Occlusive hydrocephalus is an increase in the volume of cerebrospinal fluid in the ventricular system due to blocking of the cerebrospinal fluid pathways. It leads to an increase in pressure inside the skull, clinically manifested by cephalgia, vomiting, visual impairment, ataxia, autonomic dysfunction, depression of consciousness. Diagnosis is carried out according to the results of neurological, ophthalmological examination, neuroimaging data (ultrasound through the fontanel, MRI, CT, MSCT). Surgical treatment: emergency external drainage, planned elimination of blocking factor, correction of congenital anomaly, shunt placement, ventriculocysternostomy.
General information
The term “hydrocephalus” in neurology refers to an increased accumulation of cerebrospinal fluid (CSF) in the cranial cavity. If the cause of the pathology was occlusion (blockage, compression) of the cerebrospinal fluid pathways, then hydrocephalus is called occlusive. The term “closed hydrocephalus” is synonymous with this condition, since occlusion leads to the closure of the cerebrospinal fluid circulation system and the accumulation of cerebrospinal fluid in it. In the ICD-10, occlusive hydrocephalus is listed under the name “obstructive”. The disease is secondary in nature, always has a causal pathology. Occlusive hydrocephalus occurs at any age, in children and adults, and may be congenital. In some cases, acute occlusion is observed, requiring immediate medical attention.
Causes
The liquor system is represented by four ventricles: paired lateral, unpaired — the third and fourth. Cerebrospinal fluid from the lateral ventricle through the interventricular opening of Monroe enters the III ventricle, then through the Sylvian aqueduct into the IV, from which it flows through the holes of Lyushka and Mozhandi into the cisterns of the cerebral and spinal subarachnoid space. Occlusive hydrocephalus develops when an obstacle occurs in any part of the described cerebrospinal fluid circulation system. Occlusion factors can be:
- Anomalies of brain development. Congenital stenosis, underdevelopment of the Sylvian aqueduct, Dandy-Walker syndrome, Arnold-Chiari anomaly are genetically determined or formed under conditions of intrauterine infection, fetal hypoxia, teratogenic effects. Anatomical changes in these defects lead to the development of hydrocephalus in the antenatal period or shortly after birth.
- Cerebral tumors. Neoplasms of the ventricles reduce their volume, cause blockage of the communicating holes. Tumors of the cerebral cisterns prevent the flow of cerebrospinal fluid from the ventricles into them. Pericentricular tumors, neoplasms of the trunk, cerebellum, as they grow, squeeze the liquor-bearing pathways. The result of these processes is the accumulation of cerebrospinal fluid in the ventricles.
- Intracerebral hematoma. It is formed as a result of traumatic brain injury (including intracranial birth trauma), hemorrhagic stroke. Occlusive hydrocephalus is caused by compression of the outflow pathways of the cerebrospinal fluid by the resulting hematoma.
- Colloidal cyst of the III ventricle is a benign formation of a non—tumor nature. Increasing in size, the cyst blocks the entrance to the Sylvian water supply. Violation of outflow causes the development of hydrocephalus.
- Hemorrhages in the ventricles of the brain. They occur with injuries, ruptures of arteriovenous malformation vessels, a breakthrough of a hematoma into the ventricles. The blood that has poured into the ventricular cavity coagulates − clots form, clogging the holes of Monroe, Lyushka, Mozhandi, a narrow channel of the cerebral aqueduct.
Pathogenesis
Blockage, compression of the cerebrospinal tracts leads to disruption of outflow and accumulation of cerebrospinal fluid in the ventricles of the brain. The volume of the ventricles increases, in conditions of a closed intracranial space, this entails an increase in pressure inside the skull. The rate of increase of intracranial hypertension depends on the degree and mechanism of occlusion. Obturation of the Monroe hole leads to an increase in the lateral ventricle, blockage at the level of the sylvian aqueduct leads to expansion of the III and both lateral ventricles, at the level of the Mozhandi and Lyushka holes — to total dilation of the ventricular system.
