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.

Speech difficulties and patient health communication mediating effects on worry and health-related quality of life in children, adolescents, and young adults with Neurofibromatosis Type 1.

The objective was to investigate the serial mediating effects of speech difficulties, patient health communication, and disease-specific worry in the relationship between neurofibromatosis (NF) symptoms (pain and skin symptoms) and total generic health-related quality of life (HRQOL) in children, adolescents, and young adults with NF Type 1 (NF1) from the patient perspective. The Speech, Communication, Worry, Pain, Skin Itch Bother, and Skin Sensations Scales from the Pediatric Quality of Life Inventory (PedsQL) NF1 Module and the PedsQL 4.0 Generic Core Scales were completed in a multi-site national study by 305 patients ages 5-25 years. A serial multiple mediator model analysis was conducted to test the hypothesized sequential mediating effects of speech difficulties, health communication, and worry as intervening variables in the association between NF1 symptoms and HRQOL. Symptoms predictive effects on total generic HRQOL were serially mediated by speech difficulties, patient health communication, and worry. In predictive analytics models utilizing hierarchical multiple regression analyses with age and gender demographic covariates, the pain, skin itch bother, and skin sensations multiple mediator models accounted for 61%, 59%, and 56% of the variance in generic HRQOL (p < .001), reflecting large effect sizes. Speech difficulties, patient health communication, and disease-specific worry explain in part the mechanism of symptoms predictive effects on total generic HRQOL in pediatric patients with NF1. Identifying NF1-specific predictors and serial mediators of total generic HRQOL in pediatric patients with NF1 from the patient perspective enables a patient-centered comprehensive care approach for children, adolescents, and young adults with NF1.

Impairment of Procedural Learning and Motor Intracortical Inhibition in Neurofibromatosis Type 1 Patients.

BACKGROUND: Cognitive difficulties are the most common neurological complications in neurofibromatosis type 1 (NF1) patients. Recent animal models proposed increased GABA-mediated inhibition as one underlying mechanism directly affecting the induction of long-term potentiation (LTP) and learning. In most adult NF1 patients, apparent cognitive and attentional deficits, tumors affecting the nervous system and other confounding factors for neuroscientific studies are difficult to control for. Here we used a highly specific group of adult NF1 patients without cognitive or nervous system impairments. Such selected NF1 patients allowed us to address the following open questions: Is the learning process of acquiring a challenging motor skill impaired in NF1 patients? And is such an impairment in relation to differences in intracortical inhibition? METHODS: We used an established non-invasive, double-pulse transcranial magnetic stimulation (dp-TMS) paradigm to assess practice-related modulation of intracortical inhibition, possibly mediated by gamma-minobutyric acid (GABA)ergic-neurotransmission. This was done during an extended learning paradigm in a group of NF1 patients without any neuropsychological deficits, functioning normally in daily life and compared them to healthy age-matched controls. FINDINGS: NF1 patients experienced substantial decline in motor skill acquisition (F = 9.2, p = 0.008) over five-consecutives training days mediated through a selective reduction in the early acquisition (online) and the consolidation (offline) phase. Furthermore, there was a consistent decrease in task-related intracortical inhibition as a function of the magnitude of learning (T = 2.8, p = 0.014), especially evident after the early acquisition phase. INTERPRETATIONS: Collectively, the present results provide evidence that learning of a motor skill is impaired even in clinically intact NF1 patients based, at least partially, on a GABAergic-cortical dysfunctioning as suggested in previous animal work.

The relaxation response resiliency program (3RP) in patients with neurofibromatosis 1, neurofibromatosis 2, and schwannomatosis: results from a pilot study.

NF1, NF2, and Schwannomatosis are incurable tumor suppressor syndromes associated with poor quality of life. The aim of this study was to determine the feasibility, acceptability, and preliminary efficacy of an NF adapted, 8-week group mind body skills based intervention, the relaxation response resiliency program (3RP) aimed at improving resiliency and increasing satisfaction with life. Patients seen at MGH's Neurofibromatosis Clinic were offered participation if they described difficulties coping to a treating physician. Participants completed measures of life satisfaction, resiliency, stress, mood, lifestyle, pain, post-traumatic growth and mindfulness at baseline and after completing the 3RP program. The intervention had relative feasible enrollment rate (48% rate, 32 out of 67 of patients signing the informed consent form). However, out of the 32 patients who signed the informed consent, only 20 started the study (62.5%) and only 16 completed it (50%), suggesting problems with feasibility. The main reason cited for non-participation was burden of travel to the clinic. The intervention was highly acceptable, as evidenced by an 80% completion rate (16/20). Paired t tests showed significant improvement in resiliency, satisfaction with life, depression, stress, anxiety, mindfulness and post traumatic growth, with effect sizes ranging from 0.73-1.33. There was a trend for significance for improvement in somatization and sleepiness (p = 0.06), with effect sizes of 0.54-0.92 respectively. Statistically nonsignificant improvement was observed in all other measures, with effect sizes small to medium. In sum, the 3RP was found to be relatively feasible, highly acceptable and preliminary efficacious in decreasing symptom burden in this population, supporting the need of a randomized controlled trial.

