Neuroimaging in tuberous sclerosis: a clinicoradiological evaluation in pediatric patients

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 The petitioners' experts often espoused outdated, erroneous causation theories that lacked an acceptable medical or scientific foundation and were frequently criticized by the court.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.

Clinical profile of tuberous sclerosis complex patients with and without epilepsy: a need for awareness for early diagnosis

BACKGROUND

Tuberous sclerosis complex (TSC) is a multisystemic disorder. Its clinical features manifest differently in several organs, prompting the need for better knowledge.

OBJECTIVE

The goal of the present study is to evaluate the neurological findings of TSC, such as cerebral lesions and epilepsy, and to raise awareness of non-neurological findings that could contribute to an earlier diagnosis and treatment.

METHODS

This was a natural history study of patients with a definitive diagnosis of TSC who were referred to a specialized outpatient clinic and followed-up for 2 years with clinical and radiological exams.

RESULTS

A total of 130 TSC patients (59 males [45.4%], mean age 20.4 years old [1 to 56 years old]); 107 patients (82.3%) were diagnosed with epilepsy. Seizures predominantly began at < 1 year old (72.8%); focal seizures predominated (86.9%); epileptic spasms occurred in 34.5% of patients, and refractory epilepsy was present in 55.1%. Neuropsychiatric disorders, cortical tubers and cerebellar tubers were significantly more frequent in the epilepsy group. Moreover, rhabdomyomas were significantly more frequent in the epilepsy group (p = 0.044), while lymphangioleiomyomatosis was significantly less frequent in the epilepsy group (p = 0.009). Other non-neurological findings did not differ significantly between the groups with and without epilepsy.

CONCLUSIONS

The present study of TSC patients demonstrated the predominantly neurological involvement and significantly higher proportion of TSC-associated neuropsychiatric disorders in the epilepsy group. Higher proportions of cortical and cerebellar tubers may be a risk factor for epilepsy and neurodevelopmental disorders.

Cerebellar Tubers in Tuberous Sclerosis Complex Patients: New Imaging Characteristics and the Relationship with Cerebral Tubers

Objective The imaging characteristics, evolution, and clinical features of cerebellar tubers in tuberous sclerosis complex (TSC) patients have not been well described. The purpose of this study is to investigate the imaging characteristics of cerebellar tubers, including their dynamic changes, and to evaluate the relationship with cerebral tubers in TSC patients.

Materials and Methods Two observers retrospectively reviewed 75 consecutive TSC patients to identify cerebellar tubers and to evaluate their imaging characteristics, including location, presence of retraction change, calcification, contrast enhancement, and the presence of an associated vascular anomaly, as well as dynamic changes in these characteristics. The number of cerebral tubers was compared between TSC patients with and without cerebellar tubers.

Results Twenty-five TSC patients with 28 cerebellar tubers were identified. All cerebellar tubers occurred within the lateral portions of the cerebellar hemispheres. Thirteen cerebellar tubers demonstrated calcification. Ten cerebellar tubers showed contrast enhancement, half of which demonstrated a zebra-like appearance. A vascular anomaly was associated with 12 tubers, one of which subsequently developed parenchymal hemorrhage. Fifteen cerebellar tubers demonstrated complex dynamic changes in size and contrast enhancement. Patients with cerebellar tubers had more cerebral tubers (p = 0.001).

Conclusion Cerebellar tubers demonstrate a specific distribution, suggesting a possible influence on higher brain function. The presence of an associated vascular anomaly may be an important imaging characteristic. Cerebellar tubers may be associated with a more severe manifestation of TSC, given their association with increased numbers of cerebral tubers. These findings may provide insights into the pathogenesis and clinical manifestations of cerebellar tubers in TSC patients.

The Cerebellar Involvement in Autism Spectrum Disorders: From the Social Brain to Mouse Models

Autism spectrum disorders (ASD) are pervasive neurodevelopmental disorders that include a variety of forms and clinical phenotypes. This heterogeneity complicates the clinical and experimental approaches to ASD etiology and pathophysiology. To date, a unifying theory of these diseases is still missing. Nevertheless, the intense work of researchers and clinicians in the last decades has identified some ASD hallmarks and the primary brain areas involved. Not surprisingly, the areas that are part of the so-called “social brain”, and those strictly connected to them, were found to be crucial, such as the prefrontal cortex, amygdala, hippocampus, limbic system, and dopaminergic pathways. With the recent acknowledgment of the cerebellar contribution to cognitive functions and the social brain, its involvement in ASD has become unmistakable, though its extent is still to be elucidated. In most cases, significant advances were made possible by recent technological developments in structural/functional assessment of the human brain and by using mouse models of ASD. Mouse models are an invaluable tool to get insights into the molecular and cellular counterparts of the disease, acting on the specific genetic background generating ASD-like phenotype. Given the multifaceted nature of ASD and related studies, it is often difficult to navigate the literature and limit the huge content to specific questions. This review fulfills the need for an organized, clear, and state-of-the-art perspective on cerebellar involvement in ASD, from its connections to the social brain areas (which are the primary sites of ASD impairments) to the use of monogenic mouse models.

Isolated cortical tuber in an infant with genetically confirmed tuberous sclerosis complex 1 presenting with symptomatic West syndrome

Tuberous sclerosis complex (TSC) is an autosomal dominant hereditary disorder caused by mutations in either TSC1 on chromosome 16 or TSC2 on chromosome 9, clinically characterized mainly by facial angiofibroma, epilepsy, and intellectual disability. Cortical dysplasias, subependymal nodules, and subependymal giant cell astrocytoma are characteristic central nervous system lesions among 11 major features in the current clinical diagnostic criteria for TSC. We encountered an unusual case of genetically confirmed TSC1 presenting with symptomatic West syndrome due to an isolated cortical dysplasia in the left occipital lobe of a six-month-old male infant who did not meet the clinical diagnostic criteria for TSC. The patient underwent left occipital lesionectomy at age 11 months and has been seizure-free for nearly six years since then. Histological examination of the resection specimen revealed cortical neuronal dyslamination with abundant dysmorphic neurons and ballooned cells, consistent with focal cortical dysplasia (FCD) type IIb. However, the lesion was also accompanied by unusual features, including marked calcifications, dense fibrillary gliosis containing abundant Rosenthal fibers, CD34-positive glial cells with abundant long processes confined to the dysplastic cortex, and multiple nodular lesions occupying the underlying white matter, consisting exclusively of ballooned cell and/or balloon-like astrocytes with focal calcifications. Genetic testing for TSC1 and TSC2 using the patient's peripheral blood revealed a germline heterozygous mutation in exon 7 (NM_000368.5: c.526dupT, p.Tyr176fs) in TSC1. Isolated FCD with unusual features such as calcification, dense fibrillary gliosis, Rosenthal fibers and/or subependymal nodule-like lesions in the white matter may indicate the possibility of a cortical tuber even without a clinical diagnosis of TSC. Identification of such histopathological findings has significant implications for early and accurate diagnosis and treatment of TSC, and is likely to serve as an important supplementary feature for the current clinical diagnostic criteria for TSC.

