Cerebral edema
Encyclopedia
Cerebral edema or cerebral œdema is an excess accumulation of water in the intracellular or extracellular spaces of the brain
.
(BBB). This allows normally excluded intravascular proteins and fluid to penetrate into cerebral parenchymal extracellular space.
Once plasma constituents cross the BBB, the edema spreads; this may be quite fast and widespread. As water enters white matter it moves extracellularly along fiber tracts and can also affect the gray matter.
This type of edema is seen in response to trauma, tumors, focal inflammation, late stages of cerebral ischemia
and hypertensive encephalopathy
.
Some of the mechanisms contributing to BBB dysfunction are: physical disruption by arterial hypertension or trauma, tumor-facilitated release of vasoactive and endothelial destructive compounds (e.g. arachidonic acid
, excitatory neurotransmitters, eicosanoids, bradykinin, histamine, and free radicals). Some of the special subcategories of vasogenic edema include:
Hydrostatic cerebral edema
Cerebral edema from brain cancer
High Altitude Cerebral Edema
This edema is due to the derangement in cellular metabolism
resulting in inadequate functioning of the sodium and potassium pump in the glial cell
membrane. As a result there is cellular retention of sodium and water. There are swollen astrocytes in gray and white matter. Cytotoxic edema is seen with various intoxications (dinitrophenol, triethyltin, hexachlorophene
, isoniazid
), in Reye's syndrome
, severe hypothermia
, early ischemia
, encephalopathy
, early stroke
or hypoxia
, cardiac arrest, pseudotumor cerebri, and cerebral toxins.
), syndrome of inappropriate antidiuretic hormone
secretion (SIADH), hemodialysis
, or rapid reduction of blood glucose
in hyperosmolar hyperglycemic state (HHS), formerly hyperosmolar non-ketotic acidosis (HONK), the brain osmolality will then exceed the serum osmolality creating an abnormal pressure gradient down which water will flow into the brain causing edema.
This form of edema is due to rupture of the CSF-brain barrier resulting in trans-ependymal flow of CSF which causes CSF to penetrate the brain and spread to the extracellular spaces and the white matter. This is differentiated from vasogenic edema in that interstitial cerebral edema CSF contains almost no protein.
using mannitol
, diuretics and surgical decompression
.
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
.
Vasogenic
Due to a breakdown of tight endothelial junctions which make up the blood-brain barrierBlood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
(BBB). This allows normally excluded intravascular proteins and fluid to penetrate into cerebral parenchymal extracellular space.
Once plasma constituents cross the BBB, the edema spreads; this may be quite fast and widespread. As water enters white matter it moves extracellularly along fiber tracts and can also affect the gray matter.
This type of edema is seen in response to trauma, tumors, focal inflammation, late stages of cerebral ischemia
Ischemia
In medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
and hypertensive encephalopathy
Encephalopathy
Encephalopathy means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.-Terminology:...
.
Some of the mechanisms contributing to BBB dysfunction are: physical disruption by arterial hypertension or trauma, tumor-facilitated release of vasoactive and endothelial destructive compounds (e.g. arachidonic acid
Arachidonic acid
Arachidonic acid is a polyunsaturated omega-6 fatty acid 20:4.It is the counterpart to the saturated arachidic acid found in peanut oil, Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6).It is the counterpart to the saturated arachidic acid found in peanut oil,...
, excitatory neurotransmitters, eicosanoids, bradykinin, histamine, and free radicals). Some of the special subcategories of vasogenic edema include:
Hydrostatic cerebral edema
- This form of cerebral edema is seen in acute, malignant hypertension. It is thought to result from direct transmission of pressure to cerebral capillary with transudation of fluid into the ECF (extracellular fluid) from the capillaries.
Cerebral edema from brain cancer
- Cancerous glial cellGlial cellGlial cells, sometimes called neuroglia or simply glia , are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system such as in the autonomous nervous system...
s (gliomaGliomaA glioma is a type of tumor that starts in the brain or spine. It is called a glioma because it arises from glial cells. The most common site of gliomas is the brain.-By type of cell:...
) of the brain can increase secretion of vascular endothelial growth factorVascular endothelial growth factorVascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....
(VEGF) which weakens the junctions of the blood-brain barrierBlood-brain barrierThe blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
. DexamethasoneDexamethasoneDexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
can be of benefit in reducing VEGF secretion.
High Altitude Cerebral Edema
- High altitude cerebral edemaHigh altitude cerebral edemaHigh altitude cerebral edema is a severe form of altitude sickness. HACE is the result of swelling of brain tissue from fluid leakage and almost always begins as acute mountain sickness...
(or HACE) is a severe form of (sometimes fatal) altitude sicknessAltitude sicknessAltitude sickness—also known as acute mountain sickness , altitude illness, hypobaropathy, or soroche—is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude...
. HACE is the result of swelling of brain tissue from leakage of fluids from the capillaries due to the effects of hypoxiaHypoxia (medical)Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
on the mitochondria-rich endothelial cells of the blood-brain barrier.
