Lissencephaly: symptoms, causes and treatment

Sometimes the alteration of the neuronal migration process causes agiria, a brain malformation that causes the cortex has an abnormally smooth appearance, the characteristic gyrus and grooves being absent region. When these signs appear, the diagnosis of "lissencephaly" is used.

In this article we will describe what is lissencephaly, what are its causes and its most common symptoms and how such disturbances can be treated or at least managed.

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What is lissencephaly?

Lissencephaly is a set of disorders characterized by a smoothing of brain regions in which there are usually folds and crevices. These malformations frequently cause alterations in the development of the nervous system and therefore of the cognitive and psychomotor functions.

During intrauterine development the cerebral cortex it folds in on itself in many places. This allows the volume of nerve tissue that fits inside the skull to be much greater than if the surface of the brain were completely smooth.

However, in cases of lissencephaly the furrows and folds of the brain are not formed correctly, so that this organ shows a homogeneous appearance. The intensity of this smoothing can vary in each individual, depending on the causes of the alteration.

It is a very rare disorder that can have significant consequences for physical and mental development. In the most severe cases, intellectual functioning is severely affected, while in others the deficits may be minimal.

Life expectancy is around 10 years. The most common causes of death are asphyxia by choking, diseases of the respiratory system and epileptic seizures, which can be very serious.

Symptoms and main signs

The symptoms of lissencephaly depend on the severity of the malformations in the cerebral cortex, as well as the specific regions that are affected. The fundamental aspect is agiria, a technical term used to refer to the flat appearance of the cerebral cortex.

In many cases, the size of the head of babies born with this disease is very small compared to that of other newborns. Although this is a very characteristic sign of lissencephaly, it is not present in all people affected by a disorder of this type. Hydrocephalus (accumulation of cerebrospinal fluid) sometimes occurs.

Alterations in the cerebral cortex cause delays and deficits in physical, psychomotor and cognitive development. It is also common for physical malformations to occur in the hands, as well as in the fingers and toes. On the other hand, muscle spasms and seizures are common.

Lissencephaly also tends to cause swallowing problems, which in turn makes food and fluid intake difficult. Consequently, in many cases, physical development is further affected by nutrient deficiencies.

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Causes of this alteration

Lissencephaly appears as a consequence of alterations in the formation of the cerebral cortex that occur during pregnancy. The causes of these errors can be very diverse; However, the most common are related to genetic factors.

When intrauterine development progresses normally, between the twelfth and fourteenth weeks after fertilization the nerve cells of the embryo begin to move from the regions of the brain where they are generated to other different. In lissencephaly this cell migration process does not take place properly.

Scientific research reveals that this problem is usually due to mutations in multiple genes: brain development is affected by not being able to express these correctly. The genes involved appear to be located on chromosomes X, 7 and 17, although they are probably not the only ones.

Virus infections and decreased blood flow that the fetus receives can also cause signs of lissencephaly by interfering with the development of the central nervous system.

An association between lissencephaly and two genetic diseases has been identified: Miller-Dieker syndrome and Walker-Warburg syndrome. It is very common for agiria to present itself in the broader context of one of these disorders.

Treatment 

Since it is an alteration in the morphology of the brain, lissencephaly cannot be corrected by itself. It is clear that it is not possible to go back in the development of the nervous system once it has occurred.

Because of this the treatment of lissencephaly is basically symptomatic and its objectives are to improve the quality of life and enhance the functioning of the affected people.

Thus, for example, in cases where swallowing difficulties are very marked a gastric tube may need to be applied to the stomach of babies so they can feed properly.

Muscle spasms and epileptic seizures can be managed through the use of specific medications for these types of disorders. On the other hand, when there is hydrocephalus, surgical interventions are carried out to drain the accumulated cerebrospinal fluid.