A mother sustains the skull of the newborn baby with microcephaly.
The word microcephaly have Greek etymology: comes mikros, which means ‘small’ and kephale, meaning ‘head’. Literally, microcephaly means small head, or rather, smaller what would touch a child by age and sex. The head growth is determined by the growth of the brain, so a small head means that the brain is smaller than normal. The exception to this is the craniosynostosis, in which the skull bones are fused and do not allow the growth of the brain.
Microcephaly is defined as a head where the skull circumference or occipitofrontal is more than two standard deviations below the average (there are those who consider that they would be three standard deviations). I.e., the perimeter of the head below the percentile 3 for the age and the sex of the child. In the case of premature children there are special tables to make the determination of the percentile.
You could be considered a cranial perimeter between two or three standard deviations below the average would be a limit microcephaly or a limit low of normality. Between 3 and 5 standard deviations would be a moderate microcephaly, and severe microcephaly would correspond to a measure more than 5 standard deviations below the average. We should also distinguish whether it is a harmonic microcephaly (which is also associated with delayed growth in terms of weight and size) or not.
However, it should be pointed out that there are people who have rather small head of constitutional form without to ensure them a problem. To evaluate a possible microcephaly in a child, should take into account the size of the head of the parents. On the other hand, not all races have the same head size, so if curves are used the World Health Organization standards, there would be some populations or ethnic groups that would be carried out diagnostics of micro or macrocephaly by excess or defect.
Microcephaly can be an isolated problem, without other associated malformations, brain can have a structure and even a normal operation. Not to be confused a small head, but within the bounds of normalcy, with this entity. The most common in any case is that the child with microcephaly have other problems of development, some associated with neuroanatómico syndrome or diseases of metabolism.
Microcephaly can be diagnosed before birth in gestation routine revisions, although many times it is not apparent until the third quarter. Often is not diagnosed until after childbirth or in periodic inspections are carried out. Microcephaly may appear up to three years of age. Thus, present, congenital microcephaly stands already at birth or at 36 weeks of gestation, postnatal microcephaly, which is stopping the growth of the brain that had a normal size at birth.
Microcephaly is a present abnormality from birth which may be due to various causes.
There are microcefalias that are due to a primary change in the development of the brain. Microcephaly is present from birth. In these cases there are lesser number and size of brain cells:
- Microcephaly can be a problem isolated, present from birth and without other complications and associated problems. Also called ‘ microcephaly vera or true ‘, or ‘primary microcephaly’. It is a very rare genetic disorder. Is there a way to autosomal recessive, another key, and otherwise linked to the X chromosome has been described.
- Syndromic microcephaly is the one associated with different syndromes that microcephaly is one of the signs of the syndrome. Syndromes in which the microcephaly is feature include: Down syndrome, Trisomy of chromosome 18, Trisomy of chromosome 13, Seckel syndrome, Smith-Lemli-Opitz syndrome, Williams-Beuren syndrome, the syndrome of Cornelia de Lange, the Miller-Dieker lissencephaly, Wolf-Hirschhorn syndrome, the syndrome of the cat’s Meow, the monosomy 1 p 36 Mowat-Wilson syndrome, Rubinstein-Taybi syndrome and Aicardi-Goutieres syndrome.
- On the other hand, multiple abnormalities neuroanatomical are associated with microcephaly, defects of the neural tube (anencephaly, hydranencephaly, encephalocele), holoprosencephaly, atelencefalia, lissencephaly, esquizencefalia, polymicrogyria, macrogiria or paquigiria, and disruptive sequence of the fetal brain. All of them are associated with alterations of the IQ and the development of the child, and may affect the vital prognosis to a greater or lesser extent according to the degree of involvement. Many are incompatible with life.
Microcephaly may also be secondary to an arrest of brain growth. One could distinguish:
- Toxic in-utero exposure: alcohol, tobacco, cannabis, cocaine, heroin, anticancer drugs, antiepileptic drugs, ionizing radiation, toluene.
- Prenatal infections: rubella, chicken pox, herpes, Cytomegalovirus, toxoplasma, syphilis, HIV, Zika, and others.
- Infections of the central nervous system in early childhood: meningitis and viral, bacterial meningoencephalitis, brain abscesses, cerebral tuberculosis…
- Perinatal brain damage: suffocation, hypoxic-ischemic encephalopathy, hypoglycemia, dehydration, extreme malnutrition, traumatic brain injury.
- Hormonal disorders: hypothyroidism, Hypopituitarism, Hypoadrenalism.
- Maternal metabolic diseases such as diabetes mellitus or untreated phenylketonuria.
- Metabolic disorders: phenylketonuria, aminoacidopatias and organic acidurias, mitochondrial diseases, peroxisomal diseases.