Intracranial calcifications in childhood: Part 1

This article is the first of a two-part series on intracranial calcification in childhood. Intracranial calcification can be either physiological or pathological. Physiological intracranial calcification is not an expected neuroimaging finding in the neonatal or infantile period but occurs, as children grow older, in the pineal gland, habenula, choroid plexus and occasionally the dura mater. Pathological intracranial calcification can be broadly divided into infectious, congenital, endocrine/metabolic, vascular and neoplastic. The main goals in Part 1 are to discuss the chief differences between physiological and pathological intracranial calcification, to discuss the histological characteristics of intracranial calcification and how intracranial calcification can be detected across neuroimaging modalities, to emphasize the importance of age at presentation and intracranial calcification location, and to propose a comprehensive neuroimaging approach toward the differential diagnosis of the causes of intracranial calcification. Finally, in Part 1 the authors discuss the most common causes of infectious intracranial calcification, especially in the neonatal period, and congenital causes of intracranial calcification. Various neuroimaging modalities have distinct utilities and sensitivities in the depiction of intracranial calcification. Age at presentation, intracranial calcification location, and associated neuroimaging findings are useful information to help narrow the differential diagnosis of intracranial calcification. Intracranial calcification can occur in isolation or in association with other neuroimaging features. Intracranial calcification in congenital infections has been associated with clastic changes, hydrocephalus, chorioretinitis, white matter abnormalities, skull changes and malformations of cortical development. Infections are common causes of intracranial calcification, especially neonatal TORCH (toxoplasmosis, other [syphilis, varicella-zoster, parvovirus B19], rubella, cytomegalovirus and herpes) infections.

Cerebellar lesions as potential predictors of neurobehavioural phenotype in tuberous sclerosis complex

AIM

To improve the genetic, clinical, and neuroradiological characterization of cerebellar involvement in tuberous sclerosis complex (TSC) and determine whether cerebellar lesions could be a reliable biomarker of neurological impairment.

METHOD

This retrospective cohort study, held at two tertiary paediatric university centres, was conducted on patients with a confirmed diagnosis of TSC who underwent brain magnetic resonance imaging between October 2009 and May 2016. The study population consisted of 112 patients with TSC (median age 10y; range 5mo-38y; 61 females, 51 males).

RESULTS

The results from multivariable statistical analysis indicated that cerebellar involvement (34 out of 112 patients, none carrying a TSC1 mutation) was the most powerful predictor of supratentorial cortical tuber load; however, cerebellar involvement was not the best predictor of clinical phenotype when supratentorial tuber load and TSC2 mutations were taken into consideration. The association between cerebellar lesions and a more severe clinical and neuroradiological phenotype was statistically significant and may be due to its strong association with TSC2 mutations and higher cortical tuber load.

INTERPRETATION

Cerebellar involvement is not the best predictor of neurobehavioural outcome, including TSC-related autism, after adjusting for TSC2 and the number of cortical tubers. Its role in the TSC clinical phenotype needs to be investigated further.

WHAT THIS PAPER ADDS

Cerebellar involvement is a powerful predictor of supratentorial cortical involvement and a potential biomarker of disease severity. Cerebellar lesions significantly correlate with a more severe clinical and neuroradiological phenotype. Cerebellar involvement is not the best predictor of neurobehavioural outcome.

The natural history of subependymal giant cell astrocytomas in tuberous sclerosis complex: a review

Tuberous sclerosis complex (TSC) is an auto-somal-dominant inherited condition with an incidence of approximately 1:6000 births, characterised by deregulated mTOR activity with multi-site hamartomas. Subependymal giant cell astrocytomas (SEGA) are one such hamartoma, affecting up to 24% of patients with TSC. Their intraventricular location may lead to life-threatening obstructive hydrocephalus. Current management is hampered by a lack of understanding regarding the natural history, behaviour and growth patterns of SEGA. We review the current literature to summarise what is known about SEGA in the following areas: (1) diagnostic criteria, (2) prevalence, (3) origin, (4) imaging characteristics, (5) growth rate, (6) genotype-phenotype correlation, (7) congenital SEGA and (8) SEGA as a marker of severity of other TSC manifestations.

Six different extremely calcified lesions of the brain: brain stones

BACKGROUND

This study aimed to extend clinical documentation of cerebral calculi by reporting six cases of cerebral calculi with distinct etiologies and localizations.

METHODS

We evaluated the age, sex distribution, presenting symptoms, neurological examination findings, pathology results, and location of the calcifications of six patients with intracranial calcifications.

RESULTS

Three of the six patients with brain stones were female (50%), and three were male (50%). The patient ages ranged from 12 to 46 years. A radiological examination of each patient's cranium was performed with pre-operative cranial computed tomography and magnetic resonance imaging. All of the lesions were completely excised. The patients' pathologies were determined to be distinct hyalinization, dystrophic calcification, hamartoma, ossification developing from widespread pituitary adenoma tissue, benign mesenchymal neoplasia, a mass consisting of sporadically ossified fibrous tissue, and angiomatous meningioma with distinct hyalinization and fibrosis.

CONCLUSIONS

Intracranial calcifications are a common phenomenon in neurosurgical practice. However, brain stones, as well as solid calcifications also termed cerebral calculi, are rarely encountered. Brain stones can be classified on the basis of their etiology and localization. Additionally, we suggest that lesions smaller than 1 cm might be classified as calcifications and those greater than 1 cm as brain stones. We further suggest that the differentiation between calcification and brain stones might be based on size. These pathologies typically manifest as seizures and are occasionally identified during routine brain tomography. Meningiomas constitute an important portion of extra-axial calcifications, whereas tumorous and vascular causes are more prevalent among intra-axial calcifications.

