Cortical tuber count: a biomarker indicating neurologic severity of tuberous sclerosis complex

Do vaccines cause epilepsy? Review of cases in the National Vaccine Injury Compensation Program

OBJECTIVE

The National Childhood Vaccine Injury Act of 1986 created the National Vaccine Injury Compensation Program (VICP), a no-fault alternative to the traditional tort system. Since 1988, the total compensation paid exceeds $5 billion. Although epilepsy is one of the leading reasons for filing a claim, there has been no review of the process and validity of the legal outcomes given current medical information. The objectives were to review the evolution of the VICP program in regard to vaccine-related epilepsy and assess the rationale behind decisions made by the court.

METHODS

Publicly available cases involving epilepsy claims in the VICP were searched through Westlaw and the US Court of Federal Claims websites. All published reports were reviewed for petitioner's theories supporting vaccine-induced epilepsy, respondent's counterarguments, the final decision regarding compensation, and the rationale underlying these decisions. The primary goal was to determine which factors went into decisions regarding whether vaccines caused epilepsy.

RESULTS

Since the first epilepsy case in 1989, there have been many changes in the program, including the removal of residual seizure disorder as a vaccine-related injury, publication of the Althen prongs, release of the acellular form of pertussis, and recognition that in genetic conditions the underlying genetic abnormality rather than the immunization causes epilepsy. We identified 532 unique cases with epilepsy: 105 with infantile spasms and 427 with epilepsy without infantile spasms. The petitioners' experts often espoused outdated, erroneous causation theories that lacked an acceptable medical or scientific foundation and were frequently criticized by the court.

SIGNIFICANCE

Despite the lack of epidemiological or mechanistic evidence indicating that childhood vaccines covered by the VICP result in or aggravate epilepsy, these cases continue to be adjudicated. After 35 years of intense litigation, it is time to reconsider whether epilepsy should continue to be a compensable vaccine-induced injury.

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.

Responsive Neurostimulation for the Treatment of Children With Drug-Resistant Epilepsy in Tuberous Sclerosis Complex

BACKGROUND

To review seizure outcomes in children with tuberous sclerosis complex (TSC) and drug-resistant epilepsy (DRE) treated with the responsive neurostimulation (RNS) System.

METHODS

We retrospectively reviewed children (<21 years old) with TSC implanted with the RNS System at Texas Children's Hospital between July 2016 and May 2022.

RESULTS

Five patients meeting the search criteria were identified (all female). The median age of the RNS implantation was 13 years (range: 5 to 20 years). The median epilepsy duration before the RNS implantation was 13 years (range: 5 to 20 years). Surgeries before RNS implantation included vagus nerve stimulator placement (n = 2), left parietal resection (n = 1), and corpus callosotomy (n = 1). The median number of antiseizure medications tried before RNS was 8 (range: 5 to 12). The rationale for the RNS System implantation included seizure onset in eloquent cortex (n = 3) and multifocal seizures (n = 2). The maximum current density for each patient ranged between 1.8 and 3.5 μC/cm², with an average daily stimulation of 2240 (range: 400 to 4200). There was an 86% median seizure reduction (range 0% to 99%) at a median follow-up duration of 25 months (range: 17 to 25 months). No patient experienced implantation or stimulation-related complications.

CONCLUSIONS

We observed a favorable improvement in seizure frequency in pediatric patients with DRE secondary to TSC treated with the RNS System. The RNS System may be a safe and effective treatment for DRE in children with TSC.

Spine morphogenesis and synapse formation in tubular sclerosis complex models

Tuberous sclerosis complex (TSC) is caused by mutations in the Tsc1 or Tsc2 genes, whose products form a complex and inactivate the small G-protein Rheb1. The activation of Rheb1 may cause refractory epilepsy, intellectual disability, and autism, which are the major neuropsychiatric manifestations of TSC. Abnormalities in dendritic spines and altered synaptic structure are hallmarks of epilepsy, intellectual disability, and autism. In addition, spine dysmorphology and aberrant synapse formation are observed in TSC animal models. Therefore, it is important to investigate the molecular mechanism underlying the regulation of spine morphology and synapse formation in neurons to identify therapeutic targets for TSC. In this review, we focus on the representative proteins regulated by Rheb1 activity, mTORC1 and syntenin, which are pivotal downstream factors of Rheb1 in the alteration of spine formation and synapse function in TSC neurons.

MR Imaging Detection of CNS Lesions in Tuberous Sclerosis Complex: The Usefulness of T1WI with Chemical Shift Selective Images

BACKGROUND AND PURPOSE

CNS lesions of tuberous sclerosis complex are diagnosed mainly by T2WI, FLAIR, and sometimes T1WI with magnetization transfer contrast. The usefulness of T1WI with chemical shift selective images was recently reported in focal cortical dysplasia type IIb, which has histopathologic and imaging features similar to those of tuberous sclerosis complex. We investigated the usefulness of the T1WI with chemical shift selective images in detecting CNS lesions of tuberous sclerosis complex.

MATERIALS AND METHODS

We retrospectively reviewed 25 consecutive patients with tuberous sclerosis complex (mean age, 11.9 [SD, 8.9] years; 14 males) who underwent MR imaging including T1WI, T1WI with magnetization transfer contrast, T1WI with chemical shift selective, T2WI, and FLAIR images. Two neuroradiologists assessed the number of CNS lesions in each sequence and compared them in 2 steps: among T1WI, T1WI with magnetization transfer contrast and T1WI with chemical shift selective images, and among T2WI, FLAIR, and T1WI with chemical shift selective images. We calculated the contrast ratio of the cortical tubers and of adjacent normal-appearing gray matter and the contrast ratio of radial migration lines and adjacent normal-appearing white matter in each sequence and compared them.

RESULTS

T1WI with chemical shift selective images was significantly superior to T1WI with magnetization transfer contrast for the detection of radial migration lines and contrast ratio of radial migration lines. There was no significant difference between T1WI with chemical shift selective images and T1WI with magnetization transfer contrast for the detection of cortical tubers and the contrast ratio of the cortical tubers. Both T2WI and FLAIR were statistically superior to T1WI with chemical shift selective images for the detection of cortical tubers. T1WI with chemical shift selective images was significantly superior to T2WI and FLAIR for the detection of radial migration lines.

