The brain is the result of several thousand years of evolution of our species. It is one of the most complex natural phenomena we are aware of, and the essence of what makes us human. Although it is not uncommon in the context of scientific knowledge, new unknowns arise every day about how it works.
Its appearance is also very striking. On the outside, it is made up of a group of convolutions (Bumps with similar shapes and location for almost all people) and grooves (cracks or spaces between coils), which serve as a correct location of anatomical sections.
The adoption of its particular form occurs throughout the gestation process and is related to the way genes act on our prenatal development. Genetic alterations, or maternal exposure to certain pathogens and toxins, can compromise such a delicate biological balance.
This article will address in particular these clinical circumstances, the paquigiria, Which implies a situation of great gravity and a risk for the continuity of life. Here you will discuss its most essential characteristics, common causes and symptoms.
What is paquigiria?
The paquigiria is a severe congenital malformation, which affects the organization of neurons and the structure of the brain. It is characterized by the presence of slightly pronounced cerebral turns, as well as by the thinning of the cortex, which alters the overall structure of the organ (few apparent elevations on its surface, being the thickest and widest convolutions. than those observed in the average population). This neuropathology, which has multiple consequences for those who suffer from it, would be included in the nosological category of cortical dysgenesis.
More precisely, the paquigiria belongs to the lysencephaly family, Between actia (total absence of convolutions) and subcortical band heterotopia (presence of a “layer” of gray matter in the area between the walls of the lateral ventricles and the cortex itself), according to the Dobyns classification . Such structural alteration is usually primarily posterior, although it sometimes also disperses to the front of the brain and compromises a wide range of cognitive functions.
In fact, it is a serious health problem, with very high mortality rates in the early years (It affects 1 / 90,000 people in its severe forms, although no information is available regarding the mild forms). It is also associated with the presence of physical and mental symptoms of enormous importance, which compromise daily autonomy and / or pose a real danger to survival. The most notable are muscle hypotonia, ataxia or seizures (resistant to medical treatment and early onset), as well as severe intellectual disability and general developmental delay.
Diagnosis is usually made using two very different but also complementary strategies: clinical examination of signs / symptoms and the use of structural neuroimaging techniques such as magnetic resonance imaging.
This last procedure is very useful, because it allows to obtain images with all the luxury of details on the furrows / cracks and convolutions, which greatly facilitates the clinical certification of this pathology (especially if one takes into account that good number of their symptoms can be confused with other more common problems). The absence of dysmorphia (facial alterations inherent in chromosomal abnormalities) could hinder its early detection.
What are the symptoms of paquigiria?
Pachygiria has three basic symptoms: seizures, severe developmental disorders, and intellectual disability. This triad can be easily detected from the fourth / fifth month of life and is usually worth a consultation with the pediatrician. Although the overall prognosis is bleak (as these are symptoms resistant to drug intervention or directly insoluble), early care can minimize or prevent the onset of more serious complications, such as infectious processes, which are common. in these patients.).
1. Epileptic attacks
Pachygiria is one of the diseases that present with childhood epileptic seizures, which can pose a serious risk to life. Its creation is early, so a high percentage of people experience it between the fourth and seventh month after birth (Exceptionally after 18 months). These are generally sudden onset convulsions, both in flexion (abdominal torsion in which the body adopts a posture similar to that of a “closed razor”) and in extension (arms and legs stretched out in the shape of a “ cross”). Until the expansion of functional neuroimaging technologies, these epilepsies were considered cryptogenic (of unknown origin).
2. Developmental delay
Delay in motor development, as well as in the use of language, is a common feature among people diagnosed with paquigiria. It is often very common not to acquire the basic verbal catalog to fully construct communication acts, or to be lax in the arms and legs.
Many of these children are unable to maintain their standing, upright position without the support / help of others. A large percentage also shows a sign that will predict the problems mentioned: microcephaly, Or what is equal, a reduction in the expected growth of the head circumference.
3. Intellectual disability
People with paquigiria have severe intellectual disability, seeing almost all cognitive functions impaired and the potential to develop full personal autonomy.
