Studies of agenesis of the corpus callosum. Symptoms and diagnosis. Provoking factors and symptoms

Agenesis of the corpus callosum – congenital pathology, an important role in the development and spread of which genetic factors play. The corpus callosum itself is the largest structural formation of the brain, which connects both hemispheres to each other. The intersection of fibers, as well as their connection with the hemispheres, begins already at twelve, thirteen weeks. Agenesis of the corpus callosum, the consequences, treatment and symptoms of which will be discussed below, occurs with the partial or complete absence of it itself, as such.

The corpus callosum is a dense plexus of nerves in the brain. It is designed to connect right and left cerebral hemispheres. It consists of up to two hundred and fifty million neurons. The corpus callosum is flat and wide, consists of axons, and is located directly under the cortex. The fibers mainly run in the transverse direction and connect the symmetrical parts of the brain, but there are also longitudinal fibers that connect the asymmetrical parts of the opposite hemispheres, or one part. Agenesis of the corpus callosum, the consequences of which are reflected in the intellectual abilities of a person, is part of many widespread congenital developmental disorders, pathologies and diseases. The main callosal commissure in this case is partially or completely absent; it is replaced by transparent columns of the fornix, short and incomplete septa. The frequency of occurrence of this kind of defects is one case in two thousand conceptions, the reason for this is heredity or spontaneous unexplained gene mutations.

Symptoms of agenesis of the corpus callosum

Interruption of the beginning of its origin and development;
Porencephaly;
Atrophy of the optic and auditory nerves;
Lipomas of various types;
Schizencephaly;
Localization of cysts and neoplasms in the area of connection of the hemispheres;
Spina bifida;
Visual defects;
Microencephaly;
Seizures;
Splitting syndrome;
Inhibition of psychomotor development;
Facial dysmorphism;
Aicardi syndrome;
Deviations in the development of the gastrointestinal tract, the presence of tumors in it;
Lacunar transformations in the fundus;
Previously puberty and so on.

Symptoms of agenesis of the corpus callosum can manifest themselves in different ways, one way or another, expressed in intellectual retardation of various levels, epileptic seizures, motor disorders physical activity, as well as anomalies of formation and growth internal organs person. Often the disease manifests itself in conjunction with Aicardi syndrome, a rare genetic disease characterized by special changes in the electroencephalography of the head and abnormalities in the development of the eyes. There are also skeletal anomalies and skin lesions associated with agenesis.

Treatment

Treatment of agenesis of the corpus callosum comes down to minimizing serious symptoms and eliminating infantile spasms. The therapy is actually ineffective and has not been fully developed, so various potent drugs are used in maximum courses and dosages. Treatment for agenesis of the corpus callosum is in development, but the disease itself is still being closely studied, and the disease is very poorly diagnosed at the stage of its onset, due to the peculiarities of fetal presentation and the inability to clearly visualize the cavities and structures of the fetal brain. The absence of the corpus callosum or its underdevelopment leads to disturbances in the neurological development of the child. But statistics recorded a number of cases where there were no other anomalies, and a normal karyotype was determined. The duration of observation of children in this example ranged from several months to eleven years.

Hypoplasia of the corpus callosum in a newborn is a very serious diagnosis, but at the same time, fortunately, quite rare. According to statistical data, such a disease occurs in one out of two thousand babies born.

By its nature, the pathological condition under consideration, as well as agenesis of the specified structure, refers to defects in the intrauterine stage of development of brain tissue. However, in contrast to agenesis, which consists in the complete absence of the corpus callosum, in the case of hypoplasia the latter is preserved, but is present in the brain in an underdeveloped state and, accordingly, does not fulfill the full scope of the functional duties assigned to it.

Taking into account the consequences of hypoplasia of the corpus callosum in the newborn, this pathology should be considered as a disease with not very favorable prognosis. Especially considering the fact that the pathological condition in question does not always occur in isolation. Often, it is accompanied by other disorders affecting the brain.

Causes of hypoplastic corpus callosum syndrome

In order to clearly understand why hypoplasia of the corpus callosum of the brain is dangerous in a child, it is necessary to have an idea of what kind of structure it is and what its role is in the human body.

