Contribution of the corticospinal tract to motor impairment in spina bifida

Multiparametric prenatal imaging characterization of fetal brain edema in Chiari II malformation might help to select candidates for fetal surgery

OBJECTIVE

To identify brain edema in fetuses with Chiari II malformation using a multiparametric approach including structural T2-weighted, diffusion tensor imaging (DTI) metrics, and MRI-based radiomics.

METHODS

A single-center retrospective review of MRI scans obtained in fetuses with Chiari II was performed. Brain edema cases were radiologically identified using the following MR criteria: brain parenchymal T2 prolongation, blurring of lamination, and effacement of external CSF spaces. Fractional anisotropy (FA) values were calculated from regions of interest (ROI), including hemispheric parenchyma, internal capsule, and corticospinal tract, and compared group-wise. After 1:1 age matching and manual single-slice 2D segmentation of the fetal brain parenchyma using ITK-Snap, radiomics features were extracted using pyradiomics. Areas under the curve (AUCs) of the features regarding discriminating subgroups were calculated.

RESULTS

Ninety-one fetuses with Chiari II underwent a total of 101 MRI scans at a median gestational age of 24.4 weeks and were included. Fifty scans were visually classified as Chiari II with brain edema group and showed significantly reduced external CSF spaces compared to the nonedema group (9.8 vs. 18.3 mm, p < 0.001). FA values of all used ROIs were elevated in the edema group (p < 0.001 for all ROIs). The 10 most important radiomics features showed an AUC of 0.81 (95%CI: 0.71, 0.91) for discriminating between Chiari II fetuses with and without edema.

CONCLUSIONS

Brain edema in fetuses with Chiari II is common and radiologically detectable on T2-weighted fetal MRI sequences, and DTI-based FA values and radiomics features provide further evidence of microstructure differences between subgroups with and without edema.

CLINICAL RELEVANCE STATEMENT

A more severe phenotype of fetuses with Chiari II malformation is characterized by prenatal brain edema and more postnatal clinical morbidity and disability. Fetal brain edema is a promising prenatal MR imaging biomarker candidate for optimizing the risk-benefit evaluation of selection for fetal surgery.

KEY POINTS

Brain edema of fetuses prenatally diagnosed with Chiari II malformation is a common, so far unknown, association. DTI metrics and radiomics confirm microstructural differences between the brains of Chiari II fetuses with and without edema. Fetal brain edema may explain worse motor outcomes in this Chiari II subgroup, who may substantially benefit from fetal surgery.

Electrophysiological Study in the Right Upper and Lower Limbs in Infants with Lumbosacral Meningomyelocele and in Normal Infants: A Case-control Study

Objective

The study aimed to assess the electrophysiological parameters (Hofmann reflex [H-reflex] and motor nerve conduction velocity [MNCV]) on children's upper and lower limbs with lumbosacral meningomyelocele (MMC) and age-matched control to see the effect of the MMC on the cervical segment of the spinal cord.

Materials and Methods

The present study was performed on infants with lumbosacral MMC. Twenty-five infants were examined with a mean age of 50 days of either sex. Out of them, 13 infants were in control and the remaining 12 were diagnosed with MMC. The H-reflex parameter and MNCV were recorded in these children's right upper and lower limbs.

Results

H-reflex was elicited in all the control group babies. In MMC, the H-reflex was elicited in the upper limbs. However, H-reflex was not elicited in the lower limbs of a few MMC babies. The upper limb's H-reflex parameters and conduction velocity were significantly higher than those corresponding lower limbs in control babies. In MMC, where the H-reflex was elicited, such differences in the lower and upper limbs were not observed. However, the values of MNCV in the upper limb (right median nerve) were significantly less, and the values of Hmax in the lower limb (soleus muscle) were significantly more in MMC babies than in the control group.

Conclusions

The values of electrophysiological parameters were higher in the upper limbs as compared to the corresponding lower limbs in control. These values were not altered in the upper limbs than those corresponding lower limbs of MMC, suggesting that motor function development was impaired/delayed in the spinal segment cranial to MMC lesion, and motor impairment in MMC children is mostly a result of upper motor neuron dysfunction.

