Microcephaly is a congenital malformation, characterized by a significant decrease in the brain, and then the skull, due to a violation of the process of growth of brain tissue during fetal intrauterine development.
The disease can be an independent anomaly, or be the result of various genetic disorders (true microcephaly). The disease can develop in the fetus even if the pregnant woman has suffered from various pathologies (false microcephaly).
But, anyway, and for this deviation is characterized by a lag in the mental development of the child, or the manifestation of other disorders of the central nervous system.
What it is?
Microcephaly is a severe neurological disease, accompanied by a significant decrease in the mass of the brain and a subsequent decrease in the skull by more than 2 to 3 sigmatic deviations (when compared with generally accepted normal values). The disease occurs in 1 out of 10,000 cases, and its prevalence is the same among boys and girls.
In 10% of cases, as observations show, microcephaly is the cause of the development of oligophrenia. In a newborn child with such a defect, the head circumference, as a rule, does not exceed 25 - 27 cm, while the parameters of 35 - 37 cm are considered normal. The brain mass in children with microcephaly is about 250 g at a rate of 400 g.
Causes of development
Microcephaly is divided into primary (true or hereditary) and secondary (false, syndromic). Primary microcephaly occurs in 7 - 34% of all cases, and is recorded mainly in children with hereditary diseases.
True (primary) microcephaly: causes
Primary microcephaly has several forms that are individual pathological abnormalities:
- Giacomini syndrome is a genetically determined microcephaly, accompanied by mental disorders that are often combined with convulsive syndrome and progressive paralysis.
- Payne syndrome. Another hereditary disease that occurs only in boys. It is characterized by leg cramps, cardiac abnormalities, and nervous disorders.
In addition, microcephaly may be associated with:
- Down Syndrome. The disease occurs due to the presence of an extra chromosome in 21 pairs, which leads to a child lagging in mental development, microcephaly and a decrease in the cerebellum and other abnormalities.
- Patau Syndrome. In this case, the extra chromosome appears in 13 pairs, which leads to low body weight of the newborn baby, microcephaly and other developmental abnormalities.
- Edwards Syndrome. This genetic disorder develops when an extra chromosome appears from the 18th pair. This defect is characterized by narrowness and elongation of the skull, underweight of the newborn, underdevelopment of the brain and cerebellum. In Edwards syndrome, there is a defect in the development of the facial skeleton, feet and many internal organs.
- Feline cry syndrome. This is a chromosome defect in pair 5, which provokes microcephaly, insufficient body weight, a lag in the mental and physical development of the baby. In addition, the child has a cry, similar to the cat's meow, which is the result of damage to the laryngeal cartilage.
- Prader-Willi Syndrome. This damage to chromosome 15, which is characteristic not only of microcephaly, but also delayed psychomotor development, defects in the work of internal organs and bones.
- Miller-Dicker Syndrome, in which the defect is noted in chromosome 17. This pathology is accompanied by a violation of the development of brain neurons in the embryo. This explains the fact that the brain in the newborn is smaller, and also has an insufficient number of convolutions. In addition, the infant has hypotonia, multiple malformations of internal organs and a lag in mental and physical development.
- Phenylketonuria. This is a hereditary pathology in which the processing of the amino acid phenylalaline is impaired. As a result, substances that have toxic properties are formed and have a very negative effect on the nervous system of the future mother. In parallel with this, the development and growth of the brain in the fetus is inhibited.
The development of false (secondary) microcephaly occurs under the influence of negative factors affecting the fetus during the laying and formation of the brain. The genetic apparatus of the parents is not subject to any changes.
To provoke a secondary microcephaly can:
- Infectious diseases - rubella, cytomegalovirus, toxoplasmosis, measles, etc.
- Alcohol intake by a pregnant woman. Ethanol penetrates the fetus through the placenta, which can provoke the so-called fetal alcohol syndrome. The disease is characterized by a child’s mental retardation, as well as malfunctioning of the internal organs.
- Addiction. Drugs consumed by a pregnant woman easily penetrate the placenta to the fetus, causing numerous defects and anomalies of its development.
- Taking medications that are contraindicated during pregnancy. These are antibiotics, hormones, antidepressants, etc.
- Hypoxia of the fetus. Oxygen starvation of fetal tissues leads to a delay in its formation, development and growth. As a result, mental retardation and other anomalies arise.
- Starvation. If a woman is keen on starvation, or does not consume protein foods in the right quantity, this has a negative effect on the formation of fetal organs. This is fraught with the development of dystrophies and various vices.
