Cerebral ischemia
Encyclopedia
Brain ischemia, also known as cerebral ischemia, is a condition in which there is insufficient blood flow to the brain
to meet metabolic demand. This leads to poor oxygen supply or cerebral hypoxia
and thus to the death of brain tissue or cerebral infarction
/ ischemic stroke
. It is a sub-type of stroke along with subarachnoid hemorrhage
and intracerebral hemorrhage.
Ischemia leads to alterations in brain metabolism, reduction in metabolic rates, and energy crisis.
There are two types of ischemia: focal ischemia, which is confined to a specific region of the brain; and global ischemia, which encompasses wide areas of brain tissue.
The main symptoms involve impairments in vision
, body movement, and speaking
. The causes of brain ischemia vary from sickle cell anemia to congenital heart defects. Symptoms of brain ischemia can include unconsciousness, blindness, problems with coordination, and weakness in the body. Other effects that may result from brain ischemia are stroke
, cardiorespiratory arrest, and irreversible brain damage.
demonstrated that ischemia induced in mammalian brains for up to an hour can be at least partially recovered. Accordingly, this discovery raised the possibility of intervening after brain ischemia before the damage becomes irreversible.
" can be divided into three categories: brain ischemia, subarachnoid hemorrhage
and intracerebral hemorrhage. Brain ischemia can be further subdivided, by cause, into thrombotic
, embolic, and hypoperfusion. Thrombotic and embolic are generally focal or multifocal in nature while hypoperfusion affects the brain globally.
or embolism.
. If sufficient circulation
is restored within a short period of time, symptoms may be transient. However, if a significant amount of time passes before restoration, brain damage may be permanent. While reperfusion may be essential to protecting as much brain tissue as possible, it may also lead to reperfusion injury
. Reperfusion injury is classified as the damage that ensues after restoration of blood supply to ischemic tissue.
may result in symptoms such as blindness in one eye, weakness in one arm or leg, or weakness in one entire side of the body. Ischemia within the arteries branching from the vertebral arteries
in the back of the brain may result in symptoms such as dizziness
, vertigo
, double vision
, or weakness on both sides of the body . Other symptoms include, difficulty speaking, slurred speech, and the loss of coordination. The symptoms of brain ischemia range from mild to severe. Further, symptoms can last from a few seconds to a few minutes or extended periods of time. If the brain becomes damaged irreversibly and infarction
occurs, the symptoms may be permanent.
Similar to cerebral hypoxia
, severe or prolonged brain ischemia will result in unconsciousness
, brain damage
or death
, mediated by the ischemic cascade
.
Multiple cerebral ischemic events may lead to subcortical ischemic depression
, also known as vascular depression. This condition is most commonly seen in elderly depressed patients. Late onset depression is increasingly seen as a distinct sub-type of depression, and can be detected with an MRI.
, plaque buildup in the arteries, blood clots, extremely low blood pressure as a result of heart attack, and congenital heart defects have a higher predisposition to brain ischemia in comparison their healthy counterparts.
Sickle cell anemia may cause brain ischemia associated with the irregularly shaped blood cells. Sickle shaped blood cells clot more easily than normal blood cells, impeding blood flow to the brain.
Compression of blood vessels may also lead to brain ischemia, by blocking the arteries that carry oxygen to the brain. Tumors are one cause of blood vessel compression.
Ventricular tachycardia represents a series of irregular heartbeats that may cause the heart to completely shut down resulting in cessation of oxygen flow. Further, irregular heartbeats may result in formation of blood clots, thus leading to oxygen deprivation to all organs.
Blockage of arteries due to plaque buildup may also result in ischemia. Even a small amount of plaque build up can result in the narrowing of passageways, causing that area to become more prone to blood clots. Large blood clots can also cause ischemia by blocking blood flow.
A heart attack can also cause brain ischemia due to the correlation that exists between heart attack and low blood pressure. Extremely low blood pressure usually represents the inadequate oxygenation of tissues. Untreated heart attacks may slow blood flow enough that blood may start to clot and prevent the flow of blood to the brain or other major organs. Extremely low blood pressure can also result from drug overdose and reactions to drugs. Therefore, brain ischemia can result from events other than heart attacks.
Congenital heart defects may also cause brain ischemia due to the lack of appropriate artery formation and connection. People with congenital heart defects may also be prone to blood clots.
Other pathological events that may result in brain ischemia include, cardiorespiratory arrest, stroke
, and severe irreversible brain damage.
