Brainnetome and Harvard-Oxford atlases, brain regions were parcellated into 318 discrete regions. Expert neuroradiologists spatially labeled all tubers in TSC patients using ITK-SNAP. The pyradiomics toolbox was used to extract 88 radiomic features based on IBSI guidelines, comparing tuber-affected and non-tuber-affected parenchyma in TSC patients, as well as normal brain tissue in control patients. For model training and validation, regions with tubers from 20 TSC patients and 30 normal control subjects were randomly divided into two training sets (80%) and two validation sets (20%). Additional model testing was performed on a separate group of 20 healthy controls. LASSO (least absolute shrinkage and selection operator) was used to perform variable selection and regularization to identify regions containing tubers. Relevant radiomic features selected by LASSO were combined to produce a radiomic score ω, defined as the sum of squared differences from average control group values. Region-specific ω scores were converted to heat maps and spatially coregistered with brain MRI to reflect overall radiomic deviation from normal.

RESULTS

The proposed radiomic workflow allows for quantification of deviation from normal in 318 regions of the brain with the use of a summative radiomic score ω. This score can be used to generate spatially registered heatmaps to identify brain regions with radiomic abnormalities. The pilot study of TSC showed radiomic scores ω that were statistically different in regions containing tubers from regions without tubers/normal brain (p < 0.0001). Our model exhibits an AUC of 0.81 (95% confidence interval: 0.78-0.84) on the testing set, and the best threshold obtained on the training set, when applied to the testing set, allows us to identify regions with tubers with a specificity of 0.91 and a sensitivity of 0.60.

CONCLUSION

We describe a whole-brain atlas-based radiomic approach to identify abnormal brain regions in TSC patients. This approach may be helpful for identifying specific regions of interest based on relatively greater signal deviation, particularly in clinical scenarios with numerous or poorly defined anatomic lesions.

Severe Epilepsy in an Individual With a TSC2 R905Q Variant Prompting Late Diagnosis in Affected Family Members

BACKGROUND

Tuberous sclerosis complex (TSC) is a multisystemic disorder caused by inactivating variants in the mTOR pathway inhibitor genes TSC1 and TSC2. Individuals with TSC are predisposed to benign tumors in multiple organs as well as TSC-associated neuropsychiatric disorders (TAND) and epilepsy. Pathogenic variants in TSC2 are typically associated with a more severe phenotype compared with TSC1; the TSC2 R905Q variant has been shown to be an exception, where patients have been reported to present with unusually mild TSC features that may be undetected.

METHODS

We studied the TSC phenotype of a 13-year-old individual and three family members with a TSC2 c.2714G>A (R905Q) pathogenic variant.

RESULTS

Patient 1 presented with severe medically refractory epilepsy without tubers or subependymal nodules and only mild dermatologic features of TSC missed on virtual examinations. Her mother and maternal aunt (Patients 2 and 3-diagnosed after age 50 years) presented with a mild phenotype, with dermatologic features and TAND. Her maternal uncle (Patient 4-diagnosed at age 47 years) displayed the most severe phenotype, presenting with intellectual disability, medically refractory epilepsy, obsessive-compulsive disorder, post-traumatic stress disorder, and psychosis.

CONCLUSIONS

This study expands the possible phenotypic spectrum of TSC2 R905Q variant, demonstrating an association with severe epilepsy without associated neuroradiological stigmata. This presentation highlights the possibility of occult focal cortical dysplasia in TSC and emphasizes the importance of genetic testing in individuals with severe epilepsy. Moreover, a late adult diagnosis was subsequently made in other family members allowing for appropriate TSC surveillance to occur.

Is tuberous sclerosis complex-associated autism a preventable and treatable disorder?

BACKGROUND

Tuberous sclerosis complex (TSC) is a genetic disorder caused by inactivating mutations in the TSC1 and TSC2 genes, causing overactivation of the mechanistic (previously referred to as mammalian) target of rapamycin (mTOR) signaling pathway in fetal life. The mTOR pathway plays a crucial role in several brain processes leading to TSC-related epilepsy, intellectual disability, and autism spectrum disorder (ASD). Pre-natal or early post-natal diagnosis of TSC is now possible in a growing number of pre-symptomatic infants.

