Generality
Cerebral edema is a collection of fluid that forms in a brain tissue, pressing against the blood capillaries of the affected area. This compression blocks the flow of blood and the supply of oxygen, damaging at first the affected brain area and then causing its death.
The symptoms of cerebral edema are numerous and can vary greatly from patient to patient.
Diagnosis must be rapid and timely therapy, as cerebral edema is a clinical emergency, which, if left untreated, can cause permanent brain damage.
What is cerebral edema
Brain edema, or edema of the brain, is an excessive accumulation of fluid in the intra- and / or extra-cellular spaces of brain tissue.
The oedematous (or transudate ) fluid comes from the blood vessels and is mainly composed of plasma ; after massing inside and / or outside the brain cells, this liquid begins to compress the blood capillaries and the walls of the skull. This compression, called intracranial pressure, blocks the supply of oxygen and nutrients, slowly causing the death of edematous brain tissue and a severe headache.
Furthermore, again due to edema, the cerebrospinal fluid (or CSF ) may remain confined in the cerebral ventricles, where it is produced, without having the possibility to move. This situation, better known as hydrocephalus, causes the liquor to accumulate excessively inside the brain, further worsening the disorders caused by the edema.
Causes
Cerebral edema can occur due to different causes. Below are the conditions that most frequently cause its appearance:
- Brain trauma (or head trauma) . This is a head injury that damages the brain. Usually, it is the consequence of a car accident, an involuntary fall, an impact against an object, a gesture of private violence, etc. In addition to forming an edema in the brain, the most severe brain traumas can break the skull (or the bone covering of the brain) and cause bleeding (or a blood leak). The blood, which comes out in this way, goes to increase the intracranial pressure and to worsen the cerebral edema.
- Ischemic stroke . The term stroke identifies a serious pathological condition, which occurs when the blood supply, directed to the brain, stops or is greatly reduced. In the case of ischemic stroke, blockage of cerebral blood circulation depends on a blood clot (a thrombus or an embolus ). Without blood, the affected brain areas no longer receive oxygen and slowly begin to die. This deleterious mechanism lays the foundation, in some cases, for the formation of a cerebral edema.
- Hemorrhagic stroke and hypertension . Stroke is hemorrhagic when the absence of blood and oxygen supplies depends on the rupture of a blood vessel. This blood loss, also known as cerebral hemorrhage, increases intracranial pressure and promotes the appearance of edema. Among the main causes of hemorrhagic stroke is hypertension (high blood pressure), which is therefore also considered one of the main risk factors for cerebral edema.
- Infections . Infections are diseases caused by pathogens, such as viruses, bacteria and parasites; those that can give rise to cerebral edema are: meningitis, encephalitis, toxoplasmosis and subdural empyema . The latter are pus collections located between the dura mater and arachnoid meninges.
- Brain tumors . A brain tumor is an abnormal mass of cells that grows inside the brain. The formation of a tumor, in addition to being a possible cause of cerebral edema, promotes the increase in intracranial pressure, as the presence of the skull reduces the space available to the tumor mass. This, in fact, as it grows, pushes on the bony walls and above all on the surrounding brain areas.
- High altitude (or altitude sickness) . Being at high altitude (from 2500 meters upwards) can cause various disorders, such as headaches, nausea, dizziness, shortness of breath, palpitations, etc. In some individuals, these disorders may get worse and worse, eventually causing cerebral edema and pulmonary edema. The explanation of how to reach this situation has not yet been clarified, however, at the first symptoms of the so-called altitude sickness, it is advisable not to go up further and possibly descend towards the valley. Attention, under 2500 meters the disturbances that someone can feel are not generally considered altitude sickness and, usually, they don't have serious consequences.
- Opiate drug abuse . Opiate drugs (morphine, codeine, oxycodone, etc.) are taken for their strong pain-relieving powers. Their immoderate use is however at the origin of various complications, including cerebral edema.
- Diabetes . It is a metabolic disease caused by impaired insulin activity. In particular, cerebral edema can occur due to a condition, which affects some diabetic patients, called diabetic ketoacidosis .
