Predicting myofiber cross-sectional area and triglyceride content with electrical impedance myography: A study in db/db mice.

BACKGROUND: Electrical impedance myography (EIM) provides insight into muscle composition and structure. We sought to evaluate its use in a mouse obesity model characterized by myofiber atrophy. METHODS: We applied a prediction algorithm, ie, the least absolute shrinkage and selection operator (LASSO), to surface, needle array, and ex vivo EIM data from db/db and wild-type mice and assessed myofiber cross-sectional area (CSA) histologically and triglyceride (TG) content biochemically. RESULTS: EIM data from all three modalities provided acceptable predictions of myofiber CSA with average root mean square error (RMSE) of 15% in CSA (ie, ±209 µm2 for a mean CSA of 1439 µm2 ) and TG content with RMSE of 30% in TG content (ie, ±7.3 nmol TG/mg muscle for a mean TG content of 25.4 nmol TG/mg muscle). CONCLUSIONS: EIM combined with a predictive algorithm provides reasonable estimates of myofiber CSA and TG content without the need for biopsy.

Visual field outcomes in children treated for neurofibromatosis type 1-associated optic pathway gliomas: a multicenter retrospective study.

BACKGROUND: Optic pathway gliomas associated with neurofibromatosis type 1 (NF1-OPGs) may adversely affect visual acuity, but data regarding visual field (VF) outcomes after treatment in children are limited. The purpose of this study was to investigate the effects of NF1-OPGs on VF function in a large cohort of children after treatment with chemotherapy. METHODS: We performed a retrospective, international, multicenter study of VF outcomes in patients treated with chemotherapy for NF1-OPGs. RESULTS: A total of 25 participants underwent VF testing using formal perimetric techniques. At the end of treatment, 19 participants (76%) had persistent VF deficits. Formal VF testing was available for 16 participants (64%) at initiation and completion of treatment. Of the 16 children who underwent VF testing at initiation and completion of treatment, 7 (44%) showed stability of VF changes, 3 (19%) showed improvement of VF function, and 6 (38%) had worsening of VFs. Improvement or worsening of VF outcome did not always correlate with visual acuity outcome. Posterior tumor location involving the optic tracts and radiations was associated with more frequent and more profound VF defects. CONCLUSIONS: In our study cohort, children undergoing initial chemotherapy for NF1-OPGs had a high prevalence of VF loss, which could be independent of visual acuity loss. A larger, prospective study is necessary to fully determine the prevalence of VF loss and the effects of chemotherapy on VF outcomes in children with NF1-OPGs.

IQ predictors in pediatric opsoclonus myoclonus syndrome: a large international cohort study.

AIM: To determine predictors of full-scale IQ (FSIQ) in an international pediatric opsoclonus myoclonus syndrome (OMS) cohort. METHOD: In this retrospective and prospective cohort study at three academic medical centers (2006-2013), the primary outcome measure, FSIQ, was categorized based on z-score: above average (≥+1), average (+1 to -1), mildly impaired (-1 to -2), and impaired (<-2). Univariate analysis and multivariable linear regression modeling using stepwise selection with Akaike's information criterion was performed to understand the relationship between exposures and FSIQ. RESULTS: Of 81 participants, 37 with sufficient data had mean FSIQ 84.38 (SD 20.55) and median 90 (40-114) at latest available evaluation (mean age 8y 5mo). Twenty (54%), nine (24.3%), and eight (21.6%) had normal, mildly impaired, and impaired FSIQ respectively. The final multivariable linear regression model included 34 participants with evaluable data: number of relapses occurring before neuropsychological testing (p<0.001) and OMS severity score at last follow-up (p<0.001) predicted FSIQ (adjusted R2 =0.64). There was a mean decrease of 2.4 FSIQ points per OMS relapse. INTERPRETATION: Number of relapses negatively correlates with FSIQ in pediatric OMS. Demographic and clinical measures available at OMS onset did not predict FSIQ. Strategies to reduce OMS relapses may improve intellectual outcomes.

Natural History and Management of Incidentally Discovered Focal Brain Lesions Indeterminate for Tumor in Children.

