What is a Brain Edema: A Comprehensive Guide

An inflammation could harm any body region, although it tends to manifest more visibly in the hands, arms, feet, ankles, and legs. It can usually be brought on by medications, pregnancies, or an underlying malady, which is frequently scarring of the liver, congestive cardiac failure, or renal failure.

This fluid overload is frequently relieved by getting treatment to drain interstitial water and consume less sodium. When the swelling is a manifestation of a deeper illness, that affliction needs to be treated separately.

An edema can also occur in the brain, which is often life-threatening and could lead to death if left untreated. A cerebral edema formation could be due to a traumatic brain injury or a brain tumour, which leads to increased intracranial pressure.

Treatment for cerebral edema 1or cerebral oedema can be quite challenging. Additionally, irreparable harm may result. To answer the question of what is a brain edema more specifically, the following article will come in use.

Cerebral Edema

The simplest explanation to the question “what is a brain edema?” is brain swelling. The different categories include vasogenic, cellular, osmotic, or interstitial causes of cerebral edema. This can originate from disorders like cerebral abnormalities, head trauma, arterial occlusion, and restrictive encephalopathy that induces interstitial edema.

Malignancies, infections, hypoxia, parasites, electrolyte abnormalities, or severe hypertension can all cause cerebral edema. Several causes may be divided into neuronal and non-neurological categories.

Hepatitis, Reye syndrome, carbon monoxide overdose, exposure to toxins, and cerebral edema from higher elevations are among more non-neurologic reasons. Pseudotumor cerebri is a rare reason for cerebral edema.

Symptoms of Cerebral Edema

Diagnosing cerebral edema2 can be complicated for medical professionals without the right tests and careful examination. After an accident or infection, there are a few signs to watch out for that could mean enlargement.

The following symptoms of cerebral edema include headaches, sickness, vertigo, manque of coordination, and tingling.

You might suffer indications such as changes in mood, cognitive impairment, speech difficulties, wetting, alteration in perception, convulsions, and lethargy if cerebral edema is more severe. Several factors lead to the development of cerebral edema, which in turn helps explain brain edema.

To understand and comprehend what is a brain edema, the article will further discuss and differentiate between TBI (traumatic brain injury), high altitude cerebral edema, and cytotoxic edema3, and explain what a blood-brain barrier is.

Blood-Brain Barrier

The blood-brain barrier is the most basic and important structure that an individual needs to comprehend to seek answers for what is brain edema. All body organs and tissues depend on circulatory arteries to carry oxygen and other nutrients.

The blood-brain barrier, a special property of said venous arteries, which then assist and enhance the brain’s central nervous system (CNS), allows these vessels to carefully manage the transportation of ions, chemicals, and cellular seen between blood and the brain.

Careful regulating CNS equilibrium enables adequate neurological functionality, which safeguards subcortical structures from contaminants and infections. Modifications to these membrane qualities play a significant role in the pathophysiology and development of various neurological illnesses of the brain tissue and brain cells.

Endothelial Cells

Endothelial cells (ECs), which make up the blood vasculature, have a variety of morphological, transportation, and biochemical features that work together to produce the functional barrier.

Interactions between various cerebrovascular, immunological, and neuronal components control these qualities. It is crucial to comprehend how these brain cell groupings connect to control the membrane qualities to comprehend what is a brain edema and how well the brain operates in both wellness and sickness.

Traumatic Brain Injury (TBI)

Traumatic brain injury (TBI) occurs whenever a swift, outward, violent injury harms the brain. It ranks as one of the primary causes of mortality and disability in adults. TBI is a comprehensive term that covers a diverse range of neurological ailments.

Damage to the brain may be localised (limited to a particular location) or broad (occurring in many areas of the brain). A cerebral injury’s magnitude may fluctuate from just a minor concussion to a catastrophic one, leaving a victim in a coma or even dying. One of two things can happen to cause brain damage that leads to the development of cerebral edema.

Brain damage with closure

It is a form of a traumatic brain injury where there is no fracture in the skull and only a nonpenetrating brain impairment; this condition is known as a closed brain injury, which helps to understand what is a brain edema. A sudden to-and-fro manoeuvre and oscillation of the brain inside the cranium can result in a closed brain injury through bruising and ripping the brain tissue and blood vessels.

