Abnormalities of brain development (Cerebral malformations). Abnormalities or malformations of the brain Surgery to remove gray matter heterotopia

Rice. 3.18. Lissencephaly. MRI.

a - T1-weighted image, sagittal plane. Agyria of the occipital lobe. The convolutions of the parietal lobe are thickened and wide.

b - IR IP, axial plane. The thickness of the cortex is increased, the ventricles of the brain are expanded.

Rice. 3.19. Periventricular heterotopia. MRI. a - IR IP, axial plane; b - IR IP, coronal plane.

Multiple nodes of heterotopia are located along the walls of the lateral ventricles.

The following forms of heterotopia are distinguished: periventricular nodular, periventricular and subcortical, both with and without changes in the structure of the cortex, giant, combined with cortical dysplasia, and ribbon-like.

Periventricular nodular heterotopia is characterized by clearly defined nodes located along the wall of the brain ventricle. The nodes can be either single or multiple and usually protrude into the ventricular cavity (Fig. 3.19).

Periventricular and subcortical heterotopia, both with and without changes in the structure of the cortex, is manifested by nodular periventricular heterotopia and accumulation of gray matter in the subcortical regions. The defeat in most cases is unilateral. Subcortical accumulation of gray matter can lead to local deformation of the sulci and thickening of the cortex (Fig. 3.20).

A giant form of heterotopia with a change in the structure of the cortex is a large accumulation of gray matter, occupying most of the hemisphere, from the wall of the ventricle to the surface of the cortex, leading to deformation of the cortical surface of the brain. With this form of heterotopia, accumulation of gray matter in the form of individual nodes is not observed. The giant form of heterotopia, due to the large size of the affected area, must be differentiated from pathological formations. With heterotopia, unlike tumors, perifocal edema, displacement of midline structures are not detected, and there is no signal enhancement after the administration of a contrast agent.

Rice. 3.20. Periventricular-subcortical heterotopia. MRI.

a - IR IP, axial plane. Heterotopia nodes are located along the wall of the left lateral ventricle and in the subcortical sections of the white matter. Between the subcortical nodes, layers of white matter are preserved. The surface of the cortex is deformed.

b - T2-weighted image, coronal plane. The subependymal nodes protrude into the cavity of the left lateral ventricle, which makes its contours wavy.

Ribbon heterotopia, or double cortex syndrome, manifests itself as a well-defined ribbon-like layer of neurons separated from the cortex by a strip of white matter. This pathology can only be diagnosed using MRI data. In this case, the images reveal a smooth, clearly defined strip of gray matter located parallel to the lateral ventricle and separated from the cortex and wall of the ventricle by a layer of gray matter. The cerebral cortex may be unchanged or may change from moderate pachygyria to complete agyria (Fig. 3.21). Foci of hyperintense signal may be detected in the white matter on T2-weighted images. Ribbon heterotopia is difficult to differentiate from lissencephaly: they probably represent different degrees of the same general process of impaired neuronal migration. Unlike lissencephaly, with ribbon-like heterotopia, changes in the cortex are less pronounced.

Rice. 3.21. Ribbon heterotopia. MRI.

a - IR IP, axial plane; b - T2-weighted image, axial plane.

A band of heterotopic gray matter is separated

layer of white matter from the cortex and ventricles of the brain.

Rice. 3.22. Bilateral open schizencephaly. MRI.

a - T2-weighted image, axial plane; b - T1-weighted image, coronal plane.

In both hemispheres of the brain, clefts are identified, extending from the subarachnoid space to the lateral ventricle. In the right hemisphere there is a wide connection between the subarachnoid space and the lateral ventricle. There is a narrow cleft in the left hemisphere of the brain. The ventricles of the brain are dilated and deformed.

Rice. 3.23. Open schizencephaly of the right frontal lobe. MRI.

a - IR IP, axial plane.

The edges of the cleft, located in the right frontal lobe, are represented by dysplastic gray matter. The cleft cavity is filled with cerebrospinal fluid. In the left hemisphere, a change in the course of the furrows and thickening of the cortex are determined.

b - T1-weighted image, coronal plane.