BACKGROUND: The incidental discovery of brain lesions in children has increased due to greater utilization of neuroimaging. Standardized surveillance and management guidelines following the discovery of such lesions remain nonexistent. OBJECTIVE: To study the natural history and management of incidental brain lesions in children. METHODS: A retrospective analysis of pediatric patients who were treated at our institution between 2000 and 2016 with incidentally detected brain lesions that were indeterminate for neoplasm on MRI. RESULTS: We identified 445 patients with incidental brain abnormalities of whom 144 had lesions indeterminate for neoplasm. Average age at diagnosis was 11.2 (SD = 4.14) yr and average follow-up was 3.8 yr (range 1-13.2 yr). Lesions showed no progression in 112 patients (77.8%), whereas progression was detected in 31 patients (21.5%). Mean time to progression was 32.3 months (SD = 24.4). A change in management was made in 13/144 patients (9%), which included surgical resection (n = 11), biopsy (n = 1), and lumbar puncture (n = 1). Lesion size, location, multiplicity, new-onset symptoms, associated contrast enhancement, or edema were not predictive of radiologic progression. Larger lesions and those with contrast enhancement or edema were significantly more likely to undergo surgery (P < .001 each). Median geometric diameter of lesions that did not undergo surgery was 6.5 mm, whereas that of surgically resected lesions was 12.5 mm (P < .001). CONCLUSION: Most incidental brain lesions indeterminate for neoplasm have an indolent, benign course. For asymptomatic patients with radiologically stable lesions, we recommend conservative management with MRI and clinical surveillance at 6, 12, 24, 36, and 60 mo after detection.

The Connectivity Fingerprint of the Fusiform Gyrus Captures the Risk of Developing Autism in Infants with Tuberous Sclerosis Complex.

Tuberous sclerosis complex (TSC) is a rare genetic disorder characterized by benign tumors throughout the body; it is generally diagnosed early in life and has a high prevalence of autism spectrum disorder (ASD), making it uniquely valuable in studying the early development of autism, before neuropsychiatric symptoms become apparent. One well-documented deficit in ASD is an impairment in face processing. In this work, we assessed whether anatomical connectivity patterns of the fusiform gyrus, a central structure in face processing, capture the risk of developing autism early in life. We longitudinally imaged TSC patients at 1, 2, and 3 years of age with diffusion compartment imaging. We evaluated whether the anatomical connectivity fingerprint of the fusiform gyrus was associated with the risk of developing autism measured by the Autism Observation Scale for Infants (AOSI). Our findings suggest that the fusiform gyrus connectivity captures the risk of developing autism as early as 1 year of age and provides evidence that abnormal fusiform gyrus connectivity increases with age. Moreover, the identified connections that best capture the risk of developing autism involved the fusiform gyrus and limbic and paralimbic regions that were consistent with the ASD phenotype, involving an increased number of left-lateralized structures with increasing age.

Increased electroencephalography connectivity precedes epileptic spasm onset in infants with tuberous sclerosis complex.

OBJECTIVE: To identify whether abnormal electroencephalography (EEG) connectivity is present before the onset of epileptic spasms (ES) in infants with tuberous sclerosis complex (TSC). METHODS: Scalp EEG recordings were collected prospectively in infants diagnosed with TSC in the first year of life. This study compared the earliest recorded EEG from infants prior to ES onset (n = 16) and from infants who did not develop ES (n = 28). Five minutes of stage II or quiet sleep was clipped and filtered into canonical EEG frequency bands. Mutual information values between each pair of EEG channels were compared directly and used as a weighted graph to calculate graph measures of global efficiency, characteristic path length, average clustering coefficient, and modularity. RESULTS: At the group level, infants who later developed ES had increased EEG connectivity in sleep. They had higher mutual information values between most EEG channels in all frequency bands adjusted for age. Infants who later developed ES had higher global efficiency and average clustering coefficients, shorter characteristic path lengths, and lower modularity across most frequency bands adjusted for age. This suggests that infants who went on to develop ES had increased local and long-range EEG connectivity with less segregation of graph regions into distinct modules. SIGNIFICANCE: This study suggests that increased neural connectivity precedes clinical ES onset in a cohort of infants with TSC. Overconnectivity may reflect progressive pathologic network synchronization culminating in generalized ES. Further research is needed before scalp EEG connectivity measures can be used as a potential biomarker of ES risk and treatment response in pre-symptomatic infants with TSC.

A case-control analysis of maternal diet and risk of neural tube defects in Bangladesh.