Diagnostica neuroradiologica delle facomatosi del sistema nervoso

La Neuroradiologia moderna ha profondamente modificato lo studio delle facomatosi del sistema nervoso. La radiologia convenzionale mantiene qualche indicazione nel bilancio delle lesioni displasiche ossee craniche e rachidee nella neurofibromatosi tipo 1.

La tomografia computerizzata è efficace per la ricerca dei neurofibromi dei plessi cervicale e lombosacrale, per la diagnosi della sclerosi tuberosa di Bourneville e dell'angiomatosi encefalo-trigeminale di Sturge-Weber (salvo nel caso d'angioma non calcifico).

La risonanza magnetica in TI dopo contrasto è il mezzo più efficace per il bilancio delle lesioni intra-durali della neurofibromatosi di tipo 1 e 2, per la ricerca dei tuberi degenerati della sclerosi tuberosa di Bourneville e per il bilancio della malattia di von Hippel Lindau. La mielografia non mantiene praticamente più indicazioni salvo per la conferma di certi meningoceli di difficile diagnosi, soprattutto nel quadro della neurofibromatosi di tipo 1 associate a delle importanti scoliosi. L'angiografia, diagnostica e terapeutica, è utile nel caso di emangioblastoma.

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.

MRI characteristics of cerebellar tubers and their longitudinal changes in children with tuberous sclerosis complex

PURPOSE

Cerebellar tubers have been recognized as a feature of tuberous sclerosis complex (TSC), but the evolution of cerebellar tubers with brain maturation remains unclear. The aim of this study was to assess the evolution of MRI characteristics of cerebellar tubers in children with TSC longitudinally.

METHODS

The MRI features of cerebellar tubers including number, location, shape, enhancement, presence of hemorrhage, calcifications, retraction, and the longitudinal changes of these features were assessed in children with TSC.

RESULTS

Cerebellar tubers were seen in 69/193 (35.8%) cases. Cerebellar tubers were wedge shaped, nodular, or demonstrated folia distortion; 33/101 (32.7%) cerebellar tubers showed enhancement, 29/101 (28.7%) showed calcification, and 75/101 (74.3%) had retraction abnormality. No lesion showed hemorrhage. One hundred fifty-two of our patients had more than one MRI examinations and were followed for a mean of 5.3 years from the time of their first MRI till their last study. Of those with follow-up MRI, 53 patients had cerebellar tubers; 15/53 (28.3%) patients and 20/101 (19.8%) of the cerebellar tubers demonstrated an increase in size, enhancement, or calcification longitudinally. The majority of the increase in size, enhancement, or calcification occurred in the first 8 years of life. None of the cerebellar tubers showed a reduction in size or enhancement. There was no new cerebellar tuber.

CONCLUSION

We have found an increase in size, enhancement, and calcification of cerebellar tubers which occurred mainly in the first 8 years of life. Further study that correlates the genetics and clinical manifestation with more advanced imaging of the cerebellar tubers may help us understand the underlying neurobiology of the changes in cerebellar tubers.

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.

Subependymal giant cell astrocytoma: current concepts, management, and future directions

BACKGROUND

Subependymal giant cell astrocytoma (SEGA) is the most common central nervous system tumor in patients with tuberous sclerosis complex (TSC). SEGAs are generally benign, non-infiltrative lesions, but they can lead to intracranial hypertension, obstructive hydrocephalus, focal neurologic deficits, and even sudden death.

DISCUSSION

Surgical resection has been the standard treatment for SEGAs, and it is generally curative with complete resection. However, not all SEGAs are amenable to safe and complete resection. Gamma Knife stereotactic radiosurgery provides another treatment option as a primary or adjuvant treatment for SEGAs, but it has highly variable response effects with sporadic cases demonstrating its efficacy. Recently, biologically targeted pharmacotherapy with mammalian target of rapamycin (mTOR) inhibitors such as sirolimus and everolimus has provided a safe and efficacious treatment option for patients with SEGAs. However, SEGAs can recur few months after drug discontinuation, indicating that mTOR inhibitors may need to be continued to avoid recurrence. Further studies are needed to evaluate the advantages and adverse effects of long-term treatment with mTOR inhibitors. This review presents an overview of the current knowledge and particularly highlights the surgical and medical options of SEGAs in patients 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.

MRI characterization and longitudinal study of focal cerebellar lesions in a young tuberous sclerosis cohort

BACKGROUND AND PURPOSE

There are few articles characterizing cerebellar lesions in patients with TSC and no published series documenting longitudinal evaluation of these lesions, to our knowledge. Recent suggestion of a correlation between autism and cerebellar lesions in patients with TSC heightens the importance of understanding these lesions. Our purpose was to characterize cerebellar lesions in a cohort of young patients with TSC with specific interest in assessing longitudinal changes.

MATERIALS AND METHODS

We retrospectively reviewed MR images from 145 pediatric and young adult patients with tuberous sclerosis (mean age, 7.6 years). A number of imaging characteristics of cerebellar tubers were recorded, and patients were evaluated for SGAs. Patients with follow-up scans >3 months from the original scan were further analyzed for longitudinal tuber characterization.

RESULTS

There were 24.1% of patients with focal cerebellar lesions; 52.4% of patients with cerebellar lesions demonstrated change in imaging characteristics during longitudinal analysis. Fifty-one percent of the lesions were enhanced after gadolinium administration. Twenty percent of the patients with cerebellar lesions had pathologically confirmed SGAs compared with the incidence of 11% in the 145 patients with TSC reviewed.

CONCLUSIONS

In our large cohort of young patients with TSC, cerebellar tubers were common and 52% of patients had tubers that changed with time. A higher percentage of patients with cerebellar lesions developed SGAs than patients with TSC without cerebellar lesions. Because this is the first reported longitudinal study of cerebellar lesions in TSC, further investigation may provide additional insight into TSC pathology and associated clinical manifestations, such as autism, developmental delay, and seizures.

