Hydrocephalus

Hydrocephalus is a condition that has many etiological factors. It arises from an imbalance between production and absorption of cerebrospinal fluid: less liquor is absorbed than produced. The cause of this may be an obstructive process in the ventricles or in the subarachnoid space. More rarely the cause is a true hyperproduction of the cerebrospinal fluid, as, for example, with papilloma of the villous plexus.

General information The frequency of congenital hydrocephalus according to the literature is 3-4 cases per 1000 live births. In the form of an isolated congenital disorder, hydrocephalus appears with a frequency of 0.9-1.5: 1000 live births.

In combination with splitting of vertebrae (spina bifida) hydrocephalus is observed with a frequency of 1.3-2.9: 1000 live births; 95% of children with spina bifida develop hydrocephalus. In general, hydrocephalus produces less CSF than normal. It was revealed that in hydrocephalus the metabolism in adjacent brain tissues was reduced.

Classification and etiology Hydrocephalus is traditionally divided into communicable and uncommunicative. These terms were introduced to describe the effect of pathological factors on liquor circulation. This separation of hydrocephalus is important in the choice of treatment. For example, in the presence of communicating hydrocephalus, ventriculoscopy of the third ventricle is useless, and with unreported hydrocephalus there will be no use for lumboritoneal shunting. Perhaps the more correct terms are "obstructive" and "non-obstructive" hydrocephalus, although in almost all cases with hydrocephalus there are elements of disruption of the resorption of the cerebrospinal fluid.

Non-communicating hydrocephalus is caused by a process that causes blockage of the ventricular system.

1. Acquired
   • Tumors, most often tumors of the fourth ventricle, such as medulloblastoma or ependymoma, although other tumors can also cause the development of hydrocephalus.
   • Fibrosis of leptomnenix due to meningitis or intraventricular hemorrhage.
   • Stenosis of the aqueduct is usually secondary to glia. The cause of late development of stenosis of the aqueduct can become glioma of the tire. With stenosis of the aqueduct, the lateral and third ventricles are enlarged, and the size of the fourth ventricle is not changed.
2. Congenital
   • Stenosis of the aqueduct can be observed in a variety of options. The splitting of the aqueduct can take place in combination with the myelomeningocele and Arnold-Chiari malformation. Stenosis can be caused by the presence of a septum, or a true constriction. In cases of congenital stenosis of the aqueduct, a small size of the posterior cranial fossa is characteristic.
   • Dandy-Walker syndrome is characterized by cystic dilatation of the fourth ventricle in the absence of either hypoplasia of the cerebellum and elevation of pulp (torcula). In the development of this defect, atresia of the holes of Magendi and Lushka, which occurs during embryogenesis, can play a role.
   • Galena vein aneurysms and other vascular malformations can also cause hydrocephalus.
   • Benign intracranial cysts, such as arachnoid and ependymal cysts.
   • Tumors.
   • Hydrocephalus linked to the X chromosome refers to the rare forms of congenital hydrocephalus in men.

Communicated hydrocephalus occurs when the obstruction of the liquor is distal to the exit from the fourth ventricle or at the level of pachyon granulations.

1. Acquired
   • Inflammation of leptomeninge may result from meningitis or intraventricular hemorrhage.
   • Thrombosis of veins can also cause hydrocephalus. Partial stenosis of the venous sinus can be explained by the preservation of hydrocephalus in patients after removal of the tumor of the posterior cranial fossa.
   • Carcinomatous meningitis can be the result of a lesion in the tumor process of the basal cistern.
   • Trauma, accompanied by subarachnoid hemorrhage with subsequent inflammation of the adjacent arachnoid membrane, may cause acquired hydrocephalus.
2. Congenital
   • Inflammation of leptomeninge.
   • Encephalocele
   • Lissencephalia (agyria).
   • Platybazia (basilar impression).

Functional hydrocephalus can develop as a result of hypersecretion of the cerebrospinal fluid with papilloma of the villous plexus. This tumor and itself can clog the ventricular system, leading to the development of unreported hydrocephalus. In other cases, small hemorrhages from these tumors can cause obstruction of subarachnoid spaces. This explains the cases of preservation of hydrocephalus after removal of the tumor.

Hydrocephalus ex vacuo - an increase in the ventricular system due to atrophy of the brain tissue. This condition is not a true hydrocephalus, as the production of cerebrospinal fluid is equivalent to its resorption. Radiological examination reveals an increase in the size of the ventricles in combination with signs of atrophy (for example, widening of the furrows). The size of the head is usually less than the norm (depending on the age) and its growth is slowed down.

