Autistic regression associated with seizure onset in an infant with tuberous sclerosis

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

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

The UK guidelines for management and surveillance of Tuberous Sclerosis Complex

BACKGROUND

The severity of Tuberous Sclerosis Complex (TSC) can vary among affected individuals. Complications of TSC can be life threatening, with significant impact on patients' quality of life. Management may vary dependent on treating physician, local and national policies, and funding. There are no current UK guidelines. We conducted a Delphi consensus process to reach agreed guidance for the management of patients with TSC in the UK.

METHODS

We performed a literature search and reviewed the 2012/13 international guideline for TSC management. Based on these, a Delphi questionnaire was formed. We invited 86 clinicians and medical researchers to complete an online survey in two rounds. All the people surveyed were based in the UK. Clinicians were identified through the regional TSC clinics, and researchers were identified through publications. In round one, 55 questions were asked. In round two, 18 questions were asked in order to obtain consensus on the outstanding points that had been contentious in round one. The data was analysed by a core committee and subcommittees, which consisted of UK experts in different aspects of TSC. The Tuberous Sclerosis Association was consulted.

RESULTS

About 51 TSC experts took part in this survey. Two rounds were required to achieve consensus. The responders were neurologists, nephrologists, psychiatrist, psychologists, oncologists, general paediatricians, dermatologist, urologists, radiologists, clinical geneticists, neurosurgeons, respiratory and neurodisability clinicians.

CONCLUSIONS

These new UK guidelines for the management and surveillance of TSC patients provide consensus guidance for delivery of best clinical care to individuals with TSC in the UK.

Regression in autism spectrum disorder: Reconciling findings from retrospective and prospective research

The way in which the behavioral manifestations of autism spectrum disorder (ASD) emerge in infancy is variable. Regression-loss of previously acquired skills-occurs in a subset of children. However, the etiology and significance of regression remains unclear. Until recently, investigation of regression relied on retrospective report by parents or examination of home videos from early in life. However, home videos and retrospective report of the nature and timing of regression, and association with factors such as illness or immunization, is potentially subject to bias. The advent of prospective studies of infant siblings at familial high-risk of ASD has the potential to document regression as it occurs. Recent research has suggested that subtle loss of skills occurs in a larger proportion of children with ASD than previously assumed; however, there are few reports of clear-cut regressions, such as that involving dramatic loss of language and other established skills, in the prospective literature. This could be because of the following: clear-cut regression occurs less commonly than parent report suggests, study design limits the potential to detect regression, or there are differences between multiplex and simplex families in the rate of de novo genetic mutations and therefore regression risk. This review will bring together literature from retrospective and prospective research and attempt to reconcile diverging findings, with a specific focus on methodological issues. Changing conceptualizations of regression will be discussed, as well as etiological factors that may be associated with regression. The main challenges that need to be addressed to measure regression in prospective studies will be set out. Autism Research 2018, 11: 1602-1620. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Regression-a loss of previously established skills-occurs in a subset of children with ASD. Parental recall is not always accurate but studying younger siblings of children with ASD, 10-20% of whom will develop ASD, should make it possible to measure regression as it occurs. Clear-cut regression, like loss of language, has not often been reported in infant sibling studies, but recent research suggests that gradual loss of social engagement might be more common. This review looks at the evidence for regression from infant sibling studies and asks how study design affects the likelihood of capturing regression.

Tuberous Sclerosis Complex: Clinical Spectrum and Epilepsy: A Retrospective Chart Review Study

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic neurocutaneous disorder, with heterogeneous manifestations. We aimed to review the clinical presentation of TSC and its association with epilepsy among Saudi population. This was a retrospective chart review study of 88 patients diagnosed with TSC with or without epilepsy. In 38.6% of patients, symptoms began before 1 year of age. The most frequent initial manifestations of TSC were new onset of seizures (68.2%), skin manifestations (46.6%) and development delay (23.9%). During the evolution of the disease 65.9% had epilepsy, 17% facial angiofibromas, 13.6% Shagreen patch, 18.2% heart rhabdomyomas and 12.5% retinal hamartomas. The genetic study for TSC diagnosis was done for 44 patients, 42 (95,4%) of them were genetically confirmed, for whom 13 patients had TSC1 mutation (29.5%), 29 patients were carrying TSC2 gene mutation (65.9%), Genetic test for TSC 1 and TSC 2 were negative for 2 patients (4.5%) despite positive gene mutation in their relative with TSC. The most common manifestations were central nervous system (predominantly epilepsy) and dermatological manifestations. Most of the patients develop epilepsy with multiple seizure types. TSC 2 mutation is more common than TSC 1 mutation.

