Thalamo-striatal T2-weighted hyperintensities (unidentified bright objects) correlate with cognitive impairments in neurofibromatosis type 1 during childhood

The role of unidentified bright objects in the neurocognitive profile of neurofibromatosis type 1 children: a volumetric MRI analysis

PURPOSE

Cognitive impairment is described in 80% of Neurofibromatosis type 1 (NF1) patients. Brain focal areas of T2w increased signal intensity on MRI, the so-called Unidentified Bright Objects (UBOs) have been hypothesized to be related to cognitive dysfunction, although conflicting results are available in literature. Here, we investigated the possible relation between UBOs' volume, cognitive impairment, and language disability in NF1 patients.

MATERIAL AND METHODS

In this retrospective study, clinical and MRI data of 21 NF1 patients (M/F = 12/9; mean age 10.1 ± 4.5) were evaluated. Brain intellectual functioning and language abilities were assessed with specific scales, while the analyzed MRI sequences included axial 2D-T2-weighted and FLAIR sequences. These images were used independently for UBOs segmentation with a semiautomatic approach and obtained volumes were normalized for biparietal diameters to take into account for brain volume. Possible differences in terms of normalized UBOs volumes were probed between cognitively affected and preserved patients, as well as between subjects with or without language impairment.

RESULTS

Patients cognitively affected were not different in terms of UBOs volume compared to those preserved (p = 0.35 and p = 0.30, for T2-weighted and FLAIR images, respectively). Similarly, no differences were found between patients with and without language impairment (p = 0.47 and p = 0.40, for the two sequences).

CONCLUSIONS

The relation between UBOs and cognition in children with NF1 has been already investigated in literature, although leading to conflicting results. Our study expands the current knowledge, showing a lack of correlation between UBOs volume and both cognitive impairment and language disability in NF1 patients.

Gender-Specific Fine Motor Skill Learning Is Impaired by Myelin-Targeted Neurofibromatosis Type 1 Gene Mutation

Neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene. The clinical presentation of NF1 includes diverse neurological issues in pediatric and adult patients, ranging from learning disabilities, motor skill issues, and attention deficit disorder, to increased risk of depression and dementia. Preclinical research suggests that abnormal neuronal signaling mediates spatial learning and attention issues in NF1; however, drugs that improve phenotypes in models show inconclusive results in clinical trials, highlighting the need for a better understanding of NF1 pathophysiology and broader therapeutic options. Most NF1 patients show abnormalities in their brain white matter (WM) and myelin, and links with NF1 neuropathophysiology have been suggested; however, no current data can clearly support or refute this idea. We reported that myelin-targeted Nf1 mutation impacts oligodendrocyte signaling, myelin ultrastructure, WM connectivity, and sensory-motor behaviors in mice; however, any impact on learning and memory remains unknown. Here, we adapted a voluntary running test-the complex wheel (CW; a wheel with unevenly spaced rungs)-to delineate fine motor skill learning curves following induction of an Nf1 mutation in pre-existing myelinating cells (pNf1 mice). We found that pNf1 mutant females experience delayed or impaired learning in the CW, while proper learning in pNf1 males is predominantly disrupted; these phenotypes add complexity to the gender-dependent learning differences in the mouse strain used. No broad differences in memory of acquired CW skills were detected in any gender, but gene-dose effects were observed at the studied time points. Finally, nitric oxide signaling regulation differentially impacted learning in wild type (WT)/pNf1, male/female mice. Our results provide evidence for fine motor skill learning issues upon induction of an Nf1 mutation in mature myelinating cells. Together with previous connectivity, cellular, and molecular analyses, these results diversify the potential treatments for neurological issues in NF1.

A new era for myelin research in Neurofibromatosis type 1

Evidence for myelin regulating higher-order brain function and disease is rapidly accumulating; however, defining cellular/molecular mechanisms remains challenging partially due to the dynamic brain physiology involving deep changes during development, aging, and in response to learning and disease. Furthermore, as the etiology of most neurological conditions remains obscure, most research models focus on mimicking symptoms, which limits understanding of their molecular onset and progression. Studying diseases caused by single gene mutations represents an opportunity to understand brain dys/function, including those regulated by myelin. Here, we discuss known and potential repercussions of abnormal central myelin on the neuropathophysiology of Neurofibromatosis Type 1 (NF1). Most patients with this monogenic disease present with neurological symptoms diverse in kind, severity, and onset/decline, including learning disabilities, autism spectrum disorders, attention deficit and hyperactivity disorder, motor coordination issues, and increased risk for depression and dementia. Coincidentally, most NF1 patients show diverse white matter/myelin abnormalities. Although myelin-behavior links were proposed decades ago, no solid data can prove or refute this idea yet. A recent upsurge in myelin biology understanding and research/therapeutic tools provides opportunities to address this debate. As precision medicine moves forward, an integrative understanding of all cell types disrupted in neurological conditions becomes a priority. Hence, this review aims to serve as a bridge between fundamental cellular/molecular myelin biology and clinical research in NF1.

