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Stroke Education
A to Z Glossary of Stroke Terms
Types of Stroke
Causes of Stroke
The Brain
Common Deficits
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Below is a comprehensive list of definitions for the various terms associated with stroke.  It is the intent of The Stroke Network to provide our visitors with a resource for any stroke term you may be confronted with.  Click on a letter of the alphabet, above, to browse the glossary of stroke terms for that letter. 




Acute Hospital - short-term medical treatment in a hospital for patients having a stroke.


Acute Stroke - a stage of stroke starting at the onset of symptoms and last for a few hours thereafter.

Agnosia - a cognitive disability characterized by ignorance of or inability to acknowledge one side of the body or one side of the visual field.

Apnea - See sleep apnea

Anoxia - a state of almost no oxygen delivery to a cell, resulting in low energy production and possible death of the cell; see Hypoxia.

Aphasia - the inability to understand or create speech, writing, or language in general due to damage to the speech centers of the brain.

Apoplexy - a historical, but obsolete term for a cerebral stroke, most often intracerebral hemorrhage, that was applied to any condition that involved disorientation and/or paralysis.

Apoptosis - a form of cell death involving shrinking of the cell and eventual disposal of the internal elements of the cell by the body's immune system. Apoptosis is an active, non-toxic form of cell suicide that does not induce an inflammatory response. It is often called programmed cell death because it is triggered by a genetic signal, involves specific cell mechanisms, and is irreversible once initiated.

Apraxia - a movement disorder characterized by the inability to perform skilled or purposeful voluntary movements, generally caused by damage to the areas of the brain responsible for voluntary movement.

Aneurysm - An abnormal widening or ballooning of a section of a blood vessel.  Aneurysms can rupture, leading to stroke.  Aneurysms may be congenital (present at birth), or may develop later in life due to such factors as hypertension or atherosclerosis.

Anticoagulants - a drug therapy, such as Heparin or Warafarin, used to prevent the formation of blood clots that can become lodged in cerebral arteries and cause strokes.

Antiplatelet Agents - a type of anticoagulant drug therapy that prevents the formation of blood clots by preventing the accumulation of platelets that form the basis of blood clots; some common antiplatelets include aspirin and ticlopidine; see anticoagulants.

Antithrombotics - a type of anticoagulant drug therapy that prevents the formation of blood clots by inhibiting the coagulating actions of the blood protein thrombin; some common antithrombotics include Heparin or Warafarin; see anticoagulants.

Aphasia - the inability to understand or create speech, writing, or language in general due to damage to the speech centers of the brain.

Apoplexy - a historical, but obsolete term for a cerebral stroke, most often intracerebral hemorrhage, that was applied to any condition that involved disorientation and/or paralysis.

Apraxia - a movement disorder characterized by the inability to perform skilled or purposeful voluntary movements, generally caused by damage to the areas of the brain responsible for voluntary movement.

Arteriography - an X-ray of the carotid artery taken when a special dye is injected into the artery.

Arteriovenous Malformation (AVM) - a congenital disorder characterized by a complex tangled web of arteries and veins.  The cause of AVM is unknown, but it is sometimes genetic or part of certain syndromes.

Ataxia - loss of muscle control in arms and legs, which may lead to a lack of balance, coordination, and possibly a disturbance in gait. Ataxia may affect the fingers, hands, arms, legs, body, speech, and even eye movements.

Atherosclerosis - a blood vessel disease characterized by deposits of lipid material on the inside of the walls of large to medium-sized arteries which make the artery walls thick, hard, brittle, and prone to breaking.

Atrial Fibrillation - irregular beating of the left atrium, or left upper chamber, of the heart.



Basilar Artery - The artery that supplies blood to the cerebellum, the brainstem, and the back of the brain.

Blood-Brain Barrier - an elaborate network of supportive brain cells, called glia, that surrounds blood vessels and protects neurons from the toxic effects of direct exposure to blood.

Blood Coagulation - a process in which liquid blood is changed into a semisolid mass (a blood clot)

Brain Stem - the brain structure that is the major communication route among the brain, spinal cord, and peripheral nerves; controls heart rate, breathing, and other vital functions.

Brain Stem Stroke - the brain stem is a very delicate area attached to the spinal cord by thick nerve fibers. It controls life-sustaining functions such as breathing, blood pressure, and heart rate. Damage to this part of the brain can cause serious impairment in this life- sustaining functions. Symptoms of dizziness, slurred speech and double vision are also common. It may also cause paralysis on both sides of the body.  Click here for more information about brain stem stroke.  

