Diagnosis and management of tuberous sclerosis complex

Symptomatic improvement using everolimus in infants with cardiac rhabdomyoma

Background:

Cardiac rhabdomyoma (CR) often shows spontaneous regression and needs close follow-up. These tumors may be associated with tuberous sclerosis complex (TSC), caused by the disinhibition of m-TOR protein.

Objective:

The aim of the study is to observe the efficacy of everolimus in infants with significant CR.

Materials and Methods:

This is a single-center prospective observational study including infants with significant CR causing either clinical symptoms or obstruction to the blood flow. Everolimus was administered at a dose of 4.5 mg/M2/wk till the symptomatic improvement. Liver and renal function tests were monitored during treatment.

Results:

There were six cases of suspected CR included in the study. Median age and weight of patients were 5 days (range: 1–90 days) and 3.2 kg (range: 2.2–4.5 kg), respectively. One patient was excluded after surgical excision biopsy during concomitant closure of associated large perimembranous ventricular septal defect confirmed it as a fibroma. The remaining all five cases showed regression of tumor during mean follow-up of 6.1 ± 5.1 months. One child developed varicella infection necessitating temporary discontinuation of medicine during follow-up. One case had sudden death at 4 months of age.

Conclusion:

Everolimus appears to be useful in selected cases of symptomatic CR. Multicentric studies are needed to determine its safety and efficacy in larger population.

Pulsed arterial spin-labeled MR imaging evaluation of tuberous sclerosis

BACKGROUND AND PURPOSE

Tuberous sclerosis presents with characteristic cortical hamartomas and subependymal nodules associated with seizures. The purpose of this study was to use pulsed arterial spin-labeling (PASL) to quantify the perfusion of the cortical hamartomas and correlate the perfusion values with seizure frequency.

MATERIALS AND METHODS

A retrospective search yielded 16 MR imaging examinations including conventional MR imaging and PASL perfusion performed in 13 patients (age range, 7 months to 23 years) with a history of tuberous sclerosis. The mean perfusion of each cortical hamartoma greater than 5 mm in size localized with conventional MR imaging sequences was obtained with use of manually drawn regions of interest. Cortical hamartomas were classified as normal, hyperperfused, or hypoperfused on the basis of the mean and SD of the unaffected cortex. Correlation was made between perfusion imaging, conventional imaging, and clinical history.

RESULTS

Of the 245 cortical hamartomas, 227 (92.7%) were hypoperfused, 10 (4.1%) were hyperperfused, and 8 (3.3%) were unchanged relative to the mean gray matter. One patient had a subependymal giant cell astrocytoma with a mean perfusion of 93.5 mL/100 g tissue/min. There was a statistically significant positive correlation between seizure frequency and the number of hyperperfused cortical tubers (r = 0.51; n = 16; P = .04), with higher seizure frequency associated with a greater number of hyperperfused cortical tubers. There was no significant correlation, however, between seizure frequency and the overall number of cortical tubers (r = 0.20; n = 16; P = .47).

CONCLUSIONS

The PASL technique can assess and quantify the perfusion characteristics of a cortical hamartoma. Most lesions are hypoperfused; however, both normally perfused and hyperperfused lesions occur. The presence of hyperperfused cortical tubers was associated with increased seizure frequency.

Recombination as a mechanism for sporadic mutation in the surfactant protein-C gene

OBJECTIVE

To determine haplotype background of common mutations in the genes encoding surfactant proteins B and C (SFTPB and SFTPC) and to assess recombination in SFTPC.

STUDY DESIGN

Using comprehensive resequencing of SFTPC and SFTPB, we assessed linkage disequilibrium (LD) (D'), and computationally inferred haplotypes. We computed average recombination rates and Bayes factors (BFs) within SFTPC in a population cohort and near SFTPC (+/-50 kb) in HapMap cohorts. We then biochemically confirmed haplotypes in families with sporadic SFTPC mutations (n = 11) and in individuals with the common SFTPB mutation (121ins2, n = 30).

RESULTS

We detected strong evidence (weak LD and BFs > 1,400) for an intragenic recombination hot spot in both genes. The 121ins2 SFTPB mutation occurred predominantly (89%) on 2 common haplotypes. In contrast, no consistent haplotypes were associated with mutated SFTPC alleles. Sporadic SFTPC mutations arose on the paternal allele in four of five families; the remaining child had evidence for somatic recombination on the mutated allele.

CONCLUSIONS

In contrast to SFTPB, disease alleles at SFTPC do not share a common haplotype background. Most sporadic mutations in SFTPC occurred on the paternal allele, but somatic recombination may be an important mechanism of mutation in SFTPC.

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.

