Showing posts with label Anencephaly. Show all posts
Showing posts with label Anencephaly. Show all posts

Monday, May 4, 2009

The prevalence and predictors of anencephaly and spina bifida in Texas.

Canfield MA, Marengo L, Ramadhani TA, Suarez L, Brender JD, Scheuerle A. The prevalence and predictors of anencephaly and spina bifida in Texas. Paediatric and Perinatal Epidemiology. 2009 Jan;23(1):41-50.

Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, Austin, TX, USA.

Texas shares a 1255-mile border with Mexico and encompasses a variety of ecosystems, industries and other potential environmental exposures. The Texas Birth Defects Registry is an active surveillance system which covers all pregnancy outcomes (livebirths, fetal deaths and elective pregnancy terminations). This study describes the occurrence and the predictors of neural tube defects (anencephaly and spina bifida) in Texas between 1999 and 2003. Birth prevalence, crude and adjusted prevalence ratios and 95% confidence intervals were calculated using Poisson regression, for each defect, by fetal/infant sex, delivery year and maternal sociodemographic characteristics. Among approximately 1.8 million livebirths, a total of 1157 neural tube defects cases were ascertained by the Registry, resulting in an overall prevalence of 6.33 cases per 10 000 livebirths. The prevalences of anencephaly and spina bifida were 2.81 and 3.52 per 10 000 livebirths respectively. Prevalences of both defects were highest in Hispanics, among mothers living along the border with Mexico, among women of higher parity and among mothers who were 40+ years of age. In addition, the prevalence of each defect was higher among women with no record of prenatal care and among women with less than 7 years of education. Hispanic ethnicity was an important predictor for anencephaly, along with sex, maternal age, parity and border residence. However, only border residence and delivery year were significant predictors for spina bifida.

PMID: 19228313

Urban-rural residence and the occurrence of neural tube defects in Texas, 1999-2003.

Luben TJ, Messer LC, Mendola P, Carozza SE, Horel SA, Langlois PH. Urban-rural residence and the occurrence of neural tube defects in Texas, 1999-2003. Health Place. 2009 Sep;15(3):848-54. Epub 2009 Feb 23.

US Environmental Protection Agency, 109 T.W. Alexander Drive, Mail Drop B-243-01, RTP, NC 27711, USA.

Neural tube birth defects (NTDs) affect more than 4000 pregnancies in the US annually. The etiology of NTDs is believed to be multifactorial, but much remains unknown. We examined the pattern and magnitude of urban-rural variation in anencephaly, spina bifida without anencephaly, and encephalocele in Texas in relation with urban-rural residence for the period 1999-2003. There was no evidence that urban-rural residence was associated with changes in the rate of anencephaly or spina bifida without anencephaly in unadjusted or adjusted analyses. In contrast, rates of encephalocele were statistically significantly higher in areas classified as suburban or more rural compared to urban areas using four different urban-rural residence indicators.

PMID: 19299192

Anencephaly and spina bifida among Hispanics: Maternal, sociodemographic, and acculturation factors in the National Birth Defects Prevention Study.

Canfield MA, Ramadhani TA, Shaw GM, Carmichael SL, Waller DK, Mosley BS, Royle MH, Olney RS; The National Birth Defects Prevention Study. Anencephaly and spina bifida among Hispanics: Maternal, sociodemographic, and acculturation factors in the National Birth Defects Prevention Study. Birth Defects Research Part A; Clinical and Molecular Teratology. 2009 Mar 30.

Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, Austin, Texas.

BACKGROUND: We used data from the multisite National Birth Defects Prevention Study for expected delivery dates from October 1997 through 2003, to determine whether the increased risk in anencephaly and spina bifida (neural tube defects (NTDs)) in Hispanics was explained by selected sociodemographic, acculturation, and other maternal characteristics.

METHODS: For each type of defect, we examined the association with selected maternal characteristics stratified by race/ethnicity and the association with Hispanic parents' acculturation level, relative to non-Hispanic whites. We used logistic regression and calculated crude odds ratios (ORs) and their 95% confidence intervals (CIs).

RESULTS: Hispanic mothers who reported the highest level of income were 80% less likely to deliver babies with spina bifida. In addition, highly educated Hispanic and white mothers had 76 and 35% lower risk, respectively. Other factors showing differing effects for spina bifida in Hispanics included maternal age, parity, and gestational diabetes. For spina bifida there was no significant elevated risk for U.S.-born Hispanics, relative to whites, but for anencephaly, corresponding ORs ranged from 1.9 to 2.3. The highest risk for spina bifida was observed for recent Hispanic immigrant parents from Mexico or Central America residing in the United States <5 years (OR = 3.28, 95% CI = 1.46-7.37).

CONCLUSIONS: Less acculturated Hispanic parents seemed to be at highest risk of NTDs. For anencephaly, U.S.-born and English-speaking Hispanic parents were also at increased risk. Finally, from an etiologic standpoint, spina bifida and anencephaly appeared to be etiologically heterogeneous from these analyses. Birth Defects Research (Part A), 2009. (c) 2009 Wiley-Liss, Inc.

PMID: 19334286

Sunday, April 27, 2008

A unifying hypothesis of hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida

Williams H. A unifying hypothesis of hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida. Cerebrospinal Fluid Research. 2008 Apr 11;5(1):7

ABSTRACT: This review 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 mesodermal growth insufficiency influences both neural tube closure and central nervous system pressure, leading to dysraphism.

PMID: 18405364

Tuesday, July 24, 2007

Embryology of myelomeningocele and anencephaly

Dias MS, Partington M. Embryology of myelomeningocele and anencephaly. Neurosurgical Focus. 2004 Feb 15;16(2):E1. Review.

The authors review current views on of the embryogenesis of the neural tube defects (NTDs) myelomeningocele and anencephaly. In this context, the following four approaches to the study of NTDs are discussed: normal morphogenesis and timing of early human neural development from conception to the ascent of the conus medullaris; mechanical and molecular biology of neural tube closure derived from experimental and animal models; morphological and biomechanical features of the NTDs myelomeningocele and anencephaly; and the experimental evidence for the importance of both genetic and environmental influences on human NTDs. Although considerable insight into both normal neural tube closure and the factor(s) by which this process may be disrupted has been reported in recent years, the exact mechanism(s) by which human myelomeningoceles and anencephaly arise remain elusive.

PMID: 15209484

Friday, July 20, 2007

Mutations in VANGL1 associated with neural-tube defects.

Kibar Z, Torban E, McDearmid JR, Reynolds A, Berghout J, Mathieu M, Kirillova I, De Marco P, Merello E, Hayes JM, Wallingford JB, Drapeau P, Capra V, Gros P. Mutations in VANGL1 associated with neural-tube defects. New England Journal of Medicine. 2007 Apr 5;356(14):1432-7.

Neural-tube defects such as anencephaly and spina bifida constitute a group of common congenital malformations caused by complex genetic and environmental factors. We have identified three mutations in the VANGL1 gene in patients with familial types (V239I and R274Q) and a sporadic type (M328T) of the disease, including a spontaneous mutation (V239I) appearing in a familial setting. In a protein-protein interaction assay V239I abolished interaction of VANGL1 protein with its binding partners, disheveled-1, -2, and -3. These findings implicate VANGL1 as a risk factor in human neural-tube defects. Copyright 2007 Massachusetts Medical Society.

PMID: 17409324