Using a semi-automated approach to quantify Unidentified Bright Objects in Neurofibromatosis type 1 and linkages to cognitive and academic outcomes

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous syndrome that affects multiple organ systems resulting in widespread symptoms, including cognitive deficits. In addition to the criteria required for an NF1 diagnosis, approximately 70% of children with NF1 present with Unidentified Bright Objects (UBOs) or Focal Areas of Signal Intensity, which are hyperintense bright spots seen on T2-weighted magnetic resonance images and seen more prominently on FLAIR magnetic resonance images (Sabol et al., 2011). Current findings relating the presence/absence, quantities, sizes, and locations of these bright spots to cognitive abilities are mixed. To contribute to and hopefully disentangle some of these mixed findings, we explored potential relationships between metrics related to UBOs and cognitive abilities in a sample of 28 children and adolescents with NF1 (M=12.52 years; SD=3.18 years; 16 male). We used the Lesion Segmentation Tool (LST) to automatically detect and segment the UBOs. The LST was able to qualitatively and quantitatively reliably detect UBOs in images of children with NF1. Using these automatically detected and segmented lesions, we found that while controlling for age, biological sex, perceptual IQ, study, and scanner, "total UBO volume", defined as the sum of all the voxels representing all of the UBOs for each participant, helped explain differences in word reading, phonological awareness, and visuospatial skills. These findings contribute to the emerging NF1 literature and help parse the specific deficits that children with NF1 have, to then help improve the efficacy of reading interventions for children with NF1.

Evaluating Focal Areas of Signal Intensity (FASI) in Children with Neurofibromatosis Type-1 (NF1) Treated with Selumetinib on Pediatric Brain Tumor Consortium (PBTC)-029B

Background: Understanding the effect of selumetinib on FASI may help elucidate the biology, proliferative potential, and role in neurocognitive changes for these NF1-associated lesions. Methods: Patients with NF1-associated LGG and FASI treated with selumetinib on PBTC-029B were age-matched to untreated patients with NF1-associated FASI at Cincinnati Children’s Hospital Medical Center. Paired bidirectional measurements were compared over time using nonparametric tests. Results: Sixteen age-matched pairs were assessed (age range: 2.8–16.9 years, 60% male). Initial FASI burden was not different between groups (median range 138.7 cm2 [88.4–182.0] for the treated subjects vs. 121.6 cm2 [79.6—181.9] for the untreated subjects; p = 0.98). Over a mean follow-up of 18.9 (±5.9) months, the LGG size consistently decreased with treatment while no consistent change among the treated or untreated FASI size was seen. At the paired time points, the median treated LGG decreased significantly more than the treated FASI (−41.3% (LGG) versus −10.7% (FASI), p = 0.006). However, there was no difference in the median size change in the treated versus untreated FASI (−10.7% (treated FASI) versus −17.9% (untreated FASI), p = 0.08). Among the treated subjects, there was no correlation between the change in LGG and FASI (r = −0.04, p = 0.88). Conclusions: Treatment with selumetinib did not affect the overall FASI size in children with NF1 treated for progressive low-grade glioma.

Comprehensive neurological evaluation of a cohort of patients with neurofibromatosis type 1 from a single institution

Neurofibromatosis type 1 (NF1) is a phenotypically heterogenous multisystem cancer predisposition syndrome manifesting in childhood and adolescents. Central nervous system (CNS) manifestations include structural, neurodevelopmental, and neoplastic disease. We aimed to (1) characterize the spectrum of CNS manifestations of NF1 in a paediatric population, (2) explore radiological features in the CNS by image analyses, and (3) correlate genotype with phenotypic expression for those with a genetic diagnosis. We performed a database search in the hospital information system covering the period between January 2017 and December 2020. We evaluated the phenotype by retrospective chart review and imaging analysis. 59 patients were diagnosed with NF1 [median age 10.6 years (range, 1.1-22.6); 31 female] at last follow-up, pathogenic NF1 variants were identified in 26/29. 49/59 patients presented with neurological manifestations including 28 with structural and neurodevelopmental findings, 16 with neurodevelopmental, and 5 with structural findings only. Focal areas of signal intensity (FASI) were identified in 29/39, cerebrovascular anomalies in 4/39. Neurodevelopmental delay was reported in 27/59 patients, learning difficulties in 19/59. Optic pathway gliomas (OPG) were diagnosed in 18/59 patients, 13/59 had low-grade gliomas outside the visual pathways. 12 patients received chemotherapy. Beside the established NF1 microdeletion, neither genotype nor FASI were associated with the neurological phenotype. NF1 was associated with a spectrum of CNS manifestations in at least 83.0% of patients. Regular neuropsychological assessment complementing frequent clinical and ophthalmologic testing for OPG is necessary in the care of each child with NF1.