OBJECTIVES: Mothers need a nutrient-rich diet for healthy neural tube development. Neural tube defect risk can be reduced through fortifying grain products with folic acid and taking folic acid supplements. Fortification is not required in Bangladesh. Maternal supplement use rates are low, similar to other countries. This study evaluates maternal dietary intake during pregnancy to identify possible interventions. METHODS: A food frequency questionnaire (FFQ) assessed maternal diet. The primary aim compared dietary intake (calories, fat, carbohydrate, protein, fiber, vitamins, and minerals) between mothers of infants with myelomeningocele (cases) and mothers of controls. Secondary aims included (i) comparing foods consumed and (ii) evaluating if rice intake correlated with arsenic exposure. Paired t-tests, Wilcoxon signed rank tests, McNemar's chi-squared test, and linear regression were used. RESULTS: This study included 110 matched mother-infant pairs (55 cases/55 controls). Mothers of cases and mothers of controls had similar caloric intake [median 2406 kcal/day vs. 2196 kcal/day (p = 0.071)]. Mothers in both groups consumed less than half the daily recommended 600 µg of folate. Diets were potentially deficient in vitamins A, D, E, potassium, sodium, and iron. Steamed rice was the primary food consumed for both groups, and this rice intake was not associated with toenail arsenic. CONCLUSIONS: Dietary interventions should increase folate, vitamins A, D, E, potassium, sodium, and iron intake in Bangladeshi mothers. Folic acid fortification of grain products maybe the only viable strategy to achieve adequate folate intake for mothers. Given the central role of rice to the Bangladeshi diet, fortifying rice may be a viable option.

Longitudinal Effects of Everolimus on White Matter Diffusion in Tuberous Sclerosis Complex.

OBJECTIVE: We studied the longitudinal effects of everolimus, an inhibitor of the mammalian target of rapamycin (mTOR), on callosal white matter diffusion tensor imaging (DTI) in patients with tuberous sclerosis complex (TSC). METHODS: Serial imaging data spanning nine years were used from the open label, Phase I/II trial (NCT00411619) and open-ended extension phase of everolimus for the treatment of subependymal giant cell astrocytoma associated with TSC. From 28 patients treated with everolimus and 25 untreated control patients, 481 MRI scans were available. Rigorous quality control resulted in omission of all scans with diffusion weighted imaging data in less than 15 directions or more than eight artifacted volumes, and all postsurgical scans. We applied a linear mixed-effects model to the remaining 125 scans (17 treated, 24 controls) for longitudinal analysis of each DTI metric of manually drawn callosal regions of interest. RESULTS: On a population level, mTOR inhibition was associated with a decrease in mean diffusivity. In addition, in treated patients only, a decrease of radial diffusivity was observed; in untreated patients only, an increase of axial diffusivity was seen. In patients below age 10, effect-sizes were consistently greater, and longer treatment was associated with greater rate of diffusion change. There was no correlation between DTI metrics and reduction of subependymal giant cell astrocytoma volume, or everolimus serum levels. CONCLUSIONS: Effects from mTOR overactivity on white matter microstructural integrity in TSC were modified through pharmacologic inhibition of mTOR. These changes sustained over time, were greater with longer treatment and in younger patients during a time of rapid white matter maturation.

Estimating Myofiber Size With Electrical Impedance Myography: a Study In Amyotrophic Lateral Sclerosis MICE.

INTRODUCTION: A method for quantifying myofiber size noninvasively would find wide use, including primary diagnosis and evaluating response to therapy. METHODS: Using prediction algorithms, including the least absolute shrinkage and selection operator, we applied multifrequency electrical impedance myography (EIM) to amyotrophic lateral sclerosis superoxide dismutase 1 G93A mice of different ages and assessed myofiber size histologically. RESULTS: Multifrequency EIM data provided highly accurate predictions of myofiber size, with a root mean squared error (RMSE) of only 14% in mean myofiber area (corresponding to ± 207 µm2 for a mean area of 1,488 µm2 ) and an RMSE of only 8.8% in predicting the coefficient of variation in fiber size distribution. DISCUSSION: This impedance-based approach provides predictive variables to assess myofiber size and distribution with good accuracy, particularly in diseases in which myofiber atrophy is the predominant histological feature, without the requirement for biopsy or burdensome quantification. Muscle Nerve 58: 713-717, 2018.

Cerebellar volume as an imaging marker of development in infants with tuberous sclerosis complex.