A clinical update on tuberous sclerosis complex-associated neuropsychiatric disorders (TAND)

Tuberous sclerosis complex (TSC) is associated with a wide range of behavioral, psychiatric, intellectual, academic, neuropsychological, and psychosocial difficulties, which are often underdiagnosed and undertreated. Here, we present a clinical update on TSC-associated neuropsychiatric disorders, abbreviated as "TAND," to guide screening, diagnosis, and treatment in practice. The review is aimed at clinical geneticists, genetic counselors, pediatricians, and all generalists involved in the assessment and treatment of children, adolescents and adults with TSC, and related disorders. The review starts with a summary of the construct and levels of TAND, before presenting up-to-date information about each level of investigation. The review concludes with a synopsis of current and future TAND research.

Characterizing the Interplay Between Autism Spectrum Disorder and Comorbid Medical Conditions: An Integrative Review

Co-occurring medical disorders and associated physiological abnormalities in individuals with autism spectrum disorder (ASD) may provide insight into causal pathways or underlying biological mechanisms. Here, we review medical conditions that have been repeatedly highlighted as sharing the strongest associations with ASD-epilepsy, sleep, as well as gastrointestinal and immune functioning. We describe within each condition their prevalence, associations with behavior, and evidence for successful treatment. We additionally discuss research aiming to uncover potential aetiological mechanisms. We then consider the potential interaction between each group of conditions and ASD and, based on the available evidence, propose a model that integrates these medical comorbidities in relation to potential shared aetiological mechanisms. Future research should aim to systematically examine the interactions between these physiological systems, rather than considering these in isolation, using robust and sensitive biomarkers across an individual's development. A consideration of the overlap between medical conditions and ASD may aid in defining biological subtypes within ASD and in the development of specific targeted interventions.

Early developmental pathways to autism spectrum disorder in tuberous sclerosis complex

Purpose

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

Design/methodology/approach

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

Findings

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

Originality/value

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

Early onset epileptic encephalopathy or genetically determined encephalopathy with early onset epilepsy? Lessons learned from TSC

BACKGROUND

In tuberous sclerosis complex (TSC) a relationship has been shown between early and refractory seizures and intellectual disability. However, it is uncertain whether epilepsy in TSC is simply a marker in infants who are destined to develop an encephalopathic process or if seizures play a causal role in developing an encephalopathy.

METHODS

This paper summarizes the key points discussed during a European TSC workshop held in Rome, and reviews the experimental and clinical evidence in support of the two theories.

RESULTS/CONCLUSION

There are many factors that influence the appearance of both early seizure onset and the encephalopathy resulting in neurodevelopmental deficits. Experimental studies show that as a consequence of the TSC genes mutation, mammalian target of Rapamycin (mTOR) overactivation determines an alteration in cellular morphology with cytomegalic neurons, altered synaptogenesis and an imbalance between excitation/inhibition, thus providing a likely neuroanatomical substrate for the early appearance of refractory seizures and for the encephalopathic process. At the clinical level, early signs of altered developmental trajectories are often unrecognized before 12 months of age. Evidence from experimental research shows that encephalopathy in TSC might have a genetic cause, and mTOR activation caused by TSC gene mutation can be directly responsible for the early appearance of seizures and encephalopathy.

Autism Spectrum Disorder and Epilepsy: Two Sides of the Same Coin?

Autism spectrum disorders and epilepsy commonly co-occur. In this review, we consider some unresolved questions regarding the temporal relationship, causal mechanisms, and clinical stratification of this comorbidity, highlighting throughout the interplay between autism spectrum disorder, epilepsy, and intellectual disability. We present data on the clinical characterization of children with autism spectrum disorder and epilepsy, discussing distinctive phenotypes in children with this comorbidity. Although some distinctive clinical features emerge, this comorbidity also informs convergent pathways in genetic variants that cause synaptic dysfunction. We then move beyond diagnostic categorization and consider the extent to which electrophysiology as a quantitative biomarker may help guide efforts in clinical stratification and outcome prediction. Epilepsy, and atypical electrophysiological patterns, in autism spectrum disorder may inform the definition of biologically meaningful subgroups within the spectrum that, in turn, can shed light on potential targets for intervention.