CONCLUSIONS

The usefulness of T1WI with chemical shift selective images in detecting radial migration lines was demonstrated. Our findings suggest that the combination of T1WI with chemical shift selective images, T2WI, and FLAIR would be useful to evaluate the CNS lesions of patients with tuberous sclerosis complex in daily clinical practice.

Synaptic hyperexcitability of cytomegalic pyramidal neurons contributes to epileptogenesis in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a developmental disorder associated with epilepsy, autism, and cognitive impairment. Despite inactivating mutations in the TSC1 or TSC2 genes and hyperactive mechanistic target of rapamycin (mTOR) signaling, the mechanisms underlying TSC-associated neurological symptoms remain incompletely understood. Here we generate a Tsc1 conditional knockout (CKO) mouse model in which Tsc1 inactivation in late embryonic radial glia causes social and cognitive impairment and spontaneous seizures. Tsc1 depletion occurs in a subset of layer 2/3 cortical pyramidal neurons, leading to development of cytomegalic pyramidal neurons (CPNs) that mimic dysplastic neurons in human TSC, featuring abnormal dendritic and axonal overgrowth, enhanced glutamatergic synaptic transmission, and increased susceptibility to seizure-like activities. We provide evidence that enhanced synaptic excitation in CPNs contributes to cortical hyperexcitability and epileptogenesis. In contrast, astrocytic regulation of synapse formation and synaptic transmission remains unchanged after late embryonic radial glial Tsc1 inactivation, and astrogliosis evolves secondary to seizures.

Wu et al. demonstrate that Tsc1 inactivation in late embryonic radial glial cells (RGCs) produces cytomegalic pyramidal neurons that mimic TSC-like dysplastic neurons. They find that enhanced excitatory synaptic transmission in Tsc1-null cytomegalic pyramidal neurons contributes to cortical hyperexcitability and epileptogenesis.

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

BACKGROUND AND OBJECTIVE

Multiple factors have been found to contribute to the high risk of epilepsy in infants with Tuberous Sclerosis Complex (TSC), including evolution of EEG abnormalities, TSC gene mutation and MRI characteristics. The aim of the present prospective multi-center study was to: 1) identify early MRI biomarkers of epilepsy in infants with TSC aged < 6 months and before seizure onset, and 2) associate these MRI biomarkers with neurodevelopmental outcomes at 2 years of age. The study was part of the EPISTOP project.

METHODS

We evaluated brain MRIs performed in infants with TSC younger than 6 months of age. We used harmonized MRI-protocols across centers and children were monitored closely with neuropsychological evaluation, and serial video EEG. MRI characteristics defined as tubers, radial migration lines, white matter abnormalities, cysts, calcifications, subependymal nodules (SEN) and subependymal giant cell astrocytoma (SEGA) were visually evaluated and lesions were detected semi-automatically. Lesion to brain volume ratios were calculated and associated with epilepsy and neurodevelopmental outcomes at two years.

RESULTS

Lesions were assessed on MRIs from 77 TSC infants, 62 MRIs were sufficient for volume analysis. The presence of tubers and higher tuber-brain ratios were associated with the development of clinical seizures, independently of TSC gene mutation and preventive treatment. Furthermore, higher tuber-brain ratios were associated with lower cognitive and motor development quotients at two years, independently of TSC gene mutation and presence of epilepsy.

DISCUSSION

In infants with TSC, there is a significant association between characteristic TSC lesions detected on early brain MRI and development of clinical seizures, as well as neurodevelopmental outcomes in the first two years of life. According to our results, early brain MRI findings may guide clinical care for young children with TSC.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that in infants with TSC, there is a significant association between characteristic TSC lesions on early brain MRI and the development of clinical seizures and neurodevelopmental outcomes in the first two years of life.

Long-term treatment with everolimus in TSC-associated therapy-resistant epilepsies

PURPOSE

To investigate the efficacy and tolerability of long-term treatment with Everolimus (EVO) in patients with tuberous sclerosis complex (TSC) and therapy-resistant epilepsy in a compassionate use trial.

METHODS

After a 3-month baseline, patients were treated with EVO. Treatment was divided into treatment phases each lasting at least 9 months. Patients started with one of three target serum levels. In case of insufficient seizure control, subsequent treatment phases with other target serum levels followed. The accompanying antiseizure medication (ASM) remained stable during the baseline phase and for at least the initial three treatment phases. We evaluated changes in seizure frequency and seizure-free days compared to baseline for each patient (Cox-Stuart-test).

RESULTS

Fifteen patients were followed up for up to 10 years (minimum 0.6 years, median 5.8 years). Twelve patients (80%) experienced a significant reduction in seizure frequency or an increase in seizure-free days: Six (40%) patients became seizure-free and four patients (26.7%) remained seizure free for > 7 years, of which three required no additional ASM. All participants reported at least one adverse effect, the vast majority (92.5%) of which were mild or moderate.

CONCLUSION

Long-term treatment with EVO was highly efficacious, safe and well tolerated. While EVO can be a therapeutic option for therapy-resistant epilepsy in TSC, it can take a long time for seizure relief to manifest.

The Complex Interplay of Cortex, Cerebellum, and Age in a Cohort of Pediatric Patients With Tuberous Sclerosis Complex

BACKGROUND

The neurodevelopmental impairment in tuberous sclerosis complex (TSC) has a multifactorial origin. Various factors have been proposed as predictors of neurological outcome such as tuber load, seizure onset, and TSC2 mutation. Cerebellar lesions have been associated with worse neuroradiological phenotype, but their contribution is not well understood.

METHODS

A partly retrospective and partly prospective pediatric cohort study was conducted at three hospitals in Greece between 2015 and 2020. Patients aged ≤ 18 years with a confirmed TSC daignosis were included and underwent brain imaging, a semistructured interview (authorized Greek version of the tuberous sclerosis-associated neuropsychiatric disorders, or TAND, checklist), and intellectual ability assessment.

RESULTS

The study populations consisted of 45 patients with TSC (22 females, 23 males; mean age 9.53 years). Twenty patients (44.4%) had cerebellar lesions. Cerebellar involvement was the most powerful predictor of tuber load (P = 0.03). Cerebellar lesions were associated with giant cell astrocytomas (SEGAs) (P = 0.01) and severe neurological outcome (P = 0.01). Even though in the univariate analysis early seizure onset, tuber load, and cerebellar involvement were associated with intellectual impairment and neurological severity, none of them was an independent predictor of cognitive outcome and neurological severity.

