Normally, during normal brain development, a series of folds or twists are formed 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 from malformations. An example of this is polymicrogiria, which affects the morphology of the folds of the cerebral cortex .

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

What is polymicrogyny?

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

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

Polymicrogyny 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%) has occipital lobes affected. It also appears that the lateral fissures that separate the frontal and parietal lobes from the temporal lobes are more frequently deformed (60%).

Signs and symptoms

While focal and unilateral forms tend to give no more problems than medication-controllable seizures, when they are bilateral the severity of symptoms shoots up. Some symptoms include:

  • Epilepsy
  • Developmental delay
  • Strabismus
  • Speech and swallowing problems
  • Muscle weakness or paralysis

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

Often polymicrogyny does not occur alone or in a 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. A percentage of cases occur because the mother has an intrauterine infection during pregnancy. Some viruses that are related to the development of polymychromy are cytomegalovirus, toxoplasmosis , syphilis and the chickenpox virus.

Hereditary causes include both chromosomal syndromes, that is, syndromes affecting several genes at once, 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 polymicrogiria among other manifestations.

The GPR56 gene has been identified as one of the main causes of polymicrogiria in its global and bilateral version. One study found that all the patients examined had some modification in this gene, which resulted in central nervous system involvement. It is known that this gene is very 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 or are at risk of suffering from polymicrogiria 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 the gestation.

Management of the patient after diagnosis

After imaging, a full evaluation will be necessary in the domains affected by polymicrogiria . Pediatricians, neurologists, physiotherapists and occupational therapists should intervene to assess the risk of developmental delay, intellectual disability or even cerebral palsy. In this sense, special educational needs will be indicated so that the patient can learn at the speed that his or her illness allows, and speech will be evaluated in those who have the lateral fissure affected, as well as vision and hearing.

The symptoms will be treated through physical therapy, pharmacological intervention with antiepileptic drugs, 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 performed.

Finally, parent training is a cornerstone of symptom management. They will need to be trained in questions about how seizures occur and what to do when one occurs. Support measures can be used to prevent joint problems or bedsores from occurring due to sitting too long in the same position.