[Imaging of lateral ventricle tumors]

Lateral ventricular neoplasms are rare, and account for 50% of all intraventricular tumors in adults and 25% in children. Although these neoplasms are easily detected with computed tomography (CT) and magnetic resonance imaging (MRI), both techniques are relatively unspecific in identifying the type of tumor. However, few imaging patterns are specific for a particular pathological process and useful conclusions can be made from the morphological appearance of the lesion, its location and enhancement pattern. The aim of this article was to review and illustrate the CT and MRI findings of a wide spectrum of tumors of the lateral ventricle. We reviewed choroid plexus tumors, meningioma, subependymal giant cell astrocytoma, central neurocytoma, and less frequent lesion such as lymphoma and metastases.

Progressive calcified tuber in a young male with tuberous sclerosis complex

Tubers are the most common brain lesions in tuberous sclerosis complex (TSC), and typically remain stable in size and appearance. We present the case of a young male with global developmental impairment and autistic features as well as multiple and mixed daily seizures. The patient had a prominent right frontal cortical tuber characterized by a calcified component, which changed on consecutive magnetic resonance imaging between the age of 4 and 11 years, at which time the patient underwent a lesionectomy. A poor long-term outcome is reported since the patient presents an intractable mixed seizure disorder status post-epilepsy surgery and no significant neuropsychological improvements. Histopathology findings show typical characteristics of tubers in TSC as well as numerous calcifications within the resected nodular lesion. This case supports the notion that tubers with calcified components are not necessarily static lesions and can change with time. Investigation of the relationship between the presence of calcification in tubers and epileptogenecity in a large group of patients would provide insights into the pathogenesis of the seizures and cognitive impairment and hopefully, eventually provide better treatment options for patients with TSC.

Management of subependymal giant cell tumors in tuberous sclerosis complex: the neurosurgeon's perspective

BACKGROUND

Tuberous sclerosis complex (TSC), an autosomal dominant genetic disorder, can lead to the development of hamartomas in various organs, including the heart, lungs, kidneys, skin and brain. The management of subependymal giant cell tumors (SGCTs) is still controversial, and peri- and/or intraventricular neoplasms may lead to life-threatening hydrocephalus. In the last years, many progresses have been made in research into the tumorigenesis and behaviors of SGCTs. This review aims to clarify the specific role of neurosurgeons in the multidisciplinary management of SGCTs in children with TSC.

DATA SOURCES

Based on the recent scientific literature and personal experience, we reviewed the up-to-date data and discussed the trends in the management of SGCTs in children with TSC. The data were collected after a bibliography made using PubMed/Medline with these terms: subependymal, subependymal giant cell astrocytoma, subependymal giant cell tumor, and tuberous sclerosis complex.

RESULTS

SGCTs are shown to be generated from a glioneuronal lineage, but their filiation with subependymal nodules (SENs) is still under debate. While SENs may develop anywhere in the ventricular walls, SGCTs arise almost exclusively around the Monro foramina. In children with TSC, precise clinical and/or imaging criteria are mandatory to differentiate SENs that are always asymptomatic and riskless from SGCTs that have the potential to grow and therefore to obstruct cerebrospinal fluid pathways leading to hydrocephalus.

CONCLUSIONS

An earlier diagnosis of SGCT in neurologically asymptomatic children with TSC may allow a precocious surgical removal of the tumor before the installation of increased intracranial pressure signs, an attitude that is being progressively adopted to lessen the morbimortality rate.

Cerebellar abnormality in children and young adults with tuberous sclerosis complex: MR and diffusion weighted imaging findings

OBJECTIVES

The goal of our study was to: determine the incidence of cerebellar lesions in a cohort of children and young adults with TSC, and analyze the magnetic resonance imaging (MRI) findings of cerebellar TSC lesions including their contrast behavior and diffusion characteristics.

MATERIAL AND METHODS

MRI studies of 27 TSC patients (mean age, 10.6 years) were evaluated for: cortical/subcortical tubers, white matter lesions, subependymal nodules, and giant cell astrocytomas. Patients with cerebellar involvement were further analyzed for the imaging and diffusion characteristics. ADC measurements of the cerebellar tubers were performed and compared with the contralateral normal appearing cerebellum. The clinical charts were revisited for symptoms suggesting cerebellar involvement.

RESULTS

Cerebellar tubers were seen in 8/27 patients, cerebellar atrophy in 1/27 patients. Cerebellar tubers showed a pyramidal/wedge appearance with a broad base reaching the cortex. The majority of the cerebellar tubers (11/12, 92%) showed a "zebra-like" contrast enhancement. All cerebellar tubers had increased ADC values (mean ADC 1472×10(-6) mm(2)/s). None of the patients had "typical" cerebellar symptoms.

CONCLUSION

Thirty-three percent of TSC patients had cerebellar lesions, most of them being cerebellar tubers. Cerebellar tubers differ from supratentorial tubers both concerning shape and contrast behavior. The exact etiology of contrast enhancement remains unclear. Future studies have to determine the impact of cerebellar lesions on neurocognitive development.

Prevalence of subependymal giant cell tumors in patients with tuberous sclerosis and a review of the literature

BACKGROUND AND PURPOSE

To investigate the prevalence of subependymal giant cell ependymomas (SEGA) in patients with tuberous sclerosis complex (TSC).

METHODS

We performed a retrospective cross-sectional study in a cohort of 285 patients with known TSC. Institutional review board approval was obtained. We included all 214 TSC-patients who had received a contrast-enhanced computed tomography (CT) scan of the brain. The most recent scan was evaluated for SEGA and presence of hydrocephalus. Additionally, a literature search was performed, and pooled estimates of SEGA prevalence in TSC were calculated. We used descriptive statistics, two sample t-test, chi-squared-test, and meta-analysis as appropriate.

RESULTS

Computed tomography showed radiological evidence of SEGA in 43 of the 214 TSC-patients (20%); 23 of 105 men (22%) and 20 of 109 women (18%; P = .52). Average maximum tumor size was 11.4 mm (range, 4-29 mm). Patients with SEGA (mean, 31 years; range, 16-58 years) were on average younger than patients without SEGA (mean, 37 years; range, 10-72 years; P = 0.007). No association between tumor size and patient age was detected. Nine patients had bilateral SEGA. Hydrocephalus was present in six of the 43 patients (14%). Meta-analysis of reported prevalence and our current study showed that studies using radiological evidence to diagnose SEGA gave a higher pooled estimate of the prevalence of SEGA in TSC (0.16; 95% CI: 0.12, 0.21) than studies using mainly histopathological evidence of SEGA (0.09; 95% CI: 0.07, 0.12).