Recently, Moyamoya disease has also been identified as a potential cause for brain ischemia. Moyamoya disease is an extremely rare cerebrovascular condition that limits blood circulation
to the brain, consequently leading to oxygen deprivation.
and substrate
. The brain is not able to switch to anaerobic metabolism and because it does not have any long term energy stored the levels of adenosine triphosphate
(ATP) drop rapidly and approach zero within 4 minutes. In the absence of biochemical energy, cells begin to lose the ability to maintain electrochemical gradients. Consequently, there is a massive influx of calcium
into the cytosol
, a massive release of glutamate from synaptic vesicles, lipolysis
, calpain
activation, and the arrest of protein synthesis. Additionally, removal of metabolic wastes is slowed. The interruption of blood flow to the brain for ten seconds results in the immediate loss of consciousness. The interruption of blood flow for twenty seconds results in the stopping of electrical activity.
The outcome of brain ischemia is influenced by the quality of subsequent supportive care. Systemic blood pressure (or slightly above) should be maintained so that cerebral blood flow is restored. Also, hypoxaemia and hypercapnia
should be avoided. Seizures can induce more damage; accordingly, anticonvulsants should be prescribed and should a seizure occur, aggressive treatment should be undertaken. Hyperglycaemia should also be avoided during brain ischemia.
Anticoagulation with warfarin
or heparin
may be used if the patient has atrial fibrillation
.
Operative procedures such as carotid endarterectomy
and carotid stenting
may be performed if the patient has a significant amount of plaque in the carotid arteries associated with the local ischemic events.
has been attempted to improve results post brain ischemia . This procedure was suggested to be beneficial based on its effects post cardiac arrest. Evidence supporting the use of therapeutic hypothermia after brain ischemia, however, is limited.
A closely related disease to brain ischemia is brain hypoxia. Brain hypoxia is the condition in which there is a decrease in the oxygen supply to the brain even in the presence of adequate blood flow
. If hypoxia lasts for long periods of time, coma
, seizures, and even brain death
may occur. Symptoms of brain hypoxia are similar to ischemia and include, inattentiveness, poor judgment, memory loss
, and a decrease in motor coordination
. Potential causes of brain hypoxia are suffocation
, carbon monoxide poisoning
, severe anemia
, and use of drugs such as cocaine
and other amphetamines. Other causes associated with brain hypoxia include drowning
, strangling
, choking
, cardiac arrest
, head trauma, and complications during general anesthesia
. Treatment strategies for brain hypoxia vary depending on the original cause of injury.
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,...
to meet metabolic demand. This leads to poor oxygen supply or cerebral hypoxia
Cerebral hypoxia
Cerebral hypoxia refers to a reduced supply of oxygen to the brain. Cerebral anoxia refers to a complete lack of oxygen to the brain. There are four separate categories of cerebral hypoxia; in order of severity they are; diffuse cerebral hypoxia , focal cerebral ischemia, cerebral infarction, and...
and thus to the death of brain tissue or cerebral infarction
Cerebral infarction
A cerebral infarction is the ischemic kind of stroke due to a disturbance in the blood vessels supplying blood to the brain. It can be atherothrombotic or embolic. Stroke caused by cerebral infarction should be distinguished from two other kinds of stroke: cerebral hemorrhage and subarachnoid...
/ ischemic 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...
. It is a sub-type of stroke along with subarachnoid hemorrhage
Subarachnoid hemorrhage
A subarachnoid hemorrhage , or subarachnoid haemorrhage in British English, is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain...
and intracerebral hemorrhage.
Ischemia leads to alterations in brain metabolism, reduction in metabolic rates, and energy crisis.
There are two types of ischemia: focal ischemia, which is confined to a specific region of the brain; and global ischemia, which encompasses wide areas of brain tissue.
The main symptoms involve impairments in vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
, body movement, and speaking
SPEAKING
In sociolinguistics, SPEAKING or the SPEAKING model, is a model socio-linguistic study developed by Dell Hymes...
. The causes of brain ischemia vary from sickle cell anemia to congenital heart defects. Symptoms of brain ischemia can include unconsciousness, blindness, problems with coordination, and weakness in the body. Other effects that may result from brain ischemia are 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...
, cardiorespiratory arrest, and irreversible brain damage.