Such a difficulty would respond to the abnormal migration of neurons (which will be detailed below) and becomes more evident when the child has to struggle with any academic demands or other contexts that require social and / or motor skills. The identification of this situation is essential, because it will depend on it that an appropriate curriculum adaptation program and therapeutic pedagogy can be deployed.
What are the causes of paquigiria?
I would pack it it causes abnormal migration of neurons during pregnancy. This process runs from the seventh to the twentieth week and is essential for the system to acquire proper functionality from birth.
It is a particular “journey” that the nerve cells undertake to move in such a way as to allow the cognition characteristic of human beings, and which requires its ambulation from the ventricles to the outer cerebral cortex (repeating enormous distances in proportion to their size) . Such a phenomenon does not occur continuously, but appears as intermittent “streaks”.
even if the general goal is to form six distinct layers of fabric, Prepared to adapt to the unfathomable complexity of the mind, in which case they would only come in Form-4 (and more prone to many structural issues). This laminar arrangement motivates the agenesis of convolutions and / or furrows, resulting from a deficient organization of the brain. The observation of this anomaly, thanks to optical or electronic microscopes, shows an anatomopathology that we proceed to highlight (for each of its four layers).
The first layer (molecular or plexiform), which is the outermost of our cerebral cortex, would not present any aberration.. Neurons in this region are said to be identical in shape and location to a brain without problems. However, in the second, significant differences already appear: the number of cells is significantly lower, and they are disorganized, coexisting with the neurons of layers II, V and VI of the normal brain. This quantitative / qualitative alteration has an impact on the general appearance of the organ (because it forms the true cortex of itself).
The third layer is also very different from that of the six-leaf cortex. Here, the neurons are poorly organized and distributed in wide columns, giving rise to low density or thick tissue. Some are also appreciated signs of laminar necrosis, Responsible for hindering proper cell migration. Finally, the fourth layer would also look thin, but built with white matter invaded by a myriad of heterotopic neurons (located in spaces other than those they should occupy).
In addition to deficiencies in neuronal migration, which is the etiological basis common to all lysencephaly, multiple environmental and genetic risk factors are known. In the following lines we describe in detail.
1. Exposure to viral substances and / or infections
Paquigiria usually appears in the fourth month of gestation, after the phase of neural migration. Although this is a problem that tends to occur sporadically (possibly influenced by genetic factors), it is known that exposure to certain chemicals is closely related to the likelihood of.
The most common are ethanol (ethyl alcohol), methylmercury (which results from the activity of industry that uses acetaldehyde, such as paper, plastics, paints, rubber or leather) and retinoic acid (1 metabolite of vitamin A); but radiation exposure could also play a key role.
Cytomegalovirus infections (Throughout pregnancy) have been linked to both stimulation and other serious alterations in neuronal migration. When an individual comes into contact with this particular pathogen, it is usually stored for life, but acute episodes during pregnancy can be very dangerous. The problem is that it tends not to be too invasive (asymptomatic) for healthy people, so it is recommended to perform diagnostic tests in case it is believed to have been in contact with an infected person. acute phase.
2. Genetic alterations
A succession of genome alterations have been described which are linked to an increased risk of pachygiria. The most common is the one involving chromosomes 17 and X, What are the most frequently detected when a cause is affiliated at this level (which is not always possible). In other cases, a mutation has been found in the reelin gene (essential for neural migration) on chromosome 7.
Finally, the absence of the LIS1 gene is also known to seriously damage the structure of neurons and their cortical arrangement, it has therefore been postulated as a suspect in the etiopathogenesis of paquigiria.
- Tombul, T., Milanlioglu, A. and Odabas, O. (2015). A cause of refractory epilepsy: posterior bilateral actionic-pachygria. Dusunen Adam: The Journal of Psychiatry and Neurological Sciences, 28, 175-178.
- Xiao, J. Liu, Ch. Y Wei, Y. (2003). CT and MRI of pachygria and agoria. Sheng wu yi xue gong cheng xue za zhi. Journal of Biomedical Engineering, 20, 291-294.