The corpus callosum has been an unsolved mystery for anatomists for many times. For a long time, researchers were unable to establish what exactly this brain region is responsible for. But, as they say, if you dig for a long time, you will definitely get to the bottom of something.

Today it is known that this structure is nothing more than a group nerve fibers connecting the right and left half brain and thereby providing neural connection between them. It is through this anatomical formation that motor, sensitive and cognitive information is transmitted from one hemisphere to the other, due to which the coordinated work of the whole organism occurs.

The main reason why a baby develops hypoplasia of the corpus callosum syndrome, doctors call disorders that occur during the formation of brain structures, which occurs in initial stages embryo development. But today even the most professional doctors are unable to clearly explain why such violations occur.

The whole point is insufficient knowledge of the etiology of this pathological condition. Nowadays, it is possible to talk only about some of the factors that can cause the appearance of this disease. The first places among them are occupied by mutations affecting chromosomes, as well as heredity aggravated by the disease in question.

Hypoplasia of the corpus callosum in a child can also develop as a result of intrauterine infections. Other possible reasons The described condition is still being studied by doctors.

Symptoms of hypoplasia of the corpus callosum in a newborn baby

Clinical manifestations of this pathology, as a rule, are varied. For this reason, the disease in question can be detected both in the early childhood, which most often occurs within a period of up to two years if there is severe course illness, and already in an adult, and completely by accident, which is typical for the asymptomatic course of the disease.

Children who for some reason similar diagnosis was not diagnosed prenatally, at first they seem quite healthy. The first symptoms of hypoplasia of the corpus callosum appear from the age of three months. Before this, the baby’s development proceeds at a normal pace and does not differ from the norm.

Clinical picture begins with the appearance of infantile spasms in the baby, which may be accompanied by attacks reminiscent of.

Children suffering from this pathology often experience convulsions, such children usually lag behind in motor development, they also have little modulation of their cry, and sensory reaction disorders develop. In the future, they may notice low communication skills.

In the older period of childhood, hypoplasia of the corpus callosum of the brain produces consequences in the form of impaired regulation of body temperature such as hypothermia; patients develop a lack of coordination, and visual and auditory memory suffers.

Treatment and consequences of hypoplasia of the corpus callosum

For such a pathological condition as hypoplasia of the corpus callosum, treatment that could boast high efficiency, not yet developed. However, this does not mean that you should neglect seeing a doctor.

On modern stage In the development of medicine, therapy for the disease in question provides only a set of measures aimed at minimizing deviations in the development of a patient suffering from this pathology.

Experts practicing neuropsychology recommend that such patients perform a special complex at regular intervals. physical exercise, developed specifically for the treatment of the described illness. Such exercises help restore interhemispheric connections. In addition, the patient may be prescribed information wave therapy.

As mentioned above, the pathology in question can be combined with other diseases, due to which its prognosis is rather unfavorable.

Patients exhibit various kinds neurological problems, intellect is impaired, development is delayed. In particular, according to researchers, in at least 71% of cases, hypoplasia of the corpus callosum has consequences in the form of mental retardation.

In addition, the described anomaly of the corpus callosum often plays an important role in the occurrence of, for example, such as.

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Agenesis The corpus callosum is a defect whose incidence and clinical significance are unknown. According to various studies the frequency of its detection varies and depends on the characteristics of the population being studied and diagnostic methods.

Calculated frequency for the general population typically ranges from 0.3 to 0.7% and ranges from 2 to 3% for groups with developmental disabilities. The etiology of the disease is heterogeneous. Perhaps genetic factors play an important role in its development. Autosomal dominant, autosomal recessive and sex-linked modes of inheritance have been recorded for it.

Agenesis of the corpus callosum also part of many Mendelian syndromes. High frequency The identification of associated defects in this condition suggests that agenesis of the corpus callosum is part of many widespread developmental disorders.

According to one of antenatal studies accompanying anatomical defects were found in 50% of cases and were mainly represented by Dendy-Walker syndrome and heart defects. Karyotype anomalies (trisomy 18 and 8) were detected in 20% of cases.