- Symptoms can include headache, loss of coordination (ataxia), weakness, and decreasing levels of consciousness including disorientation, loss of memory, hallucinations, psychotic behavior, and coma. It generally occurs after a week or more at high altitude. Severe instances can lead to death if not treated quickly. Immediate descent is a necessary life-saving measure (2,000 - 4,000 feet). There are some medications (e.g. dexamethasoneDexamethasoneDexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
) that may be prescribed for treatment in the field, but these require proper medical training in their use. Anyone suffering from HACE must be evacuated to a medical facility for proper follow-up treatment. A gamow bagGamow bagA Gamow bag is an inflatable pressure bag large enough to accommodate a person inside. By inflating the bag with a foot pump, the effective altitude can be decreased by 1000 to as much as 3000 meters . It is primarily used for treating severe cases of altitude sickness.The gamow bag was named after...
can sometimes be used to stabilize the sufferer before transport or descending.
- Climbers may also suffer high altitude pulmonary edemaHigh Altitude Pulmonary EdemaHigh altitude pulmonary edema is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes typically above ....
(HAPE), which affects the lungs. While not as life threatening as HACE in the initial stages, failure to descend to lower altitudes or receive medical treatment can also lead to death.
Cytotoxic
In this type of edema the BBB remains intact.This edema is due to the derangement in cellular metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
resulting in inadequate functioning of the sodium and potassium pump in the glial cell
Glial cell
Glial cells, sometimes called neuroglia or simply glia , are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system such as in the autonomous nervous system...
membrane. As a result there is cellular retention of sodium and water. There are swollen astrocytes in gray and white matter. Cytotoxic edema is seen with various intoxications (dinitrophenol, triethyltin, hexachlorophene
Hexachlorophene
Hexachlorophene, also known as Nabac, is a disinfectant. The compound occurs as a white to light-tan crystalline powder, which either is odorless or produces a slightly phenolic odor. In medicine, hexachlorophene is very useful as a topical anti-infective, anti-bacterial agent, often used in soaps...
, isoniazid
Isoniazid
Isoniazid , also known as isonicotinylhydrazine , is an organic compound that is the first-line antituberculosis medication in prevention and treatment. It was first discovered in 1912, and later in 1951 it was found to be effective against tuberculosis by inhibiting its mycolic acid...
), in Reye's syndrome
Reye's syndrome
Reye's syndrome is a potentially fatal disease that causes numerous detrimental effects to many organs, especially the brain and liver, as well as causing a lower than usual level of blood sugar . The classic features are liver damage, aspirin use and a viral infection...
, severe hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
, early ischemia
Ischemia
In medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
, encephalopathy
Encephalopathy
Encephalopathy means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.-Terminology:...
, early stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
or hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
, cardiac arrest, pseudotumor cerebri, and cerebral toxins.
Osmotic
Normally cerebral-spinal fluid (CSF) and extracellular fluid (ECF) osmolality of the brain is slightly lower than that of plasma. When plasma is diluted by excessive water intake (or hyponatremiaHyponatremia
Hyponatremia is an electrolyte disturbance in which the sodium concentration in the serum is lower than normal. In the vast majority of cases, hyponatremia occurs as a result of excess body water diluting the serum sodium and is not due to sodium deficiency. Sodium is the dominant extracellular...
), syndrome of inappropriate antidiuretic hormone
Syndrome of inappropriate antidiuretic hormone
The syndrome of inappropriate antidiuretic hormone hypersecretion is characterized by excessive release of antidiuretic hormone from the posterior pituitary gland or another source. The result is hyponatremia and sometimes fluid overload...
secretion (SIADH), hemodialysis
Hemodialysis
In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy...
, or rapid reduction of blood glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
in hyperosmolar hyperglycemic state (HHS), formerly hyperosmolar non-ketotic acidosis (HONK), the brain osmolality will then exceed the serum osmolality creating an abnormal pressure gradient down which water will flow into the brain causing edema.
Interstitial
Occurs in obstructive hydrocephalus.This form of edema is due to rupture of the CSF-brain barrier resulting in trans-ependymal flow of CSF which causes CSF to penetrate the brain and spread to the extracellular spaces and the white matter. This is differentiated from vasogenic edema in that interstitial cerebral edema CSF contains almost no protein.
Treatment
Treatment approaches can include osmotherapyOsmotherapy
Osmotherapy is a medical treatment, using intravenous injection or oral administration of an agent to induce dehydration. The goal of dehydration is to reduce the amount of accumulated fluid in the brain. The earliest description in medical literature dates back to 1919.- Treatment :Osmotherapy can...
using mannitol
Mannitol
Mannitol is a white, crystalline organic compound with the formula . This polyol is used as an osmotic diuretic agent and a weak renal vasodilator...
, diuretics and surgical decompression
Decompressive craniectomy
Decompressive craniectomy is a neurosurgical procedure in which part of the skull is removed to allow a swelling brain room to expand without being squeezed. It is performed on victims of traumatic brain injury and stroke. Use of the surgery is controversial....
.
External links
- MedPix Vasogenic Edema