Hydrocephalus

Hydrocephalus is enlargement of the ventricles of the brain with excess cerebrospinal fluid. Symptoms of hydrocephalus include enlargement of the head and brain atrophy. Increased intracranial pressure causes restlessness and a bulging fontanelle. Diagnosis is based on ultrasound in newborns and CT or MRI in older children. Treatment for hydrocephalus usually involves shunt surgery to open the ventricles of the brain.

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Causes hydrocephalus

Hydrocephalus is the most common cause of abnormally large head size in neonates. It results from obstruction of the cerebrospinal fluid pathways (obstructive hydrocephalus) or impaired reabsorption of cerebrospinal fluid (communicating hydrocephalus). Obstruction most often occurs in the area of the aqueduct of Sylvius, but sometimes in the area of the outlet of the fourth ventricle (foramina of Luschka and Magendie). Impaired reabsorption in the subarachnoid space usually results from inflammation of the meninges secondary to infection or the presence of blood in the subarachnoid space (eg, in a premature infant with intraventricular hemorrhage).

Obstructive hydrocephalus may be caused by Dandy-Walker or Chiari II (formerly Arnold-Chiari) syndrome. Dandy-Walker syndrome is a progressive cystic enlargement of the fourth ventricle. In Chiari II syndrome, which often occurs with spina bifida and syringomyelia, marked elongation of the cerebellar tonsils causes them to protrude through the foramen magnum, with the tubercles of the quadrigeminal tubercles fusing to form a beak and thickening of the cervical spinal cord.

In 1931, W. Dandy proposed a classification of hydrocephalus that is still used today and reflects the mechanisms of excessive accumulation of cerebrospinal fluid. According to this classification, closed (occlusive - occurs due to a violation of the flow of cerebrospinal fluid within the ventricular system or at the border between the ventricular system and the subarachnoid space) and open (communicating - occurs due to a violation of the balance between the production and resorption of cerebrospinal fluid) hydrocephalus are distinguished.

Occlusive hydrocephalus is divided into monoventricular (occlusion at the level of one of the openings of Monro), biventricular (occlusion at the level of both openings of Monro, the anterior and middle part of the third ventricle), triventricular (occlusion at the level of the cerebral aqueduct and the fourth ventricle) and tetraventricular (occlusion at the level of the openings of Luschka and Magendie). In turn, open hydrocephalus can have hypersecretory, hydroresorptive and mixed forms.

Among the causes that cause persistent occlusion of the cerebrospinal fluid circulation pathways, it is necessary to highlight their congenital underdevelopment (the presence of membranes that close the openings of Monro, Lnschka or Magendie, agenesis of the cerebral aqueduct), cicatricial deformation after a traumatic brain injury or an inflammatory process (meningoencephalitis, ventriculitis, meningitis), as well as compression by a volumetric formation (tumor, aneurysm, cyst, hematoma, granulation, etc.).

Hyperproduction of cerebrospinal fluid is an isolated cause of hydrocephalus in only 5% of cases and occurs against the background of inflammatory processes in the ependyma in ventriculitis, against the background of subarachnoid hemorrhage, and also in the presence of a tumor of the ventricular plexus, ependyma. A decrease in cerebrospinal fluid resorption can occur due to a persistent increase in venous pressure in the superior sagittal sinus as a result of impaired patency of the venous outflow system, as well as with cicatricial deformation of the subarachnoid spaces, inferiority of the membrane apparatus or suppression of the function of its enzymatic systems responsible for the absorption of cerebrospinal fluid.

Thus, based on the etiological feature, it is possible to distinguish congenital hydrocephalus, post-inflammatory hydrocephalus, tumor hydrocephalus, hydrocephalus that arose on the basis of vascular pathology, as well as hydrocephalus of unknown etiology.

The development of communicating hydrocephalus leads to the formation of so-called internal hydrocephalus - accumulation of cerebrospinal fluid mainly in the cavities of the ventricular system while maintaining its free movement throughout the entire cerebrospinal fluid circulation system. This feature of the course of open hydrocephalus is explained by the uneven distribution of tangentially and radially directed forces relative to the brain cape under conditions of increased cerebrospinal fluid pressure. The prevalence of tangentially directed forces leads to stretching of the brain cape and veptriculomegaly.

In accordance with this, external and internal forms of hydrocephalus are distinguished.

Depending on the value of cerebrospinal fluid pressure, hypertensive, normotensive and hypotensive forms of hydrocephalus are distinguished. From the point of view of the dynamics of the disease, progressive, stationary and regressive, as well as active and passive forms are distinguished.

