Neural tube defect | Symptoms & Causes | Diagnosis
 


What this section contains?
1. What is Neural tube defect?
2. Cause
3. Diagnosis & Tests
4. Prevention & Risk Factors
5. Treatments & Therapies
Neural tube defect

What is Neural tube defect?

Neural tube defects are birth defects of the brain, spine, or spinal cord. It happen in the first month of pregnancy, often before a woman even knows that she is pregnant.
The two most common neural tube defects are spina bifida and anencephaly.
In spina bifida, the fetal spinal column doesn't close completely. There is usually nerve damage that causes at least some paralysis of the legs.

In anencephaly, most of the brain and skull do not develop. Babies with anencephaly are usually either stillborn or die shortly after birth.

Another type of defect, Chiari malformation, causes the brain tissue to extend into the spinal canal.The exact causes of neural tube defects aren't known.

You're at greater risk of having an infant with a neural tube defect if you Have obesity, Have poorly controlled, diabetes, Take certain antiseizure medicines.

Getting enough folic acid, a type of B vitamin, before and during pregnancy prevents most neural tube defects.

Cause

Folate deficiency
Neural Tube Defect can be attributed primarily to inadequate levels of folate (vitamin B9) and vitamin B12 during pregnancy. Despite both being part of the same biopathway, folate deficiency has a much higher chance of occurence. Folate is required for the production and maintenance of new cells, for DNA and RNA synthesis. Folate is needed to carry one carbon groups for methylation and nucleic acid synthesis. It has been hypothesized that the early human embryo may be particularly vulnerable to folate deficiency due to functional enzymes pathway differentiation during embryogenesis combined with high demand for post translational methylations of the cytoskeleton in neural cells during neural tube closure.Its Failure of post-translational methylation of the cytoskeleton, required for differentiation has been implicated in neural tube defects. Vitamin B12, an important receptor in the folate biopathway such that studies have shown deficiency in vitamin B12 contributes to risk of NTDs as well. There is substantial evidence that direct folic supplementation increases blood serum levels of bioavailable folate even though at least one study have shown slow and variable activity of dihydrofolate reductase in human liver. A diet rich in natural folate can show as much increase in plasma folate as taking low levels of folic acid in individuals. However a comparison of general population outcomes across many countries with different approaches to increasing folate consumption has found that only general food fortification with folic acid reduces neural tube defects.
A deficiency of folate itself does not cause neural tube defects. The association seen between reduced neural tube defects and folic acid supplementation is due to a gene-environment interaction such as vulnerability caused by the C677T Methylenetetrahydrofolate reductase (MTHFR) variant. Supplementing folic acid during pregnancy reduces the prevalence of NTDs by not exposing this otherwise sub-clinical mutation to aggravating conditions. Other potential causes can include folate antimetabolites (such as methotrexate), mycotoxins in contaminated corn meal, arsenic, hyperthermia in early development, and radiation. Maternal obesity has also been found to be a risk factor for NTDs. Studies have shown that both maternal cigarette smoking and maternal exposure to secondhand smoke increased the risk for neural tube defects in offspring. A mechanism by which maternal exposure to cigarette smoke could increase NTD risk in offspring is suggested by several studies that show an association between cigarette smoking and elevations of homocysteine levels.[citation needed] Cigarette smoke during pregnancy, including secondhand exposure, can increase the risk of neural tube defects. All of the above may act by interference with some aspect of normal folic acid metabolism and folate linked methylation related cellular processes as there are multiple genes of this type associated with neural tube defects.

Diagnosis & Tests

Neural Tube deduction could be done in multiple manner as detailed below: 1. Ultrasound Examination 2.Measurement of maternal serum alpha-fetoprotein (MSAFP)
The primary screening tool for NTDs is Second trimester ultrasound and secondary tool is MSAFP.
The reason being increased safety and sensitivity with decreased false positive rate of ultrasound as compared to MSAFP. Tests like Amniotic fluid alpha-fetoprotein (AFAFP) and amniotic fluid acetylcholinesterase (AFAChE) are also used to confirming if ultrasound screening indicates a positive risk. Often, these defects are apparent at birth, but acute defects may not be diagnosed until much later in life.

Prevention & Risk Factors

It is necessary to notice that in the primary four weeks of maternity (when most ladies don't even notice that they're pregnant), adequate vitamin B complex intake is important for correct operation of the neurulation method. Therefore, girls who may become pregnant are suggested to eat foods fortified with B or take supplements additionally to consumption folate-rich foods to cut back the risks of significant birth defects. In Canada, necessary fortification of chosen foods with B has been shown to cut back the incidence of neural tube defects by forty sixth.Women who could become pregnant are suggested to induce four hundred micrograms of B daily. girls who have previously given birth to a baby with a neural tube defect could have the benefit of a supplement containing recommended dosage advised by the doctor.

Treatments & Therapies

As of 2008, treatments of NTDs depends on the severity of the complication. No treatment is offered for congenital anomaly and infants typically don't survive over some hours. Aggressive surgical management has improved survival and also the functions of infants with congenital anomaly, meningoceles and delicate myelomeningoceles. The success of surgery usually depends on the number of brain tissue concerned within the birth defect. The goal of treatment for NTDs is to permit the individual to attain the best level of operate and independence. vertebrate surgery in utero before twenty six weeks gestation has been performed with some hope that there's benefit to the ultimate outcome as well as a reduction in Arnold