The early closure of all cranial sutures present at birth or craniosynostosis manifests also with microcephaly.
Microcephaly can have very serious consequences for the baby, from mental retardation to sensory or motor changes.
The symptom of microcephaly more frequent, and present in greater or measured in most of the cases from the moderate, is mental retardation. The brain is smaller and does not work in a normal way. Depending on the cause of microcephaly and the degree of involvement, this mental retardation can be more or less serious and condition the cognitive development of the child to a greater or lesser degree.
In addition to mental retardation, according to the cause may be other associated symptoms:
- Some crisis. There may be further movement disorders or defects of the mobility. Cerebral palsy is relatively frequent.
- Neurosensory disorders: blindness and deafness.
- Psychological disorders and behavior disorders.
- Malformations of other organs of the body such as the heart or kidneys. Increasing the size of the liver or spleen may be secondary to intrauterine infection.
- Atypical appearance: a classic example is Down syndrome, but also in other commented syndromes that are associated with microcephaly child has a more or less characteristic phenotype of the syndrome suffered by. The head, in addition to being small, can be deformed.
- Feeding difficulties: anatomical alterations or difficulty swallowing. There may be frequent cleft palate.
- Cutaneous alterations in some cases of intrauterine infections or certain metabolic diseases.
Prognosis of microcephaly
Microcephaly prognosis depends on the cause that has occurred. The prognosis is worse in those cases in which the microcephaly is part of a syndrome with important manifestations as the trisomy of chromosome 13 (more than 90% of infants die before reaching the year) or 18 (half of the babies died in the first week of life and 90% does not a year).
The prognosis of these babies also tends to be bad if there has been an intrauterine infection, such as rubella, toxoplasma and Cytomegalovirus, and in cases of severe malformations such as anencephaly (where the child is often born dead or died within hours of birth).
With regard to mental retardation, in a study of 680 cases of children with microcephaly, 65% had mental retardation and 43% epilepsy. In two other studies IQ was much lower as it was the size of the head. In a study that followed 57 infants with postnatal diagnosis of microcephaly, only 23% had normal cognitive development at age 4. In any case, to maintain the growth of the head, even in low percentiles, the prognosis is better than if the head does not grow.
Measurement of the cranial perimeter of an infant with suspected microcephaly.
In the prenatal period microcephaly is diagnosed by ultrasound when cranial circumference is 3 standard deviations below the average or below the percentile for gestational age 2. This diagnosis is complicated because it is not easy to measure accurately the cranial perimeter of the fetus and actually there is a precise correlation between the cranial growth curves before and after birth. If there is a child with microcephaly prior performs an ultrasound evaluation in the 20th week of gestation. Another additional option is a fetal MRI. Consult a specialist and perform new scans ultrasound, although really little can be done even when it detects. In addition, even a severe microcephaly can not be diagnosed until birth.
He is tracked every child from birth of her cranial perimeter measurement. If detected at some point that this is very low, compatible with microcephaly, must be a fuller assessment by a neuropaediatrician. There will be occasions where microcephaly is evident from birth but in other occasions is detected the passing of the months.
To make the diagnosis of microcephaly or rule out it is essential to perform a complete medical history, including the size of the head of the parents, diseases that may have parents or siblings and maternal health during pregnancy. Should we explore the child in full, noting any data or alteration that suggest the presence of a syndrome or disease of the commented as the cause of microcephaly. In addition to the extent of the cranial perimeter, you must be an analysis of the curve of growth in terms of weight and size.
It is important to perform a complete physical examination to detect any such alteration that the child may have. In addition, it will ask potential symptoms or problems that may exist, such as movement disorders, some crisis, changes in a neuropsychological development… Although typically, that parents would have already consulted for any problems which had arisen, or that have been detected in routine revisions to the children. However, not in all countries and areas are made these revisions, so it sometimes can reach the query children with problems unattended.
According to findings from the history and physical examination, you can perform additional tests as genetic studies to detect an intrauterine infection (if not diagnosed during pregnancy), or tests to diagnose diseases metabolic or from deposit (although many are detected at an early stage in the test of the heel that is carried out in many countries). As the magnetic resonance neuroimaging studies allow to study brain structure. Axial tomography to detect intracerebral calcifications. In patients with epilepsy, electroencephalography is useful.
The majority of cases of microcephaly can not prevent or treat.
There is no specific treatment for microcephaly. Only some symptoms can be alleviated to some extent. For example, if you have seizures will be antiepileptic drugs. Physiotherapy, speech therapy, early stimulation and special education are needs compelling for most of these children and their families who will also need an important psychological and social support.