Normotensive hydrocephalus is usually observed in adults, and not in pediatric practice. With this form of hydrocephalus, liquor pressure is not increased. This condition occurs with an incomplete block of ways of resorption of the cerebrospinal fluid, which allows liquor pressure to be maintained within physiological limits. Over time, overgrowth of nerve fibers can lead to progressive thinning of white matter in the brain. The classic triad of symptoms is dementia, ataxia and urinary incontinence.

Hydrocephalus and prematurity

• Among newborns weighing less than 1500g. In 35-70% intraventricular hemorrhage (IVH) will occur; In 20-50% of these cases, ventriculomegaly will develop.
• The source of hemorrhage is the underdeveloped embryonic matrix.
• Hemorrhage usually occurs within the first 48 hours after birth, and in 50% of cases - during the first 24 hours.
• Observation, including a daily measurement of the head circumference, repeated cranial ultrasonography and an assessment of the fontanel and seam condition, allows to diagnose IVH and control the development of hydrocephalus.
• First, treatment with lumbar punctures is recommended. If this is technically impossible or inadequate, it is recommended to install a subcutaneous ventricular reservoir (or any type of draining system) for the daily withdrawal of a part of the CSF.
• Shunting should be performed when the child has grown, his condition is stable, and the protein content in the cerebrospinal fluid has decreased.

Clinical diagnosis

1. Congenital hydrocephalus in a newborn can be suspected if there are the following symptoms:
   • Abnormally large head
   • Thin skin
   • The paresis of the gaze upwards is a "symptom of the setting sun"
   • Translucency of the skull bones
   • Swelling of the veins of the scalp
   • Divergence of the seam of the skull
   • Bulging fontanel
2. Postnatal diagnosis is based on the following vivid symptoms:
   • Disproportionately rapid increase in head size (the growth rate exceeds the average deviation from the normal value, crossing the percentile lines in the corresponding diagrams)
   • Bubble or strain of the anterior fontanelle and its absence of pulsation
   • Development indicators lag behind normal or do not reach the norm
   • The sound of a "cracked pot" with percussion of the skull
   • Divergence of the seam of the skull
   • Symptom of the "setting sun"
   • Edema of the nipples of the optic nerves
3. It is necessary to distinguish the congenital macrocrania from hydrocephalus. The first is characterized by a normal growth rate of the head and a family history of the macrocrania

Paraclinical Diagnosis Normal radiography of the skull allows us to identify the symptom of "finger impressions" and the divergence of the sutures. According to craniograms, it is possible to assume the type of hydrocephalus: for example, the small dimensions of the posterior cranial fossa indicate the stenosis of the aqueduct, and the larger dimensions - on the Dandy-Walker syndrome. Ultrasonography helps to assess the degree of expansion of the ventricles of the brain and can reveal an intraventricular hemorrhage. This is a simple, inexpensive study that can be performed at the patient's bed and which is especially suitable for premature infants with unstable clinical condition. It can be repeated until the fontanelle is overgrown. This method is also useful for intrauterine diagnosis of hydrocephalus CT allows to obtain a much more accurate image of the ventricular system and to detect in some cases intra-gingival septa. It also identifies such accompanying anomalies as Arnold-Chiari malformation. This study is especially useful in obstructive hydrocephalus, which is caused by a tumor or vascular anomaly. With the multi-chambered ventricular system, the introduction of a contrast medium into various cavities makes it possible to assess their communicability. MRI should be used in cases of a combination of hydrocephalus with tumors and vascular malformations, as well as with multichamber ventricles.

Angiography is indicated in cases of a combination of hydrocephalus with malformations of the veins of Galen and other vascular anomalies.

Treatment Remove the cause of obstruction of the CSF, if possible (eg, tumors). The shunting of the CSF into such cavities of the body, where it will be absorbed. Common shunting systems are ventriculoperitoneal, ventriculoatrial and lumboritoneal shunts. Ventriculopleural shunts and ventriculocisternostomy (according to Torkildsen) are used much less often. Ventriculourethroanastomosis and ventriculocholecystostomy are rarely used.

Ventriculostomy of the third ventricle consists in creating a surgical communication between the third ventricle and intercostal cistern.

There are no drugs for adequate treatment of hydrocephalus. However, in some patients, additional therapy with acetazolamide may be indicated.

Catamnesis Children with implanted shunts should be observed by neurosurgeons throughout their life. Infants should be examined more often due to the risk of an inconspicuous development of shunt dysfunction. After installing the shunt or after its revision, children should also be observed more often, with a gradual transition to surveys at a frequency of once a year.