Background
An interruption of blood flow to the brain for more than 10 seconds causes unconsciousness, and an interruption in flow for more than a few minutes generally results in irreversible brain damage. In 1974, Hossmann and ZimmermanZimmerman
Zimmerman derives from the German last name Zimmermann which means carpenter. Within the United States, it is ranked as the 441st-most common surname....
demonstrated that ischemia induced in mammalian brains for up to an hour can be at least partially recovered. Accordingly, this discovery raised the possibility of intervening after brain ischemia before the damage becomes irreversible.
Classification
The broad term, "strokeStroke
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...
" can be divided into three categories: brain ischemia, subarachnoid hemorrhage
Subarachnoid hemorrhage
A subarachnoid hemorrhage , or subarachnoid haemorrhage in British English, is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain...
and intracerebral hemorrhage. Brain ischemia can be further subdivided, by cause, into thrombotic
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
, embolic, and hypoperfusion. Thrombotic and embolic are generally focal or multifocal in nature while hypoperfusion affects the brain globally.
Focal brain ischemia
Focal brain ischemia occurs when a blood clot has occluded a cerebral vessel. Focal brain ischemia reduces blood flow to a specific brain region, increasing the risk of cell death to that particular area. It can be either caused by thrombosisThrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
or embolism.
Global brain ischemia
Global brain ischemia occurs when blood flow to the brain is halted or drastically reduced. This is commonly caused by cardiac arrestCardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
. If sufficient circulation
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
is restored within a short period of time, symptoms may be transient. However, if a significant amount of time passes before restoration, brain damage may be permanent. While reperfusion may be essential to protecting as much brain tissue as possible, it may also lead to reperfusion injury
Reperfusion injury
Reperfusion injury is the tissue damage caused when blood supply returns to the tissue after a period of ischemia or lack of oxygen. The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and...
. Reperfusion injury is classified as the damage that ensues after restoration of blood supply to ischemic tissue.
Symptoms
The symptoms of brain ischemia reflect the anatomical region undergoing blood and oxygen deprivation. Ischemia within the arteries branching from the internal carotid arteryInternal carotid artery
In human anatomy, the internal carotid arteries are two major arteries, one on each side of the head and neck. They arise from the common carotid arteries where these bifurcate into the internal and external carotid artery, and they supply the brain....
may result in symptoms such as blindness in one eye, weakness in one arm or leg, or weakness in one entire side of the body. Ischemia within the arteries branching from the vertebral arteries
Vertebral artery
The vertebral arteries are major arteries of the neck. They branch from the subclavian arteries and merge to form the single midline basilar artery in a complex called the vertebrobasilar system, which supplies blood to the posterior part of the circle of Willis and thus significant portions of the...
in the back of the brain may result in symptoms such as dizziness
Dizziness
Dizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....
, vertigo
Vertigo (medical)
Vertigo is a type of dizziness, where there is a feeling of motion when one is stationary. The symptoms are due to a dysfunction of the vestibular system in the inner ear...
, double vision
Diplopia
Diplopia, commonly known as double vision, is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, or diagonally in relation to each other...
, or weakness on both sides of the body . Other symptoms include, difficulty speaking, slurred speech, and the loss of coordination. The symptoms of brain ischemia range from mild to severe. Further, symptoms can last from a few seconds to a few minutes or extended periods of time. If the brain becomes damaged irreversibly and infarction
Infarction
In medicine, infarction refers to tissue death that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.-Causes:...
occurs, the symptoms may be permanent.
Similar to cerebral hypoxia
Cerebral hypoxia
Cerebral hypoxia refers to a reduced supply of oxygen to the brain. Cerebral anoxia refers to a complete lack of oxygen to the brain. There are four separate categories of cerebral hypoxia; in order of severity they are; diffuse cerebral hypoxia , focal cerebral ischemia, cerebral infarction, and...
, severe or prolonged brain ischemia will result in unconsciousness
Unconsciousness
Unconsciousness is the condition of being not conscious—in a mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is a type of unconsciousness. Fainting due to a drop in blood pressure and a...
, brain damage
Brain damage
"Brain damage" or "brain injury" is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors...
or death
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
, mediated by the ischemic cascade
Ischemic cascade
The ischemic cascade is a series of biochemical reactions that are initiated in the brain and other aerobic tissues after seconds to minutes of ischemia . This is typically secondary to stroke, injury, or cardiac arrest due to heart attack. Most ischemic neurons that die do so due to the...
.
Multiple cerebral ischemic events may lead to subcortical ischemic depression
Subcortical ischemic depression
Subcortical ischemic depression, also known as vascular depression is a medical condition most commonly seen in elderly depressed patients. Late onset depression is increasingly seen as a distinct variety of depression, and is commonly detected with an MRI...