Symptoms and Complications
Cerebral edema is considered a clinical emergency, which must be recognized as soon as possible in order to cure it and prevent it from getting worse.
The symptoms of cerebral edema are numerous and can vary considerably, from patient to patient, both in terms of severity and type; they depend on various factors, such as triggers, age of onset and the area of the brain involved.
To better understand what has just been said, some particular examples will be described; first, however, here are the most classic manifestations of brain edema:
- Headache
- Nausea and vomit
- Dizziness
- Irregular heart beat
- Loss or changes in vision (blurred vision, double vision, etc.)
- Neck pain and stiffness
- Memory loss (amnesia)
- Motor disabilities, such as difficulty walking and / or balancing
- Lack of coordination in movements
- Difficulty speaking ( aphasia )
- Sense of numbness, malaise and dizziness (or lethargy)
- Attacks of epilepsy
- Confusion or loss of consciousness
- Difficulty of understanding
- Temperature
- Hydrocephalus
AGE OF THE PATIENT
The age of the patient has a decisive influence on the consequences of a symptom in particular, hydrocephalus.
Figure: a characteristic symptom of cerebral edema is headache
This condition, if it occurs in childhood, causes disorders such as increased head circumference, loss of appetite, difficulty in sucking and feeding, deviation of the eyes downwards, irritability and sudden mood swings; all these signs do not occur, or are not so marked, among adults.
Among these pathological manifestations, the increase in the infant's head circumference is the most characteristic, since it is due to the not yet complete welding of the bones of the skull.
CEREBRAL AREA AFFECTED
The brain is divided into different areas and each of them controls distinct functions.
It follows that a cerebral edema occurring at the level of the occipital lobe of the brain has different consequences with respect to a cerebral edema developed in the temporal or frontal lobe. For example, if the occipital lobe is affected, there will be visual disturbances, while if the temporal lobe is hit the spoken language will fail.
Figure: hydrocephalus in the child
The exact location of the affected area of brain is very important, because it allows to better plan the surgery.
COMPLICATIONS
If action is not taken promptly, cerebral edema can cause permanent brain damage and sometimes lethal consequences. All this, moreover, can be made even more serious by the type of triggering cause, since the more difficult it is to cure, the more its effects are irreversible.
Possible complications of cerebral edema include: coma, paralysis, cognitive disabilities of various kinds, developmental delay (among young patients), muscle weakness and permanent motor and learning deficits.
Diagnosis
The diagnosis of a cerebral edema requires extreme speed and intuition, on the part of the doctor, since it is a clinical emergency to be treated in the shortest possible time.
The first diagnostic check consists of an accurate but rapid physical examination; after that, we go on to a neurological examination, some radiological tests and, if there are suspicions of diabetes and or an ongoing infection, an analysis of the patient's blood.
EXAMINATION OBJECTIVE
During the physical examination, the doctor asks the patient to describe the symptoms and if he remembers an event that triggered them.
Head trauma, having suffered from particular diseases or diabetes, having been in the mountains at high altitudes or having taken opiate drugs are all useful information for a correct diagnosis.
After this rapid investigation, the patient is examined to assess the extent of the symptoms and undergo the classic checks of pressure and heart rate.
Attention : at this stage of the diagnosis, the doctor may need to talk to a relative or a close friend of the patient, as the latter may not remember certain episodes and unintentionally omit some very useful information.
NEUROLOGICAL EXAMINATION
All those who complain of symptoms such as headaches, loss of motor skills, cognitive deficits, language deficits and / or vision loss require a neurological examination, as they indicate brain involvement.
People with a suspected cerebral edema are subjected to rapid hearing checks, sight, speech, balance, coordination and reflexes. The partial or total loss of one or more of these abilities can help the doctor to understand which area of the brain is affected by edema.
RADIOLOGICAL TESTS
Radiological examinations consist of a nuclear magnetic resonance ( NMR ) and / or a computerized axial tomography ( CT ), both in the brain.