CONCLUSIONS

In our cohort, CT demonstrated evidence of SEGA in 20% of TSC-patients. Prevalence of SEGA in TSC is higher in studies using radiological evidence to diagnose SEGA than in studies using histopathological evidence.

Pictorial review of tuberous sclerosis in various organs

Tuberous sclerosis is a rare autosomal dominant neurocutaneous syndrome characterized by the presence of benign congenital tumors in multiple organs. The diagnosis is usually established on the basis of diagnostic criteria applied to physical or radiologic findings. Because the classical triad of epilepsy, mental retardation, and adenoma sebaceum is uncommonly seen at clinical examination, radiologic examinations can play an important role in the diagnosis of tuberous sclerosis and in treatment. Cardiac rhabdomyoma, renal angiomyolipoma, and neurologic involvement encompassing cortical or subependymal tubers and white matter abnormalities are the common radiologic findings. Detection of these entities can be strong evidence for suspecting tuberous sclerosis. The presence of pulmonary lymphangioleiomyomatosis, multifocal micronodular pneumocyte hyperplasia, or multiple renal cysts also raises suspicion of tuberous sclerosis. Moreover, tuberous sclerosis can involve bone, liver, and the alimentary tract. The clinical course and patient prognosis depend on the sites of manifestations. Familiarity with the clinical and radiologic findings in various organs is crucial in diagnosis and treatment.

Biological markers of intellectual disability in tuberous sclerosis

BACKGROUND

Intellectual disability (ID) is highly prevalent in tuberous sclerosis (TS). Putative neurobiological risk factors include indices of cortical tuber (CT) load and epilepsy. We have used univariate and multivariate analyses, including both CT and epilepsy measures as predictors, in an attempt to clarify the pattern of cross-sectional associations between these variables and ID in TS.

METHOD

Forty-eight children, adolescents and young adults with TS were identified through regional specialist clinics. All subjects underwent thorough history taking and examination, and had brain magnetic resonance imaging (MRI) scans. The number and regional distribution of CTs was recorded. Subjects were assigned to one of nine ordered intellectual quotient (IQ) categories (range 130) using age-appropriate tests of intelligence.

RESULTS

On univariate analyses, ID was significantly associated with both a history of infantile spasm (IS) (Z=-2.49, p=0.01) and total CT count (Spearman's rho=-0.30, p=0.04). When controlling for total CT count, the presence of CTs in frontal (regression coefficient=-2.43, p=0.02) and temporal (regression coefficient=-1.60, p=0.02) lobes was significantly associated with ID. In multivariate analyses the association between IS and ID was rendered insignificant by the inclusion of the presence of CTs in temporal and frontal lobes, both of which remained associated (p=0.05 and p=0.06 respectively) with ID.

CONCLUSIONS

The presence of CTs in specific brain regions as opposed to a history of IS was associated with ID in TS. The significance of these findings is discussed in relation to previous work in TS, and the neural basis of intelligence.

Value of fetal cerebral MRI in sonographically proven cardiac rhabdomyoma

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant phakomatosis associated with intracardiac rhabdomyomas.

OBJECTIVE

The aim of our study was to examine the value of cerebral MRI in diagnosing TSC in fetuses with intracardiac rhabdomyomas, applying the TSC Consensus Conference (TSCCC) criteria.

MATERIALS AND METHODS

In a prospective manner six consecutive fetuses with cardiac rhabdomyomas (21-34 weeks' gestation) underwent cerebral MRI. The MRI results were correlated with clinical follow-up at 10-34 months after birth, histology, and genetic data.

RESULTS

In five of the six fetuses the diagnosis of TSC was established. In two of five fetuses MRI demonstrated cerebral manifestations of TSC that correlated well with severe epilepsy manifesting during the follow-up period. In another two of five fetuses MRI as well as clinical follow-up were normal. One of five pregnancies was terminated and histology demonstrated microscopically small subependymal nodules not demonstrated by MRI.

CONCLUSION

The results of our study agree with the available literature that fetal MRI is sufficient for the detection of cerebral lesions in TSC and should be better promoted. The TSCCC criteria can also be applied to fetal MRI.

Cerebellar lesions in tuberous sclerosis complex: neurobehavioral and neuroimaging correlates

We assessed the structural and functional imaging features of cerebellar lesions and their neurobehavioral correlates in a large cohort of patients with tuberous sclerosis complex. A consecutive series of 78 patients with tuberous sclerosis complex underwent magnetic resonance imaging (MRI) and positron emission tomography (PET) studies with [(18)F]fluorodeoxyglucose (FDG) and alpha-[(11)C]methyl-l-tryptophan (AMT) as part of their evaluation for epilepsy surgery. Neurobehavioral assessment included the Gilliam Autism Rating Scales (GARS) and the Vineland Adaptive Behavior Scales (VABS). Twenty-one patients (27%) had cerebellar lesions (10 boys; mean age 9 +/- 8 years; 9 had right-sided, 10 had left-sided, and 2 had bilateral cerebellar lesions). The lesions showed decreased glucose metabolism (0.79 +/- 0.10) and increased (1.04 +/- 0.10) AMT uptake compared with the normal (nonlesional) cerebellar cortex. Comparisons between patients with (n = 20) and without (n = 57) a cerebellar lesion on neurobehavioral functioning, controlling for the number and location of cortical tubers, revealed that the cerebellar lesion group had higher overall autistic symptomatology. Within-group analyses of the cerebellar lesion group revealed that children with right-sided cerebellar lesions had higher social isolation and communicative and developmental disturbance compared with children with left-sided cerebellar lesions. The side of the cerebellar lesion was not related to adaptive behavior functioning. These findings provide additional empiric support for a role of the cerebellum in autistic symptomatology. Further investigation of the potential role of the right cerebellum in autism, particularly with regard to the dentatothalamofrontal circuit, is warranted.