Broca Area - region of the brain that contains motor neurons involved in the control of speech. Damage to the frontal lobe can result in a language disorder known as Broca aphasia.



Carotid Artery - an artery, located on either side of the neck, that supplies the brain with blood.

Carotid Endarterectomy - surgery used to remove fatty deposits from the carotid arteries.

Central Pain (Central Pain Syndrome [CPS]) - pain caused by damage to an area in the thalamus. The pain is a mixture of sensations, including heat and cold, burning, tingling, numbness, and sharp stabbing and underlying aching pain.  Click here for more information about central pain. 

Cerebellum - located just above the brain stem and toward the back of the brain. The cerebellum is involved in the coordination of voluntary motor movement, balance and equilibrium and also muscle tone. Click here for more information about the cerebellum.

Cerebral Blood Flow (CBF) - the flow of blood through the arteries that lead to the brain, called the cerebrovascular system.

Cerebrospinal Fluid (CSF) - clear fluid that bathes the brain and spinal cord.

Cerebrovascular Disease - a reduction in the supply of blood to the brain either by narrowing of the arteries through the buildup of plaque on the inside walls of the arteries, called stenosis, or through blockage of an artery due to a blood clot.

Cerebral Infarction - (See Infarction) The death of part of the brain from a lack of oxygen-carrying blood. It is basically just another name for stroke.

Cerebrum - the cerebrum or cortex is the largest part of the brain. The cerebrum is divided into two hemispheres. Each hemispere is divided into four distinct sections called lobes. Click here for more information about the cerebrum.

Cholesterol - a waxy substance, produced naturally by the liver and also found in foods, that circulates in the blood and helps maintain tissues and cell membranes. Excess cholesterol in the body can contribute to atherosclerosis and high blood pressure.

Clipping - surgical procedure for treatment of brain aneurysms, involving clamping an aneurysm from a blood vessel, surgically removing this ballooned part of the blood vessel, and closing the opening in the artery wall.

Complete Blood Count (CBC) - gives important information about the kinds and numbers of cells in the blood, especially red blood cells, white blood cells, and platelets.

Computed Tomography (CT) Scan - a series of cross-sectional X-rays of the brain and head; also called computerized axial tomography or CAT Scan.

Coumadin - a commonly used anticoagulant, also known as Warafarin.

Cranial Nerves - There are total 12 pairs of cranial nerves that originate from our brain and brain stem. Each of them carries different functions related to different senses of the body. Apart from sensory functions there are also some that work as motor nerves or mixed nerves. Click here for more information. 

Cytokines - small, hormone-like proteins released by leukocytes, endothelial cells, and other cells to promote an inflammatory immune response to an injury.

Cytotoxic Edema - a state of cell compromise involving influx of fluids and toxic chemicals into a cell causing subsequent swelling of the cell.



Detachable Coil - a platinum coil that is inserted into an artery in the thigh and strung through the arteries to the site of an aneurysm. The coil is released into the aneurysm creating an immune response from the body. The body produces a blood clot inside the aneurysm, strengthening the artery walls and reducing the risk of rupture.

Duplex Doppler Ultrasound - a diagnostic imaging technique in which an image of an artery can be formed by bouncing sound waves off the moving blood in the artery and measuring the frequency changes of the echoes.

Dysarthria - a disorder characterized by slurred speech due to weakness or lack of coordination of the muscles involved in speaking.

Dysphagia - inability to safely swallow, essential for adequate nutrition and hydration, and preventing food from entering the lungs.



Edema - the swelling of a cell that results from the influx of large amounts of water or fluid into the cell. Also known as bruising. 

Embolic Stroke - a stroke caused by an embolus.

Embolism - A blockage of blood flow through a vessel in the brain by a blood clot that formed elsewhere in the body and traveled to the brain.

Embolus - a free-roaming clot that usually forms in the heart.

Emotional Lability - also known as the Pseudobulbar Effect (PBA).  Emotional Lability is a distinct neurologic disorder that causes involuntary crying or uncontrollable episodes of crying and/or laughing, or other emotional displays.It can happen with many neurological conditions and often happens after a stroke. Some people describe feeling as though all their emotions are much nearer the surface or more exaggerated after their stroke. For example some people may become upset more easily, or cry at things they would not have cried at before their stroke. Their emotional response is in line with their feelings, but is much stronger than before the stroke. For other people the symptoms can be more exaggerated, and some people find that they cry for little or no reason. Less commonly, people laugh rather than cry, but again the emotion is out of place and does not match how they are feeling at the time.

