Prenatal counseling for myelomeningocele in the era of fetal surgery: a shared decision-making approach

OBJECTIVE

The Management of Myelomeningocele Study demonstrated that fetal surgery, as compared to postnatal repair, decreases the rate of hydrocephalus and improves expected motor function. However, fetal surgery is associated with significant maternal and neonatal risks including uterine wall dehiscence, prematurity, and fetal or neonatal death. The goal of this study was to provide information about counseling expectant mothers regarding myelomeningocele in the era of fetal surgery.

METHODS

The authors conducted an extensive review of topics pertinent to counseling in the setting of myelomeningocele and introduce a new model for shared decision-making to aid practitioners during counseling.

RESULTS

Expectant mothers must decide in a timely manner among several potential options, namely termination of pregnancy, postnatal surgery, or fetal surgery. Multiple factors influence the decision, including maternal health, fetal heath, financial resources, social support, risk aversion, access to care, family planning, and values. In many cases, it is a difficult decision that benefits from the guidance of a pediatric neurosurgeon.

CONCLUSIONS

The authors review critical issues of prenatal counseling for myelomeningocele and discuss the process of shared decision-making as a framework to aid expectant mothers in choosing the treatment option best for them.

The effect of magnetic resonance imaging on neural tube development in an early chicken embryo model

PURPOSE

We aimed to determine whether varying the magnetic field during magnetic resonance imaging would affect the development of chicken embryos and neural tube defects.

METHODS

Following incubation for 24 h, we exposed chicken embryos to varying magnetic fields for 10 min to assess the impact on development. Three magnetic resonance imaging devices were used, and the eggs were divided into four groups: group 1 is exposed to 1 T, group 2 is exposed to 1.5 T, group 3 is exposed to 3 T, and group 4, control group, was not exposed to magnetic field. After MRI exposure, all embryos were again put inside incubator to complete 48 h. "The new technique" was used to open eggs, a stereomicroscope was used for the examination of magnified external morphology, and each embryo was examined according to the Hamburger and Hamilton chicken embryo stages. Embryos who had delayed stages of development are considered growth retarded. Growth retardation criteria do not include small for stage.

RESULTS

Compared with embryos not exposed to a magnetic field, there was a statistically significant increase in the incidence of neural tube closure defects and growth retardation in the embryos exposed to magnetic fields (p < 0.05). However, although the incidence of neural tube closure defects was expected to increase as exposure (tesla level) increased, we found a higher rate of defects in the 1.5-T group compared with the 3-T group. By contrast, the highest incidence of growth retardation was in the 3-T group, which was consistent with our expectation that growth retardation would be more likely as tesla level increased.

CONCLUSIONS

We therefore conclude that the use of magnetic resonance imaging as a diagnostic tool can result in midline closure defects and growth retardation in chicken embryos. We hypothesize that this may also be true for human embryos exposed to MRI. If a pregnant individual is to take an MRI scan, as for lumbar disc disease or any other any other reason, our results indicate that consideration should be given to an avoidance of MRI during pregnancy.

Maternal periconceptional factors affect the risk of spina bifida-affected pregnancies: an Italian case-control study

PURPOSE

Neural tube defects, including spina bifida and anencephaly, are the second most common birth defects with an incidence in Italy of 0.4-1/1,000. Information on factors playing a role in the pathogenesis of spina bifida is based on populations with different exposures, lifestyle, social and cultural habits compared to Italian people. Our objective was to fill this gap by using data from a case-control interview study carried out at the G. Gaslini Children's Hospital, Genoa, from 2000 to 2008.

METHODS

We surveyed questionnaires from 133 case mothers and 273 control women providing information on periconceptional risk factors. Univariate and multivariate logistic regression analyses were used to estimate risks by odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

Univariate results suggest that birth order, low maternal educational level, age, smoking habits, alcohol consumption, high caffeine intake, lack of folate supplementation, low and high calorie diet, occasional consumption of fruit and vegetables, high emotional stress, and environmental pollution are associated with an increased spina bifida risk. Nevertheless, high caffeine intake (OR = 10.82; 95% CI, 3.78-31), low calorie diet (OR = 5.15; 95%CI, 1.79-14), occasional consumption of fruit and vegetables (OR = 3.38; 95% CI, 1.67-6.82), alcohol consumption (OR = 3.05; 95% CI, 1.24-7.50) and, above all, lack of folate supplementation at any time of pregnancy (OR = 20.54; 95% CI, 5.41-77) mainly determined spina bifida risk in the multivariate analysis.