Tuberous sclerosis complex: correlation of magnetic resonance imaging (MRI) findings with comorbidities

We studied the magnetic resonance imaging (MRI) findings in a cohort of Chinese children with tuberous sclerosis complex to determine the relationship between age, sex, mental retardation, autism, epilepsy, infantile spasm, and early age at onset of seizures and the numbers and locations of tubers detected. We searched our tuberous sclerosis registry, established in 1985 (N = 44), and performed an analysis of children who had MRIs of the brain performed (n = 22). A neuroradiologist blinded to the clinical findings scored the MRIs according to the total number and site of the tubers. The following factors were analyzed: age, sex, presence of autism (n = 7), presence (n = 19) and severity of mental retardation (mild [n = 12], moderate to severe [n = 7]), presence of epilepsy (n = 21) or infantile spasm (n = 8), and age at onset of seizures less than 1 year (n = 10). There was no significant relationship between the number and site of tubers and the following factors: sex, autism, mental retardation, degree of mental retardation, epilepsy, history of infantile spasm, or age at onset of seizures less than 1 year. Only the presence of cortical tubers in the parietal regions had a significant relationship with the history of infantile spasm (P = .012). Using multiple regression analysis of all of the risk factors, only age is related to the number of tubers in the MRI (P = .047), and a history of infantile spasm is related to the presence of tubers in the parietal (P = .009) and occipital (P = .031) lobes. The associated comorbidities in tuberous sclerosis complex might be explained by more complex underlying genetic or pathologic issues rather than purely by the site of the cortical tubers. We suggest that a developmental approach, by analyzing the age at the appearance of tubers in both symptomatic and asymptomatic cases with the development of other neuropsychiatric comorbidities, should be undertaken to assess the causal relationship.

Prognostic significance of tuber count and location in tuberous sclerosis complex

The objectives of this study were (1) to test the utility of tuber count and tuber location as biomarkers of disease severity in patients with tuberous sclerosis complex and (2) to examine the relationship between gene mutation, tuber count, and tuber location. We found that an increased tuber count per lobe and in total was associated with an increased risk of infantile spasms (P < .01). Increased tuber count in the occipital lobe was associated with an increased risk of pervasive developmental disorder (P = .0074). The mean tuber count per lobe and in total was higher in those with poorly controlled seizures and those with off-track development; however, these differences were not statistically significant (P > .01). The TSC2 gene mutation was associated with a significant increase in the tuber count per lobe and in total (P < .01). In summary, increased tuber count is strongly associated with infantile spasms and a TSC2 gene mutation. Seizure control and developmental delay do not show the strong association with tuber count suggested by the earlier literature.

Imagerie cérébrale de la sclérose tubéreuse de bourneville chez l’enfant

Tuberous sclerosis (TS) is a frequent phakomatosis, with autosomal dominant transmission. The diagnosis relies on a list of criteria (2 major criteria or 1 major criterion and 2 minor criteria). Brain MRI is very important for diagnosis, already showing the major signs during fetal life: subependymal nodules, tubers and giant cell astrocytomas. In childhood, FLAIR sequences are the more interesting while in fetuses, neonates and infants T1 sequences are required because of the myelination process.

Behavioral and cognitive aspects of tuberous sclerosis complex

Tuberous sclerosis complex is a multisystem genetic disorder. Of all the possible manifestations of this complex disorder, the cognitive and behavioral problems represent the area of greatest concern to parents and caregivers. This review outlines the current evidence regarding global intellectual abilities, behavioral problems, psychiatric diagnoses, learning disorders, and specific neuropsychologic deficits for which individuals with tuberous sclerosis complex are at particularly increased risk, and outlines approaches to intervention. Approximately half of individuals diagnosed with tuberous sclerosis complex present with global intellectual impairment and developmental psychopathologies. Those with normal intellectual abilities are also at high risk of specific neuropsychologic deficits and behavioral, learning, and other psychiatric disorders. There is no evidence for an inevitable decline in cognition or behavior, and any such changes should be investigated. The evolving neurocognitive literature suggests that frontal brain systems might be most consistently disrupted by tuberous sclerosis complex-related neuropathology, thus leading to abnormalities in regulatory and goal-directed behaviors.

The relation of infantile spasms, tubers, and intelligence in tuberous sclerosis complex

BACKGROUND

The aetiology of the learning difficulty in tuberous sclerosis is debated. It may be related to the amount of tubers in the brain or caused by the infantile spasms that occur in early life.

AIMS

To examine the relative contributions to final intelligence (IQ) made by both cerebral tubers and infantile spasms.

METHODS

As part of an epidemiological study of tuberous sclerosis in the south of England, patients were recruited who were able to undergo magnetic resonance imaging (MRI) without the need for an anaesthetic. Epilepsy history was determined by interview and review of clinical records. IQ was assessed using either Wechsler intelligence scales or Raven's matrices.

RESULTS

A total of 41 patients consented to have an MRI scan. IQ scores were normally distributed about a mean of 91. Twenty six patients had a positive history of epilepsy, and 11 had suffered from infantile spasms. There was a significant relation between the number of tubers and IQ. Infantile spasm status partly confounded the relation between tubers and IQ, but did not render the relation statistically insignificant. The relation between infantile spasms and learning difficulty remained strong even when controlling for the number of tubers.

Neuropsychiatric problems in tuberous sclerosis complex

Tuberous sclerosis complex is an autosomal dominant disorder characterized by abnormal cellular differentiation and proliferation, as well as abnormal neuronal migration. It is a disease affecting multiple organ systems and typically has brain involvement, causing severe disabilities. This article reviews the literature of the commonly associated neuropsychiatric complications, including mental retardation, autism-like features, and other behavior problems, which are discussed in the context of the neuropathology and epilepsy observed in tuberous sclerosis complex. The potential pathogenesis of neuropsychiatric problems is explored, including links to the genetics, neuropathology, neurotrophins, and epilepsy factors associated with tuberous sclerosis complex. Treatment of neuropsychiatric symptoms, including autism-like features, attention deficits, and sleep disorders, is also discussed.

Subependymal giant cell astrocytoma in children with tuberous sclerosis

METHODS

Out of 105 patients with tuberous sclerosis (TS) admitted to the Hospital Nacional de Pediatría "Juan P. Garrahan" (Buenos Aires, Argentina), we surgically treated 17 children between January 1988 and December 2000. Two patients were operated on because of epilepsy and 15 patients because of an intraventricular tumor (subependymal giant cell astrocytoma [SGCA]). In this report we focus on tumors. Twelve of the 15 patients presented with hydrocephalus but none of them had a preoperative shunt. All tumors were surgically resected using frontal transventricular or transcallosal routes. Total removal was achieved in 12 out of 15 and subtotal removal in 3 out of 15 patients (resection of 70-95%).