Occlusive hydrocephalus of tumor genesis is formed gradually, with posttraumatic hematoma — within a few days. Occlusion by a blood clot, part of an intraventricular tumor, occurs suddenly, leading to acute hydrocephalus. Intraventricular neoplasms, colloidal cysts can cause occlusive crises — a transient blockage of the cerebrospinal fluid circulation that occurs when the formation is displaced. Significant intracranial hypertension causes compression of brain tissues, feeding vessels. Hypoxia occurs, dysmetabolic changes leading to the death of neurons. The continued increase in pressure causes displacement of cerebral structures (mass effect), leading to severe complications.
Classification
In clinical practice, occlusive hydrocephalus is divided according to etiological and anatomical and topographic affiliation. Both classifications are important when choosing the most appropriate method of treatment. According to the etiological principle , there are:
- Congenital form — formed in the prenatal period due to developmental defects of the cerebrospinal fluid system, cerebral anomalies (for example, brain cysts), squeezing the cerebrospinal tracts. It manifests itself from the first days of life.
- Acquired form — occurs during life, due to injuries and diseases of the central nervous system. It manifests itself in combination with other symptoms of causal pathology.
According to the anatomical and topographic classification, occlusive hydrocephalus is divided into:
- Monoventricular — one lateral ventricle is dilated. The cause is a blockage of the interventricular orifice.
- Biventricular — the volume of the two lateral ventricles is increased. Occlusion at the level of the III ventricle.
- Triventricular — the expansion covers three ventricles. The obstacle to the cerebrospinal fluid outflow is located in the area of the brain’s water supply.
- Tetraventricular — dilation of all ventricles. Cerebrospinal fluid circulation is disrupted at the level of outflow pathways from the IV ventricle.
Symptoms
Regardless of the level of the cerebrospinal fluid block, the leading signs in the clinical picture are signs of intracranial hypertension. Patients report intense headache (cephalgia), non-food-related nausea, vomiting, frequent nosebleeds. Cephalgia causes a forced position of the head, accompanied by a feeling of pressure on the eyeballs. The onset of symptoms occurs acutely or subacutely against the background of the clinic of the underlying pathology. In some cases, occlusive hydrocephalus is the first sign of the disease.
The cochleovestibular and optic nerves suffer most often in conditions of intracranial hypertension. There is vestibular ataxia, tinnitus, hearing loss, deterioration of visual acuity, the formation of defects in visual fields. Epileptic paroxysms are often noted. Concomitant focal deficiency depends on causal pathology, is represented by paresis, paralysis, sensitivity disorders, cognitive impairment, cerebellar syndrome. The cerebrospinal fluid block at the level of the third ventricle is characterized by diencephalic symptoms: pulse lability, blood pressure drops, hyperhidrosis, skin discoloration (pallor, hyperemia). Obturation of the Sylvian aqueduct is accompanied by dissociation of pupillary reactions to light, violation of convergence, paresis of the gaze. The block in the area of the fourth ventricle is accompanied by cerebellar ataxia.
Occlusive hydrocephalus in young children is manifested by an increase in the size of the skull, divergence of cranial sutures, expansion and bulging of fontanelles. For congenital hydrocephalus, an enlarged spherical head, a relatively small trunk, deep eye sockets, and swollen scalp veins are typical. Children lag behind in psychophysical development. The severity of intellectual disabilities depends on the age of onset of the disease, duration, and severity of intracranial hypertension.
Complications
Occlusive hydrocephalus may be accompanied by an acute almost complete block of cerebrospinal fluid outflow — an occlusive hydrocephalic crisis. The attack proceeds with sharp intense cephalgia, repeated vomiting, facial hyperemia followed by pallor, oculomotor disorders, depression of consciousness, vegetative symptoms. The most formidable complication of hydrocephalus is the mass effect. Displacement of brain tissues in the direction of the large occipital foramen leads to compression of the medulla oblongata, where vital centers of regulation of cardiovascular and respiratory activity are localized. Violation of the function of the latter causes the possibility of a fatal outcome.
