Anencephaly (anencephaly) is a lethal, or fatal, developmental defect. What is anencephaly characterized by and why is it a problem at all? Are there any ways to prevent anencephaly?

Anencephaly( anencephaly ) is one of the most common neural tube defects. According to American statistics, anencephaly is found in 1 in 1000 pregnancies, but children with anencephaly are born much less - this problem statistically affects 1 in 10 thousand babies born. This differentiation is due to a very simple reason - in most cases of anencephaly, a child miscarries even in the early stages of pregnancy.

Anencephaly: reasons

One specific cause of anencephaly has not been distinguished so far. Currently, the dominant view is that the appearance of anencephaly in children is caused by a combination of genetic disorders and various environmental factors.

Pathological phenomena leading to anencephaly occur early, even before the fetus is one month old. Under normal conditions, around the third week of fetal life, the precursor of the human nervous system, the so-called nerve gutter. Various pathologies that impede this process may lead to craniocerebral clefts, the most severe form of which is anencephaly.

So far, many genes have been studied, the mutations of which - occurring in both mothers and children - may contribute to the occurrence of anencephaly. Some of the genetic defects have been better studied (as in the case of the MTHFR gene, the product of which is involved in folate transformations and whose mutations can lead to anencephaly), other mutations have been less well known so far, however, in the light of current knowledge it is not possible indication of specific mutations that could particularly lead to the appearance of anencephaly.

Environmental factors are also important in the etiology of anencephaly. These types of potential causes of anencephaly include:

  • folic acid deficiency (deficiency of this nutrient in the diet of a pregnant woman generally favors the occurrence of neural tube defects in children)
  • maternal he alth problems such as diabetes orobesity
  • use of various medications by the mother (e.g. certain antiepileptic drugs)
  • exposure of the fetus to overheating (harmful hyperthermia may occur as a result of both the mother's high fever and it may be associated with staying in a very warm place, e.g. in a sauna)

Anencephaly: clinical picture

Anencephaly, as already mentioned, is caused by non-closure of the structures of the primary nervous system. The effect of this is that the nervous tissue of the fetus is exposed to the amniotic fluid - the structures of the nervous system are extremely fragile and, if not protected by the structures of the skull, eventually degenerate. For this reason, children with anencephaly will not develop either the hemispheres of the brain or the cerebellum.

Another problem that is typically associated with anencephaly is malformation of the bony structures of the skull. A child born with anencephaly, usually in the place where the brain structures are typically located, has a baggy structure of reddish color made of connective tissue. It is possible that this part of the baby's head will be covered with skin, but this is actually a rarity.

Children born with anencephaly have many different disorders, such as:

  • breathing disorders
  • significant increase in muscle tone
  • intensified deep reflexes

Anencephaly: diagnostics

The diagnosis of anencephaly can be made after the baby is born, on the basis of changes characteristic for this pathology. However, it is definitely possible to diagnose anencephaly in the course of intrauterine life. Among the tests that are performed on pregnant women and on the basis of which it is possible to make a suspicion of anencephaly, the following can be mentioned:

  • determination of the concentration of alpha-fetoprotein in the mother's blood (in the case of various defects of the fetal neural tube, including anencephaly, the concentration of this marker in the pregnant blood increases)
  • ultrasound examinations (during ultrasound it is possible to find out that the child has disorders in the development of the nervous system - it should be emphasized, however, that the bony structures of the skull become clearly visible on ultrasound after the 12th week of pregnancy, therefore anencephaly in ultrasound can only be diagnosed after crossing the first trimester of pregnancy)

Anencephaly: treatment and prognosis

In the case of anencephaly, it's hard to talk about treatment at all - unfortunately, this condition is incurable. Some babies with anencephaly are born deadin turn, those that are born alive die within a dozen or so hours, up to a few days after giving birth. The latter occurs when the patient develops a residual brain (including centers that control breathing and heart function). In reality, however, there is no rescue for children with anencephaly, and that's why making persistent attempts to keep them alive is actually contraindicated.

Anencephaly: prevention

Even the early diagnosis of anencephaly, during the development of pregnancy, does not allow for the treatment of this defect. For this reason, it is most important to take measures to prevent the occurrence of anencephaly. Anencephaly prevention is based primarily on folic acid supplementation. The most important thing is to deliver this mineral to the body when the structures of the nervous system develop in the fetus. Not all pregnancies are planned, however, in the case of these planned pregnancies, in turn, patients often find out with a delay that they will be mothers in some time. For this reason, supplementation with folic acid should be implemented before trying to become pregnant. The general recommendations mention the intake of 0.4 mg of folic acid per day, in the case of women who have had a child with a neural tube defect in the past or in whose families this problem has occurred, it is sometimes recommended to take an increased dose of folic acid, up to 4 mg per day. .

Anencephaly: risk of disease in subsequent pregnancies

Couples who will give birth to a child with anencephaly may be concerned about whether they may also give birth to a child with the same individual from the next pregnancy. In such a situation, the risk of anencephaly in another child is unfortunately actually increased (compared to the general population) and it is estimated at 2 to 4%. U.S. Materials National Library of Medicine, on-line access: https://ghr.nlm.nih.gov/condition/anencephalyresources2. Materials of the Centers for Disease Control and Prevention, on-line access: https://www.cdc.gov/ncbddd/birthdefects/anencephaly.html 3. Robert G Best, "Ancencephaly", Medscape, on-line access: http://emedicine.medscape.com/article/1181570-overviewa1

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

Category:

Neurology