CONCLUSIONS

Cerebellar lesions are common among individuals with TSC. Cerebellar involvement correlates with supratentorial derangement and the development of SEGAs, which is suggestive of a more severe clinical and neuroradiological phenotype. Cerebellar involvement and early seizure onset were not independent predictors of either neurological severity or intellectual disability or neurobehavioral outcome; their role in TSC clinical phenotype should be further investigated.

Prediction of tuberous sclerosis-associated neurocognitive disorders and seizures via machine learning of structural magnetic resonance imaging

PURPOSE

Tuberous sclerosis complex (TSC) is a genetic disorder characterized by multiorgan hamartomas, including cerebral lesions, with seizures as a common presentation. Most TSC patients will also experience neurocognitive comorbidities. Our objective was to use machine learning techniques incorporating clinical and imaging data to predict the occurrence of major neurocognitive disorders and seizures in TSC patients.

METHODS

A cohort of TSC patients were enrolled in this retrospective study. Clinical data included genetic, demographic, and seizure characteristics. Imaging parameters included the number, characteristics, and location of cortical tubers and the presence of subependymal nodules, SEGAs, and cerebellar tubers. A random forest machine learning scheme was used to predict seizures and neurodevelopmental delay or intellectual developmental disability. Prediction ability was assessed by the area-under-the-curve of receiver-operating-characteristics (AUC-ROC) of ten-fold cross-validation training set and an independent validation set.

RESULTS

The study population included 77 patients, 55% male (17.1 ± 11.7 years old). The model achieved AUC-ROC of 0.72 ± 0.1 and 0.68 in the training and internal validation datasets, respectively, for predicting neurocognitive comorbidity. Performance was limited in predicting seizures (AUC-ROC of 0.54 ± 0.19 and 0.71 in the training and internal validation datasets, respectively). The integration of seizure characteristics into the model improved the prediction of neurocognitive comorbidity with AUC-ROC of 0.84 ± 0.07 and 0.75 in the training and internal validation datasets, respectively.

CONCLUSIONS

This proof of concept study shows that it is possible to achieve a reasonable prediction of major neurocognitive morbidity in TSC patients using structural brain imaging and machine learning techniques. These tools can help clinicians identify subgroups of TSC patients with an increased risk of developing neurocognitive comorbidities.

Fetal Brain Magnetic Resonance Imaging Findings Predict Neurodevelopment in Children with Tuberous Sclerosis Complex

OBJECTIVE

To correlate fetal brain magnetic resonance imaging (MRI) findings with epilepsy characteristics and neurodevelopment at 2 years of age in children with tuberous sclerosis complex (TSC) to improve prenatal counseling.

STUDY DESIGN

This retrospective cohort study was performed in a collaboration between centers of the EPISTOP consortium. We included children with definite TSC, fetal MRIs, and available follow-up data at 2 years of age. A pediatric neuroradiologist masked to the patient's clinical characteristics evaluated all fetal MRIs. MRIs were categorized for each of the 10 brain lobes as score 0: no (sub)cortical lesions or doubt; score 1: a single small lesion; score 2: more than one small lesion or at least one large lesion (>5 mm). Neurologic manifestations were correlated to lesion sum scores.

RESULTS

Forty-one children were included. Median gestational age at MRI was 33.3 weeks; (sub)cortical lesions were detected in 97.6%. Mean lesion sum score was 4.5. At 2 years, 58.5% of patients had epilepsy and 22% had drug-resistant epilepsy. Cognitive, language, and motor development were delayed in 38%, 81%, and 50% of patients, respectively. Autism spectrum disorder (ASD) was diagnosed in 20.5%. Fetal MRI lesion sum scores were significantly associated with cognitive and motor development, and with ASD diagnosis, but not with epilepsy characteristics.

CONCLUSIONS

Fetal cerebral lesion scores correlate with neurodevelopment and ASD at 2 years in children with TSC.

Congenital subpendymal giant cell astrocytoma in children with tuberous sclerosis complex: growth patterns and neurological outcome

BACKGROUND

Literature regarding congenital subependymal giant cell astrocytomas (SEGA) is limited, and suggests they are at risk of rapid growth and complications. We sought to characterise the growth patterns of congenital SEGA. The second part of the study was an exploratory analysis of congenital SEGA as a possible biomarker for poor neurological outcome.

METHODS

This single-centre case series describes ten patients with TSC who had SEGA diagnosed before 12 months. SEGA diameter and volumetric growth were analysed using serial MRIs. Neurological outcomes were compared to a genotype-matched group.

RESULTS

All children with congenital SEGA had a TSC2 mutation. Patients were followed for 1-8.7 years, during which median SEGA growth rate was 1.1 mm/yr in diameter or 150 mm³/yr volumetrically. SEGA with volume > 500 mm³ had a significantly higher growth rate compared with smaller SEGA (462 mm³/yr vs. 42 mm³/yr, p = 0.0095). Children with congenital SEGA had a high prevalence of severe epilepsy, developmental disability and autism spectrum disorder.

CONCLUSION

Congenital SEGA can follow a relatively benign course with a lower growth rate compared with published literature. Frequent neuroimaging surveillance is recommended for congenital SEGA with volumes exceeding 500 mm³.

IMPACT

Congenital SEGA occur in 9.2% of paediatric patients with tuberous sclerosis complex. There are few published cases of congenital SEGA to date. This case series of ten patients adds our experience seen in a tertiary referral hospital over 10 years. Congenital SEGA can follow a relatively benign course with a lower growth rate compared with published literature. Congenital SEGA with volume exceeding 500 mm³ had a significantly higher growth rate compared with smaller SEGA and should have more frequent neuroimaging surveillance.

The role of glia in epilepsy, intellectual disability, and other neurodevelopmental disorders in tuberous sclerosis complex

Background

Tuberous sclerosis complex (TSC) is a genetic disorder characterized by severe neurological manifestations, including epilepsy, intellectual disability, autism, and a range of other behavioral and psychiatric symptoms, collectively referred to as TSC-associated neuropsychiatric disorders (TAND). Various tumors and hamartomas affecting different organs are the pathological hallmarks of the disease, especially cortical tubers of the brain, but specific cellular and molecular abnormalities, such as involving the mechanistic target of rapamycin (mTOR) pathway, have been identified that also cause or contribute to neurological manifestations of TSC independent of gross structural lesions. In particular, while neurons are immediate mediators of neurological symptoms, different types of glial cells have been increasingly recognized to play important roles in the phenotypes of TSC.