Association between ambulatory skills and diffusion tensor imaging of corpus callosal white matter in infants with spina bifida

OBJECTIVES

To assess brain white matter using diffusion tensor imaging (DTI) at 1 year of age in infants diagnosed with open neural tube defect (ONTD) and explore the association of DTI parameters with ambulatory skills at 30 months of age.

METHODS

Magnetic resonance imaging (MRI) was performed at an average of 12 months of age and included an echo planar axial DTI sequence with diffusion gradients along 20 non-collinear directions. TORTOISE software was used to correct DTI raw data for motion artifacts, and DtiStudio, DiffeoMap and RoiEditor were used for further postprocessing. DTI data were analyzed in terms of fractional anisotropy (FA), trace, radial diffusivity and axial diffusivity. These parameters reflect the integrity and maturation of white-matter motor pathways. At 30 months of age, ambulation status was evaluated by a developmental pediatrician, and infants were classified as ambulatory if they were able to walk independently with or without orthoses or as non-ambulatory if they could not. Linear mixed-effects method was used to examine the association between study outcomes and study group. Possible confounders were sought, and analyses were adjusted for age at MRI scan and ventricular size by including them in the regression model as covariates.

RESULTS

Twenty patients with ONTD were included in this study, including three cases that underwent postnatal repair and 17 cases that underwent prenatal repair. There were five ambulatory and 15 non-ambulatory infants evaluated at a mean age of 31.5 ± 5.7 months. MRI was performed at 50.3 (2-132.4) weeks postpartum. When DTI analysis results were compared between ambulatory and non-ambulatory infants, significant differences were observed in the corpus callosum (CC). Compared with non-ambulatory infants, ambulatory infants had increased FA in the splenium (0.62 (0.48-0.75) vs 0.41 (0.34-0.49); P = 0.01, adjusted P = 0.02), genu (0.64 (0.47-0.80) vs 0.47 (0.35-0.61); P = 0.03, adjusted P = 0.004) and body (0.55 (0.45-0.65) vs 0.40 (0.35-0.46), P = 0.01, adjusted P = 0.01). Reduced trace was observed in the CC of ambulatory children at the level of the splenium (0.0027 (0.0018-0.0037) vs 0.0039 (0.0034-0.0044) mm² /s; P = 0.04, adjusted P = 0.03) and genu (0.0029 (0.0020-0.0038) vs 0.0039 (0.0033-0.0045) mm² /s; P = 0.04, adjusted P = 0.01). In addition, radial diffusivity was reduced in the CC of the ambulatory children at the level of the splenium (0.00057 (0.00025-0.00089) vs 0.0010 (0.00084-0.00120) mm² /s; P = 0.02, adjusted P = 0.02) and the genu (0.00058 (0.00028-0.00088) vs 0.0010 (0.00085-0.00118) mm² /s; P = 0.02, adjusted P = 0.02). There were no differences in axial diffusivity between ambulatory and non-ambulatory children.

CONCLUSION

This study demonstrates a significant association between white matter integrity of connecting fibers of the corpus callosum, as assessed by DTI, and ambulatory skills at 30 months of age in infants with ONTD. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal Repair and Physical Functioning Among Children With Myelomeningocele: A Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

The Management of Myelomeningocele Study (MOMS), a randomized clinical trial of prenatal vs standard postnatal repair for myelomeningocele, found that prenatal repair reduced hydrocephalus and hindbrain herniation and improved motor function in children aged 12 to 30 months. The Management of Myelomeningocele Study Follow-up (MOMS2) was conducted in children at ages 5 to 10 years. The primary (neurocognitive) outcome has already been reported.

OBJECTIVE

To determine whether MOMS2 participants who had prenatal repair have better physical functioning than those with postnatal repair.

