Ventriculomegaly of the brain: what is it, the causes, consequences

In both hemispheres of the brain, the intermediate brain and between the cerebellum and the medulla oblongata there are four special cavities - ventriculi cerebri, which produce cerebrospinal fluid or cerebrospinal fluid. Their pathological enlargement or enlargement is defined as ventriculomegaly.

Epidemiology

The statistics given in various sources are as follows:

• prevalence of ventriculomegaly, according to The Fetal Medicine Foundation, one case per 100 fetuses at the 22nd week of pregnancy and one case per thousand infants born;
• in more than 94% of cases, ventriculomegaly of the largest lateral ventricles (ventriculi laterales) is observed;
• craniocerebral anomalies are noted in 15 -65% of cases of ventriculomegaly, and defects in chromosomes - an average of 14.7%;
• The incidence of neurodestruction associated with this pathology in infancy is approximately 12% (according to other data, almost 60%).

[1], [2]

Causes of the ventriculomegalii

Enumerating possible causes expansion of the cerebral ventricles, it should be noted that the abnormal dilation of the ventricular (ventricular) brain system - due to excessive volume of cerebrospinal fluid (CSF) in the ventricles and subarachnoid spaces and irregularities of its circulation - is called  hydrocephalus, often associated with increasing intracranial pressure.

Since intrauterine development (prenatal) is not possible to measure intracranial pressure, the terms hydrocephalus and ventriculomegaly in the fetus are used synonymously. Although hydrocephalus should be called an increase in the ventricles of the fetus to more than 15 mm.

Experts see the main causes of ventriculomegaly in brain dysgenesis, excessive quantity of CSF in the ventricular system of the brain, as well as defects in chromosomes.

Antenatal ventriculomegaly, i.e., ventriculomegaly in the fetus may result from a defect in the neural tube of the embryo, as well as from primary congenital anomalies of the brain: agenesis of the corpus callosum; subependymal heterotopy; colloid or arachnoid cyst of the brain; malformations of Arnold-Chiari type 2, leading to the  syndrome of Arnold-Chiari; Cystic dilatation of the fourth ventricle - Dandy-Walker syndrome  , etc.

[3], [4], [5], [6],

Risk factors

Risk factors associated with the age of the mother (over 35 years of age), intrauterine infections, gestosis and  oxygen starvation of the fetus.

[7], [8], [9]

Pathogenesis

The pathogenesis of the overproduction of CSF by the fetal brain ventricles may be due to:

• infections (bacterial, fungal, herpes meningitis);
• tumors (platelet glioma, an endodermal sinus tumor, a common oligodendroglial tumor);
• hypertrophy, hyperplasia or tumor of the choroid (vascular) plexus of the ventricles of the brain.

The association of the pathological dilatation of the cerebral ventricles with the trisomy of the 13th, 18th and 21st chromosomes is noted with the syndromes, respectively, of Patau, Edwards and Down.

Ventriculomegaly in a newborn child can be provoked by:

• birth trauma with a sharp increase in venous pressure in the dural sinuses or in the internal jugular veins;
• cerebral ischemia in newborns;
• narrowing of the intraventricular (monrove) openings connecting the third ventricle with the lateral;
• congenital stenosis of the Sylvian  aqueduct - a  channel between the third ventricle of the brain (ventriculus tertius) and the fourth (ventriculus quartus).

In addition, rapidly or gradually developing ventriculomegaly in a child is possible with:

• craniocerebral trauma (especially with hemorrhage);
• defeat of the brain with a pig chain -  neurocysticercosis ;
• meningioma, diffuse glial tumors or   brain teratoma;
• choroid papilloma (with lesion of the lateral ventricles of the brain).

Ventriculomegaly in adults

Secondary ventriculomegaly in adults is possible due to head trauma, cerebral membranes, cerebral neoplastic lesions, stenosis of the Sylvian  aqueduct,  intracranial aneurysm, chronic subdural hematomas, and intraventricular or general cerebral hemorrhage, including hemorrhagic strokes.