Agenesis of the corpus callosum is a defect that is accompanied by minimal anatomical changes, and therefore its diagnosis, especially before 20 weeks of pregnancy, can be difficult even for experienced specialists. The development of the corpus callosum occurs on later stages cerebral ontogenesis of the fetus, namely between 12 and 18 weeks of gestation, therefore, probably before 18 weeks in most cases it is impossible to establish a diagnosis.

During planned examinations performed after this period, the inability to visualize the cavity of the septum pellucidum or the expansion of the atrium of the lateral ventricles should suggest the possible presence of agenesis of the corpus callosum.

If you suspect this anomalies it is necessary to search for more specific signs. Direct visualization of the absence of the corpus callosum is possible using the median frontal (coronal) and longitudinal (sagittal) scanning planes. Images in these planes are not always easy to obtain, especially in parietal presentations. In such cases, transvaginal echography has great advantages.

Agenesis of the corpus callosum may be complete or partial. IN the latter case, which is called dysgenesis of the corpus callosum, its caudal part (commissure and body) is absent in varying degrees. Complete agenesis is usually considered a malformation resulting from a disorder of embryogenesis, while partial agenesis can represent either a true malformation or a disruption that occurred at some stage of pregnancy.

Besides, echographic signs partial agenesis is even more difficult to detect than in the presence full form. In this regard, antenatal diagnosis of this condition is impossible in many cases.

Forecast with an isolated form of agenesis the corpus callosum remains unexplored. Many authors believe that agenesis of the corpus callosum does not lead to significant consequences for neurological development. However, the magnitude of the specific risk indicator is currently unknown.

Until now time Data were obtained on only 30 children with prenatal established diagnosis isolated agenesis of the corpus callosum (in which there were no other anomalies and a normal karyotype was determined), the duration of postnatal observation of which varied from several months to 11 years. Normal or borderline neurological development was noted in 26 cases (87%).

Educational video Ultrasound of the fetal brain is normal

Contents of the topic "Pathology" nervous system in the fetus":

Smirnova Olga Leonidovna

Neuropathologist, education: First Moscow State University medical University named after I.M. Sechenov. Work experience 20 years.

Articles written

Agenesis of the corpus callosum is a congenital pathology of the brain. It begins to develop in the prenatal period under the influence of genetic factors. This is very rare disease, affecting the plexus of nerves in the brain that connect the hemispheres. This part of the brain is called the corpus callosum. It has a flat shape and is located under the cerebral cortex.

If a child has agenesis of the corpus callosum, then the adhesions that should connect left hemisphere with the right one, practically none. The pathological process affects one in two thousand children and develops as a result hereditary predisposition or unexplained gene mutations.

The exact causes of violations often cannot be determined. The pathology is characterized by two clinical syndromes:

The first case is easier. The patient retains intellectual abilities and motor activity. Agenesis in this case can be identified by the presence of failures in the transmission of impulses from one hemisphere to the other. For example, if the patient is left-handed, then he cannot understand what is in his left hand.
The second case, in addition to agenesis, is accompanied by other malformations of the organ, observed serious violations in the movement of neurons and edema of the brain. The patient experiences seizures and his mental development slows down.

With the normal formation of all brain structures, the corpus callosum will be a dense plexus consisting of nerve fibers designed to connect the hemispheres and ensure the transfer of information between them. The formation of this area occurs at 3-4 months of pregnancy. The formation of the corpus callosum is completed in the sixth week.

Agenesis of the corpus callosum can vary in severity. This part of the organ may be completely absent, partially or incorrectly formed, or underdeveloped.

Most often, it is impossible to find out why this disease struck a child. But experts were able to identify a number of factors that increase the risk of developing such disorders in the prenatal period. This may happen:

as a result of a process of spontaneous mutation;
at genetic predisposition to illness;
under the influence of chromosome rearrangement;
due to the use of toxic medications during pregnancy;
due to lack nutrients during pregnancy;
in case of injury to a pregnant woman or infection with viral infections;
due to metabolic disorders in a woman’s body;
due to consumption alcoholic drinks and smoking during pregnancy.