, also known as vascular depression. This condition is most commonly seen in elderly depressed patients. Late onset depression is increasingly seen as a distinct sub-type of depression, and can be detected with an MRI.
Causes
Brain ischemia has been linked to a variety of diseases or abnormalities. Individuals with sickle cell anemia, compressed blood vessels, ventricular tachycardiaVentricular tachycardia
Ventricular tachycardia is a tachycardia, or fast heart rhythm, that originates in one of the ventricles of the heart...
, plaque buildup in the arteries, blood clots, extremely low blood pressure as a result of heart attack, and congenital heart defects have a higher predisposition to brain ischemia in comparison their healthy counterparts.
Sickle cell anemia may cause brain ischemia associated with the irregularly shaped blood cells. Sickle shaped blood cells clot more easily than normal blood cells, impeding blood flow to the brain.
Compression of blood vessels may also lead to brain ischemia, by blocking the arteries that carry oxygen to the brain. Tumors are one cause of blood vessel compression.
Ventricular tachycardia represents a series of irregular heartbeats that may cause the heart to completely shut down resulting in cessation of oxygen flow. Further, irregular heartbeats may result in formation of blood clots, thus leading to oxygen deprivation to all organs.
Blockage of arteries due to plaque buildup may also result in ischemia. Even a small amount of plaque build up can result in the narrowing of passageways, causing that area to become more prone to blood clots. Large blood clots can also cause ischemia by blocking blood flow.
A heart attack can also cause brain ischemia due to the correlation that exists between heart attack and low blood pressure. Extremely low blood pressure usually represents the inadequate oxygenation of tissues. Untreated heart attacks may slow blood flow enough that blood may start to clot and prevent the flow of blood to the brain or other major organs. Extremely low blood pressure can also result from drug overdose and reactions to drugs. Therefore, brain ischemia can result from events other than heart attacks.
Congenital heart defects may also cause brain ischemia due to the lack of appropriate artery formation and connection. People with congenital heart defects may also be prone to blood clots.
Other pathological events that may result in brain ischemia include, cardiorespiratory arrest, 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...
, and severe irreversible brain damage.
Recently, Moyamoya disease has also been identified as a potential cause for brain ischemia. Moyamoya disease is an extremely rare cerebrovascular condition that limits blood circulation
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
to the brain, consequently leading to oxygen deprivation.
Pathophysiology
During brain ischemia, the brain cannot perform aerobic metabolism due to the loss of oxygenOxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and substrate
Substrate (biochemistry)
In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...
. The brain is not able to switch to anaerobic metabolism and because it does not have any long term energy stored the levels of adenosine triphosphate
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
(ATP) drop rapidly and approach zero within 4 minutes. In the absence of biochemical energy, cells begin to lose the ability to maintain electrochemical gradients. Consequently, there is a massive influx of calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
into the cytosol
Cytosol
The cytosol or intracellular fluid is the liquid found inside cells, that is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into compartments....
, a massive release of glutamate from synaptic vesicles, lipolysis
Lipolysis
Lipolysis is the breakdown of lipids and involves the hydrolysis of triglycerides into free fatty acids followed by further degradation into acetyl units by beta oxidation. The process produces Ketones, which are found in large quantities in ketosis, a metabolic state that occurs when the liver...
, calpain
Calpain
A calpain is a protein belonging to the family of calcium-dependent, non-lysosomal cysteine proteases expressed ubiquitously in mammals and many other organisms. Calpains constitute the C2 family of protease clan CA in the MEROPS database...
activation, and the arrest of protein synthesis. Additionally, removal of metabolic wastes is slowed. The interruption of blood flow to the brain for ten seconds results in the immediate loss of consciousness. The interruption of blood flow for twenty seconds results in the stopping of electrical activity.
Treatment
Alteplase (tpa) is an effective medication for acute ischemic stroke. When given within 4.5 hours, treatment with tpa significantly improves the probability of a favourable outcome versus treatment with placebo.The outcome of brain ischemia is influenced by the quality of subsequent supportive care. Systemic blood pressure (or slightly above) should be maintained so that cerebral blood flow is restored. Also, hypoxaemia and hypercapnia
Hypercapnia
Hypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
should be avoided. Seizures can induce more damage; accordingly, anticonvulsants should be prescribed and should a seizure occur, aggressive treatment should be undertaken. Hyperglycaemia should also be avoided during brain ischemia.
