Project description:This work is a modified version of the Casey Holter Memorial prize essay presented to the Society for Research into Hydrocephalus and Spina Bifida, June 29th 2007, Heidelberg, Germany. It describes the origin and consequences of the Chiari malformation, and proposes that hydrocephalus is caused by inadequate central nervous system (CNS) venous drainage. A new hypothesis regarding the pathogenesis, anencephaly and spina bifida is described.Any volume increase in the central nervous system can increase venous pressure. This occurs because veins are compressible and a CNS volume increase may result in reduced venous blood flow. This has the potential to cause progressive increase in cerebrospinal fluid (CSF) volume. Venous insufficiency may be caused by any disease that reduces space for venous volume. The flow of CSF has a beneficial effect on venous drainage. In health it moderates central nervous system pressure by moving between the head and spine. Conversely, obstruction to CSF flow causes localised pressure increases, which have an adverse effect on venous drainage.The Chiari malformation is associated with hindbrain herniation, which may be caused by low spinal pressure relative to cranial pressure. In these instances, there are hindbrain-related symptoms caused by cerebellar and brainstem compression. When spinal injury occurs as a result of a Chiari malformation, the primary pathology is posterior fossa hypoplasia, resulting in raised spinal pressure. The small posterior fossa prevents the flow of CSF from the spine to the head as blood enters the central nervous system during movement. Consequently, intermittent increases in spinal pressure caused by movement, result in injury to the spinal cord. It is proposed that posterior fossa hypoplasia, which has origins in fetal life, causes syringomyelia after birth and leads to damage to the spinal cord in spina bifida. It is proposed that hydrocephalus may occur as a result of posterior fossa hypoplasia, where raised pressure occurs as a result of obstruction to flow of CSF from the head to the spine, and cerebral injury with raised pressure occurs in anencephaly by this mechanism.The current view of dysraphism is that low central nervous system pressure and exposure to amniotic fluid, damage the central nervous system. The hypothesis proposed in this essay supports the view that spina bifida is a manifestation of progressive hydrocephalus in the fetus. It is proposed that that mesodermal growth insufficiency influences both neural tube closure and central nervous system pressure, leading to dysraphism.
Project description:ObjectiveTo assess whether the severity of cases of spina bifida changed after the institution of mandatory folic acid fortification in the US.Study designSix active population-based birth defects programs provided data on cases of spina bifida for 1992-1996 (prefortification period) and 1999-2016 (postfortification period). The programs contributed varying years of data. Case information included both a medical record verbatim text description of the spina bifida diagnosis and spina bifida codes (International Classification of Diseases, Clinical Modification, or a modified birth defects surveillance coding system). Comparing the prefortification and postfortification periods, aORs for case severity (upper-level lesions [cervical, thoracic] vs lower-level lesions [lumbar, sacral]) and prevalence ratios (PRs) were estimated.ResultsA total of 2593 cases of spina bifida (out of 7 816 062 live births) met the inclusion criteria, including 573 cases from the prefortification period and 2020 cases from the postfortification period. Case severity decreased by 70% (aOR, 0.30; 95% CI, 0.26-0.35) between the fortification periods. The decrease was most pronounced for non-Hispanic White mothers. Overall spina bifida prevalence declined by 23% (PR, 0.77; 95% CI, 0.71-0.85), with similar reductions seen across the early, mid, and recent postfortification periods. A statistically significant decrease in upper-level lesions occurred in the postfortification period compared with the prefortification period (PR, 0.28; 95% CI, 0.22-0.34), whereas the prevalence of lower-level lesions remained relatively similar (PR, 0.94; 95% CI, 0.84-1.05).ConclusionsThe severity of spina bifida cases decreased after mandatory folic acid fortification in the US. Further examination is warranted to better understand the potential effect of folic acid on spina bifida severity.