In clinical terms, it is important to distinguish between compensated and decompensated forms of hydrocephalus. Decompensated hydrocephalus includes hypertensive dropsy, occlusive and progressive hydrocephalus. Compensated hydrocephalus includes stationary or regressive hydrocephalus, as well as normotensive hydrocephalus.

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Pathogenesis

Excessive accumulation of cerebrospinal fluid is the result of a malfunction of the system of its production and absorption, as well as a disruption of its flow within the cerebrospinal fluid circulation system.

The total volume of cerebrospinal fluid in the ventricles and subarachnoid space of the brain fluctuates between 130-150 ml. According to various sources, 100 to 800 ml of cerebrospinal fluid is produced daily. Consequently, it is renewed several times during the day. The normal pressure of cerebrospinal fluid is considered to be within 100-200 mm H2O, measured with the patient lying on his side.

About 2/3 of the volume of cerebrospinal fluid is produced by the choroid plexuses of the cerebral ventricles, the rest by the ependyma and meninges. Passive secretion of cerebrospinal fluid occurs through the free movement of ions and other osmotically active substances outside the vascular bed, which causes the coupled transition of water molecules. Active secretion of cerebrospinal fluid requires energy expenditure and depends on the work of ATP-dependent ion exchangers.

The absorption of cerebrospinal fluid occurs in the parasagittally located multiple granulations of the arachnoid membrane - peculiar protrusions into the cavity of venous collectors (for example, the sagittal sinus), as well as by vascular elements of the membranes of the brain and spinal cord, parenchyma and ependyma, along the connective tissue sheaths of the cranial and spinal nerves. In this case, absorption occurs both actively and passively.

The rate of CSF production depends on the perfusion pressure in the brain (the difference between mean arterial and intracranial pressure), whereas the rate of absorption is determined by the difference between intracranial and venous pressure.

This kind of dissonance creates instability in the cerebrospinal fluid dynamics system.

The mechanisms that ensure the flow of cerebrospinal fluid through the cerebrospinal fluid circulation system include the difference in hydrostatic pressure due to the production of cerebrospinal fluid, the vertical position of the body, the pulsation of the brain, as well as the movement of the ependymal villi,

Within the ventricular system, there are several narrow areas where occlusion of the CSF circulation pathways most often occurs. These include the paired foramen of Monro between the lateral and third ventricles, the cerebral aqueduct, the paired foramen of Luschka in the lateral horns of the fourth ventricle, and the unpaired foramen of Magendie, located near the caudal end of the fourth ventricle. Through the last three foramina, CSF enters the subarachnoid space of the cisterna magna.

An increase in the amount of cerebrospinal fluid in the cranial cavity can occur due to an imbalance between its production and resorption, as well as due to a disruption of its normal outflow.

Symptoms hydrocephalus

Hydrocephalus can occur at any age, but most often in early childhood. If the accumulation of cerebrospinal fluid occurs before the fusion of the cranial bones, a gradual increase in head circumference, ahead of the age norm, is observed, which leads to deformation of the skull. In parallel, atrophy or cessation of development of the tissue of the cerebral hemispheres occurs. For this reason, the increase in intracranial pressure is either softened or completely leveled. In the case of a long course of such a process, a characteristic picture of normotensive hydrocephalus with large dilated ventricles and pronounced atrophy of the brain matter is formed.

Hydrocephalus, the symptoms of which develop gradually, in which the cerebrospinal fluid pressure remains primarily normal, and the leading link in the process is progressive atrophy of brain tissue due to intranatal hypoxia of the brain, severe traumatic brain injury, ischemic stroke, endogenous atrophy of the brain matter (for example, with Pick's disease) is called passively developing.

In conditions of hypertensive ventriculomegaly, the conduction pathways that envelop the ventricles of the brain are stretched, their demyelination occurs, and as a result, conduction is disrupted, which is the cause of the development of movement disorders. In this case, the lower paraparesis often detected in patients is explained by damage to the paraventricular part of the pyramidal tract.

Hydrostatic gravitational pressure of cerebrospinal fluid on the basilar regions of the brain, in particular on the hypothalamic region, subcortical ganglia, optic nerves and tracts, underlies visual impairment, subcortical dysfunction and endocrine disorders.

Chronic increase in intracranial pressure, prolonged ischemia of brain tissue that occurs with this, disruption of the conductivity of association fibers of the cerebral hemispheres against the background of the direct influence of the factor causing hydrocephalus, together determine the development of intellectual-mnestic, mental and endocrine disorders.