A cleft of complex shape with the formation of several small blind-ending branches was identified in the frontal lobe. The adjacent subarachnoid space and the anterior horn of the lateral ventricle are dilated.

Schizencephaly is a variant of cortical dysplasia, when a cleft is defined that runs through the entire cerebral hemisphere - from the lateral ventricle to the cortical surface. Clinical symptoms depend on the severity of the changes and are manifested by seizures, hemiparesis, and developmental delay. Most often, the cleft is localized in the pre- and postcentral gyrus and can be either unilateral or bilateral (Fig. 3.22). In most cases, with unilateral schizencephaly, other types of cortical dysplasias (pachygyria, polymicrogyria) are detected in the contralateral hemisphere (Fig. 3.23). Large vessels can be traced in the area of the cleft. The gray matter covering the cleft is dysplastic, thickened, and has an uneven internal and external surface.

We specifically look for abnormalities of the cerebral cortex in epilepsy and developmental delays. Disorders of cortical development can be an isolated developmental anomaly, or combined with other developmental disorders, such as regionalization disorders. Disorders of cortical development are determined by MRI of the brain and can be divided into:

Proliferation and differentiation disorders– microcephaly, megalencephaly

Migration violations– agyria-pachygyria (lissencephaly), polymicrogyria, heterotopia

Disorders of cortical organization– microdysgenesis

Megalencephaly represents an enlargement of one or both hemispheres of the brain. With megalencephaly, MRI reveals an enlarged lateral ventricle on the corresponding side, the cortex is thickened and not divided into convolutions (agyria), and the white matter is not myelinated.

MRI. T1-dependent coronal tomogram. Agiriya.

Heterotopias. During embryogenesis, neurons may not reach their destination in the cortex. Most migration disorders have a dominant X-linked origin. Anomalies can be local or diffuse. Diffuse heterotopias are localized periventricularly. Gray matter, according to MRI, accumulates only around the lateral ventricles, without affecting the areas around the third and fourth ventricles. In a quarter of cases, heterotopia is accompanied by anomalies of the corpus callosum and cerebellum.

If the neurons do not reach the cortex at all, lissencephaly occurs. If only some neurons do not reach it, then subcortical heterotopias appear, visible on MRI in the form of nodes or stripes (“double” cortex). Clinical symptoms are usually mild - slight developmental delay, pyramidal signs and, sometimes, dysarthria.

MRI. T1-dependent axial tomogram. “Double bark.”

Focal (focal, nodular) heterotopias are also commonly called hamartomas. They occur as an independent anomaly or as a manifestation of tuberous sclerosis. On MRI the signal from the nodes is typical of gray matter and they are typically not contrasted by gadolinium. This allows them to be distinguished from subependymal nodes in tuberous sclerosis. A special type of hamartoma is the hypothalamic hamartoma. It is located in the area of the gray tubercle, between the pituitary stalk and the papillary bodies. Hypothalamic hamartoma has an exophytic type of growth and reaches 12 mm. Clinically, it is asymptomatic or manifests itself in early maturation, acromegaly and a special type of partial epilepsy - convulsions in the form of obsessive laughter, as well as mental disorders. On T1-dependent MRI hypothalamic hamartoma isointense to white matter, on T2-dependent MRI a little more hyperintense than it. The formation is homogeneous and has a clear outline. The mass effect is expressed in the displacement of the pituitary funnel. Unlike astrocytoma of the same localization, hamartoma does not involve the optic chiasm. It is more difficult to distinguish a hamartoma from a meningioma, but the latter is enhanced by contrast. Ganglioglioma of the hypothalamus is rare. It contains cysts, sometimes microcalcifications (as seen on CT) and is enhanced with contrast in approximately half of the cases. Also rare are lipomas of the hypothalamus, which have a signal characteristic of adipose tissue.

Lissencephaly is a general term that refers to a violation of the formation of grooves. Its extreme manifestation is the complete absence of convolutions - agyria. Gray matter is present, but it is not divided by fissures. Agyria can be local, usually this type is observed in the temporal lobe.