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.

Early developmental trajectories associated with ASD in infants with tuberous sclerosis complex

OBJECTIVE

We performed a longitudinal cohort study of infants with tuberous sclerosis complex (TSC), with the overarching goal of defining early clinical, behavioral, and biological markers of autism spectrum disorder (ASD) in this high-risk population.

METHODS

Infants with TSC and typically developing controls were recruited as early as 3 months of age and followed longitudinally until 36 months of age. Data gathered at each time point included detailed seizure history, developmental testing using the Mullen Scales of Early Learning, and social-communication assessments using the Autism Observation Scale for Infants. At 18 to 36 months, a diagnostic evaluation for ASD was performed using the Autism Diagnostic Observation Schedule.

RESULTS

Infants with TSC demonstrated delays confined to nonverbal abilities, particularly in the visual domain, which then generalized to more global delays by age 9 months. Twenty-two of 40 infants with TSC were diagnosed with ASD. Both 12-month cognitive ability and developmental trajectories over the second and third years of life differentiated the groups. By 12 months of age, the ASD group demonstrated significantly greater cognitive delays and a significant decline in nonverbal IQ from 12 to 36 months.

CONCLUSIONS

This prospective study characterizes early developmental markers of ASD in infants with TSC. The early delay in visual reception and fine motor ability in the TSC group as a whole, coupled with the decline in nonverbal ability in infants diagnosed with ASD, suggests a domain-specific pathway to ASD that can inform more targeted interventions for these high-risk infants.

Intellectual development before and after the onset of infantile spasms: a controlled prospective longitudinal study in tuberous sclerosis

OBJECTIVE

Infantile spasms (IS) have long been suspected to be a risk factor for impairment in intellectual development, but there are no controlled, prospective longitudinal data in well-characterized conditions to confirm this suspicion. We tested the hypothesis in a longitudinal study of children with tuberous sclerosis (TS), who have a high risk of developing IS.

METHODS

Eleven infants with TS were recruited and studied longitudinally using the Mullen Scales of Early Learning. Seizure histories were assessed using a structured parent interview and by review of medical notes. Intellectual development was examined in relation to the onset and length of exposure to IS and other types of seizures.

RESULTS

Six children developed IS and five children developed other types of seizure disorders. Among those that developed IS, estimated mean IQ dropped significantly (nonparametric test for trend p = 0.002) from 92 (prior to onset of spasms) to 73 (after exposure to IS for a month or less) and 62 (after exposure to IS for more than a month). By contrast, there was no significant drop in estimated IQ among the five infants exposed to other types of seizure disorders (nonparametric test for trend p = 0.9). All six children exposed to infantile spasms developed clinically significant intellectual impairment.

SIGNIFICANCE

These data provide the first clear evidence of clinically significant, dose dependent, impairment in intellectual development following exposure to infantile spasms. The mechanisms underlying this developmental impairment and methods for preventing it require in depth study.

A review of traditional and novel treatments for seizures in autism spectrum disorder: findings from a systematic review and expert panel

Despite the fact that seizures are commonly associated with autism spectrum disorder (ASD), the effectiveness of treatments for seizures has not been well studied in individuals with ASD. This manuscript reviews both traditional and novel treatments for seizures associated with ASD. Studies were selected by systematically searching major electronic databases and by a panel of experts that treat ASD individuals. Only a few anti-epileptic drugs (AEDs) have undergone carefully controlled trials in ASD, but these trials examined outcomes other than seizures. Several lines of evidence point to valproate, lamotrigine, and levetiracetam as the most effective and tolerable AEDs for individuals with ASD. Limited evidence supports the use of traditional non-AED treatments, such as the ketogenic and modified Atkins diet, multiple subpial transections, immunomodulation, and neurofeedback treatments. Although specific treatments may be more appropriate for specific genetic and metabolic syndromes associated with ASD and seizures, there are few studies which have documented the effectiveness of treatments for seizures for specific syndromes. Limited evidence supports l-carnitine, multivitamins, and N-acetyl-l-cysteine in mitochondrial disease and dysfunction, folinic acid in cerebral folate abnormalities and early treatment with vigabatrin in tuberous sclerosis complex. Finally, there is limited evidence for a number of novel treatments, particularly magnesium with pyridoxine, omega-3 fatty acids, the gluten-free casein-free diet, and low-frequency repetitive transcranial magnetic simulation. Zinc and l-carnosine are potential novel treatments supported by basic research but not clinical studies. This review demonstrates the wide variety of treatments used to treat seizures in individuals with ASD as well as the striking lack of clinical trials performed to support the use of these treatments. Additional studies concerning these treatments for controlling seizures in individuals with ASD are warranted.