Main body

This review summarizes the literature supporting glial dysfunction from both mouse models and clinical studies of TSC. In particular, evidence for the role of astrocytes, microglia, and oligodendrocytes in the pathophysiology of epilepsy and TAND in TSC is analyzed. Therapeutic implications of targeting glia cells in developing novel treatments for the neurological manifestations of TSC are also considered.

Conclusions

Different types of glial cells have both cell autonomous effects and interactions with neurons and other cells that are involved in the pathophysiology of the neurological phenotype of TSC. Targeting glial-mediated mechanisms may represent a novel therapeutic approach for epilepsy and TAND in TSC patients.

Tuberous Sclerosis Complex Genotypes and Developmental Phenotype

BACKGROUND

Children with tuberous sclerosis complex (TSC), caused by pathogenic variants in TSC1/TSC2, are at risk for intellectual disability. TSC2 pathogenic variants appear to increase the risk, compared with TSC1. However, the effect of TSC2 pathogenic variants on early and specific domains of development hasn't been studied. Using an extensively phenotyped group, we aimed to characterize differences in early intellectual development between genotypes.

METHODS

The study group (n = 92) included participants with TSC enrolled in a multicenter study involving genetic testing and detailed prospective phenotyping including the Mullen Scales of Early Learning, a validated measure of cognition, language, and motor development in babies and preschool children. Mean T-scores at 24 months for each Mullen Scales of Early Learning domain were calculated for children with, versus without, a TSC2 pathogenic variant. Multivariable linear regression models were used to compare the groups, adjusting for seizures.

RESULTS

T-scores on every Mullen Scales of Early Learning domain were significantly worse in the TSC2 group. Below average composite scores were present in three-fourths of the TSC2 group, compared with one-fourth of those without TSC2. Having a TSC2 pathogenic variant was associated with lower composite Mullen Scales of Early Learning scores, even when corrected for seizures.

CONCLUSIONS

In a well-characterized patient population with standardized assessment of multiple aspects of development, we found that having a TSC2 pathogenic variant was associated with significantly lower Mullen Scales of Early Learning scores at age 24 months, independent of seizures. These data suggest that a baby with a TSC2 pathogenic variant is at high risk for significant developmental delays by 24 months.

Factors affecting epilepsy prognosis in patients with tuberous sclerosis

PURPOSE

We aimed to determine the characteristics of epileptic seizures that significantly affect the cognitive functions of 83 patients followed with tuberous sclerosis complex (TSC), their resistance to treatment and risk factors causing this resistance.

MATERIALS-METHODS

In order to determine the prognosis, the seizure-free/seizure-controlled group and the group with refractory seizures were compared. In addition, risk factors affecting cognitive functions in the patients were determined.

RESULTS

There was a statistical significance between the presence of a history of seizures in the neonatal period, the age of onset of seizures being less than 2 years of age, autism, status epilepticus, Lennox-Gastaut syndrome (LGS), presence of infantile spasm, generalization of the electroencephalography (EEG) findings, the number of tubers in cerebral imaging being more than three and refractory seizures (p < 0.05). Statistically significant relationship was found between presence of a history of seizures in the neonatal period, the age of onset of seizures, autism, LGS, presence of infantile spasm, presence of status epilepticus history, history of using more than three antiepileptic drugs, generalization of EEG findings, presence of SEGA in cerebral imaging, number of tubers being more than three and the patient's mental retardation (p < 0.05).

CONCLUSION

In logistic regression analysis, the age of the seizure onset being less than 2 years of age, the presence of autism and number of tubers being more than three in cerebral magnetic resonance imaging (MRI) are determined to be the risk factors that most likely to increase the seizures to be more resistant.

Diagnosis of tuberous sclerosis complex in the fetus

Tuberous sclerosis complex is a dominantly inherited genetic disorder of striking clinical variability. It is caused by mutations in either TSC1 or TSC2 gene, which regulate cell growth and proliferation by inhibition of mTORC1 signaling. TS is characterized by the development of benign tumors in many tissues and organs and its neurological manifestations include epilepsy, autism, cognitive and behavioral dysfunction, and giant cell tumors. With mechanism-based mTOR inhibitors therapy now available for many of its manifestations, early diagnosis of TSC is very important in order to offer appropriate care, long-term surveillance and parental counseling. Fetal ultrasound and MRI imaging techniques have evolved and may capture even earlier the following TSC-associated lesions: cardiac rhabdomyomas, subependymal nodules, cortical tubers and renal cysts. Often these represent an incidental finding during a routine ultrasound. Furthermore, in the past decades prenatal molecular diagnosis of TSC has emerged as an important option for families with a known affected member; however, the existing evidence with regards to the clinical characteristics and long-term outcome of babies diagnosed prenatally with TSC is yet limited and the path that follows early TSC detection merits further research.

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.

Tumor-related epilepsy: epidemiology, pathogenesis and management

INTRODUCTION

Seizure is a common comorbidity in patients with brain tumor. It may be the presenting symptom or develop after the tumor diagnosis. The underlying pathophysiology of brain tumor-related epilepsy remains poorly understood.

METHODS

A comprehensive literature review of Pubmed English articles from 1980-2017 was performed to summarize current knowledge and treatment options of brain tumor-related epilepsy.

RESULTS

Multiple factors have been found to contribute to tumor-related epilepsy, including tumor type, speed of tumor growth, location, and tumor burden. The underlying pathogenesis of epilepsy is not clear but perturbations in the peri-tumoral regions, both structural and cellular communications, have been implicated.

CONCLUSIONS

Surgical and medical treatments of tumor-related epilepsy remain challenging as additional factors such as the extent of surgical resection, interactions with tumor-related oncological treatments and anti-epileptic medication related side effects need to be considered.

Surgical treatment for refractory epilepsy

The goal of any epilepsy surgery is to improve patient's quality of life by achieving seizure freedom or by reducing the frequency of severely debilitating seizures. To achieve this goal, non-invasive and invasive diagnostic methods must precisely delineate the epileptogenic zone (EZ), which is defined as the area that needs to be resected to obtain seizure freedom. At the same time, the correct identification of eloquent brain areas is inevitable to avoid new neurological deficits from surgery. In recent years, the technical advances in diagnostics have enabled us to achieve these goals in an increasing number of cases. As a consequence, and with new surgical treatment options available, the number of patients who might benefit from epilepsy surgery is constantly increasing. Especially in pediatric epilepsy, early surgical intervention is becoming frequently advocated as it has been shown to improve cognitive and behavioral outcome. Specialized epilepsy centers and multidisciplinary teams are required to provide adequate care and treatment. The goal of this review is to describe important diseases that are accessible to epilepsy surgery and to give an overview of current diagnostic methods. The focus lies on established as well as novel techniques in epilepsy surgery. The presurgical work-up and patient selection is outlined.

