The 'Mickey Mouse' sign and the diagnosis of anencephaly in early pregnancy. (1/149)

OBJECTIVES: To assess the sonographic screening for anencephaly in the first trimester in a low-risk obstetric population. METHODS: Since 1994, 5388 women attended our clinic for a first-trimester scan (11-14 weeks of gestation) and screening for structural and chromosomal abnormalities. The patients underwent transabdominal scanning, and transvaginal scanning if necessary. RESULTS: The ultrasonographic appearances of anencephaly in the first trimester are different from the familiar second-trimester signs. The cerebral hemispheres are present and exposed to the surrounding amniotic fluid. The ultrasound appearances in the coronal section of the head are best described as 'Mickey Mouse face'. There were six cases of anencephaly (incidence 1.1:1000). All cases were diagnosed in the first trimester and five demonstrated this sign. There were no false-positive diagnoses. The crown-rump length was significantly reduced in all affected fetuses. CONCLUSION: First-trimester ultrasonographic diagnosis of anencephaly is accurate, but sonographers should be familiar with the ultrasound appearances that are different from those in the second trimester.  (+info)

Neural tube defects along the Texas-Mexico border, 1993-1995. (2/149)

In response to a 1991 anencephaly cluster in Cameron County, Texas, a surveillance and neural tube defect (NTD) recurrence prevention project for NTDs was implemented in the 14 Texas-Mexico border counties. For 1993-1995, NTD-affected pregnancies were identified at all gestational ages through active surveillance of multiple case-ascertainment sources. There were 87 cases of anencephaly, 96 cases of spina bifida, and 14 cases of encephalocele for respective rates of 6.4, 7.1, and 1.1 per 10,000 live births. Of the 197 NTD case-women, 93% were Hispanic. The overall, Hispanic, and Anglo NTD rates were, respectively, 14.6, 14.9, and 10.6 per 10,000 live births. The NTD rate for El Paso County (9.8 per 10,000), the most northwestern Texas county, was significantly lower (p = 0.001) than the aggregate rate for the rest of the Texas border (17.1 per 10,000). The overall Texas border rate was significantly higher (p < 0.001) than a recently estimated rate of 9.3 for California and minimally higher than a recently adjusted rate of 11.3 for the Metropolitan Atlanta Congenital Defects Program counties (p = 0.052), both of which now reflect all gestational ages. Of the 197 Texas border cases, 85% (168 cases) reached a gestational age of > or =20 weeks. Excluding cases of <20 weeks' gestation in the rate had a more marked effect on reducing the anencephaly rate (4.9 per 10,000) than the spina bifida rate (6.7 per 10,000). A country of birth was known for 153 (83%) of the 184 Hispanic case-women: 63% were born in Mexico; 24%, in Texas; and 11%, elsewhere in the United States. Rates for Mexico-born Hispanic women (15.1 per 10,000) were significantly higher than rates for United States-born Hispanic women (9.5 per 10,000) (p = 0.006).  (+info)

East Ireland 1980-1994: epidemiology of neural tube defects. (3/149)

STUDY OBJECTIVE: The objective of the study was to describe the epidemiology of neural tube defects (NTD) in the eastern region of Ireland using the EUROCAT register of congenital malformations. DESIGN, SETTING AND PATIENTS: EUROCAT registries monitor the prevalence of congenital anomalies in defined populations using multiple sources for case ascertainment. All cases of NTD on the Dublin EUROCAT register born between 1980 and 1994 were extracted and analysed. The crude birth prevalence rate for all NTD, spina bifida, anencephaly and encephalocoele were calculated for each year. Parameters measured were: sex ratio, stillbirth rate, proportion of low birth-weight babies (< 2500 g) and the proportion who were premature (< 37 weeks gestation). MAIN RESULTS: Of 821 NTD cases, 419 (51.0%) had spina bifida, 322 (39.2%) had anencephaly, 69 (8.4%) had encephalocoele and 11 (1.3%) were iniencephalic. The crude birth prevalence of NTD decreased fourfold from 46.9/10,000 births in 1980 to 11.6/10,000 in 1994. The downward trend ceased during the early 1990's. Younger mothers had significantly higher rates of NTD affected births. Twenty two per cent of NTD cases had additional non-central nervous system anomalies. In 40 cases, there was a previous family history of NTD in siblings. Seasonal effects in birth prevalence were observed. Birth notification was the most frequent mechanism of ascertainment. CONCLUSION: There was a marked fall in the birth prevalence of NTD during the 15 year period. This change was real and not accounted for by pre-natal screening and diagnostic practises with termination of pregnancy, which is not legally permissible in Ireland. Dietary factors may have had an influence. Rates of NTD in this region are still higher than many other parts of Europe. Primary prevention strategies through increased folic acid intake are necessary to further reduce NTD affected births.  (+info)

