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Hydrocephalus
Last reviewed: 23.04.2024
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Hydrocephalus is an increase in the ventricles of the brain with an excessive amount of cerebrospinal fluid. Symptoms of hydrocephalus include enlargement of the head and brain atrophy. Increased intracranial pressure causes anxiety and bulging fontanel. The diagnosis is based on ultrasound in newborns and CT or MRI in older children. Treatment of hydrocephalus usually involves the operation of bypassing the ventricles of the brain.
[Causes Hydrocephalus
Causes of hydrocephalus
Hydrocephalus is the most common cause of abnormal head size in newborns. It is a consequence of the obstruction of the cerebrospinal fluid (obstructive hydrocephalus) or disrupted reabsorption of the cerebrospinal fluid (communicating hydrocephalus). Obstruction is most often developed in the area of the Sylvian aqueduct, but sometimes in the area of exit from the 4th ventricle (the holes of Lyushka and Mazendi). Disruption of reabsorption in the subarachnoid space is usually a consequence of inflammation of the brain membranes secondary to infection or the presence of blood in the subarachnoid space (for example, in a premature newborn with intraventricular hemorrhage).
Obstructive hydrocephalus may be caused by Dandy-Walker syndrome or Chiari type II (formerly Arnold-Chiari). Dandy Walker Syndrome is a progressive cystic enlargement of the 4th ventricle of the brain. With type II Chiari syndrome, which often develops with spina bifida and syringomyelia, a pronounced lengthening of the tonsils of the cerebellum causes them to bulge through the large occipital foramen with the fusion of the tubercles of the quadrupleum in the form of a beak and the thickening of the cervical spinal cord.
W. Dandy in 1931 proposed the classification of hydrocephalus, which is used to date and reflects the mechanisms of excessive accumulation of cerebrospinal fluid. According to this classification, a secretion (occlusal - arises from the disturbance of the flow of the cerebrospinal fluid within the ventricular system or at the boundary between the ventricular system and the subarachnoid space) and open (communicating - arises due to a violation of the balance between production and resorption of the cerebrospinal fluid) hydrocephalus.
Occlusal hydrocephalus is divided into monoventricular (occlusion at the level of one of the Monro's holes), biventricular (occlusion on the level of both Monro, anterior and middle ventricles of the third ventricle), triventricular (occlusion at the level of the brain and IV ventricles) and tetraventricular (occlusion at the level of the apertures Luschka and Magendie). In turn, open hydrocephalus can have hypersecretory, hydrosorptive and mixed forms.
Among the causes of persistent occlusion of the ways of liquor circulation, it is necessary to isolate their congenital underdevelopment (the presence of membranes closing the holes of Monro, Lnschka or Magendie, cerebral aqueduct neuralgia), scar deformity after having a CCI or inflammatory process (meningoencephalitis, ventriculitis, meningitis) volumetric formation (a tumor, an aneurysm, a cyst, a hematoma, granulation, etc.).
Hyperproduction of cerebrospinal fluid is an isolated cause of hydrocephalus only and 5% of cases and occurs against the background of inflammatory processes in the ependyma with ventriculitis, against a background of subarachnoid hemorrhage, and also in the presence of a ventricular plexus tumor, ependyma. Reducing the resorption of cerebrospinal fluid can occur due to a persistent increase in venous pressure in the upper sagittal sinus to a result of impaired permeability of the venous drainage system, as well as in cicatricial deformity of subarachnoidal gaps, inadequacy of the membrane apparatus or inhibition of the function of its enzymatic systems responsible for absorption of the cerebrospinal fluid.
Thus, on the basis of etiologic signs, hydrocephalus is congenital, post-inflammatory), a tumor that has arisen on the soil of vascular pathology, as well as unknown etiology.
The development of the communicating hydrocephalus leads to the formation of the so-called internal hydrocephalus - accumulation of CSF mainly in the cavities of the ventricular system while maintaining its free movement throughout the system of liquor circulation. This feature of the flow of open hydrocephalus is due to the uneven distribution of tangential and radial forces directed to the brain cloak under conditions of increased CSF pressure. The prevalence of tangentially directed forces leads to stretching of the cloak and vectriculomegaly.