Bilateral temporal arachnoid cysts associated with tuberous sclerosis complex

The association between tuberous sclerosis complex and intracranial abnormalities such as hemimegalencephaly, schizencephaly, intracranial arterial aneurysms, and corpus callosum agenesis/dysplasia has been reported in the recent literature. However, the association between tuberous sclerosis complex and bilateral temporal arachnoid cysts has not been reported. A case of an 8-year-old boy with a mental impairment and epileptic seizures that began 5 years earlier is presented. The neuro-radiological findings are consistent with tuberous sclerosis complex associated with bitemporal arachnoid cysts. His epileptic seizures were treated with antiepileptic medications. To the authors' knowledge, this is the first reported case of tuberous sclerosis complex associated with bilateral arachnoid cysts of the temporal region. In such cases, arachnoid cysts may exacerbate the clinical picture.

Epidemiology of hemimegalencephaly: a case series and review

Hemimegalencephaly (HME) is a congenital brain malformation characterized by unilateral enlargement of the cerebral hemisphere. Clinically, HME is typically associated with hemiparesis, psychomotor retardation, and intractable seizures usually apparent soon after birth. HME is often an isolated finding, but it has been described as an occasional feature of a large number of syndromes, many of which may not be readily identified at birth. There are a multitude of case series and reports of HME in the English literature; however, there is no comprehensive, unbiased, detailed survey characterizing the proportion of cases of HME that are associated with a syndrome. We performed a retrospective study of all cases of HME seen at our institution from 1990 to 2003. Of the 15 cases of HME identified, 53% (8/15) were non-syndromic and 47% (7/15) of the cases were associated with a known or suspected genetic syndrome. In patients with syndromic HME, many of the syndromic features were not readily discernible at birth or in early infancy. It is, therefore, imperative to continually evaluate any infant with HME for signs and symptoms of these and other syndromes. Knowing the relative differential diagnosis will lead to a more comprehensive evaluation, improvement in expectant management, and appropriate counseling of families before considering radical surgical options such as hemispherectomy.

Comparative analysis of MR sequences to detect structural brain lesions in tuberous sclerosis

BACKGROUND

Tuberous sclerosis (TS) is a neurocutaneous genetically inherited disease with variable penetrance characterized by dysplasias and hamartomas affecting multiple organs. MR is the imaging method of choice to demonstrate structural brain lesions in TS.

OBJECTIVE

To compare MR sequences and determine which is most useful for the demonstration of each type of brain lesion in TS patients.

MATERIALS AND METHODS

We reviewed MR scans of 18 TS patients for the presence of cortical tubers, white matter lesions (radial bands), subependymal nodules, and subependymal giant cell astrocytoma (SGCA) on the following sequences: (1) T1-weighted spin-echo (T1 SE) images before and after gadolinium (Gd) injection; (2) nonenhanced T1 SE sequence with an additional magnetization transfer contrast medium pulse on resonance (T1 SE/MTC); and (3) fluid-attenuated inversion recovery (FLAIR) sequence.

RESULTS

Cortical tubers were found in significantly (P<0.05) larger numbers and more conspicuously in FLAIR and T1 SE/MTC sequences. The T1 SE/MTC sequence was far superior to other methods in detecting white matter lesions (P<0.01). There was no significant difference between the T1 SE/MTC and T1 SE (before and after Gd injection) sequences in the detection of subependymal nodules; FLAIR sequence showed less sensitivity than the others in identifying the nodules. T1 SE sequences after Gd injection demonstrated better the limits of the SGCA.

CONCLUSION

We demonstrated the importance of appropriate MRI sequences for diagnosis of the most frequent brain lesions in TS. Our study reinforces the fact that each sequence has a particular application according to the type of TS lesion. Gd injection might be useful in detecting SGCA; however, the parameters of size and location are also important for a presumptive diagnosis of these tumors.

Levetiracetam as adjunctive antiepileptic therapy for patients with tuberous sclerosis complex: a retrospective open-label trial

Seizures are a common neurologic symptom of tuberous sclerosis complex. The use of levetiracetam as adjunctive antiepileptic therapy was assessed in 20 patients with tuberous sclerosis complex aged 2 to 19 years. In this retrospective evaluation, 40% of patients treated with levetiracetam achieved a seizure reduction of more than 50%. Levetiracetam was generally well tolerated, and adverse events were relatively uncommon in patients who responded to treatment. The most commonly reported adverse events were behavioral problems. Unstable gait, insomnia, poor appetite, and increased seizure frequency were also reported. Based on these results, the use of levetiracetam as adjunctive antiepileptic therapy can reduce seizure frequency in patients with tuberous sclerosis complex. (J Child Neurol 2006;21:53-57).