Different MRI-defined tuber types in tuberous sclerosis complex: Quantitative evaluation and association with disease manifestations

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare genetic disorder with multisystem involvement. A magnetic-resonance (MRI) based classification of tubers into types A, B and C has been proposed. However, the relationship between different tuber types and their quantitative characteristics, also the non-neurological manifestations of TSC remains unknown.

AIMS

To quantitatively evaluate different MRI-defined tuber types and to explore their relationships with major disease manifestations in patients with tuberous sclerosis complex.

METHODS

We performed quantitative manual assessment of tubers visible on T1W, T2W/FLAIR images and DW/ADC maps of 20 patients with TSC. Tubers were classified into types A, B and C based on their signal intensity on MRI. General clinical information and quantitative tuber characteristics were evaluated. Between-group comparisons were made using the nonparametric Mann-Whitney U test with Bonferroni correction.

RESULTS

In total, 20 patients with 770 tubers were evaluated. Type A tubers were most numerous followed closely by Type B tubers, whereas Type C tubers were relatively rare. Tuber size was markedly different among the three tuber types: it increased from Type A to Type B to Type C. Infantile spasms, generalized-tonic clonic seizures, poor seizure control, cardiac rhabdomyomas, SEGA and developmental delay were not associated with quantitative tuber characteristics. Increased total Type B tuber load was associated with early onset epilepsy, while individually larger Type A and Type B tubers were associated with the presence angiomyolipoma (AML) and renal cysts.

CONCLUSIONS

MRI-defined tuber types differ significantly in their size and number. Larger total Type B tuber load and larger individual Type A and Type B tubers were found to be most associated with early seizure onset and renal angiomyolipomas, respectively. One possible explanation for the observed differences in the clinical phenotype based on MRI-defined tuber types is not the intrinsic qualitative distinctions between different tuber types, but rather their individual size and total tuber load.

Epilepsy may be the major risk factor of mental retardation in children with tuberous sclerosis: A retrospective cohort study

Mental retardation (MR) is one of the most common cognitive comorbidities in children with tuberous sclerosis, and there are enormous studies about its risk factors. The genetic difference and the severity of epilepsy are the two main factors, but their weight in the occurrence of MR is still unclear. Two hundred twenty-three patients with tuberous sclerosis who received intelligence assessment, genetic mutation analysis, and the epilepsy severity assessment were included in our study. Genotype-neurocognitive phenotype correlations and epilepsy-neurocognitive phenotype correlations were analyzed by binary logistic regression analysis. No statistical significant result was found on genotype-neurocognitive phenotype correlations, which contrasted the previous report. The prevalence of MR was 50.0% for the patients with tuberous sclerosis complex-1 (TSC1) mutation, 54.5% for TSC2 (p=0.561), 54.7% for patients with protein-truncating (PT) and 50.0% for patients with nontruncating (NT) (p=0.791), and 54.3% for patients with family history and 53.7% for patients without family history (p=0.748). Statistical significant results were found on epilepsy-neurocognitive phenotype correlations, both on E-chess score (p=0.01) and the occurrence of infantile spasms (p=0.014), which was consistent to the previous study. For children with tuberous sclerosis, instead of genetic factors, epilepsy may play the main role for the presence of mental retardation. Patients with mental retardation tend to have earlier seizure attack, take more AEDs, have more seizure types, and have higher seizure frequency. Among the four cognitive functions in Denver II, social ability and language ability are more vulnerable to be influenced than fine and gross motor ability.

The genomic landscape of tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a rare genetic disease causing multisystem growth of benign tumours and other hamartomatous lesions, which leads to diverse and debilitating clinical symptoms. Patients are born with TSC1 or TSC2 mutations, and somatic inactivation of wild-type alleles drives MTOR activation; however, second hits to TSC1/TSC2 are not always observed. Here, we present the genomic landscape of TSC hamartomas. We determine that TSC lesions contain a low somatic mutational burden relative to carcinomas, a subset feature large-scale chromosomal aberrations, and highly conserved molecular signatures for each type exist. Analysis of the molecular signatures coupled with computational approaches reveals unique aspects of cellular heterogeneity and cell origin. Using immune data sets, we identify significant neuroinflammation in TSC-associated brain tumours. Taken together, this molecular catalogue of TSC serves as a resource into the origin of these hamartomas and provides a framework that unifies genomic and transcriptomic dimensions for complex tumours.

A Comprehensive Review of Pediatric Tumors and Associated Cancer Predisposition Syndromes

An understanding of the role of inherited cancer predisposition syndromes in pediatric tumor diagnoses continues to develop as more information is learned through the application of genomic technology. Identifying patients and their relatives at an increased risk for developing cancer is an important step in the care of this patient population. The purpose of this review is to highlight various tumor types that arise in the pediatric population and the cancer predisposition syndromes associated with those tumors. The review serves as a guide for recognizing genes and conditions to consider when a pediatric cancer referral presents to the genetics clinic.

Risk factors for the development of autism spectrum disorder in children with tuberous sclerosis complex: protocol for a systematic review

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant condition, caused by mutations in either the TSC1 or TSC2 gene. It has widespread systemic manifestations and is associated with significant neurological morbidity. In addition to seizures and cerebral pathology including cortical tubers, subependymal nodules, subependymal giant cell astrocytoma and abnormal white matter, there are recognised neuropsychiatric difficulties including intellectual disability, autism spectrum disorder (ASD) and a range of learning and behaviour problems, recently conceptualised as "tuberous sclerosis-associated neuropsychiatric disorders", or "TAND". ASD in TSC is of particular importance because (1) it affects up to 50% of people with TSC and is a source of considerable difficulty for them and their families and (2) it provides a model for considering neurobiological pathways involved in ASD. Multiple factors are implicated in the development of ASD in TSC, including (1) seizures and related electrophysiological factors, (2) cerebral pathology, (3) genotype and (4) child characteristics. However, the neurobiological pathway remains unclear. We will conduct a systematic review to investigate and synthesise existing evidence about the role of these risk factors, individually and in combination, in leading to the development of ASD.