Since the exact causes cannot be identified, it is possible to protect the child from this pathology by eliminating provoking factors.

How does the pathological process manifest itself?

With agenesis of the corpus callosum there may be different symptoms. It all depends on what disorders arose during the prenatal period, and how poorly developed the brain is. If this anomaly is present in a child, it will have the following manifestations:

Atrophic processes occur in the auditory and optic nerves.
Cyst-like cavities and tumors form at the junction of the cerebral hemispheres.
There is insufficient development of brain tissue.
Increased tendency to seizures, which are very difficult to tolerate.
There are disorders in the form of facial dysmorphism.
The organs of vision are underdeveloped.
Cysts appear in the hemispheres of the brain.
There are pathological abnormalities in the fundus.
Psychomotor development slows down.
Abnormal fissures form in the cerebral cortex.
Lipomas may occur. This benign neoplasms consisting of fat cells.
The gastrointestinal tract is not well developed and may contain neoplasms.
Puberty begins early.
Low muscle tone.
Coordination of movements is impaired.

In addition to these signs, the presence of agenesis may be indicated by Aicardi syndrome, when the brain and visual organs are abnormally developed. This is a fairly rare disease. With agenesis, lesions may also be observed skin And bone tissue. Such a clinical picture has an extremely negative impact on the condition and development of the child and has a rather low chance of a favorable outcome.

How to make a diagnosis

Agenesis of the corpus callosum is quite difficult to diagnose. Most cases are detected during pregnancy in the last trimester. The following methods are used to make a diagnosis:

Echography. The procedure involves studying the structure of an organ using ultrasonic waves. But it does not identify the problem in all cases. If partial developmental anomalies are observed, it is quite difficult to notice them using this study.
Ultrasonography.

It is difficult to identify agenesis due to the fact that it very often develops in combination with other genetic disorders. To accurately determine the presence of agenesis, karyotyping is performed. This is a study that analyzes the karyotype (characteristics of the set of chromosomes) of human cells. In addition to this technique, magnetic resonance imaging and ultrasound analysis are used.

Application of these diagnostic procedures allows you to accurately determine the state of the child’s brain.

Is this anomaly treatable?

To date therapeutic procedures, which would help cure a child from agenesis of the corpus callosum, there are no. Only corrective techniques are used, which are selected individually depending on the degree of violations and general condition the patient's body.

Treatment can only alleviate the symptoms of the pathology. But most experts say that all generally accepted methods do not give any results. It is mainly practiced to use potent drugs. They try to alleviate the patient’s condition with the help of:

Benzidiazepines. This psychoactive substances, which have hypnotic, sedative, muscle relaxant and anticonvulsant properties.
Phenobarbital. It is a barbiturate with antiepileptic action. It reduces the frequency of attacks if there are infantile spasms.
Corticosteroid hormones. Such as Prednisolone, Dexamethasone. They are usually combined with antiepileptic drugs.
Neuroleptics. With the help of which psychotic disorders are eliminated.
Diazepam. It helps reduce behavioral disorders.
Nootropics that have a specific effect on the mental functions of the brain. Treatment with Piracetam or Semax is usually used. They help improve the nutrition of brain tissue, which has a positive effect on its functioning.
Neuropeptides. The most commonly used is Cerebrolysin.

Also, Asparkam or Diacarb are used to alleviate the condition of children.

Except medications, sometimes there is a need for surgical intervention. For example, they can stimulate the vagus nerve. But such therapy is allowed to be carried out only in situations where, as a result of agenesis, serious disruptions in the functioning of the vital system have occurred. important organs. This procedure is carried out if other types surgical interventions will not bring results. During treatment, an electrical pulse generator is used. It sends impulses to the nerve, which is located in the neck and connects the brain to the body, and the nerve transmits them to the brain.

The pulse generator is installed under the skin in the subclavian region. After this, an incision is made in the neck and electrodes are connected to vagus nerve. The frequency of impulse transmission is determined by the doctor and adjusted at each examination.