DATA SOURCES

We searched PubMed for peer-reviewed publications published between January 2010 and April 2023 with the terms "tuberous sclerosis", "autism", or "autism spectrum disorder"," animal models", "preclinical studies", "neurobiology", and "treatment".

RESULTS

Prospective studies have highlighted that developmental trajectories in TSC infants who were later diagnosed with ASD already show motor, visual and social communication skills in the first year of life delays. Reliable genetic, cellular, electroencephalography and magnetic resonance imaging biomarkers can identify pre-symptomatic TSC infants at high risk for having autism and epilepsy.

CONCLUSIONS

Preventing epilepsy or improving therapy for seizures associated with prompt and tailored treatment strategies for autism in a sensitive developmental time window could have the potential to mitigate autistic symptoms in infants with TSC.

A single-center observational study on long-term neurodevelopmental outcomes in children with tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare multisystem disorder caused by mutations in the TSC1 or TSC2 gene. More than 90% of patients with TSC develop neurological and/or neuropsychiatric manifestations. The aim of the present study was to determine the developmental and cognitive long-term outcomes of pediatric TSC patients.

METHODS

This cross-sectional, monocenter study included pediatric TSC patients who received multidisciplinary long-term care with a last visit between 2005 and 2019. Neurological manifestations and cognitive development (BSID, K-ABC) were analyzed in relation to age and type of mutation.

RESULTS

Thirty-five patients aged 13.5 ± 7.8 years were included in the study. Diagnosis was confirmed genetically in 65.7% of patients (TSC1, 26.1%; TSC2, 65.2%; NMI, 8.7%). Mean age at diagnosis was 1.3 ± 3.5 years; 74.3% of the patients had been diagnosed within the first year of life due to seizures (62.9%) or/and cardiac rhabdomyomas (28.6%). The most common TSC manifestations included structural brain lesions (cortical tubers, 91.4%; subependymal nodules, 82.9%), epilepsy (85.7%), and cardiac rhabdomyomas (62.9%). Mean age at seizure onset was 1.5 ± 2.3 years, with onset in 80.0% of patients within the first two years of life. Infantile spasms, which were the first seizure type in 23.3% of the patients, developed earlier (0.6 ± 0.4 years) than focal seizures (1.8 ± 2.5 years). Refractory epilepsy was present in 21 (70.0%) patients, mild or severe intellectual impairment in 66.6%, and autism spectrum disorders in 11.4%. Severe cognitive impairment (33.3%) was significantly associated with epilepsy type and age at seizure onset (p < 0.05).

CONCLUSIONS

The results emphasized the phenotypic variability of pediatric-onset TSC and the high rate of neurological and neuropsychiatric morbidity. Early-onset refractory epilepsy was associated with impaired cognitive development. Children of all ages with TSC require multidisciplinary long-term care and individual early-intervention programs.

Updated clinical recommendations for the management of tuberous sclerosis complex associated epilepsy

Children with tuberous sclerosis complex (TSC), may experience a variety of seizure types in the first year of life, most often focal seizure sand epileptic spasms. Drug resistance is seen early in many patients, and the management of TSC associated epilepsy remain a major challenge for clinicians. In 2018 clinical recommendations for the management of TSC associated epilepsy were published by a panel of European experts. In the last five years considerable progress has been made in understanding the neurobiology of epileptogenesis and three interventional randomized controlled trials have changed the therapeutic approach for the management of TSC associated epilepsy. Pre-symptomatic treatment with vigabatrin may delay seizure onset, may reduce seizure severity and reduce the risk of epileptic encephalopathy. The efficacy of mTOR inhibition with adjunctive everolimus was documented in patients with TSC associated refractory seizures and cannabidiol could be another therapeutic option. Epilepsy surgery has significantly improved seizure outcome in selected patients and should be considered early in all patients with drug resistant epilepsy. There is a need to identify patients who may have a higher risk of developing epilepsy and autism spectrum disorder (ASD). In the recent years significant progress has been made owing to the early identification of risk factors for the development of drug-resistant epilepsy. Better understanding of the mechanism underlying epileptogenesis may improve the management for TSC-related epilepsy. Developmental neurobiology and neuropathology give opportunities for the implementation of concepts related to clinical findings, and an early genetic diagnosis and use of EEG and MRI biomarkers may improve the development of pre-symptomatic and disease-modifying strategies.