DESIGN, SETTING, AND PARTICIPANTS

Participants from MOMS were recruited for participation in the follow-up study, MOMS2, conducted from April 9, 2012, to April 15, 2017. For this secondary analysis of the randomized clinical trial, trained examiners without knowledge of the treatment group evaluated the physical characteristics, self-care skills, neurologic function, and mobility of the children. Physical functioning outcomes were compared between the prenatal and postnatal repair groups. MOMS2 was conducted at the same 3 clinical sites as MOMS. Home visits were conducted for families who were unable to travel to one of the clinical sites. Of the 161 children with myelomeningocele aged 5 to 10 years old enrolled in MOMS2, 154 had a physical examination and were included in the analyses.

EXPOSURES

Prenatal repair of myelomeningocele.

MAIN OUTCOMES AND MEASURES

Prespecified secondary trial outcomes of self-care skills, functional mobility, walking skills, and motor level.

RESULTS

This analysis included 78 children with postnatal repair (mean [SD] age, 7.4 [2.1] years; 50 girls [64.1%]; 69 White children [88.5%]) and 76 with prenatal repair (mean [SD] age, 7.5 [1.2] years; 43 boys [56.6%]; 70 White children [92.1%]). Children in the prenatal repair group were more competent with self-care skills (mean [SD] percentage of maximum FRESNO Scale score, 90.8% [9.6%] vs 85.5% [17.6%]) and were commonly community ambulators per the Modified Hoffer Classification (51.3% prenatal vs 23.1% postnatal; adjusted relative risk [aRR] for sex, 1.70; 95% CI, 1.23-2.34). Children with prenatal repair also performed the 10-m walk test 1 second faster (difference in medians, 1.0; 95% CI, 0.3-1.7), had better gait quality (adjusted mean difference for home distances of 5 m, 1.71; 95% CI, 1.14-2.54), and could perform higher-level mobility skills (adjusted mean difference for motor total, 5.70; 95% CI, 1.97-11.18). Children in the prenatal repair group were less likely to have a motor function level worse than their anatomic lesion level (aRR, 0.44; 95% CI, 0.25-0.77).

CONCLUSIONS AND RELEVANCE

This secondary analysis of a randomized clinical trial found that the physical functioning benefits of prenatal repair for myelomeningocele reported at age 30 months persisted into school age. These findings indicate the benefit of prenatal repair of myelomeningocele for school-aged children.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00060606.

Urodynamic Study Findings Prior to Myelomeningocele Repair in Neonates

Introduction

Myelomeningocele (MMC) is the most common cause of neurogenic bladder dysfunction in children. Neurogenic bladder dysfunction is developed before birth due to autonomous nervous system affected prenatally in patients with MMC. The aim of this study was to share urodynamic study findings before MMC repair and to discuss the correlation with neurological evaluation.

Materials and Methods

We prospectively studied 37 patients who underwent surgery for MMC repair in our institution in the first 20 h of their lives between 2013 and 2016. All patients were evaluated by a neurosurgeon, neonatologist, and pediatric surgeon. Urodynamic study was performed in first 18h of life before MMC repair in all patients. Lesion level, occurrence of hydrocephalus, neurological functions, spinal deformities, and urodynamic study results were analyzed.

Results

The study included 18 female and 19 male patients. Overactive detrusor was detected in 22 patients, and hypoactive detrusor was detected in 5 patients. Overactive sphincter muscle was detected in 32 patients, and hypoactive sphincter was detected in 2 patients. Detrusor-sphincter dyssynergia was present in 34 patients.

Conclusion

Detailed analysis of urodynamic study findings in larger patient groups may be important to understand the physiopathology of prenatal damage in patients with MMC.

Interrater Reliability of the Pediatric Neuromuscular Recovery Scale in Children with Spina Bifida

Purpose: The purpose of this study was to examine the interrater reliability of the Pediatric Neuromuscular Recovery Scale (Peds NRS) to classify motor capacity in children with myelomeningocele (MMC) form of spina bifida.Methods: Twenty-one children with MMC (1.5-10 years of age) were each scored on the Peds NRS three times: two live testing sessions and one video recorded session. Every child was scored by two physical therapists and one occupational therapist. Interrater reliability was analyzed using intraclass correlation coefficients (ICC) for individual items and the summary score.Results: Strong interrater reliability was determined for the overall Peds NRS score (ICC = 0.89; 95% CI, .80-.95). Eleven of 16 individual items exhibited good to excellent reliability (ICC ≥ 0.80). Pediatric clinicians were able to reliably administer and score the Peds NRS on children with MMC, representing a wide range of ages and functional levels.