Atypical connectivity in the cortico-striatal network in NF1 children and its relationship with procedural perceptual-motor learning and motor skills

INTRODUCTION

Neurofibromatosis type 1 (NF1) is considered a model of neurodevelopmental disorder because of the high frequency of learning deficits, especially developmental coordination disorder. In neurodevelopmental disorder, Nicolson and Fawcett formulated the hypothesis of an impaired procedural learning system that has its origins in cortico-subcortical circuits. Our aim was to investigate the relationship between cortico-striatal connectivity and procedural perceptual-motor learning performance and motor skills in NF1 children.

METHODS

Seventeen NF1 and 18 typically developing children aged between 8 and 12 years old participated in the study. All were right-handed and did not present intellectual or attention deficits. In all children, procedural perceptual-motor learning was assessed using a bimanual visuo-spatial serial reaction time task (SRTT) and motor skills using the Movement Assessment Battery for Children (M-ABC). All participants underwent a resting-state functional MRI session. We used a seed-based approach to explore cortico-striatal connectivity in somatomotor and frontoparietal networks. A comparison between the groups' striato-cortical connectivity and correlations between connectivity and learning (SRTT) and motor skills (M-ABC) were performed.

RESULTS

At the behavioral level, SRTT scores are not significantly different in NF1 children compared to controls. However, M-ABC scores are significantly impaired within 9 patients (scores below the 15th percentile). At the cerebral level, NF1 children present a higher connectivity in the cortico-striatal regions mapping onto the right angular gyrus compared to controls. We found that the higher the connectivity values between these regions, differentiating NF1 and controls, the lower the M-ABC scores in the whole sample. No correlation was found for the SRTT scores.

CONCLUSION

NF1 children present atypical hyperconnectivity in cortico-striatal connections. The relationship with motor skills could suggest a sensorimotor dysfunction already found in children with developmental coordination disorder. These abnormalities are not linked to procedural perceptual-motor learning assessed by SRTT.

Non-Oncological Neuroradiological Manifestations in NF1 and Their Clinical Implications

Simple Summary

Central nervous system involvement (CNS) is a common finding in Neurofibromatosis type 1 (NF1). Beside tumor-related manifestations, NF1 is also characterized by a wide spectrum of CNS alterations with variable impacts on functioning and life quality. Here, we propose an overview of non-oncological neuroradiological findings in NF1, with an insight on pathophysiological and embryological clues for a better understanding of the development of these specific alterations.

Abstract

Neurofibromatosis type 1 (NF1), the most frequent phakomatosis and one of the most common inherited tumor predisposition syndromes, is characterized by several manifestations that pervasively involve central and peripheral nervous system structures. The disorder is due to mutations in the NF1 gene, which encodes for the ubiquitous tumor suppressor protein neurofibromin; neurofibromin is highly expressed in neural crest derived tissues, where it plays a crucial role in regulating cell proliferation, differentiation, and structural organization. This review article aims to provide an overview on NF1 non-neoplastic manifestations of neuroradiological interest, involving both the central nervous system and spine. We also briefly review the most recent MRI functional findings in NF1.

Importance of Thalamostriatal Pathway Associated With Neurocognitive Dysfunctions in Children With Neurofibromatosis Type 1: Diffusion Tensor Imaging Findings

OBJECTIVE

To determine whether there is a difference between healthy control group and children with neurofibromatosis type 1 (NF1) in terms of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values in different regions of the brain associated with neurocognitive functions and to investigate the correlation between diffusion tensor imaging parameters and neurocognitive dysfunctions.

METHODS

The study included 28 children with NF1 and 21 controls. Nine distinct areas related to cognitive functions were selected for the analysis. The ADC and FA values were compared.

RESULTS

There was a significant difference between NF1 and healthy control in terms of ADC values obtained from all areas. The ADC values at obtained from thalamus and striatum were positively correlated with the full-scale intelligence quotient (IQ), verbal IQ, and performance IQ.

CONCLUSIONS

We are speculated that the development of microstructural damage in the thalamostriatal pathway may lead to neurocognitive dysfunction.

Are morphological and structural MRI characteristics related to specific cognitive impairments in neurofibromatosis type 1 (NF1) children?