The phakomatoses

The "phakomatosis" concept was formulated early in the twentieth century by the ophthalmologist van der Hoeve. He included 3 disorders in the group-neurofibromatosis, tuberous sclerosis complex, and von Hippel-Lindau syndrome--on the basis of the occurrence of patchy ophthalmologic manifestations in each disorder. Since the name was coined, much has been learned about the pathogenesis of these 3 disorders. It is clear that 2 of them--neurofibromatosis and tuberous sclerosis--are collective terms for multiple disorders. Each of the conditions is caused by distinct genetic defects, with little commonality in terms of protein function. Yet, in some respects, the disorders share a pathogenetic mechanism, that of the tumor suppressor gene. This review will briefly describe these disorders in light of what has been learned about underlying molecular pathogenesis. In each case, genetic testing is beginning to be available; principles of the use of genetic tests will be described.

The phakomatoses

The phakomatoses are a diverse set of disorders related principally by a similar tendency to produce patchy manifestations that affect the nervous system and various other tissues. All of the disorders involve the occurrence of benign neoplasms or hamartomatous growths, and all involve the action of a distinct gene that functions as a tumor suppressor. At present, none of the phakomatoses is amenable to effective medical treatment, so management is limited to surveillance and treatment of progressive lesions. The radiologist plays a key role in this management, participating in diagnosis and follow-up of affected patients.

Tuberous sclerosis complex and neurofibromatosis type 1: the two most common neurocutaneous diseases

TSC and NF1 are the most common of the neurocutaneous diseases, and both are autosomal dominant with a high spontaneous mutation rate. For diagnosis, two features are necessary for each disease. Skin findings for each are especially helpful for diagnosis, as is neuroimaging in TSC. For NF1, neuroimaging is not yet reliable for diagnosis. In children, brain symptoms cause most of the morbidity in TSC, and nerve sheath and nervous system tumors as well as learning disabilities cause major morbidity in NF1. Renal disease becomes a serious problem for adults with TSC. The TSC1, TSC2, and NF1 genes function as tumor suppressor genes and have other functions that are being investigated. Blood tests for diagnosis have a high false-negative rate. Therapies for TSC and for NF1 are both medical and surgical.

Tuberous sclerosis complex and neurofibromatosis type 1: the two most common neurocutaneous diseases

TSC and NF1 are the most common of the neurocutaneous diseases, and both are autosomal dominant with a high spontaneous mutation rate. For diagnosis, two features are necessary for each disease. Skin findings for each are especially helpful for diagnosis, as is neuroimaging in TSC. For NF1, neuroimaging is not yet reliable for diagnosis. In children, brain symptoms cause most of the morbidity in TSC, and nerve sheath and nervous system tumors as well as learning disabilities cause major morbidity in NF1. Renal disease becomes a serious problem for adults with TSC. The TSC1, TSC2, and NF1 genes function as tumor suppressor genes and have other functions that are being investigated. Blood tests for diagnosis have a high false-negative rate. Therapies for TSC and for NF1 are both medical and surgical.

Evaluating the risk of tuberous sclerosis in cases with prenatal diagnosis of cardiac rhabdomyoma

OBJECTIVE

To evaluate the prenatal parameters that increase the risk of tuberous sclerosis in prenatal management of fetal cardiac tumors suspected as rhabdomyoma.

METHODS

The study was a retrospective survey of 18 documented cases in which cardiac rhabdomyoma was suspected during pregnancy. The following parameters were evaluated as possible risk factors associated with tuberous sclerosis: tumor size, isolated or multiple, and family history of tuberous sclerosis.

RESULTS

Eighteen documented cases in which cardiac rhabdomyoma was found during pregnancy were evaluated. Of these cases, seven (39%) had proven tuberous sclerosis and 11 were found to be non-associated tuberous sclerosis tumors. When combining the present data with previous series, cases with diagnosis of tuberous sclerosis had equal mean tumor size to those with normal outcome. Family history of tuberous sclerosis in the presence of cardiac rhabdomyoma almost invariably ended with tuberous sclerosis (86%). All other cases with diagnosis of tuberous sclerosis and no family history had all multiple cardiac tumors.

CONCLUSION

The present data suggest that 39% of in utero suspected cardiac rhabdomyoma would have tuberous sclerosis. Family history and multifocality remain the strongest predictors of tuberous sclerosis, whereas size of the cardiac tumor can not reliably be used to predict tuberous sclerosis in prenatal counseling.

Supratentorial tuber location and autism in tuberous sclerosis complex

The high rate of autism in tuberous sclerosis complex provides an opportunity to study the pathogenesis of autism. This study investigated the relationship between a DSM-IV diagnosis of autism and tuber location in a sample of 50 individuals with tuberous sclerosis complex. Chi-square analyses revealed no differences between individuals with autism (n = 15) and those without autism (n = 35) on the occurrence of tubers in the right or left frontal, occipital, parietal, or temporal regions. There were no differences between the two groups in the occurrence of tubers in subcortical or cortical regions. In the largest sample to date, these results fail to support the hypothesis that supratentorial tuber location is a marker for autism.