The appearance of a child with hydrocephalus is characteristic. The foreground is marked by an increase in the circumference of the head, its size, especially in the sagittal direction, while maintaining the miniature size of the face. The skin on the surface of the head is thin, atrophic, multiple dilated venous vessels are visible. The bones of the cranial skull are thin, the spaces between them are enlarged, especially in the area of the sagittal and coronal sutures, the anterior and posterior fontanelles are dilated, tense, sometimes bulging, do not pulsate, and gradual divergence of the sutures that have not yet ossified is possible. Percussion of the cerebral part of the head may produce a characteristic sound of a cracked pot.

Hydrocephalus in early childhood is characterized by a violation of the motor innervation of the eyeball: fixed downward gaze (the setting sun symptom), convergent strabismus against the background of decreased visual acuity up to the formation of complete blindness. Sometimes movement disorders are accompanied by the development of hyperkinesis. Cerebellar symptoms of hydrocephalus appear somewhat later with a violation of statics, movement coordination, the inability to hold the head, sit, stand. Long-term increase in intracranial pressure, atrophy of the brain matter can lead to a gross deficiency of mnemonic functions, a lag in intellectual development. In the general condition of the child, increased excitability, irritability or, conversely, adynamia, an indifferent attitude to the environment may prevail.

In adults, the leading element of the clinical picture of hydrocephalus is the manifestation of hypertensive syndrome.

Neurologic symptoms of hydrocephalus depend on the presence of increased intracranial pressure, manifestations of which include headache (or restlessness in young children), shrill cry, vomiting, lethargy, strabismus or decreased vision, and bulging fontanelle (in infants). Papilledema is a late sign of increased intracranial pressure; its absence early in the disease does not rule out increased intracranial pressure. Sequelae of chronically increased intracranial pressure may include precocious puberty in girls, learning disabilities (eg, difficulty paying attention, learning and processing information, and memory), and organizational dysfunction (eg, difficulty representing, summarizing, generalizing, reasoning, and organizing and planning information to solve problems).

Stages

Hydrocephalus can be classified into different stages depending on the severity and nature of its manifestation. However, the stages of hydrocephalus are not always clearly distinguished, and the individual picture can vary greatly from patient to patient. Here are the general stages of hydrocephalus:

• Initial stage (compensated hydrocephalus): In this stage, the increase in the volume of cerebral fluid inside the cranial cavity can be compensated by the body. Patients may not experience obvious symptoms or have minor symptoms that may be non-specific, such as a mild headache or slight visual impairment. In this stage, the body tries to maintain relatively normal pressure inside the skull.
• Middle stage (subclinical hydrocephalus): As the volume of cerebral fluid increases, symptoms may become more severe, but are not always obvious. Patients may begin to experience more severe headaches, changes in mental status, difficulty with coordination and balance, and other neurological symptoms.
• Severe stage (decompensated hydrocephalus): At this stage, the excess cerebral fluid becomes significant and the pressure inside the skull increases greatly. Symptoms may become more obvious and severe, including intense headache, nausea, vomiting, loss of consciousness, seizures, paralysis and other neurological impairment. This stage requires immediate medical attention and treatment.

It is important to understand that chronic hydrocephalus can have a variable course and different stages.

Forms

Hydrocephalus can take many forms, including:

1. Congenital hydrocephalus: This is the form that develops before birth or in the first months of a child's life. Causes may include developmental problems with the brain or genetic factors.
2. Acquired hydrocephalus: This form develops after birth and can be caused by various conditions such as infections, brain tumors, injuries, hemorrhages, or other diseases.
3. Communicating (internal) hydrocephalus: In this form, fluid circulates freely between the cerebral ventricles and the medullary space. This may occur due to increased production or poor resorption of cerebrospinal fluid.
4. Noncommunicating (isolated) hydrocephalus: Here the normal circulation of cerebrospinal fluid between the ventricles of the brain is blocked. This can be caused by developmental abnormalities or obstructions.
5. Hydrocephalus with normal intracranial pressure: This form is characterized by hydrocephalus with normal intracranial pressure. Patients may have symptoms of hydrocephalus, but without increased pressure in the cranium.

Each of these forms may have its own characteristics and causes, and treatment will depend on the diagnosis and clinical picture.