Endothelial Wall - a flat layer of cells that make up the innermost lining of a blood vessel.

Excitatory Amino Acids - a subset of neurotransmitters; proteins released by one neuron into the space between two neurons to promote an excitatory state in the other neuron.

Extracranial/Intracranial (EC/IC) Bypass - a type of surgery that restores blood flow to a blood-deprived area of brain tissue by rerouting a healthy artery in the scalp to the area of brain tissue affected by a blocked artery.



Functional Magnetic Resonance Imaging (fMRI) - a type of imaging that measures increases in blood flow within the brain.



Glia - also called neuroglia; supportive cells of the nervous system that make up the blood-brain barrier, provide nutrients and oxygen to the vital neurons, and protect the neurons from infection, toxicity, and trauma. Some examples of glia are oligodendroglia, astrocytes, and microglia.

Glutamate - also known as glutamic acid, an amino acid that acts as an excitatory neurotransmitter in the brain.



Hemiparesis - weakness on one side of the body. 

Hemiplegia - paralysis of one side of the body.

Hemorrhage - bleeding in the brain (Intracerebral Hemmorage) caused by the rupture of an intracranial (within the head) blood vessel.

Heparin - a type of anticoagulant.

High-Density Lipoprotein (HDL) - also known as the good cholesterol; a compound consisting of a lipid and a protein that carries a small percentage of the total cholesterol in the blood and deposits it in the liver.

Homeostasis - a state of equilibrium or balance among various fluids and chemicals in a cell, in tissues, or in the body as a whole.

Hypertension - (High Blood Pressure) characterized by persistently high arterial blood pressure defined as a measurement greater than or equal to 140 mm/Hg systolic pressure over 90 mm/Hg diastolic pressure.

Hypoxia - a state of decreased oxygen delivery to a cell so that the oxygen falls below normal levels; see anoxia.



Incidence - the extent or frequency of an occurrence; the number of specific new events in a given period of time.

Incontinence - the muscles that help control bladder and bowels are weakened, thus making it likely to have an accident.  Click here for more information.  

Infarct - an area of tissue death due to a local lack of oxygen.

Infarction - a sudden loss of blood supply to tissue, causing the formation of an infarct.

Interleukins - a group of cytokine-related proteins secreted by leukocytes and involved in the inflammatory immune response of the Ischemic Cascade.

Intracerebral Hemorrhage - occurs when a vessel within the brain leaks blood into the brain.

Ischemia - a loss of blood flow to tissue, caused by an obstruction of the blood vessel, usually in the form of plaque stenosis or a blood clot.

Ischemic Cascade - a series of events lasting for several hours to several days following initial ischemia that results in extensive cell death and tissue damage beyond the area of tissue originally affected by the initial lack of blood flow.

Ischemic Penumbra - areas of damaged, but still living, brain cells arranged in a patchwork pattern around areas of dead brain cells.

Ischemic Stroke - ischemia in the tissues of the brain.

Ischemic - an ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery.



Lacunar Infarction - occlusion of a small artery in the brain resulting in a small area of dead brain tissue, called a lacunar infarct; often caused by stenosis of the small arteries, called small vessel disease.

Large Vessel Disease  - stenosis in large arteries of the cerebrovascular system.

Leukocytes - blood proteins involved in the inflammatory immune response of the Ischemic Cascade.

Lipid - another word for "fat."

Lipoprotein - small globules of cholesterol covered by a layer of protein; produced by the liver.

Lobes of the Brain - The cerebral cortex can be divided into four sections, which are known as lobes. The frontal lobe, parietal lobe, occipital lobe, and temporal lobe have been associated with different functions ranging from reasoning to auditory perception.  Click here for more explanation. 

Low-Density Lipoprotein (LDL) - also known as the bad cholesterol; a compound consisting of a lipid and a protein that carries the majority of the total cholesterol in the blood and deposits the excess along the inside of arterial walls.