Project description:Neural tube defects (NTDs) are severe congenital abnormalities, caused by failed closure of neural tube during early embryonic development. Periconceptional folic acid (FA) supplementation greatly reduces the risk of NTDs. However, the molecular mechanisms behind NTDs and the preventive role of FA remain unclear. Here, we use human induced pluripotent stem cells (iPSCs) derived from fetuses with spina bifida aperta (SBA) to study the pathophysiology of NTDs and explore the effects of FA exposure. We report that FA exposure in SBA model is necessary for the proper formation and maturation of neural tube structures and robust differentiation of mesodermal derivatives. Additionally, we show that the folate antagonist methotrexate dramatically affects the formation of neural tube structures and FA partially reverts this aberrant phenotype. In conclusion, we present a novel model for human NTDs and provide evidence that it is a powerful tool to investigate the molecular mechanisms underlying NTDs, test drugs for therapeutic approaches.
Project description:Spina bifida is a birth defect in which the vertebral column is open, often with spinal cord involvement. The most clinically significant subtype is myelomeningocele (open spina bifida), which is a condition characterized by failure of the lumbosacral spinal neural tube to close during embryonic development. The exposed neural tissue degenerates in utero, resulting in neurological deficit that varies with the level of the lesion. Occurring in approximately 1 per 1,000 births worldwide, myelomeningocele is one of the most common congenital malformations, but its cause is largely unknown. The genetic component is estimated at 60-70%, but few causative genes have been identified to date, despite much information from mouse models. Non-genetic maternal risk factors include reduced folate intake, anticonvulsant therapy, diabetes mellitus and obesity. Primary prevention by periconceptional supplementation with folic acid has been demonstrated in clinical trials, leading to food fortification programmes in many countries. Prenatal diagnosis is achieved by ultrasonography, enabling women to seek termination of pregnancy. Individuals who survive to birth have their lesions closed surgically, with subsequent management of associated defects, including the Chiari II brain malformation, hydrocephalus, and urological and orthopaedic sequelae. Fetal surgical repair of myelomeningocele has been associated with improved early neurological outcome compared with postnatal operation. Myelomeningocele affects quality of life during childhood, adolescence and adulthood, posing a challenge for individuals, families and society as a whole. For an illustrated summary of this Primer, visit: http://go.nature.com/fK9XNa.
Project description:The curly tail mouse provides a model for neural tube defects (spina bifida and exencephaly) that are resistant to prevention by folic acid. The major ct gene, responsible for spina bifida, corresponds to a hypomorphic allele of grainyhead-like 3 (Grhl3) but the frequency of NTDs is strongly influenced by modifiers in the genetic background. Moreover, exencephaly in the curly tail strain is not prevented by reinstatement of Grhl3 expression. In the current study we found that expression of Mthfd1L, encoding a key component of mitochondrial folate one-carbon metabolism (FOCM), is significantly reduced in ct/ct embryos compared to a partially congenic wild-type strain. This expression change is not attributable to regulation by Grhl3 or the genetic background at the Mthfd1L locus. Mitochondrial FOCM provides one-carbon units as formate for FOCM reactions in the cytosol. We found that maternal supplementation with formate prevented NTDs in curly tail embryos and also resulted in increased litter size. Analysis of the folate profile of neurulation-stage embryos showed that formate supplementation resulted in an increased proportion of formyl-THF and THF but a reduction in proportion of 5-methyl THF. In contrast, THF decreased and 5-methyl THF was relatively more abundant in the liver of supplemented dams than in controls. In embryos cultured through the period of spinal neurulation, incorporation of labelled thymidine and adenine into genomic DNA was suppressed by supplemental formate, suggesting that de novo folate-dependent biosynthesis of nucleotides (thymidylate and purines) was enhanced. We hypothesise that reduced Mthfd1L expression may contribute to susceptibility to NTDs in the curly tail strain and that formate acts as a one-carbon donor to prevent NTDs.
