Polymicrogyria: causes, symptoms and effects

Normally, during the normal development of the brain a series of folds or turns are formed that serve so that the surface of the brain takes up less space and fits inside the skull. Like any other organ, the brain also suffers from malformations. An example of this is polymicrogyria, which affects the morphology of the folds of the cerebral cortex..

It is a disease that causes severe neurological symptoms due to malformations that occur during fetal development. Let's briefly see what kind of formative problems we find in polymicrogyria, what is its cause and what can be done with those people who suffer from it.

What is polymicrogyria?

The etymology of the word poly- (multiple) micro- (small) -gyria (folds) clearly indicates this: it is a morphological defect in which a greater number of smaller folds is observed. This genetic defect of the cortex can be clearly observed through radiodiagnostic tests such as magnetic resonance imaging (MRI). In these images it can be seen how the cortex is thicker and more intense, indicating a greater density, and how the folds are formed superficially, different from that of a normal brain.

There are different forms of polymicrogyria, each more serious. When it only affects one part of the brain, it is called unilateral. On the other hand, it is called bilateral when both hemispheres are affected. The nomenclature does not refer only to symmetry, but also to how many areas of the brain are affected. Thus, a brain with only one area affected would suffer from focal polymicrogyria, versus generalized polymicrogyria when almost all or all of the cortex is affected.

Patterns of polymicrogyria have a predilection for some lobes over others. The most frequently affected lobes are the frontal (70%), followed by the parietal (63%) and then the temporal (18%). Only a small portion (7%) have the occipital lobes affected. Likewise, it seems that it tends to deform the lateral fissures that separate the frontal and parietal lobes from the temporal ones more frequently (60%).

• Related article: "The lobes of the brain and their different functions"

Signs and symptoms

While the focal and unilateral forms do not usually cause more problems than seizures that can be controlled through medication, when they are bilateral the severity of the symptoms skyrockets. Some symptoms include:

• Epilepsy
• developmental delay
• Squint
• Speech and swallowing problems
• Muscle weakness or paralysis

The global affectations of polymicrogyria include profound mental retardation, serious movement problems, cerebral palsy and seizures impossible to control with medication. For this reason, while the milder forms of polymicrogyria allow a fairly long life expectancy, the people who are born with a severe affectation die very young due to the complications of the disease.

Polymicrogyria frequently does not present alone or in its pure form, but in conjunction with other syndromes such as:

• Variants of Adams-Oliver syndrome
• Arima syndrome
• Galoway-Mowat syndrome
• Delleman's syndrome
• Zellweger syndrome
• Fukuyama muscular dystrophy

Causes

In most cases the cause is unknown. There is a percentage of cases that occur because the mother suffers an intrauterine infection during pregnancy. Some viruses that are related to the development of polymicrogyria are cytomegalovirus, toxoplasmosis, syphilis and the varicella virus.

Inherited causes include both chromosomal syndromes, that is, they affect several genes at the same time, and single gene syndromes. There are many genetic disorders that change the way the brain is formed. For this reason, many genetic diseases are accompanied by polymicrogyria among other manifestations.

The GPR56 gene has been identified as one of the main causes of polymicrogyria in its global and bilateral version. In a study it was found that all the patients examined suffered from some modification in this gene, which resulted in an affectation of the central nervous system. It is known that this gene is highly involved in the formation and development of the cerebral cortex of the fetus during its gestation.

For this reason, it is important that parents who suffer from or are at risk of polymicrogyria are informed of the hypothetical risk of polymicrogyria. transmit your disease to your child and determine through a genetic study what is the real probability of occurrence before starting the gestation.

Management of the patient after diagnosis

After diagnosis through imaging, a full evaluation will be necessary in the domains affected by polymicrogyria. Pediatricians, neurologists, physiotherapists and occupational therapists should intervene to assess what is the risk of developmental delay, intellectual disability, or even paralysis cerebral. In this sense, the special educational needs will be indicated so that the patient can learn at the speed that his illness allows. Speech will be evaluated in those with affected lateral cleft, vision and hearing.

The symptoms will be treated through physiotherapy, pharmacological intervention with antiepileptics, orthopedic products and surgery for patients suffering from stiffness due to muscle spasticity. When there are speech problems, a logopedic and occupational intervention will be carried out.

Ultimately, parent training is a cornerstone of symptom management. They will need to be trained on issues of how seizures occur and what to do when one occurs. Likewise, support measures can be used to prevent the appearance of joint problems. or decubitus ulcers due to the patient sitting in the same position for too long.