Massive Stroke - A massive (major) stroke is not a type of stroke but is the degree of damage caused by stroke.  It is an infarct in a relatively significant area of the brain. The location of the infarct is extremely important as it determines which brain functions are affected.  Symptoms of cerebral hypoxia can be physical or neurological in nature and tend to vary greatly based on the severity of oxygen deprivation.  Massive strokes can cause death and are the cause of permanent serious disabilities.  Many stroke survivors, who have had massive strokes, have hemiplegia and are wheelchair bound.   Some have speech deficits or cannot talk.  Also, they have difficulty performing some cognitive tasks and have very limited return to normal activities.  Click here to see a list of the more common disabilities caused from having a massive stroke.  Therefore, they cannot return to work or are considered unemployable.  Some disabilities can be recovered with the appropriate therapies.

Magnetic Resonance Angiography (MRA) - an imaging technique involving injection of a contrast dye into a blood vessel and using magnetic resonance techniques to create an image of the flowing blood through the vessel; often used to detect stenosis of the brain arteries inside the skull.

Magnetic Resonance Imaging (MRI) - a test that uses a magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the body.

Medulla Oblongata - the medulla oblongata is located in the lower portion of the brainstem. It is very important in things like heart rate and blood pressure. It's responsible for many reflexes in the body, or involuntarily controls, such as vomiting, sneezing, and coughing. See Wallenbergs Syndrome 

Medullary Stroke - pertains to the medulla, the lowest part of the brainstem. For example, medullary stroke is a stroke located in the medulla.  See Wallenbergs Syndrome

Mesencephalon - See midbrain. 

Meneninges - the three membranes that line the skull and vertebral canal and enclose the brain and spinal cord.

 Midbrain - also called the mesencephalon, is a small region of the brain that serves as a relay center for visual, auditory, and motor system information. It regulates autonomic functions, those that the body carries out without conscious thought, such as digestion, heart rate, and breathing rate.

Mild Stroke - A mild (minor) stroke is not a mini-stroke (TIA).  It is not a type of stroke but rather is the degree of damage caused by stroke.  It is an infarct in a relatively small area of the brain. The location of the infarct is extremely important as it determines which brain functions are affected.  Most disabilities caused by a mild stroke are permanent but due to the lack of severity improve with time and with the appropriate therapies.  Many people, who had mild strokes, are able to return to normal activities, ie driving, working, sports activities (running, golfing and most outdoor activities) etc. 

Mini-Stroke - A mini-stroke is also known as a Transient Ischemic Attack (TIA) Click here for the definition. 

Mitochondria - the energy producing organelles of the cell.

Mitral Annular Calcification - a disease of the mitral valve of the heart.

Mitral Valve Stenosis - a disease of the mitral heart valve involving the buildup of plaque-like material on and around the valve.

Myelin - a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers.



Necrosis - a form of cell death resulting from anoxia, trauma, or any other form of irreversible damage to the cell; involves the release of toxic cellular material into the intercellular space, poisoning surrounding cells.

Neural Pathway - A neural pathway connects regions within the brain to one another or conveys information from the peripheral nervous system to the brain.

Neuron - the main functional cell of the brain and nervous system, consisting of a cell body, an axon, and dendrites.

Neuroplasticity - the brain has the ability to reorganize itself after it sustains an injury, such as a stroke. The brain can form new neural pathways to compensate for the injury, as needed.

Neuroprotective Agents - medications that protect the brain from secondary injury caused by stroke.



Occipital Lobe - the occipital lobe is the area of the cerebrum that receives visual information from the eyes and the optic nerve and organizes it into images that the brain can recognize. Click here for more information. 

Occlusion - an obstruction or a closure of a passageway or vessel.

Oligodendroglia - tissue consisting of glial cells with sheetlike processes that form the myelin sheath of nerve fibers

Organelle - A structure or part that is enclosed within its own membrane inside a cell and has a particular function.

Oxygen-Free Radicals - toxic chemicals released during the process of cellular respiration and released in excessive amounts during necrosis of a cell; involved in secondary cell death associated with the ischemic cascade.




Paresis - (paretic) incomplete paralysis or weakness of the limbs.

Persistent Vegetative State (PVS) - a condition in which the patient is completely unresponsive to psychological and physical stimuli and displays no sign of higher brain function, being kept alive only by medical intervention.

PFO -  stands for patent foramen ovale, a hole in the wall that divides the right and left chambers of the heart. This opening can allow a blood clot from one part of the body to travel through the flap and up to the brain, causing a stroke.

Plaque - fatty cholesterol deposits found along the inside of artery walls that lead to atherosclerosis and stenosis of the arteries.

Plasticity - the ability to be formed or molded; in reference to the brain, the ability to adapt to deficits and injury.

Platelets - structures found in blood that are known primarily for their role in Blood Coagulation.