Project description:Spina bifida has been reported to co-occur with pediatric cancer, but comprehensive evaluations remained elusive. We investigated this co-occurrence in two large, population-based studies in Taiwan (N = 1900 cancer cases, 2,077,137 controls) and Denmark (N = 5508 cases, 137,700 controls). Analyses in Denmark were restricted to the period before prenatal diagnostics became available (2004) and pregnancy terminations of fetuses with birth defects became more common. Using national patient and cancer registries, we linked spina bifida and cancer diagnoses among cases and non-cases. The risk of spina bifida among all cancer cases was increased and similar in Denmark [odds ratio (OR)=8.4, 95% confidence interval (CI) 5.1-13.8] and Taiwan (OR = 8.5, 95% CI 4.0-17.8), particularly for central nervous system (CNS) tumors (Denmark: OR = 16.3, 95% CI 8.1-33.0; Taiwan: OR = 26.6, 95% CI 8.5, 83.1), including benign CNS tumors (Denmark: OR = 41.5, 95% CI 21.2, 81.4). These findings suggest the need for comprehensive investigation of shared risk factors in the link between spina bifida and pediatric cancer.
Project description:PurposeAchieving bladder continence in individuals with spina bifida is a lifetime management goal. We investigated bladder continence status through time and factors associated with this status in patients with spina bifida.Materials and methodsWe used National Spina Bifida Patient Registry data collected from 2009 through 2015 and applied generalized estimating equation models to analyze factors associated with bladder continence status.ResultsThis analysis included 5,250 participants with spina bifida in a large, multi-institutional patient registry who accounted for 12,740 annual clinic visit records during the study period. At last followup mean age was 16.6 years, 22.4% of participants had undergone bladder continence surgery, 92.6% used some form of bladder management and 45.8% reported bladder continence. In a multivariable regression model the likelihood of bladder continence was significantly greater in those who were older, were female, were nonHispanic white, had a nonmyelomeningocele diagnosis, had a lower level of lesion, had a higher mobility level and had private insurance. Continence surgery history and current management were also associated with continence independent of all other factors (adjusted OR and 95% CI 1.9, 1.7-2.1 and 3.8, 3.2-4.6, respectively). The association between bladder management and continence was stronger for those with a myelomeningocele diagnosis (adjusted OR 4.6) than with nonmyelomeningocele (adjusted OR 2.8).ConclusionsIn addition to demographic, social and clinical factors, surgical intervention and bladder management are significantly and independently associated with bladder continence status in individuals with spina bifida. The association between bladder management and continence is stronger in those with myelomeningocele.
Project description:BackgroundA National Spina Bifida Patient Registry (NSBPR) was begun in 2009 to help understand the natural history of spina bifida (SB) and the effects of treatments provided by SB clinics. We used the NSBPR to explore the relationship of sociodemographic characteristics with SB outcomes.MethodsUsing NSBPR data collected in 2009 to 2012, we examined the unadjusted association between demographic characteristics and 4 SB outcomes: bowel continence, bladder continence, mobility, and presence of pressure sores. We then developed multivariable logistic models to explore these relationships while controlling for SB clinic, SB type, and level of lesion.ResultsData were available on 2054 patients <22 years of age from 10 SB clinics. In the multivariable models, older age groups were more likely to have continence and pressure sores and less likely to be community ambulatory. Males and patients without private insurance were less likely to be continent and community ambulatory. Non-Hispanic blacks were less likely to be continent. Level of lesion was associated with all outcomes; SB type was associated with all but pressure sores; and all outcomes except community ambulation showed significant variation across clinic sites.ConclusionsSociodemographic attributes are associated with SB outcomes. In particular, males, non-Hispanic blacks, and patients without private insurance have less favorable outcomes, and age has an impact as well. These characteristics need to be considered by clinicians who care for this patient population and factored into case-mix adjustment when evaluating variation in clinical and functional outcomes among different SB clinics.
Project description:While the worldwide incidence of newborns with spinal dysraphism is decreasing, the majority of children now survive and reach adulthood, creating new challenges in patient management and long-term care. Despite medical and surgical advances with a subsequent decline in mortality, spina bifida continues to be a major cause of chronic disability and affected individuals face increased mortality in adulthood. The majority of spina bifida patients have neurogenic bladder. Reconstructive and diverting procedures may increase the neoplastic risk in the urinary tract over time, however bladder dysfunction itself may be a risk factor, therefore patients, caregivers, and physicians must be aware of the baseline risk of cancer in patients with neurogenic bladder, in addition to routine cancer screening. Optimal treatment of myelomeningocele requires a multidisciplinary care team to prevent and manage potential sequelae that may affect function, quality of life, and survival.