METHODS

Our review will report on all studies that include one or more of four predefined risk factors in the development of ASD in children with TSC. We will search five databases: MEDLINE, EMBASE, PubMed, The Cochrane Library and Web of Science (Conference Proceedings Citation Index). Studies will be selected for reporting after two authors independently (1) review all titles and abstracts, (2) read full text of all appropriate papers and (3) assess for bias using the Newcastle-Ottawa Scale recommended by the Guidelines for Meta-Analysis and Systematic Reviews of Observational Studies (MOOSE guidelines) and the ROBINS-I.

DISCUSSION

To our knowledge, this is the first systematic review investigating multiple risk factors in the development of ASD in children with TSC. Clarifying the evidence in this area will be important to researchers in the field and to clinicians providing prognostic information to families.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016042841.

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.

Topographical Distribution of Epileptogenic Tubers in Patients With Tuberous Sclerosis Complex

Tuberous sclerosis complex is a multisystem genetic syndrome often affecting the central nervous system. The purpose of the current study was to identify topographical patterns in the distribution specific to epileptogenic (n = 37) and nonepileptogenic (n = 544) tubers throughout the brain for a cohort of 23 tuberous sclerosis complex patients with a history of seizures. Tubers localized to the inferior parietal lobes, middle frontal lobes, middle temporal lobes, or central sulcus regions were associated with a high frequency of epileptogenic tubers. Epileptogenic tubers occurred statistically more frequently within the inferior parietal lobe and within the central sulcus region in children younger than 1 or between 1 and 3 years old, respectively. Results imply seizure activity in tuberous sclerosis complex patients can be associated with the location of cortical tubers.

Cross-sectional Imaging Review of Tuberous Sclerosis

Tuberous sclerosis complex (TSC) is a multisystem, genetic disorder characterized by development of hamartomas in the brain, abdomen, and thorax. It results from a mutation in one of 2 tumor suppressor genes that activates the mammalian target of rapamycin pathway. This article discusses the origins of the disorder, the recently updated criteria for the diagnosis of TSC, and the cross-sectional imaging findings and recommendations for surveillance. Familiarity with the diverse radiological features facilitates diagnosis and helps in treatment planning and monitoring response to treatment of this multisystem disorder.

Cutaneous manifestations in neuro-oncology: clinically relevant tumor and treatment associated dermatologic findings

Skin findings are a rare but important aspect of the evaluation and management of patients with tumors of the nervous system. Skin findings have the highest prevalence in genetic tumor syndromes termed neuro-genodermatoses, which include neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and tuberous sclerosis. Skin changes are observed in patients with non-syndromic nervous system malignancy, often as a result of pharmacotherapy. The skin may also manifest findings in paraneoplastic conditions that affect the nervous system, providing an early indication of underlying neoplasm, including dermatomyosistis, neuropathic itch, and brachioradial pruritus. In this article, we review the major cutaneous findings in patients with tumors of the brain, spine, and peripheral nervous system focusing on (1) cutaneous manifestations of genetic and sporadic primary nervous system tumor syndromes, and (2) paraneoplastic neurological syndromes with prominent cutaneous features.

Cerebellar Development and Autism Spectrum Disorder in Tuberous Sclerosis Complex

Approximately 50% of patients with the genetic disease tuberous sclerosis complex present with autism spectrum disorder. Although a number of studies have investigated the link between autism and tuberous sclerosis complex, the etiology of autism spectrum disorder in these patients remains unclear. Abnormal cerebellar function during critical phases of development could disrupt functional processes in the brain, leading to development of autistic features. Accordingly, the authors review the potential role of cerebellar dysfunction in the pathogenesis of autism spectrum disorder in tuberous sclerosis complex. The authors also introduce conditional knockout mouse models of Tsc1 and Tsc2 that link cerebellar circuitry to the development of autistic-like features. Taken together, these preclinical and clinical investigations indicate the cerebellum has a profound regulatory role during development of social communication and repetitive behaviors.

Intellectual abilities in tuberous sclerosis complex: risk factors and correlates from the Tuberous Sclerosis 2000 Study

BACKGROUND

Tuberous sclerosis complex (TSC) is associated with intellectual disability, but the risk pathways are poorly understood.

METHOD

The Tuberous Sclerosis 2000 Study is a prospective longitudinal study of the natural history of TSC. One hundred and twenty-five UK children age 0-16 years with TSC and born between January 2001 and December 2006 were studied. Intelligence was assessed using standardized measures at ≥2 years of age. The age of onset of epilepsy, the type of seizure disorder, the frequency and duration of seizures, as well as the response to treatment was assessed at interview and by review of medical records. The severity of epilepsy in the early years was estimated using the E-Chess score. Genetic studies identified the mutations and the number of cortical tubers was determined from brain scans.

RESULTS

TSC2 mutations were associated with significantly higher cortical tuber count than TSC1 mutations. The extent of brain involvement, as indexed by cortical tuber count, was associated with an earlier age of onset and severity of epilepsy. In turn, the severity of epilepsy was strongly associated with the degree of intellectual impairment. Structural equation modelling supported a causal pathway from genetic abnormality to cortical tuber count to epilepsy severity to intellectual outcome. Infantile spasms and status epilepticus were important contributors to seizure severity.

CONCLUSIONS

The findings support the proposition that severe, early onset epilepsy may impair intellectual development in TSC and highlight the potential importance of early, prompt and effective treatment or prevention of epilepsy in tuberous sclerosis.

Tuberous sclerosis complex; single center experience

AIM

This study was planned with the aim of retrospectively reviewing the clinical and laboratory findings and therapies of our patients diagnosed with tuberous sclerosis and redefining the patients according to the diagnostic criteria revised by the 2012 International Tuberous Sclerosis Complex Consensus Group and comparing them with the literature.

MATERIALS AND METHOD

Twenty patients diagnosed with tuberous sclerosis complex in the Pediatric Neurology Clinic were examined retrospectively in terms of clinical findings and therapies. The diagnoses were compared again according to 1998 and 2012 criteria.