In accordance with this, the external and internal forms of hydrocephalus are distinguished.
Depending on the amount of liquor pressure, hyperteptive, normotensive and hypotensive forms of hydrocephalus are isolated. From the point of view of the dynamics of the disease, there are progressive, stationary and regressive, as well as active and passive forms.
In clinical terms, it is important to isolate the compensated and decompensated forms of hydrocephalus. Decompensated refers to hypertensive edema, occlusive and progressive hydrocephalus. To the compensated form it is possible to carry a stationary or regressing hydrocephalus, in also normotensive hydrocephalus.
Pathogenesis
Hydrocephalus: what happens?
Excess accumulation of cerebrospinal fluid is the result of a disruption in the functioning of the system of its production and absorption, as well as the disturbance of its current within the system of liquor circulation.
The total volume of cerebrospinal fluid and the ventricles and subarachnoid space of the brain varies between 130 and 150 ml. Every day, according to different data, from 100 to 800 ml of cerebrospinal fluid is produced. Therefore, it is updated several times a day. Normal pressure is considered to be CSF within 100-200 mm of water. Strain, measured in the position of the patient lying on its side.
About 2/3 of the volume of CSF is produced by the vascular plexuses of the ventricles of the brain, the rest - by ependyma and brain envelopes. Passive secretion of CSF occurs by the free movement of ions and other osmotically active substances beyond the vascular bed, which causes the conjugated transition of water molecules. Active secretion of cerebrospinal fluid requires energy expenditure and depends on the work of ATP-dependent ion exchangers.
Absorption of the cerebrospinal fluid takes place in the parasagittally arranged multiple granulations of the arachnoid membrane - peculiar protrusions into the cavity of venous collectors (eg, sagittal sinus), as well as the vascular elements of the membranes of the brain and spinal cord, parenchyma and ependyma, along the connective tissue vessels of the cranial and spinal nerves. At the same time, absorption is carried out both actively and passively.
The rate of production of cerebrospinal fluid depends on the perfusion pressure in the brain (the difference between the mean arterial and intracranial pressure), while the rate of absorption is determined by the difference in intracranial and venous pressure.
This kind of dissonance generates an instability of the system of liquorodynamics.
Mechanisms that provide the liquor in the system of liquor circulation include a difference in hydrostatic pressure due to the production of cerebrospinal fluid, the vertical position of the body, pulsations of the brain, as well as the movement of villi ependyma,
Within the ventricular system, there are several narrow areas where the most frequent occurrence of occlusion of the pathways of cerebrospinal fluid circulation. These include the twin hole of the Monroe between the lateral and the third ventricle, the waterway of the brain, the twin hole Luschka in the lateral horns of the IV ventricle, and the unpaired opening of the Magendie located in the region of the caudal end of the IV ventricle. Through the last three holes, the liquor enters the subarachnoid space of the large cistern.
An increase in the amount of cerebrospinal fluid in the cranial cavity may occur as a result of a disturbance in the balance between its production and resorption, as well as due to a violation of its normal outflow.
Symptoms Hydrocephalus
Symptoms of hydrocephalus
Hydrocephalus can occur at any age, but most often in early childhood. If the accumulation of cerebrospinal fluid occurs before the onset of fusion of the bones of the skull, an increase in the head circumference, which leads to the deformation of the skull, is gradual, outstripping the age norm. In parallel, there is atrophy or a stop in the development of tissue in the large hemispheres. For this reason, the increase in intracranial pressure either softens or is completely leveled. In the case of a prolonged course of such a process, a characteristic pattern of normotensive hydrocephalus with large dilated ventricles and pronounced atrophy of the medulla is formed.
Hydrocephalus whose symptoms develop gradually, at which the pressure of the CSF remains primarily normal, and the leading part of the process is the progressive atrophy of the brain tissue due to intrapartum brain hypoxia, severe brain injury, ischemic stroke, endogenous cerebral atrophy (for example, in Pick's disease) is called passively developing.