If there is significant anatomical defects some surgical techniques may be useful. Craniosynostosis can be treated by cutting in some areas the bone and sometimes changing snippets site so there is no pressure in the brain of the child, which the brain can continue to grow and improve the appearance of the skull. If there are malformations associated with microcephaly cleft lip or cleft palate, they can operate.
There is no curative treatment for mental retardation, but you should try to improve the situation of children affected by this to the fullest. In its various forms early stimulation and psychological therapies, the play therapy, animal therapy, music… be able to help a greater levels of autonomy of the child.
There are cases of microcephaly can be avoided. A pregnant woman should not drink toxic such as tobacco and alcohol, which are very harmful as well as other drugs such as cocaine or heroin. It is sometimes said that “it is better to smoke a little to stop smoking and have anxiety in pregnancy”; This is not true except in some extreme cases of psychiatric illness: tobacco is always worse than the maternal anxiety for fetal development.
On the other hand, it is very important that all women in fertile age are vaccinated for rubella. Also, during pregnancy do not eat drugs that are not safe for fetal development, unless the benefit exceeds the risk.
Unfortunately, many microcephaly cases cannot be avoided, with the suffering that is for the family and the child with microcephaly. A specific inquiry of genetic counseling if parents wish to have more children can be performed in patients in which the cause is genetic.
Suffering from infection by Zika virus during pregnancy has been associated with microcephaly on the baby.
In recent months the Zika virus epidemic has gained new dimensions with an alarming manifestation among children born to pregnant women who have passed the infection by the virus during pregnancy. Although there have been epidemics of the Zika virus previously, it has not been until recently that has been observed the possible Association of neurological defects and microcephaly in newborns of infected mothers.
In French Polynesia, where there was an outbreak between 2013 and 2014 was notified recently an unexpected increase in neurological malformations in newborns in 2014 and 2015, thus coinciding with the Zika virus outbreak. In particular, there were 17 cases of newborn infants with neurological birth defects, when in previous years had between 0 and 2 per year. The Zika virus antibodies were found in samples of four of the mothers.
The problem has very worrying dimensions especially in Brazil, where an unusual increase in the incidence of microcephaly reported in newly born to the Northwest of the country where the Zika virus circulates. Between 2015 and late January reported almost 4783 cases of microcephaly or brain abnormalities suggestive of congenital infection. However, of the first 1113 cases investigated, in 709 scan was finally discarded microcephaly or had another cause for it. 404 elsewhere was Zika infection laboratory confirmed in 17 cases (in the rest the diagnosis was microcephaly by clinical and radiological criteria). Therefore, are many cases to investigate. Between 2010 and 2014 throughout the country had an average of 163 cases of microcephaly. It is therefore investigating the relationship between outbreaks of Zika and microcephaly, although already nobody seems to deny that this relationship exists, although more data are needed to understand it better.
Recommendations for pregnant women in areas with zika
There are countries where already is recommended to women while there is movement of the Zika virus and not the vector control be achieved (i.e. ending the mosquito that transmits the virus, very difficult thing) that do not become pregnant. In countries where there is no epidemic of native zika, is recommended to pregnant women who plan to travel to areas with zika that they postpone their trips if possible. Where you need to travel to these areas, should take extra precautionary measures to prevent mosquito bites. In addition, in the event that is your partner is in an area with epidemic of zika, not should sexual intercourse without protection for at least one month since his return, since infection is asymptomatic in 75% of cases and can be transmitted sexually.
The epidemic by the Zika virus does not imply a great danger to the general population. The majority of cases are asymptomatic, and until recently had no reported deaths or serious complications. However, the outbreak of America describes neurological complications such as Guillain-Barré Syndrome which seems that in some cases it seems that they could have been fatal. For all this and the possible involvement of the children of infected pregnant women is what the who has declared the global health emergency by the epidemic of zika.
On the other hand, there is no specific treatment that may prevent the possible involvement of the fetus when a pregnant woman infected by the zika. In addition, there will be many cases in which the woman or knows that it has infected by the high percentage of cases that go unnoticed. On the other hand, although vaccines are already being investigated, may take years until you get an effective, and in any case it would have to manage in non-pregnant women and probably neither could guarantee efficiency at 100%.
Additionally, the possible relationship between zika and microcephaly is a problem in those countries which do not allow abortion for reasons of fetal malformation, because there are women who resort to clandestine abortions with the consequent danger to your health. WHO has recommended putting contraception available to women in the areas with epidemic of zika and allow abortion in case of proven fetal malformation.
If a woman is pregnant and has to travel to an area with movement of zika, you should consult a medical service to the traveller. If you have been in an area with presence of zika, you should also consult with your obstetrician who will consult with a medical expert in infectious if necessary.