Reduction of postembolization syndrome after ablation of renal angiomyolipoma

Approximately 75% of patients with tuberous sclerosis complex develop renal angiomyolipomas. These hamartomatous lesions distort and damage renal parenchyma and can lead to hemorrhage. To reduce the risk of hemorrhage, transarterial embolization is used to necrose the angiomyolipoma while sparing normal renal tissue. Although an effective renal-sparing procedure, embolization most often is associated with an inflammatory response that causes significant fever and pain that can last for several days despite the use of acetaminophen. Reported cases show that 49 of 55 patients who underwent embolization developed this syndrome. The use of such nonsteroidal anti-inflammatory drugs as aspirin is contraindicated because of their adverse effects on platelet function. To reduce pain and fever associated with postembolization syndrome (PES), we changed our clinical management of patients postembolization to include a tapering dose of prednisone over a 2-week period. Nine patients underwent this pharmacological intervention, and one patient abstained. All patients were monitored for pain and fever. Only two patients treated with steroids developed fever, which was assuaged with acetaminophen, and no patient reported pain. The tapering dose of prednisone was well tolerated, and there were no postprocedure infections. The use of a short-term tapering dose of prednisone appeared to reduce PES compared with the reported literature and improved patient comfort.

Lamotrigine therapy of epilepsy in tuberous sclerosis

PURPOSE

Lamotrigine (LTG), a newer antiepileptic drug (AED), has activity against both partial-onset and generalized seizures. Its reported benefits for behavior, and its effectiveness in Lennox-Gastaut syndrome and other forms of refractory epilepsy, make it a logical choice for treatment of epilepsy in tuberous sclerosis complex (TSC). We present our experience with LTG therapy of epilepsy in 57 patients with TSC.

METHODS

Patients fulfilled the diagnostic criteria for clinically definite TSC. LTG was initiated and increased until improvement in seizure frequency was noted, intolerable side effects occurred, or maximal doses were reached. Seizure frequency and behavioral changes were recorded during LTG therapy and compared with those prior to the introduction of LTG.

RESULTS

Twenty-four (42%) were seizure free, and 21 (37%) had a >50% reduction in seizure frequency. Eighteen (32%) had subjectively improved behavior and/or alertness with daily activities. Thirty-eight (67%) had no change in this regard, whereas one (2%) became worse. Responders were more likely to not have a history of infantile spasms, and to have experienced only partial seizures (p < 0.05). Otherwise no phenotypic correlations with response were apparent.

CONCLUSIONS

Among patients with TSC and epilepsy, LTG was effective and well tolerated, including as initial monotherapy. Improved alertness and behavior were apparent in many patients. The incidence of side effects is similar to that reported for other pediatric populations with symptomatic partial epilepsy. The usefulness of LTG in TSC may relate to an underlying defect of glutamatergic neurotransmission in partial epilepsy.

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.

Genetic mapping of a naturally occurring hereditary renal cancer syndrome in dogs

Canine hereditary multifocal renal cystadenocarcinoma and nodular dermatofibrosis (RCND) is a rare, naturally occurring inherited cancer syndrome observed in dogs. Genetic linkage analysis of an RCND-informative pedigree has identified a linkage group flanking RCND (CHP14-C05.377-C05.414-FH2383-C05. 771-[RCND-CPH18]-C02608-GLUT4-TP53-ZuBe Ca6-AHT141-FH2140-FH2594) thus localizing the disease to a small region of canine chromosome 5. The closest marker, C02608, is linked to RCND with a recombination fraction (theta) of 0.016, supported by a logarithm of odds score of 16.7. C02608 and the adjacent linked markers map to a region of the canine genome corresponding to portions of human chromosomes 1p and 17p. A combination of linkage analysis and direct sequencing eliminate several likely candidate genes, including tuberous sclerosis 1 and 2 genes (TSC1 and TSC2) and the tumor suppressor gene TP53. These data suggest that RCND may be caused by a previously unidentified tumor suppressor gene and highlight the potential for canine genetics in the study of human disease predisposition.

Chromosomal assignment of canine TSC2, PKD1 and CLN3 genes by radiation hybrid- and linkage analyses

The canine tuberous sclerosis 2 (TSC2) gene has been mapped to canine chromosome 6 using a canine whole genome radiation hybrid panel. There is close linkage between canine TSC2 and the polycystic kidney disease 1 gene (PKD1), as has been observed in humans and other mammalian species. The gene responsible for the human juvenile form of neuronal ceroid lipofuscinosis (CLN3), maps close to TSC2 and PKD1 in humans, and is also syntenic in the dog. We further demonstrate linkage to a group of polymorphic markers assigned to canine chromosome 6 (CFA6).