CONCLUSION

Our findings point out that a common underlying mechanism, a disturbed folate/homocysteine metabolism, may be causative for the burden of spina bifida in the Italian population.

Revisiting acrania: same phenotype, different aetiologies

OBJECTIVE

To evaluate the contribution of prenatal and postmortem examinations in establishing the aetiology of acrania.

METHODS

Retrospective evaluation of 14 cases of acrania managed through elective termination of pregnancy.

RESULTS

The median maternal age was 30 years (range 18-40) and median gestational age at diagnosis was 13 weeks (range 12-15). One mother had epilepsy and was taking anticonvulsants and another had uncontrolled type II diabetes mellitus. Only 3 women were using folic acid at conception. Chromosomal abnormalities were detected in 3 of 8 cases analyzed. Unilateral anopthalmia, cervical rachischisis, midline facial and limb defects coexisted with acrania in 4 cases. Acrania with craniofacial dysmorphism and asymmetrical finger amputation were observed in a case of amniotic band syndrome. A previous history of anencephaly was documented in 1 case.

CONCLUSION

Acrania is a characteristic phenotypic expression of a variety of different aetiologies. Investigation with cytogenetic studies and postmortem are essential to provide a definitive answer. This will provide a better understanding of the underlying aetiology and help establish the recurrence risk for future pregnancies.

Myelomeningocele: a review of the epidemiology, genetics, risk factors for conception, prenatal diagnosis, and prognosis for affected individuals

Although the use of folic acid before conception decreases the chance that a fetus will have an open neural tube defect, this condition still affects 0.5-1.0/1000 pregnancies in the United States. Results of a recent survey suggest that there are gaps in obstetrician-gynecologists' knowledge of risk factors for conception, strategies for prenatal diagnosis, and prognosis for affected individuals. To address these gaps this paper reviews the epidemiology, genetics, risk factors for conception, prenatal diagnosis, and prognosis for affected individuals, presents current information, and makes suggestions for expanding obstetrician-gynecologists' knowledge of myelomeningocele.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to state that despite a large amount of professional and public education on the use of folic acid in prevention of open neural tube defects (ONTDs) the incidence still affects 0.5-1.0/1000 pregnancies and recall that a recent survey conducted by the ACOG shows substantial misunderstanding and misinformation on major categories of neural tube birth defects.

Profile of major congenital malformations at Nizwa Hospital, Oman: 10-year review

OBJECTIVE

The objective of this study was to establish the profile of major congenital malformations at Nizwa Hospital, which is a major hospital in the Al-Dakhliya region of Oman.

METHODS

All births with birthweight more than 500 g were prospectively studied from January 1993 through December 2002 for a period of 10 years. A congenital anomaly register was maintained in the special care baby unit (SCBU) and details of each case were recorded after parents' interviews, clinical evaluation and relevant radiological and laboratory investigations. The major malformations were classified as multiple or single-system abnormalities as well as genetic or non-genetic disorders.

RESULTS

Of the 21 988 births during the study period, 541 babies (24.6 per 1000 births) had major malformations. Of the 541 babies, 158 (29.2%) had multiple malformations and 335 (61.9%) had involvement of a single system. In 48 (8.9%) babies a complete evaluation was not possible. Of the cases with multiple abnormalities, 57 had recognized syndromes, of which 28 (49.1%) were autosomal recessive disorders. Seventy (12.9%) cases had chromosomal abnormalities. The most common systems involved in neonates with single-system malformations were the gastrointestinal system (100 cases), the central nervous system (79 cases) and the cardiovascular system (63 cases). Although the consanguinity rate of 53.1% among Omani births almost matched with the regional average of 52.7%, it was 76% among those with major malformations. Also, there was an increased clustering of multiple abnormalities and rare recessive disorders in cases with closely related parents and grandparents. The birth prevalence of major malformations was 14.6 per 1000 in non-Omani births as compared to 25.2 in Omani births (P < 0.05). Genetic factors could be implicated in 343 (63.4%) cases and 130 (37.9%) of these were potentially preventable.

CONCLUSION

Genetic disorders account for a significant proportion of congenital malformations in Oman.

