|
 
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| CASE SERIES |
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| Year : 2021 | Volume
: 9
| Issue : 1 | Page : 34-37 |
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Neural tube defects: A case series
Sowmya Mailaram, Y Lakshmi Nalini, PV Ramana Bai, Swapna Rani, Vijaya Lakshmi
Department of Obstetrics and Gynaecology, Malla Reddy Institute of Medical Sciences, Hyderabad, Telangana, India
| Date of Submission | 28-Oct-2020 |
| Date of Decision | 17-Dec-2020 |
| Date of Acceptance | 04-Jan-2021 |
| Date of Web Publication | 30-Mar-2021 |
Correspondence Address:
Dr. Sowmya Mailaram
H. No. - 3-5-35/1, Near Tanks Shanthi Nagar, Siricilla, Rajanna Siricilla - 505 301, Karnataka
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/mjhs.mjhs_21_20
Neural tube defects (NTDs) are the most common congenital malformations (CMFs) in developing fetus. The study was done to determine the incidence and clinical profile of NTDs at a tertiary care hospital. The study was done at Malla Reddy Institute of Medical Sciences, Suraram, Hyderabad, from June 2019 to June 2020. Ten pregnant women with confirmed NTDs were admitted and subjected to medical termination of pregnancy. Fetuses with NTDs were collected and observed externally for sex, type of NTD, and other associated anomalies. Anencephaly was the most prevalent anomaly among all NTDs. Ten babies with NTD were observed; male predominance was seen. Prenatal screening of the fetus is important to rule out the CMF of fetus.
Keywords: Anencephaly, congenital malformation, prenatal screening
How to cite this article:
Mailaram S, Nalini Y L, Ramana Bai P V, Rani S, Lakshmi V. Neural tube defects: A case series. MRIMS J Health Sci 2021;9:34-7 |
| Introduction | |  |
Neural tube defects (NTDs) are anomalies of neurulation during fetal development. The NTDs are broadly classified into cranial and spinal defects. The cranial defects are further classified into encephalocele, anencephaly, and iniencephaly. The anencephaly is further subdivided into microencephaly and holoanencephaly. The spinal defects are classified into open and closed neural defects. Open variety includes myelocele and meningomyelocele. Closed variety includes meningocele and spina bifida occulta.[1] Most of these cases are diagnosed prenatally, and termination of pregnancy for fetal anomaly is the most common outcome for fetuses with NTD.[2],[3] Recurrence risk after one affected pregnancy is 2%–3% for any open NTD. NTDs, serious birth defects of the brain and spine, are a major, preventable public health burden. Globally, it is estimated that approximately 300,000 babies are born each year with NTDs,[4] resulting in approximately 88,000 deaths and 8.6 million disability-adjusted life years.[5],[6] Periconceptional folic acid supplementations have been shown to reduce the prevalence of open NTDs by at least 60%.[7] This reduction occurred both among mothers with previously affected pregnancies and among those who have no such risk factors. On the basis of this research, it became apparent that women planning pregnancies should be advised to take a dose of 4 mg–5 mg folic acid for 2 months before conception and throughout the first trimester.[8] The present case series aims to study the clinical profile of NTD at a tertiary care teaching hospital.
| Materials and Methods | | |
The study was conducted at the Department of Obstetrics and Gynecology, Malla Reddy Institute of Medical Sciences, Suraram, for a period of 1 year from June 2019 to June 2020. All pregnant women attending regular antenatal checkup were included in the study and all women were subjected to laboratory and sonological investigations. If the sonological report shows defect in neural or spinal tissues were taken.
After confirming the NTD in patients, prior oral and written consent was taken and subjected to medical termination of pregnancy. Gestational age varied from 12 weeks to 24 weeks. Tablet mifepristone 200 mg was given orally, and 24–48 h later depending on parity and gestational age, tablet misoprostol 100 mcg–400 mcg was kept pervaginally in posterior fornix. All cases were aborted within 48 h of starting induction vaginally. The fetuses were observed in detail externally for the sex, type of NTD, and other associated anomalies, and the findings were documented.
