I. Causes of hydrocephalus – cerebrospinal fluid and its circulation
Cerebrospinal fluid (CSF)
Cerebral spinal fluid (CSF) is a colorless and transparent liquid filled in the ventricular system, the central canal of the spinal cord and the subarachnoid space, which is a non-functional extracellular fluid containing inorganic ions, glucose and a small amount of protein, with few cells, mainly monocytes and lymphocytes. It plays a role in buffering, protection, nutrition, transport of metabolites, and maintenance of normal intracranial pressure for the central nervous system. The total amount of cerebrospinal fluid is about 150 ml in adults, with a production rate of 0.3 ml/min and a daily secretion of 400~500 ml. It is in a balanced state of constant production, circulation and reflux.
1. Cerebrospinal fluid circulation
Cerebrospinal fluid (CSF) is produced by the lateral ventricular plexus and flows to the third ventricle through the interventricular foramen, and then flows into the fourth ventricle together with the cerebrospinal fluid produced by the third ventricular plexus, and then converges with the cerebrospinal fluid produced by the fourth ventricular plexus and flows into the subarachnoid space through the median and lateral foramina of the fourth ventricle, so that the brain, spinal cord, cerebral nerves and spinal nerves are all soaked with cerebrospinal fluid. The cerebrospinal fluid then flows along the subarachnoid space to the back of the brain, penetrates through the arachnoid granules into the dural sinuses (mainly the superior sagittal sinus), and flows back into the bloodstream. If an obstruction occurs in the cerebrospinal fluid circulation pathway, it can lead to hydrocephalus and increased intracranial pressure, which in turn can cause brain tissue to be displaced by pressure and even form brain herniation.
II. Concept of hydrocephalus
Hydrocephalus is a condition caused by cranio-cerebral disorders that increase the amount of cerebrospinal fluid in the skull due to excessive secretion of cerebrospinal fluid or (and) impaired circulation and absorption, and enlargement of the ventricular system or (and) enlargement of the subarachnoid space, usually due to obstruction of the cerebrospinal fluid circulation pathway and malabsorption, while excessive secretion is less common. The broader term hydrocephalus should also include subarachnoid fluid and subdural fluid.
Epidemiological statistics
According to statistical data, the incidence of hydrocephalus has a tendency to increase with the age of pregnant women, with the lowest incidence in the 25-29 age group; the same data show that the risk of hydrocephalus in the fetus can be increased by the increase in the number of births of pregnant women; it also shows that it is related to the occupation of pregnant women, with the incidence in the offspring of farmers being 4.5 times higher than that of workers The incidence rate of the offspring of farmers is 4.5 times higher than that of workers, while the incidence rate of the offspring of administrative and business people is the lowest, suggesting that it may be related to the production, living environment and working conditions of different occupations; the lower the level of education, the higher the incidence rate of congenital hydrocephalus in the population; relevant data also show that the disease, especially hydrocephalus malformation, is closely related to genetics, and analysis suggests that consanguineous marriage is an important genetic basis for hydrocephalus malformation, and twin fetuses are more susceptible to the disease than single fetuses, while The role of environmental factors in the development of the disease should be given sufficient attention.
Three, the etiology of hydrocephalus
1, obstruction of cerebrospinal fluid circulation channels.
2, excessive secretion of cerebrospinal fluid.
3, cerebrospinal fluid absorption disorders.
Fourth, hydrocephalus is the cerebrospinal fluid circulation channel obstruction
1, congenital malformations: may be related to the parents’ exposure to certain chemical radioactive substances, early pregnancy fever, taking certain drugs, abnormal fetal position, excessive amniotic fluid, etc. The more common malformations are spina bifida, midbrain aqueduct stenosis, etc.
2, infection: such as septic meningitis, tuberculous meningitis, ventriculitis, etc., due to the proliferation of fibrous tissue blocking the circulatory orifice of cerebrospinal fluid, especially in the fourth ventricular foramen and subarachnoid adhesions at the base of the brain and the occurrence of hydrocephalus.
3, hemorrhage: intracranial hemorrhage after fiber hyperplasia can cause hydrocephalus, intracranial hemorrhage after birth injury malabsorption, is also a common cause of neonatal hydrocephalus, and is often easily ignored. After traumatic brain injury, subarachnoid hemorrhage causes arachnoid adhesions and hydrocephalus.
4, tumor: intracranial tumor can block any part of the cerebrospinal fluid circulation pathway, more often seen in the vicinity of the fourth ventricle, the neonatal period is rare to meet tumor, later can occur glioma, ventricular choroid plexus papilloma and ventricular meningioma, neuroblastoma.
V. Hydrocephalus is excessive secretion of cerebrospinal fluid
There are many theories of the etiology of congenital hydrocephalus, but the accepted theory is that the lateral ventricular choroid plexus is hyperplastic and secretes a lot, causing the ventricular choroid plexus to secrete cerebrospinal fluid dysfunction, which leads to hydrocephalus.
Sixth, hydrocephalus is a cerebrospinal fluid absorption disorder
Such as fetal meningitis and other causes of cerebrospinal fluid absorption disorders and the occurrence of hydrocephalus
The pathology of hydrocephalus
1, the effect on the formation and absorption of cerebrospinal fluid
2. damage to neural tissue structures.
3.Impact on jugular venous return.