OBJECTIVE: In this cohort analysis, we studied 1-year-old infants with tuberous sclerosis complex (TSC), correlating volumes of cerebellar structures with neurodevelopmental measures. METHODS: We analyzed data from a prospective biomarker study in infants with TSC (ClinicalTrials.gov NCT01780441). We included participants aged 12 months with an identified mutation of TSC1 or TSC2. Using MRI segmentation performed with the PSTAPLE algorithm, we measured relative volumes (structure volume divided by intracranial contents volume) of the following structures: right/left cerebellar white matter, right/left cerebellar exterior, vermal lobules I-V, vermal lobules VI-VII, and vermal lobules VIII-X. We correlated relative volumes to Mullen Scales of Early Learning (MSEL) scores. RESULTS: There were 70 participants (mean age 1.03 [0.11] years): n = 11 had a TSC1 mutation; n = 59 had a TSC2 mutation. For patients with TSC2 mutation, for every percentage increase in total cerebellar volume, there was an approximate 10-point increase in MSEL composite score (ß = 10.47 [95% confidence interval 5.67, 15.27], p < 0.001). For patients with TSC1 mutation, the relationship between cerebellar volume and MSEL composite score was not statistically significant (ß = -10.88 [95% confidence interval -22.16, 0.41], p = 0.06). For patients with TSC2 mutation, there were positive slopes when regressing expressive language and visual reception skills with volumes of nearly all cerebellar structures (p ≤ 0.29); there were also positive slopes when regressing receptive language skills, gross motor skills, and fine motor skills with volumes of cerebellar right/left exterior (p ≤ 0.014). CONCLUSIONS: Cerebellar volume loss-perhaps reflecting Purkinje cell degeneration-may predict neurodevelopmental severity in patients with TSC2 mutations.

Purkinje cells derived from TSC patients display hypoexcitability and synaptic deficits associated with reduced FMRP levels and reversed by rapamycin.

Accumulating evidence suggests that cerebellar dysfunction early in life is associated with autism spectrum disorder (ASD), but the molecular mechanisms underlying the cerebellar deficits at the cellular level are unclear. Tuberous sclerosis complex (TSC) is a neurocutaneous disorder that often presents with ASD. Here, we developed a cerebellar Purkinje cell (PC) model of TSC with patient-derived human induced pluripotent stem cells (hiPSCs) to characterize the molecular mechanisms underlying cerebellar abnormalities in ASD and TSC. Our results show that hiPSC-derived PCs from patients with pathogenic TSC2 mutations displayed mTORC1 pathway hyperactivation, defects in neuronal differentiation and RNA regulation, hypoexcitability and reduced synaptic activity when compared with those derived from controls. Our gene expression analyses revealed downregulation of several components of fragile X mental retardation protein (FMRP) targets in TSC2-deficient hiPSC-PCs. We detected decreased expression of FMRP, glutamate receptor δ2 (GRID2), and pre- and post-synaptic markers such as synaptophysin and PSD95 in the TSC2-deficient hiPSC-PCs. The mTOR inhibitor rapamycin rescued the deficits in differentiation, synaptic dysfunction, and hypoexcitability of TSC2 mutant hiPSC-PCs in vitro. Our findings suggest that these gene expression changes and cellular abnormalities contribute to aberrant PC function during development in TSC affected individuals.

Everolimus for treatment of tuberous sclerosis complex-associated neuropsychiatric disorders.

Objective: To evaluate if short-term treatment with everolimus was safe and could improve neurocognition and behavior in children with TSC. Methods: This was a prospective, double-blind randomized, placebo-controlled two-center phase II study. Participants diagnosed with TSC and age 6-21 years were treated with 4.5 mg/m2 per day of oral everolimus (n = 32) or matching placebo (n = 15) taken once daily for 6 months. For efficacy, a comprehensive neurocognitive and behavioral evaluation battery was performed at baseline, 3 months, and 6 months. For safety, adverse events recorded continuously via patient diary were categorized and graded per NCI Common Toxicity Criteria for Adverse Events, version 3.0 (CTCAE 3.0). Analyses were performed on the intention-to-treat population (n = 47). Results: Nearly all assessment measures failed to demonstrate significant differences between the two groups at the end of 6 months. Only one measure each of executive function (Cambridge Neuropsychological Test Automated Battery Stockings of Cambridge) favoring placebo (P = 0.025) and social cognition (Social Responsiveness Scale Social Cognition Subscale) favoring everolimus (P = 0.011) was observed. A total of 473 adverse events (AE) were reported. The average number of total AE per subject was similar for both placebo and everolimus. Most were mild or moderate in severity and serious AE were rare. Interpretation: While safe, oral everolimus administered once daily for 6 months did not significantly improve neurocognitive functioning or behavior in children with TSC.

Effect of Angiofibromas on Quality of Life and Access to Care in Tuberous Sclerosis Patients and Their Caregivers.