Epileptic spasms: experience with a high-dose oral corticosteroid protocol

AIM

To audit clinical practice and assess early outcomes for infants with epileptic spasms after an agreed initial treatment protocol was adopted.

METHODS

We reviewed all cases of epileptic spasms diagnosed between July 2007 and June 2009 and assessed adherence to protocol, remission by day 14, spasm recurrence and side effects. The protocol required that infants be treated with high-dose oral prednisolone except those with tuberous sclerosis complex (TSC) who were treated with vigabatrin.

RESULTS

Twenty-eight infants (age 3-14 months, 17 male) were newly diagnosed. Six (21%) had no cause identified (cryptogenic), six (21%) had TSC and 16 (57%) had other non-TSC symptomatic aetiologies. Twenty-three were treated per protocol and five were not. The proportion with remission by day 14 of treatment was 100% in the cryptogenic group (all treated per protocol), 64% in those with non-TSC symptomatic aetiologies treated per protocol, 20% in those with non-TSC symptomatic aetiologies treated not per protocol and 17% in infants with TSC (all treated per protocol). Of 17 infants who received prednisolone, two were admitted for management of febrile illness.

CONCLUSION

Our experience with high-dose oral prednisolone for treatment of epileptic spasms suggests that it is effective and tolerable. The greater proportion of non-TSC symptomatic patients with timely cessation of spasms when treated by this protocol supports the use of high-dose oral prednisolone as the treatment of choice. Given the poor response of children with TSC to treatment with vigabatrin, early use of steroid therapy deserves consideration.

Long-term developmental outcome in patients with West syndrome after epilepsy surgery

It has been hypothesized that early seizure control may prevent children with intractable epileptic spasms (ES) from developmental regression and may contribute to better developmental outcome. The effectiveness of surgery for ES has been reported. We investigated long-term post-operative outcomes of seizure control and development in patients with symptomatic West syndrome (S-WS) who underwent epilepsy surgery. Six children who underwent surgical intervention for intractable ES were retrospectively investigated. Cortical malformations were observed on pre-operative MRI in all patients, with hemispheric or multilobar involvement in four children and focal lesions in two. Following surgery, we measured motor function, developmental age (DA), language skills, and sociopsychological function for up to 7years (mean, 4.9years). Post-operative seizure outcome was Engel Class I (n=4) or III (n=2). Motor function and DA was increased following surgery in six and five patients, respectively. Two patients started to speak in sentences following focal resection. Autistic features were noted in four of the five examined patients post-operatively. None of the patients showed developmental regression following surgery. Epilepsy surgery for S-WS with ES may result in good seizure control and improvement in motor development. Improvement in cognitive function was modest in this small cohort of children and autistic features were noted post-operatively in a substantial proportion of the children. While seizure control can be obtained by epilepsy surgery, early intervention for sociopsychological comorbidities may be warranted in children with S-WS.

Antiepileptic treatment before the onset of seizures reduces epilepsy severity and risk of mental retardation in infants with tuberous sclerosis complex

BACKGROUND

Epilepsy appears in 70-80% of patients with tuberous sclerosis complex, most commonly in the first year of age. Early manifestation of epilepsy is associated with drug-resistant epilepsy and mental retardation in more than 80% of patients. Clinical epileptic seizures are preceded by deterioration of EEG recording thus infants with high risk of epilepsy can be identified.

AIMS

We hypothesized that preventative antiepileptic treatment of infants with multifocal activity on EEG might lower the incidence of drug-resistant epilepsy and mental retardation.

METHODS

Forty-five infants with early diagnosis of tuberous sclerosis complex were included in the open-label study. They were divided in two groups: standard (n=31) and preventative one (n=14). In standard group the antiepileptic treatment was launched early, but after the onset of seizures. In preventative group medication was commenced when active epileptic discharges were seen on EEG, but before the onset of clinical seizures. Children were followed till the end of 2 years of age.