Brain structure and function in neurofibromatosis type 1: current concepts and future directions.

Neurofibromatosis type 1 (NF1) is a common neurogenetic condition associated with cognitive dysfunction and learning disability. Over the past decade, important and consistent findings have emerged that provide insight into the neurobiological correlates of NF1. In this review, we examine the structural and functional neuroimaging literature in individuals with NF1 and discuss findings that have emerged. Collectively, the studies reviewed here highlight structural and functional brain abnormalities as a feature of NF1 and that these abnormalities contribute to the cognitive impairments that are commonly seen. The most compelling structural finding has been an increase in total brain volume with additional areas of interest including the corpus callosum, cerebral asymmetries and differences in grey and white matter. Although the application of functional neuroimaging techniques in NF1 is in its infancy, early evidence suggests alterations in brain organisation for language and visuospatial function as well as thalamic hypometabolism. Suggestions for future research are discussed, including the importance of addressing specific hypotheses in well-defined subsamples of children with NF1 using appropriate control groups. Identifying the underlying neuropathology of NF1 will be of increased importance as targeted interventions begin to emerge.

High bone turnover and accumulation of osteoid in patients with neurofibromatosis 1.

UNLABELLED: Although it is known that neurofibromatosis 1 (NF1) patients suffer from vitamin D deficiency and display decreased bone mineral density (BMD), a systematic clinical and histomorphometrical analysis is absent. Our data demonstrate that NF1 patients display high bone turnover and accumulation of osteoid and that supplementation of vitamin D has a beneficial effect on their BMD. INTRODUCTION: Neurofibromatosis 1 results in a wide range of clinical manifestations, including decreased BMD. Although it has been reported that NF1 patients have decreased vitamin D serum levels, the manifestation of the disease at the bone tissue level has rarely been analyzed. METHODS: Thus, we performed a clinical evaluation of 14 NF1 patients in comparison to age- and sex-matched control individuals. The analysis included dual X-ray absorptiometry osteodensitometry, laboratory parameters, histomorphometric and quantitative backscattered electron imaging (qBEI) analyses of undecalcified bone biopsies. RESULTS: NF1 patients display significantly lower 25-(OH)-cholecalciferol serum levels and decreased BMD compared to control individuals. Histomorphometric analysis did not only reveal a reduced trabecular bone volume in biopsies from NF1 patients, but also a significantly increased osteoid volume and increased numbers of osteoblasts and osteoclasts. Moreover, qBEI analysis revealed a significant decrease of the calcium content in biopsies from NF1 patients. To address the question whether a normalization of calcium homeostasis improves BMD in NF1 patients, we treated four patients with cholecalciferol for 1 year, which resulted in a significant increase of BMD. CONCLUSION: Taken together, our data provide the first complete histomorphometric analysis from NF1 patients. Moreover, they suggest that low vitamin D levels significantly contribute to the skeletal defects associated with the disease.

Modelling neurofibromatosis type 1 tibial dysplasia and its treatment with lovastatin.

BACKGROUND: Bowing and/or pseudarthrosis of the tibia is a known severe complication of neurofibromatosis type 1 (NF1). Mice with conditionally inactivated neurofibromin (Nf1) in the developing limbs and cranium (Nf1Prx1) show bowing of the tibia caused by decreased bone mineralisation and increased bone vascularisation. However, in contrast to NF1 patients, spontaneous fractures do not occur in Nf1Prx1 mice probably due to the relatively low mechanical load. We studied bone healing in a cortical bone injury model in Nf1Prx1 mice as a model for NF1-associated bone disease. Taking advantage of this experimental model we explore effects of systemically applied lovastatin, a cholesterol-lowering drug, on the Nf1 deficient bone repair. METHODS: Cortical injury was induced bilaterally in the tuberositas tibiae in Nf1Prx1 mutant mice and littermate controls according to a method described previously. Paraffin as well as methacrylate sections were analysed from each animal. We divided 24 sex-matched mutant mice into a lovastatin-treated and an untreated group. The lovastatin-treated mice received 0.15 mg activated lovastatin by daily gavage. The bone repair process was analysed at three consecutive time points post injury, using histological methods, micro computed tomography measurements and in situ hybridisation. At each experimental time point, three lovastatin-treated mutant mice, three untreated mutant mice and three untreated control mice were analysed. The animal group humanely killed on day 14 post injury was expanded to six treated and six untreated mutant mice as well as six control mice. RESULTS: Bone injury repair is a complex process, which requires the concerted effort of numerous cell types. It is initiated by an inflammatory response, which stimulates fibroblasts from the surrounding connective tissue to proliferate and fill in the injury site with a provisional extracellular matrix. In parallel, mesenchymal progenitor cells from the periost are recruited into the injury site to become osteoblasts. In Nf1Prx1 mice bone repair is delayed and characterised by the excessive formation and the persistence of fibro-cartilaginous tissue and impaired extracellular matrix mineralisation. Correspondingly, expression of Runx2 is downregulated. High-dose systemic lovastatin treatment restores Runx2 expression and accelerates new bone formation, thus improving cortical bone repair in Nf1Prx1 tibia. The bone anabolic effects correlate with a reduction of the mitogen activated protein kinase pathway hyper-activation in Nf1-deficient cells. CONCLUSION: Our data suggest the potential usefulness of lovastatin, a drug approved by the US Food and Drug Administration in 1987 for the treatment of hypercholesteraemia, in the treatment of Nf1-related fracture healing abnormalities. The experimental model presented here constitutes a valuable tool for the pre-clinical stage testing of candidate drugs, targeting Nf1-associated bone dysplasia.