Complications and consequences

Complications may include:

1. Worsening neurological symptoms: Increased pressure within the skull can cause worsening headaches, nausea, vomiting, difficulty with coordination and balance, seizures, changes in mental status, and other neurological symptoms.
2. Enlarged head (in children): Children with hydrocephalus may experience an enlarged head (hydrocephalus). This can lead to skull deformities and developmental delays.
3. Brain Tissue Damage: If hydrocephalus continues unchecked for long periods of time, the pressure of the brain fluid on the brain tissue can cause brain damage and impair brain function.
4. Vision complications: Hydrocephalus can put pressure on the optic nerves, which can lead to vision loss and other eye problems.
5. Infections: Due to disruption of the normal blood supply to the brain tissue and immune defense, infections such as meningitis can occur.
6. Cerebral Palsy: Children with hydrocephalus are at risk of developing cerebral palsy, especially if the condition is not treated promptly.
7. Long-term disability: In some cases, if hydrocephalus is not controlled or is difficult to treat, it can lead to long-term disability and limitations in the ability to lead a normal life.

Diagnostics hydrocephalus

Diagnosis is often made by prenatal ultrasound. After birth, hydrocephalus is suspected if routine examination reveals an increase in head circumference; in infants, a bulging fontanelle or marked dehiscence of the cranial sutures. Similar findings may result from intracranial space-occupying lesions (eg, subdural hematomas, porencephalic cysts, tumors). Macrocephaly may result from brain lesions (eg, Alexander or Canavan disease) or may be benign, with excess cerebrospinal fluid surrounding normal brain. Patients with suspected hydrocephalus should undergo CT, MRI, or ultrasound. CT or ultrasound of the brain (if the anterior fontanelle is patent) is used to monitor the progression of hydrocephalus once the anatomical diagnosis has been made. If seizures develop, an EEG may be helpful.

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Differential diagnosis

Differential diagnosis of hydrocephalus involves the process of ruling out other possible causes of symptoms that may have similar manifestations. This is important to ensure that hydrocephalus is correctly diagnosed and that the most appropriate treatment is chosen. Some of the conditions that may mimic the symptoms of hydrocephalus and require differential diagnosis include:

1. Migraine: Migraine can cause severe headaches, nausea, and vomiting, which may be similar to the symptoms of hydrocephalus. However, migraine is not usually accompanied by an increase in head size or a change in skull size.
2. Head injury: Traumatic head injury can cause a temporary increase in cerebrospinal fluid volume and hydrocephalus-like symptoms. In this case, if the symptoms are related to the injury, the differential diagnosis may include neuroimaging to detect brain damage.
3. Hypertension: High blood pressure can cause headaches and nausea, which may resemble the symptoms of hydrocephalus. Hypertension may cause other symptoms associated with high blood pressure, such as chest pain and shortness of breath.
4. Brain Tumors: Brain tumors can cause increased cerebrospinal fluid volume and symptoms similar to hydrocephalus. Differential diagnosis includes the use of MRI or CT imaging to identify tumors.
5. Infections: Many infectious diseases, such as meningitis or inflammation of the brain, can cause symptoms similar to hydrocephalus. Cerebral spinal fluid analysis can be helpful in the differential diagnosis.
6. Degenerative brain diseases: Some neurodegenerative diseases, such as Parkinson's disease or Alzheimer's disease, can cause symptoms that overlap with those of hydrocephalus, such as changes in mental status and coordination.

To accurately diagnose hydrocephalus and rule out other possible causes of the symptoms, the patient may need to undergo various tests, such as magnetic resonance imaging (MRI), computed tomography (CT), cerebrospinal fluid analysis, and others. The results of these tests will help the doctor make the correct diagnosis and prescribe the appropriate treatment.

Treatment hydrocephalus

Treatment of hydrocephalus depends on the etiology, severity, and whether the hydrocephalus is progressive (i.e., the size of the ventricles increases over time relative to the size of the brain).

In certain cases, it is possible to use etiotropic treatment for hydrocephalus.

Hydrocephalus, the treatment of which does not eliminate the causes of the disease or gives a predictable low efficiency of etiotropic treatment manipulations, determines the need to choose pathogenetic or symptomatic treatment aimed primarily at eliminating intracranial hypertension.

Conservative treatment methods are generally ineffective and are used only in the early stages in the form of dehydration therapy courses. The basis of all significant methods of treating hydrocephalus is the surgical method.

The main indication for surgical treatment is the progression of hydrocephalus in the absence of inflammation of the meninges. The options for surgical operations for various forms of hydrocephalus differ significantly. But at the same time, they are all based on the formation of a path for the constant removal of cerebrospinal fluid into one of the body's environments, where it is utilized for one reason or another.