Posterior axis formation requires Dlx5/Dlx6 expression at the neural plate border

Neural tube defects (NTDs), one of the most common birth defects in human, present a multifactorial etiology with a poorly defined genetic component. The Dlx5 and Dlx6 bigenic cluster encodes two evolutionary conserved homeodomain transcription factors, which are necessary for proper vertebrate development. It has been shown that Dlx5/6 genes are essential for anterior neural tube closure, however their role in the formation of the posterior structures has never been described. Here, we show that Dlx5/6 expression is required during vertebrate posterior axis formation. Dlx5 presents a similar expression pattern in neural plate border cells during posterior neurulation of zebrafish and mouse. Dlx5/6-inactivation in the mouse results in a phenotype reminiscent of NTDs characterized by open thoracic and lumbar vertebral arches and failure of epaxial muscle formation at the dorsal midline. The dlx5a/6a zebrafish morphants present posterior NTDs associated with abnormal delamination of neural crest cells showing altered expression of cell adhesion molecules and defects of motoneuronal development. Our findings provide new molecular leads to decipher the mechanisms of vertebrate posterior neurulation and might help to gather a better understanding of human congenital NTDs etiology.

Safety of Transcranial Magnetic Stimulation in Children: A Systematic Review of the Literature

BACKGROUND

Data and best practice recommendations for transcranial magnetic stimulation (TMS) use in adults are largely available. Although there are fewer data in pediatric populations and no published guidelines, its practice in children continues to grow.

METHODS

We performed a literature search through PubMed to review all TMS studies from 1985 to 2016 involving children and documented any adverse events. Crude risks were calculated per session.

RESULTS

Following data screening we identified 42 single-pulse and/or paired-pulse TMS studies involving 639 healthy children, 482 children with central nervous system disorders, and 84 children with epilepsy. Adverse events occurred at rates of 3.42%, 5.97%, and 4.55% respective to population and number of sessions. We also report 23 repetitive TMS studies involving 230 central nervous system and 24 children with epilepsy with adverse event rates of 3.78% and 0.0%, respectively. We finally identified three theta-burst stimulation studies involving 90 healthy children, 40 children with central nervous system disorder, and no epileptic children, with adverse event rates of 9.78% and 10.11%, respectively. Three seizures were found to have occurred in central nervous system disorder individuals during repetitive TMS, with a risk of 0.14% per session. There was no significant difference in frequency of adverse events by group (P = 0.988) or modality (P = 0.928).

CONCLUSIONS

Available data suggest that risk from TMS/theta-burst stimulation in children is similar to adults. We recommend that TMS users in this population follow the most recent adult safety guidelines until sufficient data are available for pediatric specific guidelines. We also encourage continued surveillance through surveys and assessments on a session basis.

Factors Associated with Mobility Outcomes in a National Spina Bifida Patient Registry

OBJECTIVE

To provide descriptive data on ambulatory ability and muscle strength in a large cohort of individuals with spina bifida enrolled in a National Spina Bifida Patient Registry and to investigate factors associated with ambulatory status.

DESIGN

Cross-sectional analysis of data from a multisite patient registry.

RESULTS

Descriptive analysis of mobility variables for 2604 individuals with spina bifida aged 5 and older are presented from 19 sites in the United States. Analysis of a subset of National Spina Bifida Patient Registry data from 380 individuals from 3 sites accompanied by data from a specialized spina bifida electronic medical record revealed that those with no history of a shunt, lower motor level, and no history of hip or knee contracture release surgery were more likely to be ambulatory at the community level than at the household or wheelchair level.

CONCLUSION

This study is the first to examine factors associated with ambulatory status in a large sample of individuals with myelomeningocele and nonmyelomeningocele subtypes of spina bifida. Results of this study delineate the breadth of strength and functional abilities within the different age groups and subtypes of spina bifida. The results may inform physicians of the characteristics of those with varying ambulatory abilities.