In addition, as Canadian researchers have established, the development of ventriculomegaly, a pathogenesis of which is caused by a violation of CSF absorption or leakage of CSF into the subdural space, is more common in older people than in young people.

The reason is  brain atrophy  - loss of the volume of its parenchyma, as well as changes in glial cells and myelination of neurons, which leads to a decrease in the elasticity of the cerebral tissues.

That is, in the aging human brain, changes can occur that represent a compensatory expansion of space filled with cerebrospinal fluid - hydrocephalus ex vacuo.

[10], [11], [12], [13], [14]

Symptoms of the ventriculomegalii

The first signs of the presence of this pathology in the fetus - a large size of the ventricles of the brain, reaching 12-20 mm. The optimal period of its detection is 24-25 weeks gestation.

Symptoms of ventriculomegaly in newborns are manifested by lethargy, inactive sucking and difficulty swallowing; the child often belches and cries; the intervals of sleep are short; on the head and facial part of the skull through the skin often show blood vessels; there is a protrusion of the fontanel, a periodic jerking of the lower jaw and convulsive movements of the limbs. Until the seams of the skull have grown, there is a rapid increase in its circumference (macrocephaly).

Children have a headache for the first two or three years; pains increase with tension and sudden movements, jumps, slopes. Spontaneously there is a nausea and vomiting. In the presence of chromosomal syndromes, the symptoms become characteristic for them.

Ventriculomegaly in adults can be manifested by headaches, nausea, vomiting, increased intracranial pressure, and visual impairment. The latter is caused by edema of the optical disc - papilloma, which in the early stages may be asymptomatic or give a headache. Over time, this swelling can lead to the appearance of a blind spot, blurred vision, periodic restriction of the field of vision. As a result, complete loss of vision is possible.

If the third ventricle located in the midbrain increases, then due to the pressure on the subcortical vegetative centers in the gray medulla of its walls there can be abnormalities of gait, paresthesia, incontinence, deterioration of cognitive functions.

Stages

The degree of increase in cerebral ventricles in the neonatal period - based on the norm of its size to 10 mm (at the atrium of the posterior or anterior horn of the lateral ventricle) - determines the degree of ventriculomegaly.

Their names are not unified, so the expansion of the lateral ventricles (estimated mainly ventriculi laterales) by 20% - up to 12 mm can be defined as grade 1 ventriculomegaly or mild ventriculomegaly.

If the enlargement is 20-50% of the norm - from 12 to 15 mm, this is a moderate ventriculomegaly, and when the score> 15 mm ventriculomegaly can be classified as a more severe, expressed ventriculomegaly, and also pre-threshold or border ventriculomegaly.

With an increase in the ventricle in the fetus ≥ 20 mm, intraventricular hydrocephalus is diagnosed.

[15], [16], [17], [18], [19], [20]

Forms

Depending on the location, there are:

• ventriculomegaly of the lateral ventricles (ventriculi laterales) or lateral bilateral ventriculomegaly;
• one-sided ventriculomegaly, when only one lateral ventricle is enlarged. There may be ventriculomegaly on the left - left-sided lateral or ventriculomegaly on the right - right-sided lateral.

In cases where ventricles of different sizes (this difference should not exceed 2 mm), asymmetric ventriculomegaly is diagnosed.

If ultrasound is not found to be associated with this pathology of brain abnormalities, this is antenatal isolated ventriculomegaly. In many cases, which seem to be an isolated dilatation of the cerebral ventricles in the fetus, after the birth of the child, in fact, there are other anomalies (especially when ventriculomegaly exceeds 15 mm). According to observations, with this variant of pathology there is a 4-fold increase in the risk of an anomaly of the 21st chromosome.

Finally, replacement ventriculomegaly (more often this definition is used for hydrocephalus) means an increase in the volume of CSF to replace the lost parenchyma of the brain.

[21], [22], [23], [24], [25]

Complications and consequences

Naturally, the question arises: is ventriculomegaly dangerous?

Like all brain pathologies, the increase in its ventricles has serious consequences and complications. This macrocephaly, and the delay in the overall development of the child, and destructive changes in the structures of the brain: the size of the cerebral cortex increases significantly, neuroglia in the periventricular and supratentorial regions grows, and the ripening of the cortical sulcus lingers.

