Anencephaly
The content of the article:
- Causes and risk factors
- Forms of the disease
- Symptoms
- Diagnostics
- Treatment
- Forecast
- Prevention
Anencephaly is a gross malformation of the fetus, consisting in the complete or partial absence of the cerebral hemispheres, soft tissues and bones of the cranial vault.
Anencephaly occurs in about one fetus in every 10,000 newborns, more commonly in girls. It is usually combined with other malformations:
- splitting of the vertebral arches;
- non-closure of the upper lip (cleft lip);
- non-closure of the hard palate (wolf mouth);
- spinal hernia;
- absence of the pituitary gland;
- hypoplasia or aplasia of the adrenal glands.
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Causes and risk factors
At 3-4 weeks of gestation, the embryo is actively forming the neural tube. Violation of this process leads to non-closure of the anterior neuropore, which does not allow the development of frontal extensions of the neural tube, that is, cerebral vesicles, from which parts of the brain are to be formed in the future. The brain tissue does not develop properly; instead of it, in place of the cerebral hemispheres, fibrous tissue is formed with numerous blood vessels penetrating it. In the thickness of the fibrous tissue, single nerve cells and neuroglia are located, as well as cystic formations, the cavities of which are lined with medullary epithelium.
The following factors can lead to disturbances in the processes of bookmarking and development of the brain:
- unfavorable ecological situation;
- exposure to ionizing radiation;
- intoxication of a pregnant woman with heavy metal salts;
- severe alcohol or drug intoxication;
- viral diseases in the first trimester of pregnancy;
- hereditary factor (cases of anencephaly in the family);
- complicated pregnancy.
Unfavorable factors affecting the development of anencephaly and other fetal malformations
Forms of the disease
There are several forms of anencephaly:
- Meroacrania is a cranial defect that does not affect the foramen magnum.
- Holoacrania is a defect in the occipital bone and foramen magnum.
- Holoacrania with rachischis is a defect of the occipital bone in combination with splitting of the neural tube.
The following types of anencephaly are distinguished by anatomical location:
- frontal-occipital-vertebral - 71.4%;
- occipito-vertebral - 23.8%;
- parietotemporal-vertebral - 4.8%.
Symptoms
Children born with this defect lack certain parts of the brain, cranial bones, and soft tissues of the head. The body is usually formed without anomalies.
During pregnancy, a fetus with anencephaly lives off the mother's body and outwardly develops normally. If the baby is born alive, tactile reactions, responses to sound, breathing may be present. However, due to a serious developmental pathology, the brain cannot perform its functions. As a result of this, the newborn has breathing disorders, cardiac activity, which leads to death.
Diagnostics
With an accuracy of 96%, anencephaly can be diagnosed by ultrasound examination at a gestational age of 11-12 weeks. The main echoes of this defect are:
- the presence of vascular malformation of the primary brain;
- lack of brain tissue;
- lack of bones of the cerebral part of the skull.
An indirect sign of a defect in the formation of a neural tube is an increase in alpha-fetoprotein in the blood of a pregnant woman. This analysis is performed for a period of 13-14 weeks.
It is possible to reliably diagnose anencephaly by performing an ultrasound scan at 11-12 weeks of pregnancy
In some cases, amniocentesis is recommended. To do this, a puncture of the amniotic sac is performed through the anterior abdominal wall under ultrasound control and a small amount of fluid is taken from it for laboratory research. Elevated levels of acetylcholinerase and alpha-phenoproteins indicate a neural tube defect.
In order to clarify the diagnosis, an embryonic magnetic resonance imaging is performed. This method allows you to recreate a three-dimensional image of a developing embryo, including the brain. Fetal MRI is more informative than ultrasound.
Treatment
There is no cure for anencephaly. After diagnosing the indicated defect, the pregnant woman is recommended to terminate the pregnancy for medical reasons at any gestational age.
Forecast
The prognosis for anencephaly is unfavorable: the mortality rate is 100%. Half of the fetuses die during intrauterine development. Babies born alive die in the first hours of their life, some live up to 7-10 days. In the literature, there is a description of only one case when a girl with anencephaly lived for 30 months.
Prevention
The exact causes of anencephaly have not been established, therefore, specific prevention measures have not been developed.
It is known that a lack of folic acid (vitamin B9) in a pregnant woman's body can lead to neural tube defects. Therefore, gynecologists advise women to start taking folic acid at the planning stage of pregnancy and then continue until childbirth.
Pregnant women, especially in the first trimester, should avoid exposure to teratogenic factors.
If a married couple (or close relatives) have had a history of giving birth to children with gross malformations, genetic counseling is recommended for the spouses before planning a pregnancy.
Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