RESULTS

At 24 months of age mental retardation was significantly more frequent and severe in "standard" vs "preventative" group (48% vs 14%; p=0.031; mean IQ score 68.7 vs 92.3; p<0.05). The "preventative" group was characterized by higher ratio of seizure-free patients (93% vs 35%; p=0.004), lower incidence of drug-resistant epilepsy (7% vs 42%; p=0.021) and lower number of patients requiring polytherapy (21% vs 55%; 0.039) than the "standard group.

CONCLUSIONS

Preventative antiepileptic treatment of infants with tuberous sclerosis complex and high risk of epilepsy markedly improves their neurodevelopmental outcome and reduces the incidence of drug-resistant seizures.

Cerebral tuber count and its impact on mental outcome of patients with tuberous sclerosis complex

PURPOSE

The aim of the study was to reveal the relationships between the tuber count of the brain found in patients with tuberous sclerosis complex (TSC) and their cognitive outcome.

METHODS

A single-center, retrospective analysis was performed of patients with documented TSC seen from 1988 to 2010 at the Children's Memorial Health Institute, Warsaw, Poland.

KEY FINDINGS

Sixty-two patients were analyzed, and there was a significant correlation between younger age at the first seizure and developmental delay. The patients who did not develop seizures had normal development, despite some presenting with higher tuber load than those with seizures. There was a statistically significant negative correlation between the number of tubers within the right temporal lobe and cognition.

SIGNIFICANCE

Our findings confirm our hypothesis that the cognitive outcome in TSC is more dependent on the age of the seizure onset rather than on the tuber count.

The effect of seizure disorder on symptom presentation in atypically developing children and children with autism spectrum disorders based on the BDI-2

PURPOSE

Autism Spectrum Disorders (ASD) and seizures are highly comorbid conditions. However, little research has been done to examine this relationship. The purpose of the current study was to examine the effect that seizure disorder has on symptom presentation in children with autism spectrum disorders as compared to atypically developing children.

METHOD

The Battelle Developmental Inventory, Second Edition (BDI-2) was used as a measure of impairment across adaptive, personal-social, communication, motor and cognitive skills.

RESULTS

A MANOVA indicated significant main effects between diagnostic group and seizure status, without a significant interaction. Follow-up univariate tests were conducted.

CONCLUSIONS

Overall, results indicated that children with ASD were more impaired than atypically developing children. In addition, children with seizures tended to be more impaired than children without seizures.

Early-onset acquired epileptic aphasia (Landau-Kleffner syndrome, LKS) and regressive autistic disorders with epileptic EEG abnormalities: the continuing debate

Early-onset acquired epileptic aphasia (Landau-Kleffner syndrome) may present as a developmental language disturbance and the affected child may also exhibit autistic features. Landau-Kleffner is now seen as the rare and severe end of a spectrum of cognitive-behavioural symptoms that can be seen in idiopathic (genetic) focal epilepsies of childhood, the benign end being the more frequent typical rolandic epilepsy. Several recent studies show that many children with rolandic epilepsy have minor developmental cognitive and behavioural problems and that some undergo a deterioration (usually temporary) in these domains, the so-called "atypical" forms of the syndrome. The severity and type of deterioration correlate with the site and spread of the epileptic spikes recorded on the electroencephalogram within the perisylvian region, and continuous spike-waves during sleep (CSWS) frequently occur during this period of the epileptic disorder. Some of these children have more severe preexisting communicative and language developmental disorders. If early stagnation or regression occurs in these domains, it presumably reflects epileptic activity in networks outside the perisylvian area, i.e. those involved in social cognition and emotions. Longitudinal studies will be necessary to find out if and how much the bioelectrical abnormalities play a causal role in these subgroup of children with both various degrees of language and autistic regression and features of idiopathic focal epilepsy. One has to remember that it took nearly 40 years to fully acknowledge the epileptic origin of aphasia in Landau-Kleffner syndrome and the milder acquired cognitive problems in rolandic epilepsies.

Autism spectrum disorders in tuberous sclerosis: pathogenetic pathways and implications for treatment

Autism spectrum disorders have been reported as being much more frequent in individuals with tuberous sclerosis than in the general population. Previous studies have implicated early seizure onset and the localization of cortical tubers in the temporal lobes as risk factors for autism. However, the underlying reasons for this association remain largely unclear. The dysregulation of intracellular signaling through the activation of mTOR pathway could play a direct role in determining susceptibility to autism. Early control of seizures and an early intensive behavioral intervention of autism during the period of brain plasticity can mitigate, but not reverse the final outcome. A greater understanding of the pathogenetic mechanisms underlying autism in tuberous sclerosis could help in devising targeted and potentially more effective treatment strategies.