Figure: radiological examination of a brain affected by cerebral edema. The edema is the dark area, present on the right cerebral hemisphere. From the site: //en.wikipedia.org/
The images provided by these tests clarify the position and size of the brain edema; furthermore, if the disorder originated from a tumor or a stroke, they also show signs of these two possible causes.
Therefore, MRI and CT have a fundamental diagnostic value, especially if the patient has declared that he is not diabetic or dependent on opiate drugs.
BLOOD ANALYSIS
Blood tests are carried out if there is a suspicion that cerebral edema is due to diabetes, an infectious agent or abuse of opiate drugs. Thus, these diagnostic checks are aimed at identifying the triggering causes, not so much brain edema.
Treatment
Cerebral edema, once diagnosed, requires immediate therapeutic treatment.
The goals of the therapy are two:
- Restore blood flow and oxygen supply to the brain, so as to stop edema progression and prevent any permanent damage.
- Treating the causes of edema to the brain, as this is the only way to guarantee better and lasting healing.
These two goals can be achieved thanks to a combination of several therapeutic methods, which consist of:
- Oxygen therapy . It is the therapeutic administration of oxygen, carried out through a respirator or in a hyperbaric chamber ( hyperbaric oxygen therapy, OTI). Thanks to oxygen therapy, a better oxygenation of all the patient's tissues and organs, including the brain, is guaranteed.
- Osmotherapy . The goal of osmotherapy is to reduce high intracranial pressure. To achieve this, osmotic agents such as mannitol are administered intravenously to the patient. These substances, once in the blood, "recall" the edematous liquid back, passed from the vessels to the intra- and extra-cellular spaces of the brain. Osmotherapy is not always effective, on the contrary, in some cases it can worsen cerebral edema; therefore, its execution requires the utmost attention.
- Drug therapy . The drugs most indicated against cerebral edema are corticosteroids, diuretics and, if at the origin of the disorder there is a blood clot, anticoagulants . Drug administration, therefore, depends on the triggering causes.
- Ventriculostomy . It is the therapeutic procedure adopted in the case of hydrocephalus. It is performed by a surgeon, who, through a hole made in the patient's skull, inserts a thin plastic tube into the cerebral ventricles. This catheter, therefore, is used to aspirate excess cephalorachidid fluid, which helps to raise intracranial pressure.
- Surgery . There are two possible surgical procedures. The first procedure, known as decompressive craniectomy, consists in removing the part of the skull against which the brain area affected by edema pushes. In this way, in fact, the intracranial pressure is reduced.
The second procedure, instead, is foreseen only in case of tumor, stroke or haemorrhage in the brain (a diabetic or mountain sick person does not require this intervention, for obvious reasons) and consists in the repair and / or removal of what has triggered edema.
- Induced hypothermia . By induced hypothermia, we mean the voluntary lowering, at 32-33 ° C, of an individual's body temperature (including the brain). The purpose of this treatment is to slow the progression of brain damage and save the brain from lack of oxygen. Induced hypothermia is an innovative treatment method that, in Italy, is not yet widespread, as it is still debating its real benefits.
Prognosis and prevention
The prognosis of cerebral edema varies from patient to patient and depends on the following factors.
First of all, the timeliness of rescue operations has an impact; in fact, as has already been said several times, before we act and the consequences and permanent damage to the brain will be less.
Afterwards, the triggering factors also play a very important role, as there are more serious and less serious ones, and the location of cerebral edema, since it can arise in areas of the brain that are difficult to reach and be cured.
PREVENTION
To prevent cerebral edema, we recommend:
- Use the appropriate protective helmets, when cycling or skiing, contact sports (such as rugby or boxing) and specific jobs or tasks are performed.
- Use seat belts when driving a vehicle. Head trauma and brain edema resulting from motor vehicle accidents are very frequent.
- Keep your blood pressure under control and, if you suffer from hypertension, try to reduce blood pressure with a healthy lifestyle and with the right exercise.
- Avoid smoking .
- Give the body enough time to get used to the high altitude ( acclimatization ), in order to avoid the danger of a cerebral edema due to altitude sickness.