RESULTS

Exeresis of the tumor was not accompanied by significant morbidity and there was no perioperative mortality. Seizures and mental retardation did not improve after tumor resection. It was necessary to insert a postoperative shunt a long time after surgery in only one patient. There were no recurrences of SGCA that were totally removed after a mean follow-up of 51.7 months.

CONCLUSIONS

We encourage surgery as soon as a lesion is diagnosed as a tumor. The "transformation" of subependymal nodules (SEN) into tumors (SGCA) may be considered controversial.

From the archives of the AFIP. Cerebral intraventricular neoplasms: radiologic-pathologic correlation

Intraventricular neoplasms are readily seen on cross-sectional images, but the myriad possibilities may make a focused differential diagnosis elusive. Consideration of the tissue within and composing the ventricular lining and the clinical findings provide the means to limit the differential diagnosis when analyzing an intraventricular mass on an imaging study. Ependymomas are typically calcified, are more common in children, are more common in the fourth ventricle, and show intense enhancement on contrast-enhanced images. Subependymomas and central neurocytomas have an affinity for the anterior portion of the lateral ventricle, and both commonly demonstrate a heterogeneous cystic appearance on cross-sectional images. Subependymomas are more common in older adults, whereas central neurocytomas are more common before 40 years of age. Subependymal giant cell astrocytomas always lie near the foramen of Monro and are characterized by frequent calcification, intense enhancement on contrast-enhanced studies, and the presence of other stigmata seen in tuberous sclerosis. When a mass is centered on the choroid plexus, a highly vascular tumor-either choroid plexus papilloma, choroid plexus carcinoma, meningioma, or metastasis-should be suspected. The characteristic heavily lobulated appearance of a choroid plexus tumor favors this diagnosis over other possibilities, although it is not always possible to distinguish between the more common benign form, the choroid plexus papilloma, and the less common malignant counterpart, the choroid plexus carcinoma. By using clinical, demographic, and imaging findings, one can significantly limit the differential diagnosis for many of the most common intraventricular neoplasms.

Cyst-like cerebral lesions in tuberous sclerosis

Known brain manifestations of tuberous sclerosis (TSC) are cortical sclerotic tubera, giant cell astrocytomas, subependymal calcified nodules in the lateral walls of the lateral ventricles, and white matter heterotopias. In addition, small cyst-like lesions in the white matter have been described. We report on three TSC patients with hitherto undescribed large cyst-like cerebral lesions in subcortical and white matter locations. We emphasize that cystoid brain degeneration is a rare but typical cerebral manifestation of TSC and suggest that, in patients with such lesions, TSC should be taken into consideration.

Tumours around the foramen of Monro: clinical and neuroimaging features and their differential diagnosis

The clinical and neuroimaging features of 20 patients with lateral ventricular tumours located around the foramen of Monro were reviewed retrospectively with special emphasis on the differential diagnoses. Histologic types were: eight neurocytomas, four subependymal giant cell astrocytomas (SGCAs), three subependymomas, two fibrillary astrocytomas, and one each of pilocytic astrocytoma, malignant astrocytoma and malignant teratoma. The mean age of the patients with neurocytoma was 29.6 years, with SGCA 13.3 years and with subependymoma 55.3 years. All tumours appeared nodular in shape, and on computed tomography (CT) neurocytomas were either isodense or highdense with the brain, while all subependymomas and SGCAs were lowdense. Calcification was observed in two SGCAs, and one neurocytoma. Five neurocytomas and all four SGCAs showed mild to moderate contrast enhancement, while all three subependymomas showed either no, or scarce, enhancement. Magnetic resonance imaging (MRI) studies were available in 10 patients, with the signal characteristics of four neurocytomas and three SGCAs being nonspecific, while two subependymomas were both hypointense on T1-weighted images and hyperintense on T2-weighted images. Thus important features for differential diagnosis included age of the patient and density on precontrast CT. In this series, either an extensive excision of the tumour or a partial removal, thus relieving the obstruction of the foramina of Monro, usually provided long term survival, with 18 patients surviving a mean of 10.8 years.

Disorders of cortical formation: radiologic-pathologic correlation

The advent of newer imaging techniques, such as high-resolution MR imaging and surface reconstructions of three-dimensional data sets, has led to a greater in vivo understanding of cortical malformations of the brain. Disorders of cortical formation are illustrated with routine imaging, surface reconstruction, and pathogenic specimens.

Biological behavior and tumorigenesis of subependymal giant cell astrocytomas

In spite of the benign nature of subependymal giant cell astrocytomas (SEGAs), some show massive hemorrhage, rapid growth, and tumor recurrence. This led us to investigate the biological behavior, cell dynamics, and tumorigenesis of SEGAs. All patients (4 men and 3 women; age range, 6-27 years; mean, 13.6 years) had features of tuberous sclerosis complex and obstructive hydrocephalus. One patient had intratumoral bleeding. In two patients, sequential neuroimaging showed a subependymal nodule growing to become a SEGA. All underwent surgical resection without radiation therapy. One tumor recurred and was treated surgically. There were no postoperative deaths. The presence of cytologic atypia, mitoses and vascular proliferation had no implication in terms of the clinical course. MIB-1 labeling indices were low (mean, 0.9), indicating low proliferative potential. Unexpectedly, bcl-2 staining was sparse and bax staining predominated in majority of cases. However, the mean value of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling index was low. Immunohistochemically, tumors were positive for both glial and neuronal markers. In the majority of our cases, the expression of p53 was low. Only one tumor was focally positive for tuberin. SEGAs have low proliferative potential and apoptotic activity, and exhibit features of mixed glial-neuronal differentiation. In contrast to p53, tuberin is suggested to be the tumor suppressor in this tumor.