Epidemiology of neural tube defects

The epidemiological investigation of the common open neural tube defects (NTDs), anencephaly, and spina bifida, has a long history. The most significant finding from these past studies of NTDs was the identification of the protective effect of maternal, periconceptional supplementation with folic acid. Fortuitously, the association between folic acid and NTDs became widely accepted in the early 1990s, at a time when genetic association studies of complex traits were becoming increasingly feasible. The confluence of these events has had a major impact on the direction of epidemiological, NTD research. Association studies to evaluate genes that may influence the risk of NTDs through their role in folate-related processes, or through other metabolic or developmental pathways are now commonplace. Moreover, the study of genetic as well as non-genetic, factors that may influence NTD risk through effects on the nutrient status of the mother or embryo has emerged as a major research focus. Research efforts over the past decade indicate that gene-gene, gene-environment, and higher-order interactions, as well as maternal genetic effects influence NTD risk, highlighting the complexity of the factors that underlie these conditions. The challenge for the future is to design studies that address these complexities, and are adequately powered to detect the factors or combination of factors that influence the development of NTDs.

Spina bifida

Spina bifida results from failure of fusion of the caudal neural tube, and is one of the most common malformations of human structure. The causes of this disorder are heterogeneous and include chromosome abnormalities, single gene disorders, and teratogenic exposures. However, the cause is not known in most cases. Up to 70% of spina bifida cases can be prevented by maternal, periconceptional folic acid supplementation. The mechanism underlying this protective effect is unknown, but it is likely to include genes that regulate folate transport and metabolism. Individuals with spina bifida need both surgical and medical management. Although surgical closure of the malformation is generally done in the neonatal period, a randomised clinical trial to assess in utero closure of spina bifida has been initiated in the USA. Medical management is a lifelong necessity for individuals with spina bifida, and should be provided by a multidisciplinary team.

Epidemiology of neural tube defects

Neural tube defects (NTDs)-malformations secondary to abnormal neural tube closure between the third and fourth weeks of gestational age-have a complex and imperfectly understood etiology in which both genetic and environmental factors appear to be involved. A number of specific chromosomal or single-gene disorders, presumably not affected by environmental influences, are associated with the development of NTDs, but such syndromal cases account for a small proportion of NTDs in live-born infants. Analysis of recurrence patterns within families and of twin-concordance data provides evidence of a genetic influence in nonsyndromal cases, but factors such as socioeconomic status and geographic area (independent of race or ethnicity) are also associated with variations in the incidence of NTDs. The prevalence at birth of both anencephaly and spina bifida has decreased, but the advent of antenatal diagnosis and elective termination of affected pregnancies has undermined the reliability of birth prevalence rate as an estimate of incidence. Some occupational and other exposures, including maternal use of antiepileptic drugs (AEDs), are associated with increased risk for NTDs. Among women who have had an NTD-affected pregnancy, recurrence risk is markedly higher than the risk for a first NTD-affected pregnancy in the general population. There is strong evidence, overall, for a protective effect of adequate folate consumption. In some high-risk groups, however, such as women taking AEDs, folate supplementation has not been proven to reduce NTD risk.

Risk of stillbirth in offspring of men exposed to ionising radiation

Radiation genetic risk models are employed to predict the frequency of radiation-related stillbirths to partners of occupationally exposed male workers, using the incidence data recently reported by Parker et al from an epidemiological study of Cumbrian births. Expanding on previously developed conservative risk estimates suggests that, of the 130 observed stillbirths to partners of male radiation workers, 0.3 cases would be attributable to paternal preconceptional irradiation, in contrast to the 17.5 (95% confidence interval: 3.1 to 31.9) cases predicted by Parker et al from their preferred dose-response model. The incompatibility of the results reported by Parker et al with those from other investigations, both epidemiological and experimental, and the inability of the study to consider a number of factors which might affect stillbirth rates, particularly those relating to the mother, make it difficult to accept that paternal irradiation received occupationally could have contributed to a detectable increase in stillbirths.

Folic acid for the prevention of neural tube defects. American Academy of Pediatrics. Committee on Genetics

The American Academy of Pediatrics endorses the US Public Health Service (USPHS) recommendation that all women capable of becoming pregnant consume 400 microgram of folic acid daily to prevent neural tube defects (NTDs). Studies have demonstrated that periconceptional folic acid supplementation can prevent 50% or more of NTDs such as spina bifida and anencephaly. For women who have previously had an NTD-affected pregnancy, the Centers for Disease Control and Prevention (CDC) recommends increasing the intake of folic acid to 4000 microgram per day beginning at least 1 month before conception and continuing through the first trimester. Implementation of these recommendations is essential for the primary prevention of these serious and disabling birth defects. Because fewer than 1 in 3 women consume the amount of folic acid recommended by the USPHS, the Academy notes that the prevention of NTDs depends on an urgent and effective campaign to close this prevention gap.