In conditions of hypertensive ventriculomegaly, there is a stretching of the conducting pathways around the ventricles of the brain, their demyelination and, as a result, a conduction disorder, which is the cause of the development of motor disorders. In this case, the lower paraparesis often found in patients is explained by the lesion of the paraventricular part of the pyramidal tract.
Hydrostatic gravitational pressure of cerebrospinal fluid on the basilar parts of the brain, in particular the hypothalamic region, subcortical nodes, optic nerves and pathways underlies visual disorders, subcortical dysfunction and endocrine disorders.
Chronic increase in intracranial pressure, prolonged ischemia of the brain tissue, resulting in a violation of the conductivity of associative fibers of the cerebral hemispheres against the background of the direct influence of the factor causing hydrocephalus, in sum, determine the development of intellectual-mnestic, mental and endocrine disorders.
The sight of a child with a dropsy of the brain is characteristic. In the foreground is an increase in the circumference of the head, its dimensions, especially in the sagittal direction, while retaining the diminutive face. The skin on the surface of the head is thinned, atrophic, multiple enlarged venous vessels are visible. The bones of the cerebral skull are thin, the gaps between them are enlarged, especially in the sagittal and coronary sutures, the anterior and posterior fontanels are dilated, tense, sometimes bulging, do not pulsate, possibly a gradual divergence of the stitches that have not yet ossified. When percussion of the brain part of the head, the characteristic sound of a cracked pot may be observed.
For hydrocephalus of early childhood is characterized by a violation of motor innervation of the eyeball: a fixed gaze to the bottom (a symptom of the setting sun), convergent strabismus against a background of reduced visual acuity until the formation of complete blindness. Sometimes motor disorders are accompanied by the development of hyperkinesis. The cerebellar symptoms of hydrocephalus are manifested later by a violation of statics, coordination of movements, inability to hold the head, sitting, standing. A prolonged increase in intracranial pressure, atrophy of the brain substance can lead to a gross deficit of mnestic functions, a lag in intellectual development. In the general state of the child, increased excitability, irritability or, conversely, adynamia, an indifferent attitude towards the environment can prevail.
In adults, the leading element of the clinical picture of hydrocephalus is the manifestation of hypertensive syndrome.
Neurological symptoms of hydrocephalus depend on the presence of increased intracranial pressure, which includes headache (or anxiety in young children), a shrill scream, vomiting, drowsiness, strabismus or a decrease in vision and bulging fontanel (in infants). Edema of the optic disc is a late sign of increased intracranial pressure; the absence of it at the onset of the disease does not exclude an increase in intracranial pressure. The consequences of a chronic increase in intracranial pressure may include premature puberty in girls, learning disabilities (for example, disrupting attention, learning and processing information, memory) and disrupting the organization's function (for example, difficulty in presenting, summarizing, summarizing, justifying and planning information to solve problems).
Diagnostics Hydrocephalus
Diagnosis of hydrocephalus
The diagnosis is often made with prenatal ultrasound. After birth, hydrocephalus is suspected if, during a routine examination, an increase in the circumference of the head is detected; in infants, there is a bulging fontanelle or a pronounced divergence of the cranial sutures. Similar changes may result from intracranial volumetric formations (for example, subdural hematomas, porentsefal cysts, tumors). Macrocephaly can be a consequence of brain damage (eg, Alexander's or Canavan's disease) or it can be benign, with an excessive amount of cerebrospinal fluid surrounding the normal brain. Patients with suspected hydrocephalus are shown to have CT, MRI or ultrasound. CT or ultrasound of the brain (if a large fontanel is open) are used to monitor the progression of hydrocephalus after an anatomical diagnosis has been made. If convulsive syndrome develops, it may be useful to conduct an EEG.
Treatment Hydrocephalus
Treatment of hydrocephalus
Treatment of hydrocephalus depends on the etiology, severity, and also whether hydrocephalus progresses (ie, the size of the ventricles increases with time in relation to the size of the brain).
