If someone tells us they have fluid retention, we are probably thinking of a person with swollen legs or some part of the body that is swollen and inflamed. Put this way it may seem irrelevant, easily treatable and hardly a nuisance, as in fact it is in many cases. However, this fluid retention or oedema can be very dangerous depending on where it occurs. Because it is not the same to have fluid retention in the legs or ankles as to have it in organs such as the lung.

One of the most serious and dangerous situations that can occur in this sense is the presence of a cerebral edema, which can even be a cause of death .

Defining the concept of edema

Before talking about the brain edema itself, it is necessary to first understand what we mean when we talk about the term edema. It is understood as such to the existence of a swelling or inflammation of soft tissues due to the accumulation of fluid in or between its cells, due to imbalances in the amount of interstitial fluid leaving or entering the cells.

This inflammation can have a wide variety of causes and can be found in almost all types of soft tissue in the body. The repercussions can vary depending on the type of tissue affected.

Brain swelling: main symptoms

One of the locations where edema can occur, as well as one of the most dangerous, is in the brain tissue. In brain oedema we find an increase and accumulation of fluid between the brain cells that generates an inflammation with sufficient magnitude to cause clinical symptoms.

This inflammation is so serious in this case because the brain does not float in a vacuum , but is surrounded by a bone structure that protects it but also limits it: the skull. The accumulation of liquid can cause compression of the brain mass against the walls of the skull, which can lead to the death of the neurons.

Also, greatly increases the level of intracranial pressure as the usual electrolyte balance is not maintained, which can also alter and cause cellular degeneration. Finally, compression can affect the blood vessels, preventing oxygen from reaching any of the regions of the brain and this ends up drowning.

Depending on the compressed brain regions the symptoms can vary greatly. Generally, dizziness, fatigue and weakness tend to appear, as well as a possible alteration of the level of consciousness, headaches, gastrointestinal symptoms such as nausea and/or vomiting or perceptual alterations. Breathing may accelerate and even convulsions may occur.

Related to alterations of consciousness, in severe cases it can cause the patient’s coma or even death if the nuclei responsible for maintaining heart and breathing rhythm are compressed. In some cases it can lead to a herniation of the brain or the permanent loss of relevant functions.

In addition to these symptoms, the presence of cerebral oedema may lead to death or the appearance of some type of physical, psychic or sensory disability , which may greatly alter the person’s normal functioning, either temporarily or permanently.

Types of cerebral edema

There is not only one type of cerebral edema , but we can find different typologies depending on where and why the imbalance and the accumulation of liquid occurs. This is because the liquid can accumulate both inside the cells and in the extracellular space.

1. Cytotoxic edema

In this type of oedema, swelling occurs when fluid accumulates inside the cells themselves and an excessive amount of interstitial fluid is captured by the cells . It is usually caused by a malfunction of the sodium/potassium pumps and the channels through which the fluid enters and leaves the cells. We are faced with a problem of regulation of cell metabolism and maintenance of homeostasis. The consumption of some toxic element can be one of its causes.

2. Vasogenic edema

It is considered as such an edema that occurs as a consequence of an increase in the permeability of the nervous system, due to the rupture of the blood-brain barrier. We generally find that the blood plasma penetrates the parenchyma or extracellular space surrounding the nerve cells and accumulates there. This is the most common type of brain swelling. Tumors, strokes and head injuries tend to be some of its more common causes.

3. Hydrocephalic or interstitial edema

Edema generated by the obstruction of the channels through which the cerebrospinal fluid circulates, causing the cerebral ventricles or the areas near the blocked area to become inflamed. It appears in hydrocephalus .

Possible causes

There are a number of possible causes for the existence of brain edema. Some of the most frequent are the following.

1. Head trauma

One of the causes that may be easiest to identify is that which has to do with the existence of a head trauma. Such a blow causes blood vessels to break , flooding the brain with blood. By trying to absorb the excess fluid the cells would become inflamed.

2. Stroke

The existence of a cerebral haemorrhage or blockage of the cerebrovascular system is one of the best known causes of cerebral oedema. These accidents would either cause fluids to be directly extracted from the interior of the brain or nerve cells to die and break down, causing fluid to accumulate.

3. Viral or bacterial infections

Another possible cause of brain swelling may be found in the existence of an infection. The cells are damaged and break, generating an imbalance in the level of brain fluid. Within this group of causes we find very different diseases, from meningitis to Reye’s syndrome .

4. Tumors

The appearance of neoplasms, whether benign or malignant , may generate compression of blood vessels or block the passage of cerebrospinal fluid, which may result in the accumulation of fluid in some areas of the brain.

5. Altitude derived hypoxia

This type of edema occurs in subjects such as climbers and divers. The main cause is the existence of a sudden variation of the atmospheric pressure in the face of a rapid ascent : in the face of a lack of oxygen the organism tries to dilate the arteries and veins of the nervous system, but if this situation is prolonged or the change is generated very quickly this dilation will generate homeostatic difficulties that will culminate in the accumulation of liquids in the brain.

6. Hyponatremia

A condition that occurs in the absence of sufficient sodium in the blood, which the body tries to compensate for by increasing the entry of fluid into the cells.

7. Intoxication

The consumption of a toxic substance or poisoning can generate alterations in the nervous system that cause the existence of imbalances in the levels of intra- or extra-cellular liquid.


The treatment of a cerebral oedema is essential and requires rapid professional action in order to avoid death or irreparable damage to the patient.

The first step to be taken is the elimination of the accumulation of liquid and the reduction of inflammation. It is essential to control the vital signs at all times. It may be necessary to apply artificial breathing mechanisms to maintain a constant and sufficient flow of oxygen.

In cases where the patient’s life is in danger, it is common to use surgery immediately to control the level of inflammation by draining the fluid, or resecting part of the skull to release and reduce intracranial pressure. Once the patient is stabilized, it is necessary to analyze what has generated the problem in order to treat its causes.

It has also been proven that the induction of controlled hyperventilation decreases the formation of cerebral oedema. However, it must be very controlled, since depending on the extent and duration of the operation, it can have very harmful effects.

In this and other cases where surgery is not used, the use of different drugs is common. For example, it is very common to apply corticosteroids in order to reduce the intracranial pressure level in those cases where the problem is not of cytotoxic or hemorrhagic origin. Osmotics and diuretics may also be used to facilitate the expulsion of fluids.

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