Thanks to the procedure, the frequency of epileptic seizures decreases and they are more easily tolerated. But this treatment works differently for each patient.

Since agenesis of the corpus callosum of the brain can lead to musculoskeletal disorders and causes scoliosis, physiotherapeutic techniques and physiotherapy. Sometimes surgery may be performed.

Forecast and consequences

To date, research is being conducted that in the future may help determine the causes of pathology and find effective method treatment.

The prognosis for such a diagnosis may vary depending on the general condition of the body. If other developmental disorders are added to agenesis, the consequences will be severe.

More than eighty percent of children born with this anomaly do not have any accompanying pathologies, only minor neurological impairments may be observed.

Most often, with agenesis, various pathological processes and disorders begin to develop, so it is impossible to hope that the outcome will be favorable.

Children with agenesis suffer from disorders intellectual abilities, neurological symptoms, develop slowly and have other health problems that prevent them from living long life.

Treatment is prescribed to the patient depending on the symptoms accompanying the anomaly, but it does not bring significant results. Therefore, agenesis is referred to as congenital anomalies, which lead to many disorders and have a very unfavorable prognosis.

Agenesis of the corpus callosum is a pathology about which science knows little. Experts do not know the reasons for the development of such anomalies in the prenatal period; they do not have information that would help prolong the life of the child. Only factors are known that increase the risk of developing pathology in the fetus.

There is a possibility that in the future therapeutic methods will be discovered that will not only alleviate the course of the disease, but will also help eliminate the underlying cause.

Very rarely, the disorder develops in isolation and provides the patient with a good prognosis. At the same time, positive growth and development is observed in children whose pathology is accompanied by only minor neurological disorders. If several are combined birth defects development, then it is impossible to hope that the child will live a long life. Consequences and choices therapeutic techniques depends on how severely the central nervous system is affected.

With this developmental anomaly there are no fibers long way connecting the two hemispheres of the brain. Sometimes partial agenesis inherited via X-linked recessive type; in most cases the etiology remains unknown. With this anomaly there are two clinical syndrome. Firstly, the patient has retained intelligence and motor functions, and the anomaly itself is manifested only by a violation of the transmission of information from one hemisphere to the other: for example, a right-handed patient finds it difficult to name an object placed in his left hand, since this requires that information from the right sensory zone of the cortex enters the speech zone, localized in the left hemisphere. Secondly, most often agenesis of the corpus callosum is combined with other malformations of the brain, including lack of neuronal migration and hydrocephalus. In this case, children from the very early age there are severe seizures, lag mental development, increased head size and often hypertelorism. The diagnosis is made based on pneumoencephalography data or computed tomography.

Porencephaly

Porencephaly is a defect in the medullary mantle resulting from cyst-like expansion of the lateral ventricle, which can reach soft arachnoid. Sometimes its cause is a primary anomaly in the development of the cerebral mantle; in this case, the defect is usually bilateral with displacement of the fluid-filled temporoparietal areas of the brain. In children with a bilateral process, complete amentia occurs. More often, porencephaly is unilateral and develops secondarily as a result of focal brain damage in the last period intrauterine development or early postpartum period. Of the possible etiological reasons occlusion of cerebral vessels, encephalitis and brain puncture are noted. Depending on the localization of the pathological process, children develop spastic hemiparesis, unilateral sensory impairment or homonymous hemianopsia. Sometimes a unilateral increase in the size of the skull with thinning of the bone on the side of the porencephaly is observed. These changes are caused by fluctuations in the fluid in the cavity as a result of pulsation of the choroid plexus.

Transillumination of the skull is of great importance in the diagnosis of porencephaly, which should always be performed on a child with unexplained hemiparesis. It is differentiated from chronic accumulation of fluid in the subarachnoid space, which also results in positive result during transillumination. The diagnosis is made based on data from puncture of the subdural space and computed tomography. IN in rare cases when porencephaly is accompanied by a significant increase in head size or as it progresses motor disorders, perform bypass surgery.