INTRODUCTION

NF1 children have cognitive disorders, especially in executive functions, visuospatial, and language domains, the pathophysiological mechanisms of which are still poorly understood.

MATERIALS AND METHODS

A correlation study was performed from neuropsychological assessments and brain MRIs of 38 NF1 patients and 42 controls, all right-handed, aged 8-12 years and matched in age and gender. The most discriminating neuropsychological tests were selected to assess their visuospatial, metaphonological and visuospatial working memory abilities. The MRI analyses focused on the presence and location of Unidentified Bright Objects (UBOs) (1), volume analysis (2) and diffusion analysis (fractional anisotropy and mean diffusivity) (3) of the regions of interest including subcortical structures and posterior fossa, as well as shape analysis of subcortical structures (4). The level of attention, intelligence quotient, age and gender of the patients were taken into account in the statistical analysis. Then, we studied how diffusion and volumes parameters were associated with neuropsychological characteristics in NF1 children.

RESULTS

NF1 children present different brain imaging characteristics compared to the control such as (1) UBOs in 68%, (2) enlarged total intracranial volume, involving all subcortical structures, especially thalamus, (3) increased MD and decreased FA in thalamus, corpus callosum and hippocampus. These alterations are diffuse, without shape involvement. In NF1 group, brain microstructure is all the more altered that volumes are enlarged. However, we fail to find a link between these brain characteristics and neurocognitive scores.

CONCLUSION

While NF1 patients have obvious pathological brain characteristics, the neuronal substrates of their cognitive deficits are still not fully understood, perhaps due to complex and multiple pathophysiological mechanisms underlying this disorder, as suggested by the heterogeneity observed in our study. However, our results are compatible with an interpretation of NF1 as a diffuse white matter disease.

Impairments in communication and social interaction in children with neurofibromatosis type 1: Characteristics and role of ADHD and language delay

Background: Neurofibromatosis type 1 (NF1) is a multisystem neurocutaneous disorder with increased risk of tumor formation and higher incidence of autism spectrum disorder (ASD) than the general population. The aim of the study was to assess the presence of ASD symptoms in young children with NF1 and to examine their potential association with attention deficit hyperactivity disorder (ADHD) and speech delay.Methods: The cohort included 30 patients with NF1 attending the multidisciplinary NF1 clinic of a tertiary pediatric medical center from September 2015 through September 2016. The parents/caregivers completed the Social Communication Questionnaire (SCQ) and the Vineland Adaptive Behavior Scales (VABS II).Results: Sixteen patients (53%) had a previous diagnosis of ADHD. There was a positive association between the presence of ADHD and a low score on the VABS II interpersonal relationships subscale of the Socialization domain. Language delay, documented in 12 children (40%), also correlated with a low interpersonal relationships score.Conclusions: ADHD appears to be more a marker than an actual independent risk factor of ASD in NF1. The early evaluation of children with NF1 for interpersonal communication problems and ASD, especially those with a speech delay or ADHD, will alert clinicians to initiate appropriate and timely treatment.

Longitudinal phenotype development in a minipig model of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a rare, autosomal dominant disease with variable clinical presentations. Large animal models are useful to help dissect molecular mechanisms, determine relevant biomarkers, and develop effective therapeutics. Here, we studied a NF1 minipig model (NF1+/ex42del) for the first 12 months of life to evaluate phenotype development, track disease progression, and provide a comparison to human subjects. Through systematic evaluation, we have shown that compared to littermate controls, the NF1 model develops phenotypic characteristics of human NF1: [1] café-au-lait macules, [2] axillary/inguinal freckling, [3] shortened stature, [4] tibial bone curvature, and [5] neurofibroma. At 4 months, full body computed tomography imaging detected significantly smaller long bones in NF1+/ex42del minipigs compared to controls, indicative of shorter stature. We found quantitative evidence of tibial bowing in a subpopulation of NF1 minipigs. By 8 months, an NF1+/ex42del boar developed a large diffuse shoulder neurofibroma, visualized on magnetic resonance imaging, which subsequently grew in size and depth as the animal aged up to 20 months. The NF1+/ex42del minipig model progressively demonstrates signature attributes that parallel clinical manifestations seen in humans and provides a viable tool for future translational NF1 research.