In certain cases, it is possible to use etiotropic treatment of hydrocephalus.
Hydrocephalus treatment of which does not eliminate the cause of the disease or gives predictable low effectiveness of etiotropic therapeutic manipulations determines the need for a choice of pathogenetic or symptomatic treatment aimed primarily at eliminating intracranial hypertension.
Conservative methods of treatment are generally ineffective and are used only in the early stages as courses of dehydration therapy. The basis of all significant treatments for hydrocephalus is the surgical method.
The main indication for the surgical treatment is the progression of hydrocephalus in the absence of inflammation of the meninges. Variants of surgical operations with different forms of hydrocephalus differ significantly. But at the same time, they are all based on the formation of a way to permanently divert liquor to one of the body's environments, where it is utilized for various reasons.
Thus, in the case of open hydrocephalus, a continuous removal of the excess of cerebrospinal fluid from the cranial cavity is necessary. Considering the fact that in this case the communication between compartments of the system of liquor circulation is not violated, it is possible to use the lumbosacral-periartenal shunting; connection by means of a shunt of the lumbar cistern and peritoneal cavity.
At present, the methods of shunting the cavity of the lateral ventricle with the drainage of the cerebrospinal fluid into the right atrial cavity (ventriculocardiostomy) or into the peritoneal cavity (ventriculoperitoneostomy, are used most often) have been widely used. In this case, the shunt is carried out under the skin for a long time.
In the case of occlusive hydrocephalus, a ventriculocisternostomy operation has been performed to date (Torkildlesen, 1939): a one- or two-way joint by means of a shunt of the cavity of the lateral ventricle and a large (occipital) cistern.
Progressive hydrocephalus usually requires a shunting of the ventricles. In order to temporarily reduce the pressure of cerebrospinal fluid in infants, ventricular punctures or spinal punctures (in communicating hydrocephalus) can be used.
The type of ventricular shunt used depends on the neurosurgeon's experience, although ventriculoperitoneal shunts cause fewer complications than ventriculo-atrial shunts. With any shunt, there is a risk of infectious complications. After the formation of the shunt, the head circumference and development of the child are evaluated, and visualization studies are periodically performed (CT, ultrasound). Shunt obstruction can be an emergency; In children, signs and symptoms of a sudden increase in intracranial pressure, such as headache, vomiting, lethargy, anxiety, convergent strabismus, or paralysis of the gaze rise. Cramps may develop. If the obstruction develops gradually, there may be more blurred symptoms, such as anxiety, school difficulties and drowsiness, which can be mistaken for depression.
It should be noted that in the case of lumbosacral-peritoneal, ventriculocardial and ventriculoperitoneal bypass, the construction of the shunt, in which the valve is an obligatory element, does not allow hyperdrilling and reverse flow of the fluid.
Ventriculostomy (establishment of direct communication between the cavity of the lateral or third ventricle and subarachnoid space) and ventriculocysternostomy lead to a compensated flow of hydrocephalus in 70% of cases; installation of the shunting system gives a similar result in 90% of cases.
The complications of the described shunting methods are as follows: occlusion of the shunt at various levels and formation of its inconsistency (in the course of 5 years after the operation, 80% of patients are diagnosed); hypo- and hyperdrainage states (in 1 / 4-1 / 3 cases); infection of the shunt (in 4-5% of cases) and the development of ventriculitis, meningitis, meningoencephalitis and sepsis; epileptic seizures (in 4-7% of cases); formation of a pseudo-peritoneal cyst. All these variants of complications (except for the formation of a record number) are an indication for the replacement of the shunting system against the background of appropriate treatment of the symptomatology that has arisen.
Recently, with some variants of occlusive hydrocephalus, endoscopic operations are performed to restore the pathway of the cerebrospinal fluid.
Despite the fact that some children who have hydrocephalus, the need for shunting disappears with age, it is difficult to determine the appropriate time for its removal (which can cause bleeding or trauma). Therefore, shunts are rarely removed. Surgical correction of congenital hydrocephalus in the fetus was not successful.