Thus, in the case of open hydrocephalus, it is necessary to constantly remove excess cerebrospinal fluid from the cranial cavity. Considering that in this case the communication between the compartments of the cerebrospinal fluid circulation system is not disrupted, it is possible to use lumbar-subarachnoid-peritoneal shunting; connection with the help of a shunt of the lumbar cistern and the peritoneal cavity.

Currently, methods of shunting the lateral ventricle cavity with channeling of cerebrospinal fluid into the cavity of the right atrium (ventriculocardiostomy) or into the peritoneal cavity (ventriculoperitoneostomy, used most often) have become widely used. In this case, the shunt is carried out under the skin over a large distance.

In cases of occlusive hydrocephalus, the ventriculocisternostomy operation is still performed (Torkildsen, 1939): one- or two-sided connection using a shunt of the lateral ventricle cavity and the large (occipital) cistern.

Progressive hydrocephalus usually requires ventricular shunting. Ventricular punctures or spinal taps (for communicating hydrocephalus) may be used to temporarily reduce CSF pressure in infants.

The type of ventricular shunt used depends on the experience of the neurosurgeon, although ventriculoperitoneal shunts have fewer complications than ventriculoatrial shunts. There is a risk of infectious complications with any shunt. After shunt placement, the child's head circumference and development are assessed, and imaging studies (CT, ultrasound) are performed periodically. Shunt obstruction can be an emergency; children present with signs and symptoms of sudden increase in intracranial pressure such as headache, vomiting, lethargy, restlessness, convergent strabismus, or upward gaze palsy. Seizures may develop. If obstruction develops gradually, more subtle symptoms may occur, such as restlessness, difficulty in school, and drowsiness, which may be mistaken for depression.

It should be noted that in the case of lumbosacral, ventriculocardial and ventriculoperitoneal shunting, the design of the shunt is of particular importance, in which a valve is a mandatory element that prevents hyperdrainage and backflow of fluid.

Ventriculostomy (establishment of direct communication between the cavity of the lateral or third ventricle and the subarachnoid space) and ventriculocisternostomy lead to compensated hydrocephalus in 70% of cases; installation of a shunt system gives a similar result in 90% of cases.

Complications of the described shunting methods are as follows: occlusion of the shunt at various levels and its failure (detected in 80% of patients within 5 years after surgery); hypo- and hyperdrainage conditions (in 1/4-1/3 cases); shunt infection (in 4-5% of cases) and the development of ventriculitis, meningitis, meningoencephalitis and sepsis; epileptic seizures (in 4-7% of cases); formation of a pseudoperitoneal cyst. All of the above complications (except for the formation of episyndrome) are an indication for replacement of the shunt system against the background of appropriate treatment of the symptoms that have arisen.

Recently, in some cases of occlusive hydrocephalus, endoscopic operations have been performed to restore the patency of the cerebrospinal fluid pathways.

Although some children with hydrocephalus no longer need shunts as they age, determining the appropriate time to remove them (which can cause bleeding or injury) is difficult. Therefore, shunts are rarely removed. Surgical correction of congenital hydrocephalus in the fetus has not been successful.

Forecast

The prognosis for hydrocephalus can vary greatly depending on several factors, including the cause of the hydrocephalus, its severity, the patient's age, and the timeliness of diagnosis and treatment. Here are some general aspects of the prognosis:

1. Cause of hydrocephalus: The prognosis can vary greatly depending on the underlying cause of hydrocephalus. For example, if hydrocephalus is caused by a brain tumor, the prognosis may be worse than if the cause is a congenital abnormality that can be successfully corrected with surgery.
2. Severity of Hydrocephalus: Severe hydrocephalus, especially if left untreated, can cause serious complications and affect the patient's neurological status.
3. Age: In newborns and infants, hydrocephalus may have a better prognosis if diagnosed and treated promptly. In adults, the prognosis may be less favorable, especially if hydrocephalus develops as a result of other medical conditions.
4. Treatment: Prompt treatment, including surgery to drain excess fluid, can improve the prognosis. However, even with successful surgery, additional medical procedures and rehabilitation may be required.
5. Associated complications: Hydrocephalus can cause various complications such as damage to brain structures, neurological disorders, developmental delays, and others. The prognosis will also depend on the presence and severity of these complications.

It should be noted that modern diagnostic and treatment methods have significantly improved the prognosis for many patients with hydrocephalus. Regular medical monitoring and rehabilitation measures can help improve the quality of life of patients with this condition. However, the prognosis is best discussed with a medical professional who can assess the patient's specific situation.