Brain Tumors in NF1 Children: Influence on Neurocognitive and Behavioral Outcome

Neurofibromatosis type-1 (NF1) is a monogenic tumor-predisposition syndrome creating a wide variety of cognitive and behavioral abnormalities, such as decrease in cognitive functioning, deficits in visuospatial processing, attention, and social functioning. NF1 patients are at risk to develop neurofibromas and other tumors, such as optic pathway gliomas and other tumors of the central nervous system. Few studies have investigated the impact of an additional diagnosis of brain tumor on the cognitive outcome of children with NF1, showing unclear results and without controlling by the effect of surgery, radio- or chemotherapy. In the present mono-institutional study, we compared the behavioral and cognitive outcomes of 26 children with neurofibromatosis alone (NF1) with two age-matched groups of 26 children diagnosed with NF1 and untreated optic pathway glioma (NF1 + OPG) and 19 children with NF1 and untreated other central nervous system tumors (NF1 + CT). NF1 + CT and NF1 + OPG showed significantly impaired cognitive abilities compared to NF1 group, with weaknesses in visuo-spatial abilities, visual scanning and verbal working memory, while general verbal abilities are preserved. Moreover, NF1 + OPG patients present more frequent internalizing problems and increased oppositional-deviant behaviors. These results suggest that the co-diagnosis of a brain tumor in NF1 children may partially worsen the cognitive and emotional outcome.

Adaptive functioning in children with neurofibromatosis type 1: relationship to cognition, behavior, and magnetic resonance imaging

AIM

To characterize the adaptive behavior profile of children with neurofibromatosis type 1 (NF1) and determine its relationship to neuropsychological functioning and non-neoplastic T2-weighted hyperintense brain lesions on brain magnetic resonance imaging (MRI).

METHOD

In this cross-sectional study, we retrospectively reviewed neuropsychological reports from 104 children with NF1 (56 males, 48 females; mean age 10y 4mo; standard deviation [SD] 3y 4mo; range 3y 5mo-17y 6mo), and extracted data from a range of cognitive and behavioral measures, including the Adaptive Behavior Assessment System (ABAS). Brain MRI was retrospectively reviewed in 42 individuals.

RESULTS

Adaptive Behavior Assessment System scores were continuously distributed and pathologically shifted by 0.79 to 1.26SD across Conceptual, Social, and Practical domains, and 46.5% of individuals had a composite score in the borderline or impaired range. Impairment in adaptive functioning was correlated with deficits in executive function (r=-9.543, p<0.001), externalizing problems (r=-0.366, p<0.001), and attention (r=-9.467, p=0.001). Cluster analysis revealed three distinct phenotypic subgroups, one of which exhibited normal cognitive ability, but impaired adaptive functioning, with persistent deficits in executive function, behavioral problems, and attention-deficit/hyperactivity disorder symptomatology. There was no relationship between ABAS scores and the number or location of unidentified bright objects.

INTERPRETATION

Adaptive functioning deficits are common among children with NF1 and are associated with impairment in other cognitive/behavioral domains, independent of general cognitive ability.

WHAT THIS PAPER ADDS

Deficits in adaptive behavior are common in children with neurofibromatosis type 1 (NF1). Poor adaptive functioning is associated with impairments in executive function, externalizing behaviors, and attention, regardless of cognitive ability. The presence or location of unidentified bright objects do not predict adaptive behavior skills in children with NF1.

Neuropsychological profile in Italian children with neurofibromatosis type 1 (NF1) and their relationships with neuroradiological data: Preliminary results

BACKGROUND

Neurofibromatosis type 1 is a genetic disorder associated with cognitive deficits, learning disabilities and behavioral problems. These domains appear to have a still controversial debated association with local areas of T2-hyperintensities on MRI images, called unidentified bright objects (UBOs).

METHODS

A cohort of 36 children (aged 7-11 years) included consecutively, underwent neuropsychological and behavioral assessment to determine their cognitive and neuropsychological profile, and the frequency of specific learning disabilities. MRI examination was used to determine the impact of UBOs' presence, number, and location on the cognitive, neuropsychological and behavioral profile, and also the presence of optic glioma.

RESULTS

The mean full intelligence quotient was 104.6; only one child had mild intellectual disability. Forty one percent of children had a diagnosis of specific learning disabilities and reading was mainly involved. Twenty per cent had attention problems. All children had normal scores in visuo-motor and visuo-perceptual tests. UBOs were present in 94.0% of the MRI examinations. Two children had optic glioma. Children with UBOs in a specific location and children with UBOs elsewhere were statistically compared, no one of the location seemed to have an impact on general cognition measured with full intelligence quotient. The thalamus was associated with problems in calculation and striatum with behavioral problems. An inverse relationship between the number of UBOs and the full intelligence quotient was present, but without a statistical significance.

CONCLUSIONS

In this study, the specific location of UBOs did not seem to influence the general cognitive profile and also the relationship between their number and the full intelligence quotient was not significant; these results are still controversial in literature. Finally, the presence of UBOs in the thalamus and striatum may represent a neuroradiological pattern that influences performances in calculation and behavior respectively in children with Neurofibromatosis type 1.