Syndrome of "setting sun" or Gref syndrome can develop  .

Often there are violations of a neurological nature, which are negatively reflected in memory, learning ability, adaptive properties of the psyche and behavior.

According to some data, at the age of two children with ventriculomegaly almost in 62.5% of cases have neurological problems.

[26]

Diagnostics of the ventriculomegalii

The only method by which diagnostics of ventriculomegaly is performed is instrumental diagnostics.

For the detection of X-anomalies, a genetic analysis (karyotyping) of the fetus is necessary on the basis of a sample of the amniotic fluid. How it is taken, for more details, see  Invasive Methods of Prenatal Diagnosis

The fetus is diagnosed with ventriculomegaly during mother's pregnancy - during the ultrasound examination after the 22nd week of the period when the size of the lateral ventricles can be visualized and measured.

Evaluation of the head of the fetus involves determining the shape of the skull and its bilarium diameter (head size from one temple to another). Ultrasonic visualization allows you to clearly define the medial border of the ventricles; echovriznaki vascular plexus - occupies the central part of the lateral ventricle echogenic structure; can be seen cerebrospinal fluid.

If pathology has been detected, screening for later periods (every 4 weeks) is carried out to monitor the condition of the ventricles.

Before the 18th week, and even more so in the first trimester, no ventriculomegaly is examined for ultrasound: the echoes of the pathology may simply be absent (the accuracy of the indications is less than 47%), since the hemisphere's practical spaces completely occupy the ventriculi laterales.

More information -  Prenatal diagnosis of congenital diseases

[27], [28], [29], [30], [31]

Differential diagnosis

Clarification of the diagnosis and differential diagnosis require an MRI of the brain. It is carried out for adults and young children. Pregnant women make magnetic resonance imaging only in those cases when the ventricular system can not be evaluated because of the position of the fetus in the uterus. According to the diagnostician, in half the cases, MRI can detect additional sonographically non-visualized CNS anomalies.

MRT signs of ventriculomegaly include: a dark (low-intensity) signal from the ventricle of the brain (in the coronary plane) in T1 mode and light (increased force) in images scanned at T2 weighted mode.

Adults can undergo CT or X-ray of the brain with radioisotope contrasting - ventriculography.

Hydrocephalus from ventriculomegaly is differentiated on the basis of parameters of an enlarged cerebral ventricle and intracranial pressure - spinal puncture is performed.

Among other pathologies, chronically occurring syringomyelia with cavities in the spinal cord and inflammation of ventriculi cerebri-ventriculitis are most often isolated.

[32], [33], [34], [35], [36]

Treatment of the ventriculomegalii

Antenatal ventriculomegaly is not treated, and after the birth of an infant, the treatment of ventriculomegaly is exceptionally symptomatic, based on the recommendations of a pediatric neurologist.

In the arsenal of funds available to date, there are:

• diuretic drugs (used in hydrocephalus - Mannitol, Etakrinaic acid, etc.);
• preparations containing  potassium  (so that the balance of the interstitial fluid, to which the long-term administration of diuretics leads, does not violate);
• antihypoxants;
• vitamins for the brain.

It is useful to do massage, also the physical load is recommended for ventriculomegaly - moderate, without sudden movements.

Doctors do not hide that managing this condition and advising parents is not an easy task, since it is difficult to state with certainty the exact cause of the pathology, to predetermine the course of its development and to predict the degree of risk of consequences.

Prevention

It is believed that the correct planning of pregnancy and medical genetic counseling can be a preventive measure. And also taking folic acid (women of reproductive age) and curing all diseases before future motherhood.

[37], [38], [39], [40]

Forecast

Ventriculomegaly associated with abnormalities and structural malformations of the fetus often has an unfavorable prognosis, which varies from disability (often mild) to loss of the baby.

However, in cases of mild isolated ventriculomegaly, there is a 90% chance of a normal outcome. In other cases, there is a lag in the development of the nervous system - from mild to moderate.

[41]