Subependymal giant cell astrocytoma: clinical and neuroimaging features of four cases

The clinical history, neuroimaging features, treatments, and outcome of 4 patients with histologically verified subependymal giant cell astrocytomas (SEGA) were retrospectively reviewed. The average age at the time of surgery was 13.3 years. Headache related to raised intracranial pressure was the first and only sign in 2 patients, with the remaining 2 being admitted because of sequential neuroimaging studies over several years revealing the growth of 'subependymal nodules' into intraventricular tumours. In each case the tumour was in the region of Monro's foramen and was associated with ventricular dilatation. On computed tomography (CT), multiple subependymal nodules were found in 3 patients, and these well circumscribed isodense SEGAs were markedly enhanced by contrast medium. On magnetic resonance imaging (MRI), which was obtained in 3 patients, 2 SEGAs were isointense with the cerebral cortex and one with the white matter on T1-weighted images, and on T2-weighted images, 2 were isointense with the cortex and one with the white matter. At surgery the tumours appeared to originate from the inferolateral wall of the lateral ventricle in the region of the head of the caudate nuclei. Total macroscopic removal was achieved in 3 patients, and subtotal removal in one patient. Follow up ranged from 4.6 to 13.2 years, and all patients have exhibited similar physical and mental conditions to preoperative. So far there has been no evidence of any recurrences. The diagnosis and the surgical indications for SEGA are discussed, with periodic monitoring with neuroimaging studies being recommended even for asymptomatic patients with 'subependymal nodules'.

MRI spectrum of cortical malformations in tuberous sclerosis complex

The diagnostic and prognostic value of magnetic resonance imaging in the tuberous sclerosis complex has increasingly been recognized. In this paper, we review the presumed pathogenesis of the cerebral dysgenesis seen in this condition in the light of magnetic resonance imaging features of selected patients. In addition to typical findings related to tubers, we show and discuss varied cortical malformations (from simple localized cortical dysplasia to transmantle dysplasia and schizencephaly) similar to those seen in sporadic cerebral dysgenesis. These cases support the hypothesis that the tuberous sclerosis complex focally affects the radial glial-neuronal complex as a basic unit for brain development. Abnormal stem cells would create dysplastic glia and neurons that fail to differentiate, proliferate, migrate and form a normally organized cortex.

Tuberous sclerosis complex and epilepsy: prognostic significance of electroencephalography and magnetic resonance imaging

Tuberous sclerosis complex is a disease that affects many organs, including the central nervous system. Nervous system involvement in the form of hamartomas often results in seizures. In this study we wanted to determine the outcome of epilepsy in tuberous sclerosis complex and determine whether interictal electroencephalograms (EEGs) and hamartoma burden as seen with magnetic resonance imaging (MRI) are predictive of degree of seizure control. The study population consisted of 30 patients. For each patient two sets of EEG and MRI data, separated by at least 12 months, and information on seizure frequency at time of data collection were obtained. Sensitivity, specificity, and positive and negative predictive values of various EEG and MRI findings were determined. Seizure control improved in 20 and worsened in 10 patients. In relation to seizure control, the specificity of an abnormal sleep EEG and the positive predictive value of normal sleep EEG were 100%. MRI and EEG background were neither sensitive nor specific for predicting seizure control. A majority of children with tuberous sclerosis complex can achieve good seizure control. The sleep EEG is helpful in predicting eventual seizure control.

Neurological prognosis correlated with variations over time in the number of subependymal nodules in tuberous sclerosis

In tuberous sclerosis (TS), brain CT reveals subependymal nodules, cortical tubers and white matter lesions. This study is a retrospective analysis of the relationship between the variations over time in the number of subependymal nodules and the clinical course in cases of tuberous sclerosis. Twenty-four children with tuberous sclerosis, who attended the National Children's Hospital as outpatients, were followed by means of brain CT examinations for 7 years and 1 month on average. Cranial MRI was also performed in 22 cases. Brain CT disclosed subependymal nodules already in early infancy. In almost all cases, the number of subependymal nodules gradually increased with age, especially around the frontal horn of the lateral ventricle. The increase stopped at around age 10. The cases with five or more subependymal nodules at the initial or subsequent CT examination ( 17 patients; Group A) exhibited a significantly greater number of cortical tubers than those with less than five (five patients; Group B) and had white matter lesions unlike Group B. In addition, the number of cases with either infantile spasms or mental retardation was significantly higher in Group A than Group B (P < 0.005). In conclusion, the number of ventricular subependymal nodules may allow prediction of the severity of the cerebral dysfunction in TS. Our results suggest that its variation may reflect the degree of the embryologic disorder when neuronal cells grow in the early gestational period.

Autism in tuberous sclerosis: evoked potential evidence for a deficit in auditory sensory processing

OBJECTIVE

Autism is a frequent manifestation of tuberous sclerosis complex (TSC) being reported in up to 60% of the patients. Its presence is in association with cortical and subcortical lesions involving the temporal lobes. This study was designed to shed light on the functional mechanisms linking anatomical lesions of TSC and behavioural phenotype by investigating scalp recorded event related potentials to auditory stimuli.

METHODS

Fourteen children with TSC, seven of which fulfilled the DSM IV criteria for autistic disorder were selected for this study. All of the subjects underwent high resolution MRI, EEG, brainstem auditory evoked potentials, cognitive and behavioural evaluation. Electrical evoked responses to two different pitches, presented with different probability (80% 1000 Hz, 20% 1500 Hz) were recorded from 21 scalp electrodes in the autistic and non-autistic subgroups, to assess central auditory processing and automatic memory.

RESULTS

The first component of the long latency auditory response (N1) had a significantly prolonged latency with lower amplitude in all of the patients with autistic behaviour who, contrary to non-autistics had MRI lesions involving one or both temporal lobes. A mismatch negativity was detected in all subjects and had a longer latency in subjects with autistic behaviour.

CONCLUSIONS

To our knowledge this is the first electrophysiological evidence of a deficit in auditory information processing and automatic memory in TSC patients with autistic behaviour.

Subependymal giant-cell astrocytoma associated with tuberous sclerosis: case report

Tuberous sclerosis is a neurocutaneous syndrome with a wide variety of clinical, pathologic, and radiologic manifestations. Intracranial phakomatosis has been reported to include subependymal nodules; cortical tubers, and subependymal giant-cell astrocytomas. Subependymal giant-cell astrocytomas are rare, benign brain tumors of unknown histogenesis which cause increased intracranial pressure, seizures, and focal neurologic signs. The only treatment of these tumors is total surgical removal, because they are not sensitive to irradiation and chemotherapy. We report a patient with tuberous sclerosis who underwent surgery for a large subependymal giant-cell astrocytoma.