Autism spectrum disorders in genetic syndromes: implications for diagnosis, intervention and understanding the wider autism spectrum disorder population

BACKGROUND

An emerging literature on behavioural phenotypes has highlighted apparent associations between autism spectrum disorders (ASDs) or ASD-related phenomenology and a number of different genetically determined syndromes.

METHOD

A systematic review of the current literature regarding the association with ASD and ASD characteristics was conducted in the following syndrome groups: Fragile X, Rett, Tuberous Sclerosis Complex, Down, Angelman, CHARGE and Phenylketonuria. Specific consideration was given to the role of intellectual disability in assessing the association between ASD and these syndrome groups.

RESULTS

The review highlights that while formal diagnostic assessments may indicate an association between ASD and specific syndrome groups, detailed investigation has revealed subtle but qualitative differences in the presentation of ASD-like phenomenology in particular syndrome groups. The degree of ID of the individual clearly has a role to play with regard to the development and presentation of ASD-like characteristics, and caution should be taken when assessing ASD symptomatology in genetically determined syndromes associated with severe ID. However, degree of ID cannot solely account for the heightened prevalence of ASD characteristics in some specific syndrome groups.

CONCLUSIONS

There is a need for caution in interpreting the significance of superficial similarities between ASD and the behavioural phenotypes of certain genetically determined syndromes. However, recognition of ASD-like characteristics (even where a true diagnosis of ASD may not be relevant) in individuals with genetic syndromes is crucial in ensuring that individuals receive appropriate behavioural management and educational placement. Further research in this field requires fine-grained investigation of behavioural phenomenology within individual syndrome groups.

Medical conditions in autism spectrum disorders

Autism spectrum disorder (ASD) is a behaviourally defined syndrome where the etiology and pathophysiology is only partially understood. In a small proportion of children with the condition, a specific medical disorder is identified, but the causal significance in many instances is unclear. Currently, the medical conditions that are best established as probable causes of ASD include Fragile X syndrome, Tuberous Sclerosis and abnormalities of chromosome 15 involving the 15q11-13 region. Various other single gene mutations, genetic syndromes, chromosomal abnormalities and rare de novo copy number variants have been reported as being possibly implicated in etiology, as have several ante and post natal exposures and complications. However, in most instances the evidence base for an association with ASD is very limited and largely derives from case reports or findings from small, highly selected and uncontrolled case series. Not only therefore, is there uncertainty over whether the condition is associated, but the potential basis for the association is very poorly understood. In some cases the medical condition may be a consequence of autism or simply represent an associated feature deriving from an underlying shared etiology. Nevertheless, it is clear that in a growing proportion of individuals potentially causal medical conditions are being identified and clarification of their role in etio-pathogenesis is necessary. Indeed, investigations into the causal mechanisms underlying the association between conditions such as tuberous sclerosis, Fragile X and chromosome 15 abnormalities are beginning to cast light on the molecular and neurobiological pathways involved in the pathophysiology of ASD. It is evident therefore, that much can be learnt from the study of probably causal medical disorders as they represent simpler and more tractable model systems in which to investigate causal mechanisms. Recent advances in genetics, molecular and systems biology and neuroscience now mean that there are unparalleled opportunities to test causal hypotheses and gain fundamental insights into the nature of autism and its development.

Recent advances in neurobiology of Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC) is a multisystem genetic disorder with variable phenotypic expression, due to a mutation in one of the two genes, TSC1 and TSC2, and a subsequent hyperactivation of the downstream mTOR pathway, resulting in increased cell growth and proliferation. The central nervous system is consistently involved in TSC, with 90% of individuals affected showing structural abnormalities, and almost all having some degree of CNS clinical manifestations, including seizures, cognitive impairment and behavioural problems. TSC is proving to be a particularly informative model for studying contemporary issues in developmental neurosciences. Recent advances in the neurobiology of TSC from molecular biology, molecular genetics, and animal model studies provide a better understanding of the pathogenesis of TSC-related neurological symptoms. Rapamycin normalizes the dysregulated mTOR pathway, and recent clinical trials have demonstrated its efficacy in various TSC manifestations, suggesting the possibility that rapamycin may have benefit in the treatment of TSC brain disease.