Management
When someone presents with an ischemic event, treatment of the underlying cause is critical for prevention of further episodes.Anticoagulation with warfarin
Warfarin
Warfarin is an anticoagulant. It is most likely to be the drug popularly referred to as a "blood thinner," yet this is a misnomer, since it does not affect the thickness or viscosity of blood...
or heparin
Heparin
Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...
may be used if the patient has atrial fibrillation
Atrial fibrillation
Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
.
Operative procedures such as carotid endarterectomy
Carotid endarterectomy
Carotid endarterectomy is a surgical procedure used to prevent stroke, by correcting stenosis in the common carotid artery...
and carotid stenting
Carotid stenting
Carotid artery stenting is an endovascular, catheter-based procedure which unblocks narrowings of the carotid artery lumen to prevent a stroke. Carotid artery stenosis can present with no symptoms or with symptoms such as transient ischemic attacks or cerebrovascular accidents...
may be performed if the patient has a significant amount of plaque in the carotid arteries associated with the local ischemic events.
Research
Therapeutic hypothermiaTherapeutic hypothermia
Therapeutic hypothermia, also known as protective hypothermia, is a medical treatment that lowers a patient's body temperature in order to help reduce the risk of the ischemic injury to tissue following a period of insufficient blood flow. Periods of insufficient blood flow may be due to cardiac...
has been attempted to improve results post brain ischemia . This procedure was suggested to be beneficial based on its effects post cardiac arrest. Evidence supporting the use of therapeutic hypothermia after brain ischemia, however, is limited.
A closely related disease to brain ischemia is brain hypoxia. Brain hypoxia is the condition in which there is a decrease in the oxygen supply to the brain even in the presence of adequate blood flow
Blood flow
Blood flow is the continuous running of blood in the cardiovascular system.The human body is made up of several processes all carrying out various functions. We have the gastrointestinal system which aids the digestion and the absorption of food...
. If hypoxia lasts for long periods of time, coma
Coma
In medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as...
, seizures, and even brain death
Brain death
Brain death is the irreversible end of all brain activity due to total necrosis of the cerebral neurons following loss of brain oxygenation. It should not be confused with a persistent vegetative state...
may occur. Symptoms of brain hypoxia are similar to ischemia and include, inattentiveness, poor judgment, memory loss
Memory loss
Memory loss can be partial or total and it is normal when it comes with aging. Sudden memory loss is usually a result of brain trauma and it may be permanent or temporary. When it is caused by medical conditions such as Alzheimers, the memory loss is gradual and tends to be permanent.Brain trauma...
, and a decrease in motor coordination
Motor coordination
thumb|right|Motor coordination is shown in this animated sequence by [[Eadweard Muybridge]] of himself throwing a diskMotor coordination is the combination of body movements created with the kinematic and kinetic parameters that result in intended actions. Such movements usually smoothly and...
. Potential causes of brain hypoxia are suffocation
Suffocation
Suffocation is the process of Asphyxia.Suffocation may also refer to:* Suffocation , an American death metal band* "Suffocation", a song on Morbid Angel's debut album, Altars of Madness...
, carbon monoxide poisoning
Carbon monoxide poisoning
Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...
, severe anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, and use of drugs such as cocaine
Cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...
and other amphetamines. Other causes associated with brain hypoxia include drowning
Drowning
Drowning is death from asphyxia due to suffocation caused by water entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia....
, strangling
Strangling
Strangling is compression of the neck that may lead to unconsciousness or death by causing an increasingly hypoxic state in the brain. Fatal strangling typically occurs in cases of violence, accidents, and as the auxiliary lethal mechanism in hangings in the event the neck does not break...
, choking
Choking
Choking is the mechanical obstruction of the flow of air from the environment into the lungs. Choking prevents breathing, and can be partial or complete, with partial choking allowing some, although inadequate, flow of air into the lungs. Prolonged or complete choking results in asphyxia which...
, cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
, head trauma, and complications during general anesthesia
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
. Treatment strategies for brain hypoxia vary depending on the original cause of injury.
Further reading
- An extensive review of mechanisms by which ischemia damages the nervous system has been published by Peter Lipton.
- Chang, Steven; Doty, James; Skirboll, Stephen; Steinberg, Gary. Cerebral ischemia . cgi.stanford.edu. URL last accessed February 26, 2006.
- Ramirez, Robert; Gulli, Laith. Encyclopedia of Neurological Disorders: Hypoxia. health.enotes.com. URL last accessed February 26, 2006. (PDF format)