Tubers Affecting the Fusiform Face Area Are Associated with Autism Diagnosis

OBJECTIVE

Tuberous sclerosis complex (TSC) is associated with focal brain "tubers" and a high incidence of autism spectrum disorder (ASD). The location of brain tubers associated with autism may provide insight into the neuroanatomical substrate of ASD symptoms.

METHODS

We delineated tuber locations for 115 TSC participants with ASD (n = 31) and without ASD (n = 84) from the Tuberous Sclerosis Complex Autism Center of Excellence Research Network. We tested for associations between ASD diagnosis and tuber burden within the whole brain, specific lobes, and at 8 regions of interest derived from the ASD neuroimaging literature, including the anterior cingulate, orbitofrontal and posterior parietal cortices, inferior frontal and fusiform gyri, superior temporal sulcus, amygdala, and supplemental motor area. Next, we performed an unbiased data-driven voxelwise lesion symptom mapping (VLSM) analysis. Finally, we calculated the risk of ASD associated with positive findings from the above analyses.

RESULTS

There were no significant ASD-related differences in tuber burden across the whole brain, within specific lobes, or within a priori regions derived from the ASD literature. However, using VLSM analysis, we found that tubers involving the right fusiform face area (FFA) were associated with a 3.7-fold increased risk of developing ASD.

INTERPRETATION

Although TSC is a rare cause of ASD, there is a strong association between tuber involvement of the right FFA and ASD diagnosis. This highlights a potentially causative mechanism for developing autism in TSC that may guide research into ASD symptoms more generally. ANN NEUROL 2023;93:577-590.

Hyperactivation of mTORC1 in a double hit mutant zebrafish model of tuberous sclerosis complex causes increased seizure susceptibility and neurodevelopmental abnormalities

Tuberous sclerosis complex (TSC) is a multisystem genetic disorder caused by pathogenic variants in TSC1 and TSC2 genes. TSC patients present with seizures and brain abnormalities such as tubers and subependymal giant cells astrocytoma (SEGA). Despite common molecular and clinical features, the severity of the disease varies greatly, even intrafamilially. The second hit hypothesis suggests that an additional, inactivating mutation in the remaining functional allele causes a more severe phenotype and therefore explains the phenotypic variability. Recently, second hit mutations have been detected frequently in mTORopathies. To investigate the pathophysiological effects of second hit mutations, several mouse models have been developed. Here, we opted for a double mutant zebrafish model that carries a LOF mutation both in the tsc2 and the depdc5 gene. To the best of our knowledge, this is the first time a second-hit model has been studied in zebrafish. Significantly, the DEP domain-containing protein 5 (DEPDC5) gene has an important role in the regulation of mTORC1, and the combination of a germline TSC2 and somatic DEPDC5 mutation has been described in a TSC patient with intractable epilepsy. Our depdc5^−/−x tsc2^−/− double mutant zebrafish line displayed greatly increased levels of mammalian target of rapamycin (mTORC1) activity, augmented seizure susceptibility, and early lethality which could be rescued by rapamycin. Histological analysis of the brain revealed ventricular dilatation in the tsc2 and double homozygotes. RNA-sequencing showed a linear relation between the number of differentially expressed genes (DEGs) and the degree of mTORC1 hyperactivity. Enrichment analysis of their transcriptomes revealed that many genes associated with neurological developmental processes were downregulated and mitochondrial genes were upregulated. In particular, the transcriptome of human SEGA lesions overlapped strongly with the double homozygous zebrafish larvae. The data highlight the clinical relevance of the depdc5^−/− x tsc2^−/− double mutant zebrafish larvae that showed a more severe phenotype compared to the single mutants. Finally, analysis of gene-drug interactions identified interesting pharmacological targets for SEGA, underscoring the value of our small zebrafish vertebrate model for future drug discovery efforts.