Epilepsy surgery in tuberous sclerosis complex: early predictive elements and outcome

AIM

The aim of the study was to evaluate the surgical treatment of epilepsy and detection of possible early surgery predictive elements in patients with tuberous sclerosis complex (TSC).

MATERIALS AND METHODS

Forty-two TSC patients with epilepsy were selected and divided into two main groups: definite and fruste forms. Definite forms were divided into different groups: patients with pharmacologically controlled epilepsy, patients with pharmacoresistant epilepsy excluded from surgery after an extensive presurgical assessment, and patients with a pharmacoresistant epilepsy who underwent surgery. We compared the definite TSC groups to identify elements that predict surgical candidacy. Second, we compared all operated patients to assess surgical outcome.

CONCLUSION

We found several factors that could predict a surgical intervention even if identification of patients with refractory epilepsy who can benefit from surgery is an evolving process. Also, several positive factors for good surgical outcome were identified. Patients with the fruste form had excellent surgical outcome.

Tuberous sclerosis

Tuberous sclerosis is a genetic multisystem disorder characterised by widespread hamartomas in several organs, including the brain, heart, skin, eyes, kidney, lung, and liver. The affected genes are TSC1 and TSC2, encoding hamartin and tuberin respectively. The hamartin-tuberin complex inhibits the mammalian-target-of-rapamycin pathway, which controls cell growth and proliferation. Variations in the distribution, number, size, and location of lesions cause the clinical syndrome to vary, even between relatives. Most features of tuberous sclerosis become evident only in childhood after 3 years of age, limiting their usefulness for early diagnosis. Identification of patients at risk for severe manifestations is crucial. Increasing understanding of the molecular abnormalities caused by tuberous sclerosis may enable improved management of this disease.

What is new in autism?

PURPOSE OF REVIEW

Autism is now recognized in one out of 150 children. This review highlights the topics within the growing autism literature that are shaping current thinking on autism and advancing research and clinical understanding of autism spectrum disorders.

RECENT FINDINGS

The role of single-stranded microdeletions and epigenetic influences on brain development has dramatically altered our understanding of the etiology of the autisms. Recent research has focused on the role of synapse structure and function as central to the development of autism and suggests possible targets of interventions. Brain underconnectivity has been a focus in recent imaging studies and has become a central theme in conceptualizing autism. Despite increased awareness of autism there is no 'epidemic' and no one cause for autism. Data from the sibling studies are identifying early markers of autism and defining the broader autism phenotype.

SUMMARY

Larger datasets in genetics, a focus on the early signs of autism, and increased recognition of the importance of defining subgroups of children with autism are leading to a greater understanding of the etiologies of autism. A growing interest in defining the molecular biology of social cognition, which is at the core of autism, will lead to expansion of our presently limited choices of mechanistically based interventions.

Characterization of autism in young children with tuberous sclerosis complex

Both cognitive impairment and autism are common in the tuberous sclerosis complex, but the relationship between the 2 diagnoses has not been formally explored. The authors evaluated 20 clinic-referred children with tuberous sclerosis complex at ages 18, 24, 36, and 60 months and classified them as autism, autism spectrum disorder, or normal on the basis of the Autism Diagnostic Observation Schedule. Using the Mullen Scale of Early Learning, cognitive function in each subgroup was assessed. The authors then analyzed the subscores of the Autism Diagnostic Observation Schedule in children with autism. Children with autism showed significantly more global cognitive impairment than those without autism. In addition, all children had some baseline cognitive impairment and the majority had deficits in play scores. The authors conclude that clinic-referred children with tuberous sclerosis complex and autism are at considerable risk for cognitive impairment. These characteristics may help to guide more tailored services for these high-risk children.

Childhood autism and associated comorbidities

Autism is a heterogeneous neurodevelopmental disorder with a variety of different etiologies, but with a heritability estimate of more than 90%. Although the strong correlation between autism and genetic factors has been long established, the exact genetic background of autism is still unclear. This review refers to all the genetic syndromes that have been described in children with pervasive developmental disorders (tuberous sclerosis, fragile X, Down, neurofibromatosis, Angelman, Prader-Willi, Gilles de la Tourette, Williams, etc.). Issues covered include prevalence and main characteristics of each syndrome, as well as the possible base of its association with autism in terms of contribution to the current knowledge on the etiology and genetic base of pervasive developmental disorders.