Diagnostics
Diagnostic measures begin with the collection of anamnesis: finding out the time of the onset of symptoms of increased intracranial pressure, the nature of their development, the presence of an established diagnosis of brain disease, the fact of head injury, etc. Further diagnostic algorithm includes:
- Neurological examination. Allows the neurologist to identify objective symptoms of intracranial hypertension, existing focal deficiency. The data obtained make it possible to establish a topical diagnosis.
- Consultation with an ophthalmologist. Includes ophthalmoscopy, perimetry, visometry. Examination of the fundus determines the stagnant discs of the optic nerves, with long—term hydrocephalus – signs of optic nerve atrophy. The study of the visual fields reveals their narrowing, loss of individual areas, visometry — a drop in visual acuity.
- Echoencephalography. Due to the ease of implementation, it can serve as a screening method. It allows to diagnose increased intracranial pressure, ventricular dilation, displacement of cerebral tissues.
- Neuroimaging. In infants, it is carried out by neurosonography through the fontanel, in others — with the help of MRI of the brain. The study makes it possible to diagnose a malformation, to establish the localization of the liquor block, to determine its cause. MSCT and CT scans of the brain are performed in complex diagnostic cases in addition to MRI, if there are contraindications to MR studies.
It is necessary to differentiate occlusive hydrocephalus from subarachnoid hemorrhage, other forms of hydrocephalus. Differential diagnosis is also carried out among the possible causes of occlusion. In children of the first months of life, it is necessary to differentiate hydrocephalus from macrocrania, which is mainly of a family nature, is not accompanied by symptoms of hypertension, developmental delay.
Treatment
The only effective method of treatment is neurosurgical. There are two ways of relieving hydrocephalus: elimination of obstruction of the cerebrospinal tracts, formation of an alternative way of outflow of cerebrospinal fluid. The following types of operations are carried out as planned:
- Correction of the anomaly of the liquor system. Not all malformations are subject to correction due to the high traumatic nature of surgical interventions. The most common plastic Sylvian plumbing in the presence of atresia, adhesions.
- Elimination of the blocking factor. Surgical removal of a hematoma, tumor, cyst, causing blockage of cerebrospinal fluid circulation, is a radical solution to the problem. Too traumatic with a large amount of education.
- Shunting operations. A shunt is implanted to ensure the outflow of cerebrospinal fluid from the ventricular system. Ventriculoperitoneal, ventriculoatrial bypass surgery is possible. The inability to perform a standard operation is an indication for the use of alternative methods: ventriculo-pleural, ventriculo-urethral bypass.
- Ventriculocysternostomy. An alternative liquor outflow is created by endoscopic perforation of the bottom of the III ventricle. In comparison with shunting interventions, the method is less traumatic, there are no complications associated with the shunt (hyperdrain syndrome, shunt obturation, shunt dependence of the patient). A complication is the closure of the created hole, which serves as an indication for bypass surgery.
In conditions of rapidly increasing intracranial hypertension with the threat of mass effect, neurosurgeons urgently perform external ventricular drainage. Drainage is installed in one of the lateral ventricles. Subsequently, patients undergo one of the planned operations.
Prognosis and prevention
Due to the accumulation of cerebrospinal fluid in the ventricles, occlusive hydrocephalus is characterized by a steady progression of intracranial hypertension and without neurosurgical help leads to severe complications, death of the patient. The prognosis after surgical treatment is closely related to the nature of the underlying disease, most serious in malignant tumors, severe cerebral anomalies. Patients who have undergone bypass surgery become shunt-dependent: violations of the functioning of the shunt cause a sharp deterioration in their condition, require urgent restoration of the drainage system. Preventive measures include measures to prevent congenital anomalies, traumatic brain injuries, oncological diseases, timely treatment of pathology of cerebral vessels, brain neoplasms, malignant tumors of other localization.