Vasculature of the optic nerve in anencephaly. (4/149)

The optic nerves and globes obtained from 6 anencephalics were studied histologically and compared to normal specimens obtained from 4 stillborn infants as well as 1 case of septo-optic dysplasia. Special emphasis was placed on examination of the optic nerve, and it was found that an average of 48 vessels per high-power field were seen posterior to the lamina cribrosa in anencephalics. In contrast, control globes had an average of 12 vessels per high-power field. This suggested that an increase in the vasculature of the hypoplastic optic nerve is a characteristic feature of anencephalics.  (+info)

Congenital vertebral anomalies: aetiology and relationship to spina bifida cystica. (5/149)

A family survey of 337 patients with congenital vertebral anomalies has been carried out from the Scoliosis Clinics of Edinburgh and the Royal National Orthopaedic Hospital, London. From genetic and epidemiological evidence it is clear that multiple vertebral anomalies (without apparent spina bifida) are aetiologically related to anencephaly and spina bifida cystics, carrying a 5-10% risk to subsequent sibs for any one of these defects. The implications for prenatal diagnosis are discussed. Solitary hemivertebrae and localized anterior defects of the vertebral bodies causing kyphoscoliosis are sporadic (non-familial) in nature, carrying no risk to subsequent sibs.  (+info)

Potato avoidance during pregnancy in women with a previous infant with either anencephaly and/or spina bifida. (6/149)

This investigation is a direct attempt to test Renwick's (1972) hypothesis that 95% of anencephaly and spina bifida (ASB) is preventable by the avoidance of potatoes during pregnancy. Although the numbers involved in the study are small, the investigation fails to support the concept that short-term avoidance of potatoes before conception and throughout pregnancy in women who have had a previous ASB infant reduces the recurrence risk. In the potato-free group, of 23 pregnancies which went to term two infants had ASB (8-7%); whereas in the non-potato-free group, of 56 which went to term two infants had ASB (3-6%). The recurrence risk in both groups was about 5%. The incidence of ASB in the groups shows no significant difference (P = 0-58) and in the potato-free group was not reduced by 95% as postulated by Renwick.  (+info)

An investigation of space and space-time clustering in a large sample of infants with neural tube defects born in Cardiff. (7/149)

Altogether 406 infants with neural tube defects born in Cardiff between 1956-71 were investigated for evidence of space-time clustering and 100 similarly affected infants, together with matched controls born in Cardiff between 1964-66 were investigated for evidence of spatial clustering. No evidence of excessive prevalence in either dimension was observed.  (+info)

Maternal exposure to nitrate from drinking water and diet and risk for neural tube defects. (8/149)

In this population-based case-control study conducted in California between June 1989 and May 1991, the authors investigated the association between maternal periconceptional exposure to nitrate from drinking water and diet and risk for neural tube defects. The mothers of 538 cases and 539 nonmalformed controls were interviewed regarding residential history, consumption of tap water at home, and dietary intake during the periconceptional period. Dietary nitrate exposure was not associated with increased risk for neural tube defects. Exposure to nitrate in drinking water at concentrations above the 45 mg/liter maximum contaminant level was associated with increased risk for anencephaly (odds ratio (OR) = 4.0, 95% confidence interval (CI): 1.0, 15.4), but not for spina bifida. Increased risks for anencephaly were observed at nitrate levels below the maximum contaminant level among groundwater drinkers only (OR = 2.1, 95% CI: 1.1,4.1 for 5-15 mg/liter; OR = 2.3, 95% CI: 1.1, 4.5 for 16-35 mg/liter; and OR = 6.9, 95% CI: 1.9, 24.9 for 36-67 mg/liter compared with <5 mg/liter). Adjustment for identified risk factors for anencephaly did not substantially alter these associations, nor did control for maternal dietary nitrate, total vitamin C intake, and quantity of tap water consumed. The lack of an observed elevation in risk for anencephaly in association with exposure to mixed water containing nitrate at levels comparable with the concentration in groundwater may indicate that something other than nitrate accounts for these findings.  (+info)

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