An abnormally small number of gyri due to incomplete sulci is called pachygyria. Usually, it is also local, the convolutions are wide and smoothed. The combination of areas of pachygyria and agyria is called lissencephaly type I. At MRI thickening of the cortex, vertical Sylvian fissures and often straightened hippocampi are determined. Clinical manifestations fit into various forms (Miller-Decker, Norman-Roberts syndromes, etc.), which appear in the first year of life. Type II is characterized by a violation of the structure of the cortex itself, which is penetrated by vessels and fibroglial bundles. This type is combined with hydrocephalus and incomplete myelination. A typical clinical manifestation is Walker–Warburg syndrome.

Polymicrogyria- multiple shallow gyri. Often combined with gray matter heterotopia and hemimegalencephaly. It is believed that the pathogenesis of polymicrogyria is associated with ischemic necrosis of the fifth layer of the cortex before the 20th week of embryogenesis. Some cases are associated with congenital cytomegalovirus infection.

In addition, polymicrogyria may be part of Aicardi syndrome, an X-related dominant pathology. It occurs in the form of spasms and chorioretinopathy. At MRI Hypoplasia of the cerebellum, agenesis or underdevelopment of the corpus callosum, cysts of the PCF and midline, and papillomas of the choroid plexus are often detected.

The result of disturbances in the formation of individual cerebral structures or the brain as a whole that occur in the prenatal period. They often have nonspecific clinical symptoms: predominantly epileptic syndrome, mental and mental retardation. The severity of the clinical picture directly correlates with the degree of brain damage. They are diagnosed antenatally during obstetric ultrasound, after birth - using EEG, neurosonography and MRI of the brain. Treatment is symptomatic: antiepileptic, dehydration, metabolic, psychocorrective.

Anomalies of brain development are defects consisting of abnormal changes in the anatomical structure of cerebral structures. The severity of neurological symptoms accompanying cerebral anomalies varies significantly. In severe cases, defects are the cause of antenatal fetal death; they account for up to 75% of cases of intrauterine death. In addition, severe cerebral anomalies account for about 40% of newborn deaths. The timing of manifestation of clinical symptoms may vary. In most cases, cerebral abnormalities appear in the first months after the birth of the child. But, since the formation of the brain lasts until the age of 8, a number of defects make their clinical debut after the 1st year of life. In more than half of the cases, cerebral defects are combined with defects of somatic organs: congenital heart defects, renal fusion, polycystic kidney disease, esophageal atresia, etc. Prenatal detection of cerebral anomalies is an urgent task of practical gynecology and obstetrics, and their postnatal diagnosis and treatment are priority issues of modern neurology, neonatology, pediatrics and neurosurgery.

Brain Formation

The construction of the fetal nervous system begins literally from the first week of pregnancy. Already by the 23rd day of gestation, the formation of the neural tube ends, incomplete fusion of the anterior end of which entails serious cerebral anomalies. By approximately the 28th day of pregnancy, the anterior cerebral vesicle is formed, which subsequently divides into 2 lateral ones, which form the basis of the cerebral hemispheres. Next, the cerebral cortex, its convolutions, corpus callosum, basal structures, etc. are formed.

Differentiation of neuroblasts (germinal nerve cells) results in the formation of neurons, which form the gray matter, and glial cells, which make up the white matter. Gray matter is responsible for higher processes of nervous activity. The white matter contains various pathways that connect cerebral structures into a single functioning mechanism. A full-term newborn has the same number of neurons as an adult. But the development of his brain continues, especially intensively in the first 3 months. life. There is an increase in glial cells, branching of neuronal processes and their myelination.

Causes of brain development abnormalities

Failures can occur at various stages of brain formation. If they occur in the first 6 months. pregnancy, they can lead to a decrease in the number of formed neurons, various disorders in differentiation, and hypoplasia of various parts of the brain. At a later date, damage and death of normally formed cerebral substance may occur. The most significant reason for such failures is the influence on the pregnant woman’s body and the fetus of various harmful factors that have a teratogenic effect. The occurrence of an anomaly as a result of monogenic inheritance occurs only in 1% of cases.