Hydranencephaly

With this pathology, the cerebral hemispheres are absent. He is replaced large cavity filled with liquid. The brain stem and basal ganglia are quite developed, and sometimes rudimentary frontal and occipital parts of the cortex are identified. The etiology of the anomaly is unknown. Possible etiological factor consider insufficient development of the arteries of the brain and its destruction as a result of severe intrauterine infection.

Newborns with hydranencephaly may not look different from healthy children. Their head sizes are within normal limits or slightly enlarged. All reflexes characteristic of newborns are preserved. However, the sick child lacks the ability to visually track, and later it is revealed complete absence voluntary movements and intelligence. Seizures are often observed. A presumptive diagnosis is made based on cranial transillumination data. A similar clinical picture occurs with advanced hydrocephalus and with extensive bilateral accumulation of fluid in the subdural space. The diagnosis should be confirmed by cerebral angiography, which reveals the absence large vessels. The prognosis is poor: most children die before the age of 1 year, but there are reports of children whose life expectancy in a vegetative state was more than 3 years.

Lissencephaly

The developmental anomaly is caused by a violation of the migration of brain neurons and the associated underdevelopment of its convolutions. The surface of the hemispheres appears smooth; at microscopic examination reveal the absence of normal cell layers of the cortex and groups of neurons in the subcortical white matter. The clinical picture is of severe mental retardation. Diagnosis is possible based on computed tomography data.

Polymicrogyria

Polymicrogyria is another neuronal migration disorder that results in an excessive number of underdeveloped gyri. The pathology is combined with intrauterine cytomegalovirus infection, but in most cases the etiology is unknown. It is always accompanied by a pronounced impairment of mental development. The diagnosis is made only with an autopsy of which the head size is more than 3 times smaller than normal. The cause of the pathology is considered to be a developmental anomaly and destructive processes of the brain during intrauterine development and in the early postnatal period. More serious reasons presented in 206.

Brain weight is sometimes 25% of normal. The number and complexity of convolutions are reduced. Most poorly expressed frontal lobes, often with a disproportionately large cerebellum. For microcephaly developing as a result of perinatal and postpatal pathological processes in the cerebral cortex, there are no neurons and glial tissue.

Recessively inherited microcephaly is the most severe. The child has a noticeable posterior displacement of the forehead and ears disproportionately big size. Often he is well developed physically, but as he grows, his mental retardation becomes more and more noticeable.

The anomaly in children should be differentiated from the conditions listed in 214. Posterior displacement of the forehead, large ears and anamnestic data suggest hereditary microcephaly. Since its cause may be phenylketonuria in a pregnant woman, a chromatographic study of her urine should always be performed to identify amino acids or a test with ferric chloride. In the diagnosis of secondary microcephaly caused by intrauterine infection, skulls are of great help, spinal tap and results serological reactions. Diffuse calcification is often found in congenital toxoplasmosis, while calcifications around the cerebral ventricles are more likely to predominate in cytomegalovirus infection. In children with microcephaly born to women who abuse alcohol, alcoholic neonates should be considered; They are characterized by intrauterine growth retardation, narrow palpebral fissures and unusual palmar folds.

Microcephaly must be differentiated from the head small size with synostosis of the sagittal and coronal sutures. With craniosyostosis, pointed edges are palpated in the area of prematurely closed sutures and signs of increased intracranial pressure including nipple swelling optic nerve and impressions from the cerebral convolutions on the inner surface of the skull, revealed on an x-ray.

None of the forms of microcephaly can be cured, but its diagnosis is necessary in order to give genetically correct recommendations, since some disorders in this anomaly are inherited, while others are random.

Megalencephaly

This rare developmental defect in children causes excessive brain growth, leading to rapid pathological increase head sizes. There are reports of extremely large brains, weighing more than 2800 g. Excessive brain growth occurs due to the proliferation of glial cells rather than neurons. Its etiology is unknown, but it occurs in Hurler syndrome, Tay-Sachs disease and metachromatic leukodystrophy. Besides large sizes head, the child has mental retardation. There are no signs of increased intracranial pressure. Differentiate from hydrocephalus using computed tomography. The prognosis should be approached with caution, since severe mental retardation is often detected.