RESULTS

It was observed that the complaint at presentation was seizure in 17 of 20 patients and hypopigmented spots on the skin in 3 of 20 patients. On the initial physical examination, findings related with the disease were found in the skin in 17 of the patients, in the eye in 5, in the kidneys in 7 and in the brain with imaging in 17. No cardiac involvement was observed in the patients. Infantile spasm was observed in 7 of the patients who presented because of seizure (n=17), partial seizure was observed in 7 and multiple seizure types were observed in 3. It was found that sirolimus treatment was given to 9 of 20 patients because of different reasons, 7 of these 9 patients had epileptic seizures and sirolimus treatment had no effect on epileptic seizures. According to 2012 diagnostic criteria, no marked change occured in the diagnoses of our patients.

CONCLUSIONS

It was observed that the signs and symptoms of our patients were compatible with the literature. Molecular genetic examination was planned for the patients who were being followed up because of probable tuberous sclerosis complex. It was observed that sirolimus treatment had no marked effect on the seizure frequency of our patients.

Tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a neurocutaneous syndrome that can affect the brain, skin, eyes, kidneys, heart, and lungs. TSC alters cellular proliferation and differentiation, resulting in hamartomas of various organs, tumor formation, and altered neuronal migration. The phenotype is highly variable. Most individuals have seizures, commonly including infantile spasms, and there is variable intellectual disability and autism. Neonates can present with cardiac failure due to intracardiac rhabdomyomas. The likelihood of renal angiomyolipomas increases with age, and renal disease is the most common cause of death in adults with TSC. Pulmonary involvement occurs predominantly in women and carries a high morbidity and mortality. TSC is inherited as an autosomal dominant trait, but spontaneous mutations are common. A mutation of either TSC1 on chromosome 9 or TSC2 on chromosome 16 leads to dysfunction of hamartin or tuberin, respectively. These two proteins form a functional complex that modulates the mammalian target of rapamycin (mTOR) pathway. Medications that inhibit mTOR are being used to treat TSC-related tumors, and current studies are investigating whether these agents could alleviate other TSC complications. Consensus statements guide identification and optimal management of many of the TSC-related complications at diagnosis and throughout the lifespan. A multidisciplinary approach is necessary for optimal management of individuals with TSC.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

Recommendations for the radiological diagnosis and follow-up of neuropathological abnormalities associated with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a genetic condition with multisystem involvement, characterized by the development of tumors and other abnormalities in organs such as the brain, retina, skin, heart, kidneys, and lungs. Most patients have neuropathological abnormalities such as cortical tubers, white matter radial migration lines, subependymal nodules, and subependymal giant cell astrocytomas (SEGAs). These lesions are associated with different neurological manifestations that are frequently associated with TSC. These manifestations consist of epilepsy, intellectual disability, and neurobehavioral and psychiatric problems, including autism spectrum disorder. Hydrocephalus may also develop in patients with SEGAs due to ventricular obstruction, when this usually slow-growing tumor reaches sufficient size. Surgery has been the classical approach to treat SEGAs, although this treatment is associated with substantial morbidity and does not completely prevent tumor recurrence. Recently, the mammalian target of rapamycin (mTOR) inhibitor, everolimus, has been approved by the Food and Drug Administration and the European Medicines Agency for the treatment of patients with SEGAs associated with TSC. However, the treatment of SEGAs with these agents requires the development of guidelines that establish a differential diagnosis between SENs and SEGAs, in which neuroradiological examinations play an essential role. With the aim of improving the neuroradiological diagnosis and follow-up of the neuropathological abnormalities associated with TSC, a group of experts in this field has reviewed different aspects related to these issues and put together, a series of statements and recommendations intended to provide guidance to specialists involved in the management of TSC.

Rates and predictors of seizure freedom in resective epilepsy surgery: an update

Epilepsy is a debilitating neurological disorder affecting approximately 1 % of the world's population. Drug-resistant focal epilepsies are potentially surgically remediable. Although epilepsy surgery is dramatically underutilized among medically refractory patients, there is an expanding collection of evidence supporting its efficacy which may soon compel a paradigm shift. Of note is that a recent randomized controlled trial demonstrated that early resection leads to considerably better seizure outcomes than continued medical therapy in patients with pharmacoresistant temporal lobe epilepsy. In the present review, we provide a timely update of seizure freedom rates and predictors in resective epilepsy surgery, organized by the distinct pathological entities most commonly observed. Class I evidence, meta-analyses, and individual observational case series are considered, including the experiences of both our institution and others. Overall, resective epilepsy surgery leads to seizure freedom in approximately two thirds of patients with intractable temporal lobe epilepsy and about one half of individuals with focal neocortical epilepsy, although only the former observation is supported by class I evidence. Two common modifiable predictors of postoperative seizure freedom are early operative intervention and, in the case of a discrete lesion, gross total resection. Evidence-based practice guidelines recommend that epilepsy patients who continue to have seizures after trialing two or more medication regimens should be referred to a comprehensive epilepsy center for multidisciplinary evaluation, including surgical consideration.

Optimal management of seizures associated with tuberous sclerosis complex: current and emerging options

Seizures are clinically significant manifestations associated with 79%-90% of patients with tuberous sclerosis complex. Often occurring within the first year of life in the form of infantile spasms, seizures interfere with neuropsychiatric, social, and cognitive development and carry significant individual and societal consequences. Prompt identification and treatment of seizures is an important focus in the overall management of tuberous sclerosis complex patients. Medical management, either after seizure onset or prophylactically in infants with electroencephalographic abnormalities, is considered first-line therapy. Vigabatrin and adrenocorticotropic hormone have emerged over the past few decades as mainstay pharmacologic modalities. Furthermore, emerging research on mammalian target of rapamycin inhibitors demonstrated promise for the management of seizures and subependymal giant cell astrocytoma. For appropriate surgical candidates with an epileptogenic zone associated with one or more glioneuronal hamartomas, ideally in noneloquent cortex, resective surgery can be considered, which provides a cure in 56% of patients. For medically refractory patients who do not meet criteria for curative surgery, palliative surgical approaches focused on reducing seizure burden, in the form of corpus callosotomy and vagus nerve stimulation, are alternative management options. Lastly, the ketogenic diet, a reemerging therapy based on the anticonvulsant effects of ketone bodies, can be utilized independently or in conjunction with other treatment modalities for the management of difficult-to-treat seizures.