BACKGROUND/OBJECTIVES: Facial angiofibromas (AF) have the potential to cause disfigurement in children with tuberous sclerosis complex (TSC). Facial disfigurement can impact the quality of life (QoL) of individuals and their families, leading to negative psychosocial outcomes. QoL has not been studied in TSC patients with AF. METHODS: We conducted a cross-sectional survey study to investigate QoL of TSC patients with AF and their caregivers and to explore the current state of access to treatment for AF. TSC patients and caregivers in TSC clinic at Boston Children's Hospital and through the Tuberous Sclerosis Alliance were recruited to complete QoL surveys including the CADIS, CDLQI, and Skindex-teen questionnaires, and a survey on access to treatment of AF. RESULTS: Fifty-eight patients with TSC and 161 caregivers participated in the study. Caregivers of patients with AF had significantly poorer QoL scores compared to caregivers of those without AF, as measured by a modified CADIS questionnaire (mean 31.7 vs. 11.7, p = 0.004). Among patients with AF, those who received treatment had significantly better QoL scores compared with those without treatment, as measured by the CDLQI (mean 3.8 vs. 9.5, p = 0.001). Forty-one and two-tenths percent of subjects reported never receiving treatment for AF. Forty-seven and three-tenths percent of subjects were prescribed topical rapamycin, 47.7% of whom experienced difficulty with insurance coverage. CONCLUSIONS: Presence and lack of treatment of AF significantly impacts QoL in TSC patients and their caregivers. Access to care for AF is limited by multiple factors and should be addressed by clinicians working with this patient population.

Incidence, risk factors, and longitudinal outcome of seizures in long-term survivors of pediatric brain tumors.

OBJECTIVE: Seizures are common during and after treatment for a primary brain tumor. Our objective was to describe the incidence and risk factors for seizures in long-term survivors of pediatric brain tumors. METHODS: In a retrospective, longitudinal study, we reviewed all consecutive patients during a 12-month period who were at least 2 years post initial diagnosis of a brain tumor. Data collection included age at diagnosis, length of follow-up, extent of initial resection, tumor histology, and treatment modalities. For patients who had experienced seizures at any time, the timing and frequency of seizures, seizure semiology, electroencephalography results, and anticonvulsant use were recorded. Univariate analyses and logistic regression were performed to assess risk factors. RESULTS: The cohort included 298 patients (140 female). Average duration of follow-up was 7.6 years. Initial surgical resection was gross-total in 109 patients, and subtotal for 143. Twenty-nine patients underwent biopsy alone and 17 had no surgical intervention. Tumor location included posterior fossa (104; 36%), midline (98; 34%), cortical (85; 29%), and other (11; 3%). Most frequent diagnoses were low grade glioma, medulloblastoma, and ependymoma. Other treatments included cranial irradiation (N = 163) and chemotherapy (n = 127). Tumor recurrence occurred in 92 patients (30%). Seventy-one patients had seizures (24%). Ongoing seizures at the time of most recent follow-up were present in 42 patients. Risk factors for seizures included tumor location, tumor histology, tumor recurrence, and incomplete resection at time of initial presentation. SIGNIFICANCE: Seizures are a frequent comorbidity in pediatric brain tumor survivors, seen at presentation in 24% of patients and ongoing in 14%. Factors predisposing to seizures include tumor pathology (low/high grade glioma, glioneuronal tumor), cortical location, and subtotal resection. These data may assist in identification and management of patients at highest risk for seizures as well as identification of patients for potential treatment trials with antiepileptogenic agents.

Bayesian mixed-effects location and scale models for multivariate longitudinal outcomes: an application to ecological momentary assessment data.

In the statistical literature, the methods to understand the relationship of explanatory variables on each individual outcome variable are well developed and widely applied. However, in most health-related studies given the technological advancement and sophisticated methods of obtaining and storing data, a need to perform joint analysis of multivariate outcomes while explaining the impact of predictors simultaneously and accounting for all the correlations is in high demand. In this manuscript, we propose a generalized approach within a Bayesian framework that models the changes in the variation in terms of explanatory variables and captures the correlations between the multivariate continuous outcomes by the inclusion of random effects at both the location and scale levels. We describe the use of a spherical transformation for the correlations between the random location and scale effects in order to apply separation strategy for prior elicitation while ensuring positive semi-definiteness of the covariance matrix. We present the details of our approach using an example from an ecological momentary assessment study on adolescents.