What are Neural Tube Defects?

Neural tube defects (NTDs) are a class of birth defects that develop when the neural tube, the structure that eventually develops into the brain & spinal cord, is unable to close completely during the early stages of pregnancy. NTDs can result in a range of serious and potentially life-threatening conditions, affecting the brain, spine, and central nervous system.

The neural tube typically closes within the first twenty-eight days of pregnancy, often before a woman knows she is pregnant. When it fails to close, it can lead to various types of neural tube defects, each with its own set of symptoms and complications.

Causes of Neural Tube Defects

The root cause of neural tube defects is not fully understood. However, the researchers have identified several factors that can increase the possibility of these conditions:

• Genetic Factors: Certain genetic mutations and chromosomal abnormalities can predispose an individual to neural tube defects. If one child in a family is born with an NTD, the risk of recurrence in subsequent pregnancies is higher.
• Nutritional Deficiencies: Folic acid (vitamin B9) deficiency during the critical early stages of pregnancy is a major factor making a foetus susceptible to neural tube defects (NTDs). Folic acid is a must for the proper development of the neural tube. Vitamin B12 deficiency can also contribute to the risk of NTDs.
• Maternal Diabetes: Women with pre-existing or gestational diabetes have a higher possibility of having a child with a neural tube defect.
• Obesity: Maternal obesity is often correlated with an increased risk of neural tube defects, likely due to the underlying metabolic and nutritional factors.
• Certain Medications: Some medications, such as anti-seizure drugs, have been associated with an elevated risk of neural tube defects.
• Maternal Age: Older maternal age (over 35) has been associated with a slightly higher possibility of neural tube defects.
• Ethnicity and Geographical Location: Certain ethnic groups and regions of the globe have higher prevalence rates of neural tube defects, likely due to a combination of genetic, dietary, and environmental factors.
• Environmental Factors: More than optimal exposure to certain toxins, such as radiation, pesticides, and heavy metals, may also contribute to developing neural tube defects.
• Multiple Pregnancies: There is a greater risk of NTDs during pregnancies with twins or more, possibly due to increased nutritional demands.

Types of Neural Tube Defects

There are various neural tube defects, each with specific characteristics and implications:

• Anencephaly: This condition occurs when the neural tube fails to close at the upper (cranial) end, resulting in the absence of a significant portion of the brain and skull. Anencephaly is a lethal condition. Infants with this defect are usually stillborn or expire shortly after birth.
• Spina bifida: It is one of the most prevalent types of neural tube defects, occurring when the neural tube fails to close properly along the spine. This condition can range in severity from a small gap in the spine to a complete opening that exposes the spinal cord and nerves.
• Encephalocele: In this condition, the neural tube doesn't close near the brain, resulting in the development of an opening in the skull. A part of the brain can protrude through this opening, often resulting in intellectual disability and other neurological problems.
• Iniencephaly: This rare and severe form of neural tube defect occurs when the spine of a child is severely malformed (misshapen). It usually causes a lack of a neck and your baby's head to be bent severely backwards, along with incomplete closure of the spine and skull.

Folic Acid Role in Preventing Neural Tube Defects

Folic acid, or vitamin B9, plays a crucial role in preventing NTDs. Adequate folic acid intake, especially during the critical early weeks of pregnancy, can significantly lower the risk of these congenital abnormalities.

Folic acid is key to the proper development of the neural tube in a foetus, as it helps the cells divide and grow correctly. Studies have shown that women who take regular folic acid supplements before and during pregnancy have a much lower risk of having a child with a neural tube defect.

The daily dose of folic acid for females of childbearing age is 400-800 micrograms (mcg). However, women who have had a previous pregnancy affected by an NTD or have other risk factors may be advised to take higher doses of folic acid, up to 4,000 mcg per day.

Screening and Diagnosis of Neural Tube Defects

Early detection of neural tube defects is crucial for proper management and treatment. There are several screening and diagnostic tools available:

• Prenatal Screening Tests: These include blood tests, such as the maternal serum alpha-fetoprotein (MSAFP) test, and ultrasound examinations, which can help identify potential neural tube defects during pregnancy.
• Diagnostic Tests: Now a days ultrasound is the main diagnostic tool to identify neiral tube defects and role of invasive testing like amniocentesis or chorionic villus sampling is obsolete however in recurrent vases of NTD or ultrasound features suggestive of genetic etiology invasive testing is used to diagnose the genetic etiology & provide more detailed information about the condition.
• Postnatal Diagnosis: In some cases, neural tube defects especially closed neural tube defects may not be detected until after birth, when physical assessment and imaging tests, such as MRI or CT scans, can help identify the specific type and severity of the defect.

Treatment Options for Neural Tube Defects

The treatment for neural tube defects depends on the type and severity of the condition, as well as the specific needs of the individual. Treatment options may include:

• Surgical Interventions: For certain types of neural tube defects, such as spina bifida, surgical procedures may be performed to close the spine opening or manage associated complications.
• Shunt Placement: In cases of hydrocephalus (excessive buildup of fluid in the brain), doctors may place a surgical shunt to divert the fluid and relieve pressure on the brain.
• Rehabilitation and Supportive Care: Individuals with neural tube defects often require ongoing physical, occupational, and speech therapy, as well as assistive devices and other supportive care to manage their symptoms and enhance their quality of life.
• Palliative Care: In the case of severe and life-threatening neural tube defects, such as large open neural tube defects doctors may provide palliative care to ensure the comfort and dignity of the infant and family.

Lifestyle Changes to Prevent Neural Tube Defects

In addition to the medical interventions and treatments, several lifestyle modifications can lower the risk of neural tube defects:

• Folic Acid Supplementation: As mentioned earlier, adequate folic acid intake before and during pregnancy is vital for preventing neural tube defects. Women of childbearing age should take a daily supplement of at least 400 mcg.
• Healthy Diet: Consuming a balanced meal rich in folate-containing foods, such as leafy greens, citrus fruits, beans, and whole grains, can also help prevent neural tube defects.
• Preconception Care: Women who are planning a pregnancy should consult with their doctor to assess their risk factors and receive guidance on optimising their health and nutrition before conception.
• Chronic Condition Management: Women with pre-existing conditions, such as diabetes or epilepsy, should work closely with their medical team to ensure proper management and control of these conditions before and during pregnancy.
• Avoid Harmful Substances: Pregnant women should try to avoid alcohol, tobacco, and other potentially harmful substances, as these can increase the risk of neural tube defects and other congenital abnormalities.

Conclusion

Neural tube defects are a serious and complex group of congenital abnormalities that can significantly impact an individual's health and quality of life. However, with increased awareness, early intervention, and proactive measures, many of these defects can be prevented or effectively managed.