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

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

Neurological aspects of tuberous sclerosis in relation to MRI/MR spectroscopy findings in children with epilepsy

Our aim was to evaluate the relationship between the neurological outcome of tuberous sclerosis complex (TSC) and the findings obtained from both cranial magnetic resonance imaging (MRI) and single voxel proton spectroscopy (SVPS). MRIs of 13 children who met the diagnostic criteria for TSC were taken. Eleven of these children also underwent a prospective analysis of SVPS. Fisher's exact test and Mann-Whitney U test were used, where applicable, to detect any signs of the imaging data that would indicate poor outcome, or in other words, poor seizure control and/ or high degree of mental retardation. Poor seizure control was seen in eight of the patients and multiple seizure types in seven. Mental retardation was severe in six patients and mild/moderate in seven. MRI revealed multiple bilateral tubers and subependymal nodules (13/13), confluence of tubers (8/13), subcortical linear heterotopias (7/13), gyral cores (3/13) and cortical atrophy (3/13). SVPS findings of tubers were characterized by decreased NAA/Cr (1.43 +/- 0.33, p<0.001), increased Cho/Cr (0.91 +/- 0.082, p< 0.05) and mI/Cr (0.97 +/- 0.19, p<0.01) ratios when compared with those of the control group. Lactate peak was detected in six patients. Unfavorable outcome in TSC can be predicted with the help of the following: multiple seizure types, a number of confluent appearances of the tubers and cortical atrophy. SVPS could be a useful clue to understand the pathophysiologic function of the tubers, especially in children with refractory epilepsy along with TSC.

Longitudinal quantitative analysis of the tuber-to-brain proportion in patients with tuberous sclerosis

OBJECT

In patients with tuberous sclerosis complex (TSC), the tuber-to-brain proportion (TBP) is a marker of seizure severity and cognitive function. However, few studies have quantified the TBP. Furthermore, authors of these studies have measured the TBP at only a single time point, despite the fact that tuber cells were found to express proliferation markers, suggesting that they may be dynamic lesions. Authors of the present study used a semi-automated tuber segmentation program to determine whether the TBP changes over time.

METHODS

Axial FLAIR MR images were retrospectively identified for patients with TSC who had undergone imaging at the authors' institution between February 1998 and June 2009. Using FireVoxel software, the TBP was measured for each patient at a minimum interval of 2 years.

RESULTS

Twelve patients meeting the study inclusion criteria were identified. The mean TBP was 1.88% (range 0.38%-3.70%). Eight patients demonstrated minimal changes and 3 patients demonstrated small increases in TBP. The remaining patient exhibited a decrease of 1.00%, which correlated with a visible decrease in the size of 2 cerebellar lesions.

CONCLUSIONS

Semi-automated brain segmentation is a valuable tool in the longitudinal study of tubers. A subset of patients with TSC, particularly those with cerebellar lesions, may exhibit changes in the TBP over time.

Molecular genetic, cardiac and neurodevelopmental findings in cases of prenatally diagnosed rhabdomyoma associated with tuberous sclerosis complex

OBJECTIVE

Rhabdomyoma is the most common type of cardiac tumor in fetuses and is often associated with tuberous sclerosis complex (TSC) with neurologic sequelae. The purpose of this study was to investigate the cardiac and neurodevelopmental outcomes of fetal rhabdomyoma.

METHODS

We reviewed the clinical characteristics of 23 cases of cardiac rhabdomyoma diagnosed prenatally by fetal echocardiography at the Asan Medical Center between January 1998 and December 2009. We also reviewed postnatal results of brain magnetic resonance imaging, echocardiography, renal ultrasound examination and molecular genetic analysis to confirm the presence of cardiac rhabdomyoma with or without TSC.

RESULTS

Among 23 cases, outcome data were available for 17 (73.9%) and six cases (26.1%) were lost to follow-up. The survival rate was 100.0% (17/17). Among the 17 cases with outcome data, spontaneous tumor regression occurred in eight (47.1%), and no change in tumor size and number was observed in the remaining nine cases (52.9%). There was no evidence of long-term cardiac dysfunction caused by persisting rhabdomyomas, regardless of tumor size. TSC was found in nine patients (52.9%), of whom five (55.6%) showed neurodevelopmental morbidity. We identified mutations in one of the TSC1 or TSC2 genes in four of nine TSC infants whose parents allowed us to perform molecular genetic analysis. Three of these (75.0%) were found to have neurologic impairment. Seven (77.8%) of nine TSC cases were non-familial.

CONCLUSIONS

The overall outcome of isolated cardiac rhabdomyoma appears to be favorable. We suggest that systematic postnatal evaluation of TSC be performed even in cases of cardiac rhabdomyoma without a family history of TSC. Molecular characterization of TSC1 and TSC2 might be helpful in predicting short- and long-term neurodevelopmental outcomes.

The ability of high field strength 7-T magnetic resonance imaging to reveal previously uncharacterized brain lesions in patients with tuberous sclerosis complex

OBJECT

Tuberous sclerosis complex (TSC) brain pathology is characterized on MRI by cortical tubers, subependymal nodules, and subependymal giant cell astrocytomas. Seizures, the prominent feature of TSC, are frequently intractable to medical therapy and, in many patients, resection of tubers results in seizure control. However, in approximately 40% of patients, resection of tubers does not control seizures. This fact, as well as evidence from invasive electrophysiological recordings and experimental animal models, suggests that in patients with TSC, there may be extratuberal epileptogenic brain that does not display any apparent abnormality on conventional MRI. The authors hypothesized that high field strength MRI might uncover lesions not seen on conventional MRI in these patients.

METHODS

Institutional review board approval was obtained to scan 4 patients with TSC (ages 18-26 years) in a 7-T MR unit. Optimized 7-T sequences, including T1- and T2-weighted, FLAIR, SPACE FLAIR, T2*, and MPRAGE studies, were performed. Imaging studies were compared with identical sequences performed using a conventional 1.5-T MR scanner.

RESULTS

In all 4 patients, there was improved visualization of the findings demonstrated on conventional imaging. Importantly, new lesions were detected in all 4 patients, which were not well visualized with conventional MRI. Newly detected lesions included microtubers, radial glial signal abnormalities, subependymal nodules arising from the caudate nucleus, and caudate nucleus lesions.

CONCLUSIONS

High field strength MRI detects previously uncharacterized lesions in patients with TSC and allows better detection and delineation of subtle abnormalities. In addition, the data demonstrate a compelling relationship between intraventricular lesions and the caudate nucleus. These data support previous electrophysiological and animal-model findings that demonstrate neurological pathology beyond the conventionally detected lesions in TSC.