The most influential cause of brain defects is considered to be an exogenous factor. Many active chemical compounds, radioactive contamination, and certain biological factors have a teratogenic effect. Of no small importance here is the problem of pollution of the human environment, which causes toxic chemicals to enter the body of a pregnant woman. In addition, various embryotoxic effects may be associated with the lifestyle of the pregnant woman herself: for example, smoking, alcoholism, drug addiction. Dysmetabolic disorders in a pregnant woman, such as diabetes mellitus, hyperthyroidism, etc., can also cause cerebral abnormalities in the fetus. Many medications that a woman can take in the early stages of pregnancy, unaware of the processes occurring in her body, also have a teratogenic effect. Infections suffered by a pregnant woman or intrauterine infections of the fetus have a powerful teratogenic effect. The most dangerous are cytomegaly, listeriosis, rubella, and toxoplasmosis.

Types of brain development abnormalities

Anencephaly- absence of the brain and acrania (absence of skull bones). The place of the brain is occupied by connective tissue growths and cystic cavities. May be covered with skin or bare. The pathology is incompatible with life.

Encephalocele- prolapse of cerebral tissues and membranes through a defect in the bones of the skull, caused by its non-fusion. As a rule, it is formed along the midline, but it can also be asymmetrical. A small encephalocele may mimic a cephalohematoma. In such cases, skull radiography helps determine the diagnosis. The prognosis depends on the size and content of the encephalocele. If the protrusion is small in size and there is ectopic nerve tissue in its cavity, surgical removal of the encephalocele is effective.

Microcephaly- reduction in the volume and weight of the brain due to its underdevelopment. Occurs with a frequency of 1 case per 5 thousand newborns. Accompanied by a reduced head circumference and a disproportionate ratio of the facial/cranial skull with a predominance of the former. Microcephaly accounts for about 11% of all cases of mental retardation. With severe microcephaly, idiocy is possible. Often there is not only mental retardation, but also a lag in physical development.

Macrocephaly- increase in brain volume and mass. Much less common than microcephaly. Macrocephaly is usually combined with disorders of brain architecture and focal heterotopia of the white matter. The main clinical manifestation is mental retardation. Convulsive syndrome may occur. Partial macrocephaly occurs with enlargement of only one of the hemispheres. As a rule, it is accompanied by asymmetry of the cerebral part of the skull.

Cystic cerebral dysplasia- characterized by multiple cystic cavities of the brain, usually connected to the ventricular system. Cysts can vary in size. Sometimes they are localized only in one hemisphere. Multiple brain cysts manifest as epilepsy that is resistant to anticonvulsant therapy. Single cysts, depending on their size, may have a subclinical course or be accompanied by intracranial hypertension; their gradual resorption is often noted.

Holoprosencephaly- absence of separation of the hemispheres, as a result of which they are represented by a single hemisphere. The lateral ventricles are formed into a single cavity. Accompanied by severe dysplasia of the facial skull and somatic defects. Stillbirth or death occurs on the first day.

Agiriya(smooth brain, lissencephaly) - underdevelopment of the gyri and severe violation of the architectonics of the cortex. Clinically manifested by a severe disorder of mental and motor development, paresis and various forms of seizures (including West syndrome and Lennox-Gastaut syndrome). Usually ends in death in the first year of life.

Pachygyria- enlargement of the main convolutions in the absence of tertiary and secondary ones. Accompanied by shortening and straightening of the grooves, a violation of the architectonics of the cerebral cortex.

Micropolygyria- the surface of the cerebral cortex is represented by many small convolutions. The bark has up to 4 layers, whereas the normal bark has 6 layers. May be local or diffuse. The latter, polymicrogyria, is characterized by plegia of facial, masticatory and pharyngeal muscles, epilepsy with onset in the 1st year of life, and oligophrenia.