Increased prevalence of brain tumors classified as T2 hyperintensities in neurofibromatosis 1

Background

We sought to define the radiologic features that differentiate neoplastic from non-neoplastic T2 hyperintensities (T2Hs) in neurofibromatosis type 1 (NF1) and identify those lesions most likely to require oncologic surveillance.

Methods

We conducted a single-center retrospective review of all available brain MRIs from 68 children with NF1 (n = 190) and 46 healthy pediatric controls (n = 104). All T2Hs identified on MRI were characterized based on location, border, shape, degree of T1 hypointensity, and presence of mass effect or contrast enhancement, and subsequently classified using newly established radiologic criteria as either unidentified bright objects (UBOs) or probable tumors. Lesion classification was pathologically confirmed in 10 NF1 cases.

Results

T2Hs were a highly sensitive (94.4%; 95% confidence interval [CI] 86.4%-98.5%) and specific (100.0%; 95% CI 92.3%-100.0%) marker for the diagnosis of NF1. UBOs constituted the majority of T2Hs (82%) and were most frequently located in cerebellar white matter, medial temporal lobe, and thalamus, where they were more likely than probable tumors to be bilateral (p < 0.001) and have nondiscrete borders (p < 0.001). Surprisingly, 57% of children with T2Hs harbored lesions classified as probable tumors, and 28% of children with probable tumors received treatment. In contrast to UBOs, probable tumors were most frequently located within the globus pallidus and medulla, and rarely occurred prior to 3 years of age.

Conclusions

With the implementation of standardized radiologic criteria, a high prevalence of brain tumors was identified in this at-risk population of children, of which nearly one-third required treatment, emphasizing the need for appropriate oncologic surveillance for patients with NF1 harboring nonoptic pathway brain tumors.

The Key Search Subtest of the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C) Instrument Reveals Impaired Planning Without External Constraints in Children With Neurofibromatosis Type 1

Studies of executive function and its relationship with brain T2-weighted hyperintensities in children with neurofibromatosis type 1 (NF1) have yielded inconsistent results. We examined 16 children with NF1 aged 8 to 15 years, of normal intelligence, and compared their findings to those of 16 siblings and 16 typically developing children using the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C). NF1 patients had an adequate overall score at BADS-C, but showed significantly lower performance than typical peers in the Key Search subtest. This is a task that must be solved without any given rules, in which subjects must devise a strategy and an efficient search pattern transferable to other similar real situations. The Key Search scores were not correlated with number and signal characteristics of T2-weighted hyperintensities. Planning without external indications is impaired in children with NF1 because they have to rely entirely on self-organization and monitoring; this study provides information for remediation programs designed to improve functioning in daily life.

Cognitive and Behavioral Disorders in Children with Neurofibromatosis Type 1

AIM

The last systematic review of research on the behavior of children with neurofibromatosis type 1 (NF1) was in 2012. Since then, several important findings have been published. Therefore, the study aim was to synthesize recent relevant work related to this issue.

METHOD

We conducted a systematic review of the literature. Relevant articles were identified using the electronic databases PubMed, PsycINFO, and Scopus and a manual search of references lists. Thirty of 156 articles identified met the inclusion criteria. A quality evaluation of the articles was performed and the information was synthesized using a narrative approach.

RESULTS

Compared with controls, children and adolescents with NF1 present significant alterations in language, reading, visuospatial skills, motor function, executive function, attention, behavior, emotion, and social skills. The prevalence of attention-deficit/hyperactivity disorder (ADHD) is important and can affect cognition and executive function variables. A high prevalence of autistic traits and autistic spectrum disorder were reported. The benefits of using statins to treat cognitive deficits are unclear. However, children with NF1 and ADHD seem to benefit from methylphenidate treatment. The presence of hyperintensities in brain magnetic resonance imaging data seem to be related to poor cognitive performance. Analysis of these lesions could help to predict cognitive alterations in children with NF1.

INTERPRETATION

There has been important progress to evaluate cognitive characteristics of children with NF1 and to determine the physiological mechanisms of the concomitant disorders. However, discrepancies in relation to intelligence, learning disabilities, attention deficits, and treatment remain. Further investigations on this topic are recommended.

Brain imaging findings and social/emotional problems in Israeli children with neurofibromatosis type 1

A potential association between brain MRI findings and social/emotional difficulties in children with neurofibromatosis type 1 (NF1) was examined. Twenty-eight children with NF1 filled in the Strengths and Difficulties Questionnaire (SDQ), and possible associations between their responses and findings in their brain MRI were sought. T2 bright foci were identified in MRI scans of 24 patients (85 %). There were no associations between the presence of the bright foci in any specific brain region and any of the SDQ scores for the emotional/behavioral measures. Male patients had significantly abnormal SDQ scores and peer problems. Patients with abnormal SDQ scores were younger than those with normal SDQ scores (mean 13.2 years vs 14.3 years, respectively; p = 0.23). A comparison of the scores obtained in ours and in another group of 11 children with NF1 yielded a significant difference between the groups.