Institutional ethics committee permission was obtained for the present case series.
Statistical analysis
The data were entered into Microsoft Excel and were analyzed using proportions.
| Results | | |
The median gestational age was 18 weeks ranging from 12 weeks to 24 weeks. The number of deliveries conducted during the study period was 2420. Out of total deliveries, the number of babies born with NTDs was ten. The incidence of NTD in the present study was found to be 0.41%.
[Table 1] shows that out of 10 NTD babies, 60% were male and 40% were female and anencephaly was observed in 40% of the fetuses followed by spina bifida and meningocele.
[Table 2] shows sex, gestational age, NTD, and associated malformation observed in the fetuses. Associated malformations were observed in only 2 (20%) cases. One was female at gestational age of 23 weeks who had anencephaly found to have esophageal atresia. Other was male at 14 weeks of gestational age with acrania and meningocele found to have associated omphalocele. | Table 2: Sex, gestational age, neural tube defect, and associated malformation observed in the fetuses
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Various presentation with neural tube defects were seen in this case series. [Figure 1] shows the presentation of one fetus with anencephaly and protruded eye ball. [Figure 2] shows a different presentation like Fetus with rachischisis; whereas another presentation is shown in [Figure 3] which depicts Anencephaly with omphalocele. In [Figure 4] Fetus with meningomyelocele has been shown while in [Figure 5] Fetus with posterior encephalocele is shown.{
| Discussion | | |
NTDs arise as a result of incomplete closure of the neural tube during early embryonic development.[7],[8] This abnormal development leads to miscarriage, stillbirth in many cases, and abnormalities of central nervous system function in most affected individuals who survive. NTDs can be classified according to the type or position of the lesion, with the most common types being anencephaly and spina bifida (meningocele and myelomeningocele).
NTDs are generally believed to be multifactorial in etiology involving both genetic and environmental factors. Factors identified as possible risk factors can be grouped as fetal factors and maternal factors. Fetal factors include environmental insults to the fetus in early pregnancy. Maternal factors include advanced age, history of miscarriages, a family history of twinning or NTDs. In addition, dietary factors, in particular, folate, gestational diabetes, drugs, and the genes are associated risk factors.
The formation of the neural tube occurs before day 28 in the development of the human embryo.[8] The process begins with the laying down of a neural plate which then curves upward and fuses to form the neural tube in a process known as primary neurulation. Secondary neurulation, also known as canalization, involves the formation of a continuous lumen to the neural tube.[1] Fusion of the neural tube is now believed to involve five sites of closure which may pose points of weakness during the development of the spine.[1]
NTDs arise from the incomplete closure of the neural tube during development,[1] and they are generally classified according to the type and position of the lesion. Complete failure of the neurulation process results in craniorachischisis, a condition which is not compatible with life. Anencephaly occurs in three phases: first, the cranial part of the neural tube fails to close; second, the developed brain parts protrude and are exposed to the amniotic fluid; and third, degeneration of the exposed part results in anencephaly.
Spina bifida cystica is a term used to describe failure of closure of the neural tube in its spinal portion [Figure 2], and defects may be classified as meningoceles, in which meninges herniate out forming a cyst-like structure, and myelomeningoceles, in which the spinal cord also herniates out.[9] Myelocoeles and meningomyeloceles may be divided into upper and lower spinal lesions. Lower lesions in the lumbar region of the spine occur most commonly (Lemire, 1988). Spina bifida occulta is of different etiology and is the result of the incomplete fusion of vertebral arches in the spine.[1]
Encephalocele is a term used to denote a skin-covered herniation in the cranial region of the neural tube, and these disorders arise as a result of a postneurulation defect.[9] The presentation of NTDs, in general, depends on the size and position of the lesion.
