Normally, during normal brain development, a series of folds or gyres form that serve to make the surface of the brain take up less space and fit inside the skull. Like any other organ, the brain also suffers 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 type of training problems we find in polymicrogyria, what its cause is and what is possible to do with those people who suffer from it.
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 you can see how the cortex is thicker and more intense, indicating greater density, and how the folds are formed superficially, different from that of a normal brain.
There are different forms of polymicrogyria, each of which is more serious. When it only affects one part of the brain, it is called unilateral. It is called bilateral, however, when both hemispheres are affected. The nomenclature refers not only to symmetry, but also to how many areas of the brain are affected. Thus, a brain with only one affected area would suffer focal polymicrogyria, versus generalized polymicrogyria when it affects almost all or all of the cortex.
Polymicrogyria patterns 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 more frequently the lateral fissures that separate the frontal and parietal lobes from the temporal lobes (60%).
Signs and symptoms
While 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 increases. Some symptoms include:
The global effects of polymicrogyria present with profound mental retardation, serious movement problems, cerebral palsy and seizures impossible to control with medication. For this reason, while milder forms of polymicrogyria allow a fairly long life expectancy, people born with severe involvement die at a very young age due to complications of the disease.
Polymicrogyria frequently does not occur alone or in its pure form, but rather together with other syndromes such as:
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 chickenpox virus.
Hereditary causes include both chromosomal syndromes, that is, those that affect several genes at the same time, and single-gene syndromes. There are many genetic disorders that modify 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 one study, it was found that all the patients examined suffered from some modification in this gene, which resulted in damage to the central nervous system. It is known that this gene is closely involved in the formation and development of the cerebral cortex of the fetus during pregnancy.
For this reason, it is important that parents who suffer or are at risk of suffering from polymicrogyria are informed of the hypothetical risk of transmitting their disease to their child and determine through a genetic study what the real probability of occurrence is before starting pregnancy.
Patient management after diagnosis
After diagnosis through imaging, A complete evaluation will be necessary in the domains affected by polymicrogyria. Pediatricians, neurologists, physical therapists, and occupational therapists will need to intervene to assess the risk of developmental delay, intellectual disability, or even cerebral palsy. In this sense, the special educational needs will be indicated so that the patient can learn at the speed that their disease allows. Speech will be evaluated in those who have the affected lateral fissure, vision and hearing.
Symptoms will be treated through physiotherapy, pharmacological intervention with anti-epileptics, orthopedic products and surgery for patients suffering from stiffness due to muscle spasticity. When there are speech problems, speech therapy and occupational intervention will be carried out.
Lastly, parent training is a cornerstone of symptom management. It will be necessary to train them on issues related to how seizures occur and what to do when one occurs. Likewise, supportive measures can be used to prevent the development of joint problems or pressure ulcers due to the patient sitting in the same position for too long.