CONCLUSION

We believe that the lack of correlation between the MRI findings and the social/emotional parameters of the SDQ is another demonstration of the marked clinical variability characteristic of NF1.

Planning deficit in children with neurofibromatosis type 1: a neurocognitive trait independent from attention-deficit hyperactivity disorder (ADHD)?

Neurofibromatosis type 1 is associated with executive dysfunctions and comorbidity with attention-deficit hyperactivity disorder (ADHD) in 30% to 50% of children. This study was designed to clarify the neurocognitive phenotype observed in neurofibromatosis type 1 by testing the hypothesis that children with neurofibromatosis type 1 have specific planning deficits independently from intellectual level and ADHD comorbidity. Eighteen children with neurofibromatosis type 1 were pair-matched to 18 children with ADHD and 18 healthy controls. All groups were assessed on the presence of ADHD symptoms (Conners Scales) and planning deficits (Tower of London). Compared with control group, groups with neurofibromatosis type 1 and ADHD demonstrated significant impairment of planning and problem solving. The lack of correlation between Tower of London results and Conners subscale scores in neurofibromatosis type 1 group confirmed that the planning and problem-solving deficit is not directly related to inattention level. These findings suggested that the executive impairment probably represents a peculiar trait of neurofibromatosis type 1 neurocognitive phenotype.

Evaluation of the basal ganglia in neurofibromatosis type 1

PURPOSE

Alterations of the brain microstructure and metabolism have been identified in patients with neurofibromatosis type 1 (NF1). In this study, we analyzed the basal ganglia of NF1 subjects without cognitive delay throughout a combined approach with magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in order to better define the metabolic and microstructural characteristics of these regions and, furthermore, to verify if metabolic and microstructural abnormalities may be present in normally developed NF1 patients.

METHODS

A 3-T MRI with multivoxel MRS and DTI was performed in 14 NF1 patients and eight controls. N-acetyl-aspartate (NAA), choline (Cho), creatine (Cr) values and ratios, fractional anisotropy, and apparent diffusion coefficient (ADC) were calculated, for a total of four regions of interest (ROI) for each hemisphere.

RESULTS

NF1 patients, compared to healthy controls, showed (a) decreased NAA in all the four ROI, (b) increased Cho and decreased Cr in three of the four ROI, (c) decreased NAA/Cho ratio in three ROI, and (d) increased ADC in all the four ROI. A trend of increased ADC was present in three of the four ROI of NF1 patients with unidentified bright objects (UBOs) and younger than 18 years.

CONCLUSION

These data confirm the presence of neuroaxonal damage with myelin disturbances in NF1 patients. We showed that metabolic and microstructural anomalies can be present in the same time in NF1 patients without developmental delay or cognitive deficits. Relations between brain anomalies, UBOs, and cognitive functions need further studies.

Longitudinal assessment of cognition and T2-hyperintensities in NF1: an 18-year study

The developmental course of cognitive deficits in individuals with neurofibromatosis type 1 (NF1) is unclear. The objectives of this study were to determine the natural history of cognitive function and MRI T2-hyperintesities (T2H) from childhood to adulthood and to examine whether the presence of discrete T2H in childhood can predict cognitive performance in adulthood. We present cognitive and structural neuroimaging data from 18 patients with NF1 and five sibling controls assessed prospectively across an 18-year period. Longitudinal analyses revealed a significant increase in general cognitive function in patients with NF1 over the study period. Improvements were limited to individuals with discrete T2H in childhood. Patients without lesions in childhood exhibited a stable profile. The number of T2H decreased over time, particularly discrete lesions. Lesions located within the cerebral hemispheres and deep white matter were primarily stable, whereas those located in the basal ganglia, thalamus and brainstem tended to resolve. Our results support the hypothesis that resolution of T2H is accompanied by an improvement in general cognitive performance, possibly as a result of increased efficiency within white matter tracts.

A neuropsychological perspective on attention problems in neurofibromatosis type 1

Cognitive problems are common in children with neurofibromatosis type 1 and they can often complicate treatment. The current literature review examines cognitive functioning in neurofibromatosis type 1, with a specific focus on executive functioning. This includes exploration of how deficits in executive functioning are expressed in children with neurofibromatosis type 1 and how these deficits contrast with ADHD. The value of investigating subcomponents of executive functioning is discussed, as are implications for effective treatment and future research.