Car crashes, slips and falls, and increasingly sports-related incidents are the main causes of closed brain injuries. This kind of harm can also happen when you shake a newborn (shaken baby syndrome).

Serious brain damage

The answer to what is a brain edema cannot be only explained through something that develops internally within the cranial region. When the skull is broken, as when a gunshot pierces the brain, it results in penetrating or open, gaping brain injury.

Potentially damaging pressures could fracture the skull and harm the brain beneath. The discovery of skull fractures during a patient evaluation could be concerning. Core fractures are dangerous since they may harm arteries, neurotransmitters, and perhaps other components.

Cerebrospinal fluid 4(CSF) leakage through the nostrils or ears is conceivable if the rupture enters the sinuses. Broken bones in the skull that press against or into the brain are known as depressed skull fractures.

TBIs sometimes result in “mass lesions,” localised injuries like contusions and hematomas that put more pressure on the brain. The following list summarises the many consequences caused by TBIs:


The first injury that helps to understand what is a brain edema is a blood clot within the brain or on its surface. Hematomas may occur anywhere within the brain. An epidural hematoma is a blood collection between the dura mater (the brain’s protective covering) and the inside of the skull.

A subdural hematoma is a blood collection between the dura mater and the arachnoid layer, which sits directly on the brain’s surface.


Bruising of the brain tissue is referred to as a cerebral contusion, one of the other factors of brain edema. Brain contusions resemble bruising on many other human body parts when viewed under the microscope.

These are made up of blood that has seeped through arteries, vessels, or capillaries combined with damaged or inflamed cerebellum areas. Although they can happen anywhere, contusions most happen frequently at the bases of the brain’s frontal lobes.

Intracerebral and Subarachnoid Hemorrhage

It is a sort of brain bleeding that can occur due to different types of head trauma, particularly causing harm. The ability to eliminate the bleeding surgically varies with the size and placement of the bleeding.

Spurting blood further into subarachnoid space causes subarachnoid haemorrhage (SAH). After a TBI, it frequently looks like scattered bleeding, which has been sparsely dispersed across the brain surface. The majority of SAH cases linked to head trauma are benign. Potentially traumatic SAH could culminate in hydrocephalus5.

Ischemia or ischemic stroke

A further form of diffuse brain injury that causes cerebral edema is ischemic stroke or inadequate blood supply to some brain areas. Ischemia or inadequate blood supply to some brain areas is a further diffuse injury.

Many TBI individuals may experience a regular reduction in blood volume to very low concentrations. This is essential because a brain that has already suffered a serious injury is highly susceptible to even lower levels in blood supply.

During the initial days following a head injury, problems with blood pressure can ultimately be detrimental.

High Altitude Cerebral Edema

Contrary to traumatic brain injury, a severe case of acute mountain nausea, high-altitude cerebral edema (HACE) is an uncommon, life-threatening altitude condition referred to as acute mountain sickness (AMS); it also helps to answer what is a brain edema. Damaged vasculature in the brain seems to be to blame, which promotes fluid retention, brain swelling, brain injury and neurological damage.

Even though HACE is the most prevalent type of altitude sickness, if cerebral blood flow is not properly diagnosed and treated early, it can develop quickly into a coma and even death caused by a brain haemorrhage in about 24 hours.

The Pathophysiological Mechanisms of HACE

HACE is believed to represent the ultimate form/end-stage of AMS, which is a cause of cerebral edema, even if the precise mechanism of development is not properly known to answer what is a brain edema. As nothing more than a result of the neuro-hormonal (VEG-F, Nitric Oxide, reactive cytokines, free radicals) & systolic reactions brought on by hypoxia at elevation, the microvascular cerebral beds are over-perfused.

Due to increased capillary forces and venous permeability, this leads to increased intracranial pressure. Cerebral edema follows the rupture of the blood-brain barrier induced by multiple stresses.

The Tight Fit Hypothesis

According to the “tight fit” hypothesis, a person’s capacity to withstand rising cerebral edema inside the skull depends on how much cerebral region they have accessible. This hypothesis might aid in explaining how AMS can develop into HACE, which appears to be a chaotic system.

