Diffusion weighted imaging as a biomarker of retinoic acid induced myelomeningocele.

Neural tube defects are a common congenital anomaly involving incomplete closure of the spinal cord. Myelomeningocele (MMC) is a severe form in which there is complete exposure of neural tissue with a lack of skin, soft tissue, or bony covering to protect the spinal cord. The all-trans retinoic acid (ATRA) induced rat model of (MMC) is a reproducible, cost-effective means of studying this disease; however, there are limited modalities to objectively quantify disease severity, or potential benefits from experimental therapies. We sought to determine the feasibility of detecting differences between MMC and wild type (WT) rat fetuses using diffusion magnetic resonance imaging techniques (MRI). Rat dams were gavage-fed ATRA to produce MMC defects in fetuses, which were surgically delivered prior to term. Average diffusion coefficient (ADC) and fractional anisotropy (FA) maps were obtained for each fetus. Brain volumes and two anatomically defined brain length measurements (D1 and D2) were significantly decreased in MMC compared to WT. Mean ADC signal was significantly increased in MMC compared to WT, but no difference was found for FA signal. In summary, ADC and brain measurements were significantly different between WT and MMC rat fetuses. ADC could be a useful complementary imaging biomarker to current histopathologic analysis of MMC models, and potentially expedite therapeutic research for this disease.

Fetal Myelomeningocele After Maternal Methotrexate Administration: A Case Report.

Background: Folate supplementation in women of reproductive age has a well-established role in the prevention of neural tube defects. Methotrexate is a commonly used drug which functions by inhibiting normal folate metabolism in active cells. An association between fetal methotrexate exposure and myelomeningocele might be expected, considering this relationship. However, to our knowledge, no cases of myelomeningocele secondary to in utero methotrexate exposure have been reported. Case: We present the case of a gravid patient who, having received methotrexate for management of an ectopic pregnancy, was lost to follow-up and returned several weeks later carrying an intrauterine pregnancy. The fetus was found prenatally to be suffering from multiple congenital anomalies. At birth the infant demonstrated many of the abnormalities commonly associated with fetal methotrexate syndrome, including craniosynostosis and talipes equinovarus. Most interestingly, the newborn was also diagnosed with a lumbar myelomeningocele and concomitant type II Chiari malformation, as is often associated with such a neural tube defect. Conclusion: Methotrexate exposure may impact the fetal risk of myelomeningocele. Patients should be counseled thoroughly on the importance of follow-up care.

Arsenic is associated with reduced effect of folic acid in myelomeningocele prevention: a case control study in Bangladesh.

BACKGROUND: Arsenic induces neural tube defects in several animal models, but its potential to cause neural tube defects in humans is unknown. Our objective was to investigate the associations between maternal arsenic exposure, periconceptional folic acid supplementation, and risk of posterior neural tube defect (myelomeningocele) among a highly exposed population in rural Bangladesh. METHODS: We performed a case-control study that recruited physician-confirmed cases from community health clinics served by Dhaka Community Hospital in Bangladesh, as well as local health facilities that treat children with myelomeningocele. Controls were selected from pregnancy registries in the same areas. Maternal arsenic exposure was estimated from drinking water samples taken from wells used during the first trimester of pregnancy. Periconceptional folic acid use was ascertained by self-report, and maternal folate status was further assessed by plasma folate levels measured at the time of the study visit. RESULTS: Fifty-seven cases of myelomeningocele were identified along with 55 controls. A significant interaction was observed between drinking water inorganic arsenic and periconceptional folic acid use. As drinking water inorganic arsenic concentrations increased from 1 to 25 µg/L, the estimated protective effect of folic acid use declined (OR 0.22 to 1.03), and was not protective at higher concentrations of arsenic. No main effect of arsenic exposure on myelomeningocele risk was identified. CONCLUSIONS: Our study found a significant interaction between drinking water inorganic arsenic concentration from wells used during the first trimester of pregnancy and reported intake of periconceptional folic acid supplements. Results suggest that environmental arsenic exposure reduces the effectiveness of folic acid supplementation in preventing myelomeningocele.