Plasticity and mTOR: towards restoration of impaired synaptic plasticity in mTOR-related neurogenetic disorders

Objective. To review the recent literature on the clinical features, genetic mutations, neurobiology associated with dysregulation of mTOR (mammalian target of rapamycin), and clinical trials for tuberous sclerosis complex (TSC), neurofibromatosis-1 (NF1) and fragile X syndrome (FXS), and phosphatase and tensin homolog hamartoma syndromes (PTHS), which are neurogenetic disorders associated with abnormalities in synaptic plasticity and mTOR signaling. Methods. Pubmed and Clinicaltrials.gov were searched using specific search strategies. Results/Conclusions. Although traditionally thought of as irreversible disorders, significant scientific progress has been made in both humans and preclinical models to understand how pathologic features of these neurogenetic disorders can be reduced or reversed. This paper revealed significant similarities among the conditions. Not only do they share features of impaired synaptic plasticity and dysregulation of mTOR, but they also share clinical features—autism, intellectual disability, cutaneous lesions, and tumors. Although scientific advances towards discovery of effective treatment in some disorders have outpaced others, progress in understanding the signaling pathways that connect the entire group indicates that the lesser known disorders will become treatable as well.

Clinical sensitivity and specificity of multiple T2-hyperintensities on brain magnetic resonance imaging in diagnosis of neurofibromatosis type 1 in children: diagnostic accuracy study

Aim

To determine the prevalence, number, and location of multiple (≥2) T2-hyperintensities on brain magnetic resonance imaging (MRI) in children with neurofibromatosis type 1 (NF1) and their correlation with age, and to establish their sensitivity, specificity, and accuracy for the diagnosis of NF1 in children, especially in the early age (2-7 years).

Methods

We performed a cross-sectional study of 162 patients with NF1 from Croatian Neurofibromatosis Association Database and 163 control children between the ages of 2 and 18 years who underwent brain MRI between 1989 and 2009.

Results

Multiple T2-hyperintensities were present in 74% of NF1 patients and 1.8% of controls. They were mainly located in the basal ganglia, brainstem, and cerebellum and were significantly decreased in prevalence and number in the older age. T2-hyperintensities had excellent diagnostic accuracy with the area under the receiver operating characteristic (ROC) curve of 0.849 and 95% confidence interval (CI) of 0.805-0.886. The diagnostic sensitivity, specificity, and accuracy rate of T2-hyperintensities for NF1 were highest in the youngest age (2-7 years): 81% (95% CI 71%-89.1%), 99% (95% CI 92.3%-100%), and 85.8 (95% CI 83.3-93.8), respectively.

Conclusion

This study strongly suggests the inclusion of T2-hyperintensities on brain MRI on the list of diagnostic criteria for NF1, especially in children of early age, when the clinical penetration of the NF1 gene has not yet been completely finished.

Múltiplas hiperintensidades no sistema nervoso central em uma criança com neurofibromatose do tipo 1

OBJETIVO: Relatar o caso de uma criança com neurofibromatose do tipo 1, apresentando o achado ocasional de múltiplas hiperintensidades e de lesão hamartomatosa pré-quiasmática no sistema nervoso central. DESCRIÇÃO DO CASO: Menino de tez escura de quatro anos, cujo pai apresentava manchas café-com-leite e história de cirurgia de tumor de ouvido. A criança evoluiu com um adequado desenvolvimento neuropsicomotor, sem crises convulsivas ou déficit de aprendizagem. Ao exame físico, possuía múltiplas manchas café-com-leite e efélides. A avaliação pela ressonância nuclear magnética de encéfalo evidenciou múltiplas imagens nodulares hiperintensas em T2 e Flair, com isossinal em T1, localizadas na substância branca dos hemisférios cerebrais, cerebelo e tronco cerebral. Apresentava ainda lesão hamartomatosa pré-quiasmática. A avaliação eletroencefalográfica e o exame neurológico eram normais. COMENTÁRIOS: As imagens hiperintensas verificadas na ressonância nuclear magnética correspondem aos chamados unidentified bright objects (UBOs), observados em de 60 a 70% das crianças com neurofibromatose do tipo 1, sendo raros em adultos. Sua etiologia e significado clínico ainda não são claros. Alguns estudos os têm associado à disfunção cognitiva, déficit neurológico e risco de malignização. Hamartomas localizados próximos ao quiasma óptico são incomuns, mas podem se relacionar à puberdade precoce. A avaliação do sistema nervoso central de crianças assintomáticas com neurofibromatose do tipo 1 é discutível. Contudo, nos casos em que UBOs sejam identificados, é importante considerar seu seguimento radiológico, especialmente diante de lesões múltiplas ou atípicas.