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Other Types of Brain Edema

Some other kinds of cerebral edema that explain what is a brain edema are as follows:

Cytotoxic Edema

Cytotoxic cerebral edema is another form of brain swelling that helps to answer what is a brain edema. Exogenous fluid passes the cellular systems, causing their enlargement, and is most frequently observed in cerebral ischemia or an ischemic stroke. The blood-brain barrier here remains uncompromised.

Within minutes of the injury, cellular or cytotoxic cerebral edema frequently develops and damages the brain’s glial, neuronal, and endothelial cells. Because the export process is broken in cytotoxic edema, salt penetrates the cell quickly, and there are no blood coagulation processes in the membranes.

Accompanying the ions into the inner compartment, anions try to restore neutrality to the cell, which causes intracellular edema as the cells expand with more fluid. This kind of cerebral edema is brought on by stroke and traumatic brain damage.

Vasogenic Cerebral Edema

When the blood-brain barrier (BBB) is compromised, cerebral edema of the vasogenic variety occurs.  It is an external cerebral edema that primarily affects the white matter by microvascular fluid leakage.

Ions and proteins migrate more readily through into extracellular space due to the blood-brain barrier disruption, which results in an osmotic drawing of fluids further into cerebral interstitial space.

Interstitial Edema

Cerebrospinal fluid leaks from the intracerebral region into the intermediate brain regions, causing intermittent cerebral edema. Individuals with meningitis or hydrocephalus are two instances of individuals who are impacted by such a cause. This another type of edema that helps explain what is a brain edema.

This mounting pressure on the brain and cerebrospinal fluid (CSF) forces liquids into the brain’s parenchyma. The fluid deposits primarily in the white matter’s extracellular space, resulting in cerebral edema.

Osmotic Edema

Typically, osmolarity disorders6 such as hyponatremia, diabetic ketoacidosis (DKA), or other metabolic diseases cause osmotic cerebral edema. In these circumstances, the brain cells draw water from plasma, causing extensive cerebral edema.

Treatment for Cerebral Edema

Treatment goals are paramount to answering what is a brain edema in this article. The 2 major goals of treating cerebral edema are to stop further damage from the condition and, if possible, to address the original rupture that caused it.

The underlying problem of cerebral edema and any potentially fatal consequences are treated. Hyperventilation, osmotherapy, diuretics, corticosteroids, and surgical decompression are all treatments available.


This entire article was dedicated to answering what is a brain edema. Cerebral edema’s clinical symptoms are frequently misdiagnosed as other conditions such as alcoholism, strokes, infections, or post-ictal conditions. A significant degree of scepticism is necessary, especially in minor situations.

Careful cerebral surveillance and consultations with a neurologist and neurosurgeon are crucial in the more serious situations. Continuous interaction is necessary, especially concerning the implementation of care, including the benefits, dangers, and constraints of ICP assessment or craniotomy.

All coworkers should educate patients on preventing future difficulties, social workers should be involved to guarantee conduct and practice upon discharging, and the patient’s main caregiver should be informed to determine the correct follow-up.

  1. Jha, Ruchira M., Patrick M. Kochanek, and J. Marc Simard. “Pathophysiology and treatment of cerebral edema in traumatic brain injury.” Neuropharmacology 145 (2019): 230-246. ↩︎
  2. Raslan, Ahmed, and Anish Bhardwaj. “Medical management of cerebral edema.” Neurosurgical focus 22.5 (2007): 1-12. ↩︎
  3. Liang, Danny, et al. “Cytotoxic edema: mechanisms of pathological cell swelling.” Neurosurgical focus 22.5 (2007): 1-9. ↩︎
  4. Sakka, Laurent, Guillaume Coll, and Jean Chazal. “Anatomy and physiology of cerebrospinal fluid.” European annals of otorhinolaryngology, head and neck diseases 128.6 (2011): 309-316. ↩︎
  5. Aschoff, Alfred, et al. “The scientific history of hydrocephalus and its treatment.” Neurosurgical review 22 (1999): 67-93. ↩︎
  6. Robertson, Gary L., and Patricio Aycinena. “Neurogenic disorders of osmoregulation.” The American journal of medicine 72.2 (1982): 339-353. ↩︎

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