The current recommendation to reduce the chances of NTDs is daily supplementation of 4–5 mg of folic acid prior to pregnancy and during pregnancy.[1] Still 0.7–0.8 per 1000 pregnancies are affected by some form of NTD even after folic acid supplementation.[9] Hence, folic acid supplementation alone is not enough to eradicate NTDs.
The number of deliveries conducted during the study period is 2420, and the number of NTD babies born is ten. This study reports incidence of 4.1 per 1000 births. Worldwide, the prevalence of NTD is 1–2 per 1000 births. The prevalence of NTD in India varies from 0.5 to 11 per 1000 births. When we compare these results with previous studies published in various parts of India, our incidence appears on par.[10],[11] The prevalence of NTDs in different studies from 1992 to 2014 in different regions of India, namely, Pondicherry, Balarampur, Lucknow, Odisha, West Bengal, Andhra Pradesh (United), Kerala, Karnataka, Gujarat, and Maharashtra was 5.7, 8.21, 3.9, 9.12, 8.2, 5.08, 10.6, 3.15, 6.4, and 1.68, respectively, excluding cases of anencephaly (1.34/1000) births.
The incidence in Indian subcontinent is much higher than in developed countries where prenatal screening is the standard medical protocol.[10],[11] The prevalence in England and Wales, Australia, Germany, United States, China, and India is 0.3, 0.5, 0.58, 0.761, 6.0, and 4.1 per 1000 births, respectively.
However, in India, unplanned pregnancies and unawareness regarding benefits of folic acid supplementation are the main reason for higher incidence. Anencephaly and spina bifida comprise 95% of NTD and the remaining 5% is encephalocele. It is more common in lower socioeconomic group. The incidence of anencephaly is about 1 in 1000 births; about 70% of anencephalic fetuses are females, but in our study, male predominance is seen.
Limitations of study include
The present study was conducted at a tertiary care center and hence true incidence of NTDs could not be estimated. Folic acid supplementation during periconception and early weeks of pregnancy could not be evaluated. Few parameters such as parity, sex of abortus, gestational age, and type of anomaly were studied.
| Conclusion | | |
The women planning pregnancy should be advised to take folic acid for 2 months before conception and throughout the first trimester. In this study, the incidence of NTDs 4.1 per 1000 births is comparable to Indian context.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Jorge AL. Neural Tube Defects. Singapore: World Scientific Publishing Co Pvt. Ltd.; 2011.  |
| 2. | Garne E, Loane M, Dolk H, De Vigan C, Scarano G, Tucker D, et al. Prenatal diagnosis of severe structural congenital malformations in Europe. Ultrasound Obstet Gynecol 2005;25:6-11. |
| 3. | Boyd PA, Devigan C, Khoshnood B, Loane M, Garne E, Dolk H, et al. Survey of prenatal screening policies in Europe for structural malformations and chromosome anomalies, and their impact on detection and termination rates for neural tube defects and Down's syndrome. BJOG 2008;115:689-96. |
| 4. | Christianson AL, Howson CP, Modell B. Global Report on Birth Defects: The Hidden Toll of Dying and Disabled Children. White Plains, NY: March of Dimes Birth Defects Foundation; 2006. |
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| 7. | Lumley J, Watson L, Watson M, Bower C. Periconceptional supplementation with folate and/or multivitamins for preventing neural tube defects. Cochrane Database Syst Rev 2001;(3):CD001056. |
| 8. | Recommendations for the use of folic acid to reduce the number of cases of spina bifida and other neural tube defects. MMWR Recomm Rep 1992;41:1-7. |
| 9. | Heseker HB, Mason JB, Selhub J, Rosenberg IH, Jacques PF. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid. Br J Nutr 2009;102:173-80. |
| 10. | Prevention of neural tube defects: Results of the medical research council vitamin study. MRC vitamin study research group. Lancet 1991;338:131-7. |
| 11. | Czeizel AE, Dudás I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med 1992;327:1832-5. |
[Figure 1], [Figure 2], Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]
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