Hypoplasia/aplasia of the corpus callosum. Often occurs in the form of Aicardi syndrome, described only in girls. Characteristic are myoclonic paroxysms and flexion spasms, congenital ophthalmic defects (colobomas, scleral ectasia, microphthalmos), multiple chorioretinal dystrophic foci detected by ophthalmoscopy.

Focal cortical dysplasia(FCD) - the presence in the cerebral cortex of pathological areas with giant neurons and abnormal astrocytes. Favorite location is the temporal and frontal areas of the brain. A distinctive feature of epileptic seizures during FCD is the presence of short-term complex paroxysms with rapid generalization, accompanied in their initial phase by demonstrative motor phenomena in the form of gestures, stomping in one place, etc.

Heterotopias- accumulations of neurons that, at the stage of neuronal migration, were delayed along their path to the cortex. Heterotopions can be single or multiple, have a nodular or ribbon form. Their main difference from tuberous sclerosis is the lack of the ability to accumulate contrast. These anomalies of brain development are manifested by episyndrome and mental retardation, the severity of which directly correlates with the number and size of heterotopions. With single heterotopia, epileptic seizures, as a rule, debut after 10 years of age.

Diagnosis of brain development abnormalities

Severe brain abnormalities can often be diagnosed by visual examination. In other cases, cerebral anomaly can be suspected by cerebral retardation, muscle hypotonia in the neonatal period, and the occurrence of convulsive syndrome in children in the first year of life. The traumatic or hypoxic nature of brain damage can be excluded if there is no history of birth trauma of the newborn, fetal hypoxia or asphyxia of the newborn. Prenatal diagnosis of fetal malformations is carried out by screening ultrasound during pregnancy. Ultrasound in the first trimester of pregnancy can prevent the birth of a child with severe cerebral anomaly.

One of the methods for identifying brain defects in infants is neurosonography through the fontanel. Much more accurate data in children of any age and in adults is obtained using MRI of the brain. MRI allows you to determine the nature and localization of the anomaly, the size of cysts, heterotopias and other abnormal areas, and carry out differential diagnosis with hypoxic, traumatic, tumor, and infectious brain lesions. Diagnosis of convulsive syndrome and selection of anticonvulsant therapy is carried out using EEG, as well as prolonged EEG video monitoring. If there are familial cases of cerebral anomalies, consultation with a geneticist with genealogical research and DNA analysis may be useful. In order to identify combined anomalies, examination of somatic organs is carried out: ultrasound of the heart, ultrasound of the abdominal cavity, radiography of the chest organs, ultrasound of the kidneys, etc.

Treatment of brain development abnormalities

Treatment of brain malformations is predominantly symptomatic, carried out by a pediatric neurologist, neonatologist, pediatrician, and epileptologist. In the presence of convulsive syndrome, anticonvulsant therapy is carried out (carbamazepine, levetiracetam, valproate, nitrazepam, lamotrigine, etc.). Since epilepsy in children, which accompanies abnormalities of brain development, is usually resistant to anticonvulsant monotherapy, a combination of 2 drugs is prescribed (for example, levetiracetam with lamotrigine). For hydrocephalus, dehydration therapy is carried out, and shunt operations are used when indicated. In order to improve the metabolism of normally functioning brain tissue, to some extent compensating for the existing congenital defect, it is possible to conduct a course of neurometabolic treatment with the administration of glycine and vitamins. B, etc. Nootropic drugs are used in treatment only in the absence of episyndrome.

For moderate and relatively mild cerebral anomalies, neuropsychological correction, classes for the child with a psychologist, comprehensive psychological support for the child, children's art therapy, and education for older children in specialized schools are recommended. These techniques help to instill self-care skills, reduce the severity of mental retardation and, if possible, socially adapt children with cerebral defects.

This is the result of disturbances in the formation of individual cerebral structures or the brain as a whole that occur in the prenatal period. They often have nonspecific clinical symptoms: predominantly epileptic syndrome, mental and mental retardation. The severity of the clinical picture directly correlates with the degree of brain damage. They are diagnosed antenatally during obstetric ultrasound, after birth - using EEG, neurosonography and MRI of the brain. Treatment is symptomatic: antiepileptic, dehydration, metabolic, psychocorrective.