Plegia - lack of voluntary movement. 

Pons - the pons is a major structure in the upper part of the brain stem. The pons controls the amount of air breathed and breaths per minute, which is known as the breathing rate. It is involved in the transmission of signals to and from the cerebrum and the cerebellum. The pons is also involved in sensations such as hearing, taste, and balance. Finally, the pons is involved in the regulation of deep sleep.

Pontine Stroke - a pontine stroke is essentially a stroke within the brain stem due to a hemorrhage, or bleeding of the blood vessels in this portion of the brain.

Prevalence - the number of cases of a disease in a population at any given point in time.

Pseudobulbar Affect (PBA) - see Emotional Lability



Recombinant Tissue Plasminogen Activator (rtPA) - a genetically engineered form of tPA, a thrombolytic, anti-clotting substance made naturally by the body.



Sleep Apnea - Sleep apnea is a serious sleep disorder that occurs when a person's breathing is interrupted during sleep. Click here for more information. 

Spasticity -a state of increased tone of a muscle. For example, with spasticity of the legs there is an increase in tone of the leg muscles so they feel tight and rigid.

Small Vessel Disease - a cerebrovascular disease defined by stenosis in small arteries of the brain.

Stenosis - narrowing of an artery due to the buildup of plaque on the inside wall of the artery.

Stroke Belt - an area of the southeastern United States with the highest stroke mortality rate in the country.

Stroke Buckle - three southeastern states, North Carolina, South Carolina, and Georgia, that have an extremely high stroke mortality rate.

Subarachnoid Hemorrhage - A cause of some strokes in which arteries on the surface of the brain begin bleeding.  It is usually caused by a rupture of a intracranial aneurysm.



Temporal Lobe - the temporal lobe is the area of the cerebrum that directs sensory functions used in hearing, language, both speaking and comprehension. It also has roles in vision, memory, and emotions.  Click here for more information.   

Thalamus - a structure in the middle of the brain that is located between the cerebral cortex and the midbrain. The thalamus is composed of two parts often referred to as lobes. These lobes are symmetrical and are about the size of a walnut. It works to correlate several important processes, including consciousness, sleep and sensory interpretation.  Click here for more information.   

Tissue Necrosis Factors - chemicals released by Leukocytes and other cells that cause secondary cell death during the inflammatory immune response associated with the Ischemic Cascade.

Tissue Plasminogen Activator (tPA)  - a protein involved in the breakdown of blood clots.  Because it works on the clotting system, tPA is used in clinical medicine to treat only embolic or thrombotic stroke.  Click here for more information. 

Thrombosis - A blockage of blood flow through a vessel in the brain by a blood clot that formed in the brain itself.

Thrombolytic therapy - drugs, such as tPA, are used to dissolve blood clots that could cause serious, and possibly life-threatening, damage if they are not removed. 

Thrombotic Stroke - a stroke caused by thrombosis.

Total Serum Cholesterol - a combined measurement of a person's high-density lipoprotein (HDL) and low-density lipoprotein (LDL).

Transient Ischemic Attack (TIA) - A TIA is also known as a mini-stroke Click here for more information.   



Vasodilators - medications that increase blood flow to the brain by expanding or dilating blood vessels.

Vasospasm - a dangerous side effect of Subarachnoid Hemorrhage in which the blood vessels in the subarachnoid space constrict erratically, cutting off blood flow.

Vertebral Artery - one of two blood vessels that run up the back of the neck and join at the base of the skull to form the basilar artery.



Wallenbergs Syndrome - Wallenberg syndrome is a rare condition in which an infarction, or stroke, occurs in the lateral medulla. The lateral medulla is a part of the brain stem.  The medulla helps transfer messages to the spinal cord and the thalamus in the brain from the body and controls breathing, heart function, blood vessel function, digestion, sneezing, and swallowing.

Warafarin - a commonly used anticoagulant, also known as Coumadin.

Wernicke Area - region of the brain that contains motor neurons involved in the comprehension of speech. Damage to the temporal lobe may result in a language disorder known as Wernicke aphasia.


Stroke Warning Signs

bullet Sudden numbness or weakness of the face, arm or leg, especially on one side of the body   
bullet Sudden confusion, trouble speaking or understanding   
bullet Sudden trouble seeing in one or both eyes   
bullet Sudden trouble walking, dizziness, loss of balance or coordination   
bullet Sudden, severe headache with no known cause

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Original date 3/1/96 Revised 9/24/14