Sometimes the alteration of the neuronal migration process causes agiria, a brain malformation that makes the cortex look abnormally smooth, with the characteristic twists and furrows of this region being absent. When these signs appear, the diagnosis of “lysencephaly” is used.

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

What is lysencephaly?

Lysencephaly is a set of disorders characterized by a smoothing of regions of the brain where there are usually folds and crevices. These malformations often lead to alterations in the development of the nervous system and therefore of cognitive and psychomotor functions.

During intrauterine development, the cerebral cortex retracts 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 lysencephaly the grooves and folds of the brain are not formed correctly , so that this organ shows a homogenous appearance. The intensity of this smoothing may vary in each individual, depending on the causes of the disorder.

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

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

Main symptoms and signs

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

In many cases the head size of babies born with this disease is very small compared to other newborns. Although this is a very characteristic sign of lysencephaly, it is not present in all people affected by such a disorder. Occasionally hydrocephalus (accumulation of spinal fluid) occurs.

Alterations in the cerebral cortex cause delays and deficits in physical, psychomotor and cognitive development . It is also frequent that physical malformations are produced in the hands, as well as in the fingers and toes. On the other hand, muscle spasms and convulsions are common.

Lysencephaly also tends to cause swallowing problems, which in turn makes food and fluid intake more difficult. As a result, in many cases physical development is further impaired by nutrient deficiencies.

Causes of this alteration

Lysencephaly appears as a consequence of alterations in the formation of the cerebral cortex that occur during gestation. 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 week after fertilization the nerve cells of the embryo begin to move from the regions of the brain where they are generated to different regions. In lysencephaly this process of cell migration does not take place properly.

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

Viral infections and decreased blood flow to the fetus can also cause signs of lysencephaly by interfering with the development of the central nervous system.

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

Treatment

Since it is an alteration in the morphology of the brain, lysencephaly cannot be corrected by itself. Clearly, it is not possible to reverse the development of the nervous system once it has occurred.

Because of this the treatment of lysencephaly is basically symptomatic and aims to improve the quality of life and enhance the functioning of affected people.

Thus, for example, in cases where swallowing difficulties are very marked it may be necessary to apply a gastric tube to the babies’ stomach so that they can feed themselves correctly.

Muscle spasms and epileptic seizures can be managed by using specific medications for these types of disorders. On the other hand, when hydrocephalus is present, surgical interventions are performed to drain the accumulated cerebrospinal fluid.