ICD-10

Q00 Q01 Q02 Q04

General information

Anomalies of brain development are defects consisting of abnormal changes in the anatomical structure of cerebral structures. The severity of neurological symptoms accompanying cerebral anomalies varies significantly. In severe cases, defects are the cause of antenatal fetal death; they account for up to 75% of cases of intrauterine death. In addition, severe cerebral anomalies account for about 40% of newborn deaths. The timing of manifestation of clinical symptoms may vary. In most cases, cerebral abnormalities appear in the first months after the birth of the child. But, since the formation of the brain lasts until the age of 8, a number of defects make their clinical debut after the 1st year of life. In more than half of the cases, cerebral defects are combined with defects of somatic organs. Prenatal detection of cerebral anomalies is an urgent task of practical gynecology and obstetrics, and their postnatal diagnosis and treatment are priority issues of modern neurology, neonatology, pediatrics and neurosurgery.

Causes

The most significant cause of disruptions in intrauterine development is the influence on the pregnant woman’s body and the fetus of various harmful factors that have a teratogenic effect. The occurrence of an anomaly as a result of monogenic inheritance occurs only in 1% of cases. The most influential cause of brain defects is considered to be an exogenous factor. Many active chemical compounds, radioactive contamination, and certain biological factors have a teratogenic effect. Of no small importance here is the problem of pollution of the human environment, which causes toxic chemicals to enter the body of a pregnant woman.

Various embryotoxic effects can be associated with the lifestyle of the pregnant woman herself: for example, smoking, alcoholism, drug addiction. Dysmetabolic disorders in a pregnant woman, such as diabetes mellitus, hyperthyroidism, etc., can also cause cerebral abnormalities in the fetus. Many medications that a woman can take in the early stages of pregnancy, unaware of the processes occurring in her body, also have a teratogenic effect. Infections suffered by a pregnant woman or intrauterine infections of the fetus have a powerful teratogenic effect. The most dangerous are cytomegaly, listeriosis, rubella, and toxoplasmosis.

Pathogenesis

Types of brain abnormalities

Microcephaly- reduction in the volume and weight of the brain due to a delay in its development. Occurs with a frequency of 1 case per 5 thousand newborns. Accompanied by a reduced head circumference and a disproportionate ratio of the facial/cranial skull with a predominance of the former. Microcephaly accounts for about 11% of all cases of mental retardation. With severe microcephaly, idiocy is possible. Often there is not only mental retardation, but also a lag in physical development.

Cystic cerebral dysplasia- characterized by multiple cystic cavities of the brain, usually connected to the ventricular system. Cysts can vary in size. Sometimes they are localized only in one hemisphere. Multiple brain cysts present with epilepsy that is resistant to anticonvulsant therapy. Single cysts, depending on their size, may have a subclinical course or be accompanied by intracranial hypertension; their gradual resorption is often noted.

Diagnostics

One of the methods for identifying brain defects in infants is neurosonography through the fontanelle. Much more accurate data in children of any age and in adults is obtained using MRI of the brain. MRI allows you to determine the nature and localization of the anomaly, the size of cysts, heterotopias and other abnormal areas, and carry out differential diagnosis with hypoxic, traumatic, tumor, and infectious brain lesions. Diagnosis of convulsive syndrome and selection of anticonvulsant therapy is carried out using EEG, as well as prolonged EEG video monitoring. If there are familial cases of cerebral anomalies, consultation with a geneticist with genealogical research and DNA analysis may be useful. In order to identify combined anomalies, examination of somatic organs is carried out: ultrasound of the heart, ultrasound of the abdominal cavity, radiography of the chest organs, ultrasound of the kidneys, etc.