- Abdominal injuries during pregnancy can lead to a deterioration in the development of the brain and internal organs in the fetus. Sometimes such injuries lead to fetal death of the child.
- Radiation exposure. With the development of the embryo, active growth of all tissues occurs. The effects of radiation at this time lead to irreversible processes in the brain.
With microcephaly in the newborn, a reduced size of the skull is noted, and this defect remains for life.
The facial skull dominates over the cerebral, the patient has a narrow, sloping forehead, protruding eyebrows, the large size of the ears. The closure of the cranial sutures and large fontanel is fixed during the first months of the patient's life with microcephaly. As they grow, such children lag in weight gain and height (up to dwarfism), have a disproportionate physique, narrow sky, large and rare teeth.
Neurological disorders in this disease are accompanied by:
- muscular dystonia;
- spastic paresis;
- Cerebral palsy.
Due to a delay in development, babies with microcephaly begin to crawl late, talk, walk, hold their heads. There is a slowdown in the development of speech motility, poor vocabulary, a distorted understanding of the speech addressed to the child.
Deviations in the intellectual development of such babies can manifest themselves with varying intensity - from moronity to idiocy. If the symptoms of microcephaly are not very pronounced, the children can be trained, as well as capable of self-care and simple tasks. But, unfortunately, in most cases, patients with a similar deviation require care and constant supervision by adults.
As for temperament, children with microcephaly belong to the torpedo and eretic group. For the first case are characteristic:
- low mobility;
- lethargy and apathy;
- passively imitative activity.
Children of the eratic group:
- excessively mobile;
Emotionally, children with microcephaly are no different from their peers. They are good-natured and friendly, but sometimes they can be overly hot-tempered, their mood can change dramatically.
For the primary diagnosis, the doctor collects a history, detailing the baby's parents. Next, a visual examination of the child is carried out with an assessment of the status of the springs, measuring the circumference of the head, followed by a comparison of the parameters obtained with the centile table, and a study of the symptoms that indicate a violation of mental development.
During pregnancy, a woman regularly undergoes an ultrasound scan to compare the biometric parameters of fetal development. However, ultrasound is not always informative, therefore in 70% of cases microcephaly in the fetus is detected in the third trimester of gestation. During this period, abortion is no longer possible.
In addition, ultrasound has a high error in the final results, which in 20% of cases turn out to be false. Moreover, false positive and false negative data have almost the same frequency of occurrence. For this reason, patients at risk are recommended to carry out additional diagnostic procedures - amniocentesis, fetal karyotyping, chorionic biopsy.
It is important to differentiate microcephaly from other diseases (for example, craniostenosis), it is necessary to conduct a radiography of the skull. Comprehensive studies help determine the degree of pathology. To do this, prescribe EEG, laboratory tests of blood, CT or MRI, neurosonography.
Treatment of microcephaly
Microcephaly is an incurable disease. Therefore, during pregnancy, a woman is recommended to undergo regular diagnosis. It is also necessary if the parents of the unborn child have hereditary diseases, or the mother has suffered infectious pathologies during pregnancy. In this case, abortion is recommended in the early stages, if the fetus showed signs of microcephaly.
Even if children born with such a deviation survive, the defect remains with them until the end of life. The only thing that modern medicine can do is to provide classes for such kids to teach them self-care, improve their intellectual development, and enable them to adapt to life in society.
Microcephaly is not considered a deadly disease. But it can be dangerous if the nerve centers in the respiratory and other vital functions were damaged.
However, against the background of microcephaly, other pathological conditions can also develop in the form of:
- Cerebral palsy;
- heart defects;
- congenital cataracts;
- formation of frontal clefts;
- renal hypoplasia, etc.
In view of this, the prognosis directly depends on the overall clinical picture, concomitant microcephaly in the child. But to completely get rid of the disease, as already noted, is impossible. Often, the duration of patients is reduced, and many of them have to stay in specialized boarding schools for mentally retarded people throughout their lives.
To prevent the development of microcephaly in a child, you must:
- adhere to a rational approach to pregnancy planning;
- be regularly examined for the presence of infectious diseases and genetic pathologies in parents (especially in pregnant women);
- terminate early pregnancy if suspicious developmental abnormalities have been identified in the embryo or fetus.
Therefore, members of families where previously there were cases of birth of children with microcephaly or other brain defects, it is necessary to undergo a thorough genetic examination, which will help to assess the risks of manifestation of such deviations in future offspring.