The nervous system is one of the first systems in our body to begin developing during pregnancy. Throughout pregnancy and even during the individual’s lifetime this system will be modified and developed, especially from gestation to the beginning of adulthood.

However, in some cases the brain does not grow as it should or at the usual rate from pregnancy onwards, causing the birth of children with heads that are much smaller than average, often linked to the presence of different disorders and a certain degree of intellectual disability. This is what is known as microcephaly .

Microcephaly: concept and symptoms

We understand as microcephaly the situation, condition or neonatal affectation in which the skull and brain of the child presents an evident absence or delay of development at birth or during the first years, compared to other individuals of the same age. This is a rare disorder that can come from different causes. In general, it is considered that the cranial perimeter of a child with microcephaly is between two and three standard deviations below the average.

Although in some cases children with microcephaly may have a normative level of intelligence, as a general rule this affectation courses with a variable degree of intellectual disability . Diverse alterations can also occur such as loss of vision, feeding difficulties, generalized slowing of development and convulsions.

Over time, as the child grows, the face and the rest of the body develop, but the skull still does not grow . This is why this type of child usually has a sunken forehead and an elongated face.

This situation is usually detected throughout the pregnancy , or after the first hours after delivery. However, sometimes years may pass before an atypical development is identified, not being evident in the first months of life.

Origin of this type of medical condition

There is no single cause that can generate microcephaly, but we can find different disorders and conditions that can generate it . Most of these are conditions and diseases that are produced or transmitted during the development of the foetus or during birth.

Some disorders, mutations and genetic alterations can generate microcephaly. Among them are trisomy 18 (Edwards syndrome) and 21 (Down syndrome).

Other frequent causes of microcephaly have to do with the transmission of various viruses from the mother to the fetus . Toxoplasmosis, cytomegalovirus, rubella or the well-known Zika virus have been shown to cause alterations in the foetus that can lead to microcephaly.

In addition, pregnant women should take care of their health and treat diseases such as phenylketonuria or diabetes (which if not controlled can also alter the development of the fetus due to the absence of certain nutrients). Some drugs and the abusive use of alcohol can cause this alteration. Malnutrition also makes it difficult for the future child to develop normally.

Complications during childbirth

Even if fetal development is adequately completed, complications such as anoxia can arise during delivery that can alter the functioning and developmental ability of the brain.

Likewise, although the size of the skull generally increases throughout development thanks to the growth of the brain, with the size of the latter being what causes the former to be smaller in cases of microcephaly, there are cases in which there is premature suturing of the bones of the skull that does not allow the brain to grow, a medical condition known as craniosynostosis .


Microcephaly does not have a treatment that reverses the condition . The treatments performed are based on occupational therapy, stimulation and educational practice. It is necessary and very useful to offer therapies focused on speech and psychomotor skills so that these children improve their basic abilities, as well as to work on the emotional sphere of the child. The aim is to enable them to lead the best possible standard of living by optimising their skills and exploiting their potential.

Likewise, psycho-education and counselling for the family and the close environment is fundamental in order to help the child to develop in the most adaptive way possible, while at the same time providing information and allowing the expression of doubts and fears to the family.

One of the conditions that can cause microcephaly is the premature hardening of the bony plates of the skull or craniosynostosis, which prevents the growth and normative development of the brain by physically limiting it. This particular condition, if detected in time, can be reversed by surgery , so that harmful effects on the brain would be avoided.

Prevention is also essential. Maternal use of drugs and certain substances, malnutrition, failure to treat medical conditions such as phenylketonuria, or transmission of certain viruses such as toxoplasmosis (which can be transmitted through cat feces or the consumption of uncooked, spoiled or contaminated food) can all be possible causes of microcephaly, and in some cases can be avoided.

Bibliographic references:

  • Kinsman, S.L. & Johnston, M.V. (2016). Congenital anomalies of the central nervous system. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier.