The concept of the intracranial pressure
Brain tissue is very delicate andsensitivity to various mechanical influences, which occur under the influence of environmental factors. It is in order to preserve the delicate nature of the substance of the wise and put the human brain in a protective liquid medium (liquid subarachnoid space) and has provided its internal liquid cavities (ventricles). Thus, the brain actually weighed in a special fluid - cerebrospinal fluid (aka - CSF). Cerebrospinal fluid in the cranial cavity is under a certain pressure. It CSF pressure in the brain called intracranial pressure.
Intracranial pressure - the pressure in cavityskull (in the venous sinuses of the brain, brain ventricles, in the epidural and subarachnoid spaces), to create a dynamic equilibrium volume of cerebral blood flow, the volume of cerebrospinal fluid and brain tissue.
Normal intracranial pressure - neededcondition to ensure adequate blood supply to the brain, its metabolism and functional activity. Intracranial pressure of complicated pressure regulation mechanisms of cerebral vascular tone, brain blood flow volume, production speed and destruction of cerebrospinal fluid, etc.
It is normal for the level of intracranialpressure ranging from 7.5 to 15 mm Hg. Art. (1 to 2 kPa). Under physiological conditions, a change in one factor affecting the maintenance of intracranial pressure switch determines the level of compensatory mechanisms to normalize it, for example, increase and decrease of systemic blood pressure medium in the range of 60 to 150 mm. Hg. Art. (8 to 20 kPa) produces a rapid expansion or contraction of the brain vessels, whereby there is no significant change in cerebral blood volume and intracranial pressure.
The normal level of intracranial pressure is veryimportant for human well-being, which is why doctors neurologists pay great attention to check and normalization of intracranial pressure in patients with neurological problems.
The ratio between the total volume of tissue andliquid media in the cranial cavity and the pressure is not linear, since the increase to some extent one of the volumes (for example, the volume of brain tissue due to edema) accompanied by a simultaneous decrease in the volume of cerebrospinal fluid due to a compensatory reduction of its production or increase bone resorption. Intracranial pressure can thus remain within normal values. With the depletion of compensatory mechanisms, even a small increase in intracranial volume may lead to a significant rise in intracranial pressure.
Causes of increased intracranial pressure
All the liquid space and the ventricles are connectedby channels. The liquor is continuously circulated. In some parts of the brain, it is highlighted, and then flows through the cerebrospinal fluid ducts to other parts of the brain, which is absorbed into the bloodstream. Full update of CSF occurs in an average of 7 times a day.
Excessive accumulation of cerebrospinal fluid causes an increase in pressure on his brain substance. This is referred to as increased intracranial pressure (intracranial hypertension).
Three common causes of chronic increased intracranial pressure:
- CSF stands out too much
- liquor not fully absorbed
- impaired patency of cerebrospinal fluid circulation paths
Any of these reasons could be the result of:
- craniocerebral trauma (even very long, up to birth trauma)
- meningitis or encephalitis
- congenital structural features of the central nervous system (malformation of Arnold Chiari, idiopathic intracranial hypertension, and others.)
- violations of the outflow of venous blood from the cranial cavity
- hypoxia (oxygen starvation)
- severe poisoning
If intracranial pressure is raised significantlyand long enough time, fluid cavities of the brain can expand this extension is called hydrocephalus. Since the cranial cavity - closed space, the expansion of fluid cavities of the brain is due to the expense of reducing the mass of the medulla. It is clear that this process can have a negative impact on health.