Decreased bone mineral density in neurofibromatosis-1 patients with spinal deformities.

A cross-sectional study was carried out to obtain data on the bone mineral density status of a group of neurofibromatosis-1 patients with spinal deformities, and to search for possible accompanying changes in the bone mineral turnover. Neurofibromatosis-1 is a heredofamiliar disorder that is associated with a variety of skeletal anomalies (mostly spinal deformities) in 10-50% of patients. Intraoperatively, a poor vertebral bone quality has been observed. Efforts have been made to identify factors preventing curve progression, to optimize operational planning and to explain the pathomechanism. As part of the preoperative evaluation, dual-energy X-ray absorptiometry was used to assess the bone mineral density of the lumbar spine in 12 patients with neurofibromatosis-1, supplemented by laboratory blood/urine investigations. A significant decrease in bone mineral density of the lumbar spine was measured. An inverse relation was suggested between the severity of scoliosis and the lumbar spine Z-scores. No pivotal alterations were identified in the laboratory measurements. The bony tissue abnormality observed intraoperatively in neurofibromatosis-1 patients may be described as a diminution of the axial bone mineral density. The biochemical parameters do not support the presence of hyperparathyroidism, renal disorders or other associated diseases influencing the bone mineral turnover. The evaluation of bone mineral density in the course of the preoperative planning is proposed in neurofibromatosis-1; the exact background and the role of a possible osteoporosis in the prognosis remain to be elucidated.

Positron emission tomography in children with neurofibromatosis-1.

Neurofibromatosis-1 is an autosomal dominant genetic disorder commonly associated with neuropsychological complications. Focal areas of high signal intensity on magnetic resonance imaging (MRI) scans occur commonly but have shown inconsistent correlation with neuropsychological problems. Positron emission tomography (PET) scans utilizing [18F]fluoro-2-deoxy-D-glucose and MRI studies were performed on 10 children with neurofibromatosis-1 and multiple focal areas of high signal intensity to evaluate the regional cerebral metabolic rate for glucose of these lesions and other central nervous system structures. Co-registered PET and MRI studies confirmed reduced glucose metabolism of large focal areas of high signal intensity. Visual inspection and semiquantitative analysis of PET images demonstrated thalamic hypometabolism and varying degrees of cortical inhomogeneity in all cases of neurofibromatosis-1 compared to normal controls. Although a primary defect of the thalamus or cerebral cortex has not been defined, the metabolic abnormalities of this study suggest a potential relationship between these structures and the neuropsychological dysfunctions noted in neurofibromatosis-1.

Children and adolescents with neurofibromatosis 1: a behavioral phenotype.

Twenty 6- to 17-year-old children with neurofibromatosis 1. (NF1) were compared to 20 age- and sex-matched siblings on a wide range of neuropsychological and behavioral dimensions. In familial cases, diagnostic status was confirmed by gene linkage with greater than 98% accuracy. Visual examinations that included assessments of visual evoked responses (VER) were performed on subjects with NF1. Forty-two percent of NF1 subjects had abnormal VER and underwent magnetic resonance imagery or computed tomography scans of the brain. On a variety of skills, subjects with NF1 performed more poorly than unaffected siblings. Children with NF1 were found to be less competent on measures of cognitive, language, and motor development, visual-spatial judgment, visual-motor integration, and academic achievement. Learning disabilities were common in children with NF1. Parents and teachers reported that NF1 subjects had internalizing problems and difficulty interacting with peers. A behavioral phenotype for NF1 and recommendations for preventative interventions are proposed.