Treatment of brain abnormalities

Treatment of brain malformations is predominantly symptomatic, carried out by a pediatric neurologist, neonatologist, pediatrician, and epileptologist. In the presence of convulsive syndrome, anticonvulsant therapy is carried out (carbamazepine, levetiracetam, valproate, nitrazepam, lamotrigine, etc.). Since epilepsy in children, which accompanies abnormalities of brain development, is usually resistant to anticonvulsant monotherapy, a combination of 2 drugs is prescribed (for example, levetiracetam with lamotrigine). For hydrocephalus, dehydration therapy is carried out, and shunt operations are used according to indications. In order to improve the metabolism of normally functioning brain tissue, to some extent compensating for the existing congenital defect, it is possible to conduct a course of neurometabolic treatment with the administration of glycine and vitamins. B, etc. Nootropic drugs are used in treatment only in the absence of episyndrome.

For moderate and relatively mild cerebral anomalies, comprehensive psychological support for the child and education for older children in specialized schools are recommended. These techniques help to instill self-care skills, reduce the severity of mental retardation and, if possible, socially adapt children with cerebral defects.

Prognosis and prevention

The prognosis is largely determined by the severity of the cerebral anomaly. An unfavorable symptom is the earlier onset of epilepsy and its resistance to therapy. The prognosis is complicated by the presence of concomitant congenital somatic pathology. An effective preventive measure is the exclusion of embryotoxic and teratogenic effects on a woman during pregnancy. When planning a pregnancy, future parents should get rid of bad habits, undergo genetic counseling, and be screened for chronic infections.

Subependymal heterotopia(periventricular heterotopia) is the most common form of gray matter (GM) heterotopia, characterized by SV nodules localized directly under the ependyma of the lateral ventricles. According to morphology, it can be divided into:

unilateral focal
bilateral focal
bilateral diffuse: a wavy strip of SV surrounding the ventricles.

Epidemiology

Most cases are sporadic, some are X-linked recessive (Xq28). Women experience relatively mild cognitive impairment and subsequently develop epilepsy. In the case of boys, spontaneous termination of pregnancy is observed, usually due to malformations of the cardiovascular system. The survivors have severe disabilities.

Clinical picture

Most often, subependymal heterotopia is associated with epilepsy and developmental delay.

Pathology

Like other types of heterotopias, this type is the result of impaired neuronal migration. In some cases, the cause of the development of subependymal heterotopia is a violation of cell proliferation.

Gray matter nodules consist of clusters of neurons and glial cells. It is interesting to note that they are most common on the right side, presumably due to the later migration of neuroblasts on the right side.

In X-linked cases, mutations are observed in the gene for filamin-1, a protein that cross-links intracellular actin. In addition, filamin-1 also plays an important role in vascular development.

Diagnostics

MRI is the method of choice, although periventricular heterotopia is visible on CT and ultrasound (if very large).

Ultrasound

Subependymal SV nodules are usually hyperechoic compared with normal white matter, and they may protrude into the ventricular lumen (the wavy edge of the ventricle).

CT

On CT, subependymal heterotopia appears as a non-calcified area of tissue that does not accumulate contrast material, similar in density to normal gray matter, around the lateral ventricles.

MRI

Antenatal MRI

In late pregnancy, the diagnosis of subependymal heterotopia is relatively obvious. Before the 26th week of pregnancy, the presence of a normal telencephalic periventricular germinal matrix makes its detection difficult, as does fetal movement.

Postnatal MRI

Small nodules of gray matter are observed in the ependymal layer and distort the contour of the ventricles. Most often localized in the region of the triangle and occipital horns. Other parts of the brain appear normal.

Gray matter nodules are visualized on all sequences, including post-contrast ones, where, like normal gray matter, they do not accumulate contrast material.

Differential diagnosis

norm
- caudate nuclei
- thalamus
subependymal giant cell astrocytoma
- has a pronounced accumulation of contrast
- localized near the foramina of Monroe
subependymal nodes in tuberous sclerosis
- usually calcified (except in early childhood)
- higher T2 signal than gray matter signal
subependial hemorrhage on ultrasound and antenatal MRI
- although the picture may be similar, a control study in case of hemorrhage determines the evolution of changes