Cerebrospinal fluid is a substance of great importance for the maintenance of the brain. It is a vital element by keeping nervous tissue floating cushioning possible shocks, maintaining the level of pressure and electrochemical balance of the nervous system, helping to keep its cells nourished and eliminating the waste generated by its operation.
With a life cycle that begins with its synthesis in the lateral ventricles and ends with its reabsorption by the blood system, the cerebrospinal fluid is synthesized continuously, generally maintaining a constant balance between the amount of this liquid substance that is synthesized and that which is absorbed. . However, this balance can be altered, causing serious problems due to excess or lack of liquid. This is the case of hydrocephalus.
Hydrocephalus is a disorder in which excess cerebrospinal fluid appears for different reasons, swelling of the cerebral ventricles and/or subarachnoid space and producing a high level of pressure in the rest of the brain matter against the skull or between the different brain structures.
Hydrocephalus is a problem that without treatment can be fatal, especially if the areas of the brain stem that regulate vital signs are put under pressure. The pressure exerted on the different parts of the brain will produce a series of symptoms that can vary depending on which parts are pressed. In addition, the age of the subject and tolerance to CSF ​​also affect the appearance of certain symptoms.
However, some of the most common symptoms are headaches, nausea and vomiting, double or blurred vision, balance and coordination problems when moving and walking, drowsiness, irritability, slowing of growth and intellectual disability if it occurs in the period of neurodevelopment, alterations in consciousness or changes in personality or memory.
In newborn children who do not yet have the skull bones completely closed, it is typical to observe vomiting, convulsions or a tendency to look down. Sometimes, in addition, hydrocephalus can cause macrocephaly, that is, an exaggerated enlargement of the head in which the meninges and bones are pressed.
The causes of the excessive presence of cerebrospinal fluid can be multiple, but in general it can be considered that it is usually due to two possible groups of causes. Hydrocephalus usually occurs when the normal flow of cerebrospinal fluid is blocked. at some point, or when the balance between synthesis and absorption of this substance is broken either because too much is secreted or because it cannot be reabsorbed through the blood.
But these assumptions can be reached in very different ways, whether we are dealing with congenital or acquired hydrocephalus. Some of the causes may be malformations such as spina bifida. or that the spinal column does not close before birth (a problem known as myelomeningocele), as well as genetic difficulties.
Throughout life development, situations may also occur that end up causing this problem. Craniocerebral trauma causing internal bleeding (for example in the subarachnoid space) can cause a blockage in the flow of fluid. Tumors that pinch or press the pathways through which cerebrospinal fluid circulates are another possible cause. Certain infections, including meningitis, can also alter the normal flow rate of this substance.
Subtypes of hydrocephalus
Hydrocephalus is a problematic and very dangerous medical condition for both life and normative functioning of the human being. This disorder can be congenital, in which it appears as a consequence of situations prior to birth such as malformations, genetic predisposition, trauma or poisoning in the fetal phase, or acquired during childbirth or at some later point in the life cycle.
The problem itself is in all cases an excess of cerebrospinal fluid. which induces different problems due to the pressure caused to the brain, but depending on the cause, different types of hydrocephalus can be found.
1. Communicating hydrocephalus
We call communicating hydrocephalus that situation in which a blockage after cerebrospinal fluid leaves the ventricles. In other words, the problem is not found in the ventricles, through which the cerebrospinal fluid circulates normally, but the cause is an alteration of the parts of the arachnoid that connect with the blood vessels.
2. Obstructive or non-communicating hydrocephalus
Obstructive is the type of hydrocephalus in which the problem can be found in that the ventricles or the ducts that connect between them are altered and do not allow correct flow. This type of hydrocephalus is one of the most common the reason being especially common is an excessively narrow Sylvian aqueduct (duct that connects the third and fourth ventricles).
Ex-vacuo hydrocephalus occurs when for some reason a loss or decrease in brain mass or density has been caused. Faced with this loss, generally due to the death of neurons due to trauma, hemorrhage or neurodegenerative processes such as dementia, the ventricles have more space available within the skull, which in the long run causes them to dilate (filling with cerebrospinal fluid) until they occupy the space. available space. It is therefore about a type of passive hydrocephalus which does not correspond to an alteration in the normal functioning of the cerebrospinal fluid.
4. Normal pressure hydrocephalus
A subtype that appears especially in the elderly, this type of hydrocephalus appears to occur as a consequence of poor reabsorption of cerebrospinal fluid, in a manner similar to communicating hydrocephalus. However, in this case, although the amount of liquid is excessive, the pressure with which it circulates is practically normal (hence its name).
The fact that it usually occurs in elderly people and that the symptoms it causes are similar to those typical of dementia processes (memory loss, walking problems, urinary incontinence, slowness and loss of cognitive functions) means that it is often not be detected, making its treatment difficult.
Treatments applied in these cases
Rapid action in the case of hydrocephalus is essential if we want to prevent the problem from causing more difficulties. It must be taken into account that the cerebrospinal fluid does not stop secreting, and the blockage or dysregulation of the flow can cause the areas in which the fluid is present in excess to continue to swell and cause increasing injuries and collateral damage, given the extensive scope of this kind of complications.
Although treating the cause of hydrocephalus is necessary and the treatment of this factor will depend on the cause itself (if it is due to an infection, an inflammatory process or a tumor there will be different ways to treat the case), the first thing to do is eliminate the excess fluid itself to avoid further damage.
The treatments used in these cases They are surgical in nature the most applied being the following.
1. Extracranial bypass
One of the most applied treatments in these cases, extracranial diversion, has a relatively easy to understand operation: it involves removing excess fluid from the cranial cavity and sending it to another part of the body where it does not cause alterations, generally one of the cerebral ventricles or the blood system. The basic procedure is to place a catheter between the area from which the transfer is to be made to the area where the flow is going to be redirected, placing a valve that regulates that the drainage is neither insufficient nor excessive.
Although it is the most common and used treatment, it must be taken into account that the drainage stops working for some reason, the problem will reappear, so this resolution could only be temporary. That is why, even with this intervention, it is still necessary to investigate the causes that caused the hydrocephalus, and treat them to the extent possible. Currently it is less and less used, with other treatments being preferred.
2. Endoscopic ventriculostomy of the third ventricle
This intervention is based, like the previous one, on creating a drainage path that allows excess fluid to be eliminated. However, in this case it would be an internal and endogenous drainage pathway producing a small opening in the third ventricle that would allow excess fluid to flow into the blood (where it would end up naturally). It is usually one of the most successful and reliable types of intervention.
3. Cauterization of choroid plexuses
If the problem of hydrocephalus is caused because the synthesis of cerebrospinal fluid is excessive or it is not reabsorbed quickly enough, one treatment option is cauterization or elimination of some of the areas that produce it.
Thus, cauterizing some of the choroid plexuses that secrete cerebrospinal fluid (not all, since its renewal is necessary for the correct functioning of the brain) will reduce the rate at which the flow circulates. It is usually used in conjunction with ventriculostomy. However, it is one of the most invasive forms of intervention.
