Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
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Acquired: Anything that is not present at birth but develops some time later. In medicine, the word "acquired" implies "new" or "added." An acquired condition is "new" in the sense that it is not genetic (inherited) and "added" in the sense that was not present at birth.
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Adjacent: Lying nearby. Related terms include superjacent, subjacent, and circumjacent. From ad-, near + the Latin jacere, to lie = to lie near.
Aggressive: In oncology, quickly growing, tending to spread rapidly. As, for example, an aggressive tumor.
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Angiography: A procedure performed to view blood vessels after injecting them with a radioopaque dye that outlines them on x-ray. This technique can be usefully used to look at arteries in many areas of the body, including the brain, neck (carotids), heart, aorta, chest, pulmonary circuit, kidneys, gastrointestinal tract, and limbs.
Aphasia: One in a group of speech disorders in which there is a defect or loss of the power of expression by speech, writing, or signs, or a defect or loss of the power of comprehension of spoken or written language. See, for example, auditory aphasia .
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Apraxia: The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function. Apraxia is not related to a lack of understanding or to any kind of physical paralysis but is caused by a problem in the cortex of the brain.
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Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red.
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Ataxia: Wobbliness. Incoordination and unsteadiness due to the brain's failure to regulate the body's posture and regulate the strength and direction of limb movements. Ataxia is usually a consequence of disease in the brain, specifically in the cerebellum which lies beneath the back part of the cerebrum.
Autopsy : A postmortem examination. Also called a necropsy .
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AVM: An AVM (arteriovenous malformation) is a congenital disorder (one present at birth) of blood vessels in the brain, brainstem, or spinal cord that is characterized by a complex, tangled web of abnormal arteries and veins connected by one or more fistulas (abnormal communications).
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Back pain: Pain felt in the low or upper back. There are many causes of back pain.
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Balance: A biological system that enables us to know where our bodies are in the environment and to maintain a desired position. Normal balance depends on information from the inner ear, other senses (such as sight and touch) and muscle movement.
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Basal ganglia: A region consisting of 3 clusters of neurons (called the caudate nucleus, putamen, and the globus pallidus) located at the base of the brain that are responsible for involuntary movements such as tremors, athetosis, and chorea. The basal ganglia are abnormal in a number of important neurologic conditions including Parkinson disease and Huntington disease. The term "basal ganglia" refers to the fact that this region is in the "basement" of the brain.
Benign: Not cancer. Not malignant . A benign tumor does not invade surrounding tissue or spread to other parts of the body. A benign tumor may grow but it stays put (in the same place).
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Blood: The familiar red fluid in the body that contains white and red blood cells, platelets, proteins, and other elements. The blood is transported throughout the body by the circulatory system. Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous blood is the means by which carbon dioxide and metabolic by-products are transported to the lungs and kidneys, respectively, for removal from the body.
Blood clot: Blood that has been converted from a liquid to a solid state. Also called a thrombus .
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Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".
Brain: That part of the central nervous system that is located within the cranium ( skull ). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."
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Brainstem: The lowest part of the brain which merges with the spinal cord and provides the major route by which the upper realms of the brain send information to, and receives information from, the spinal cord and peripheral nerves. The brainstem consists of the medulla oblongata, midbrain, and pons. All but two of the 12 cranial nerves originate in the brainstem. The brainstem influences basic processes such as alertness, breathing, blood pressure, and heart rate.
Bridge: A set of one or more false teeth supported by a metal framework, used to replace one or more missing teeth.
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Bruit: A sound, especially an abnormal one. A bruit may be heard over an artery or vascular channel, reflecting turbulence of flow. Listening for a bruit in the neck is a simple, safe, and inexpensive way to screen for stenosis (narrowing) of the carotid artery .
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Capillaries: Capillaries are the smallest of blood vessels. They serve to distribute oxygenated blood from arteries to the tissues of the body and to feed deoxygenated blood from the tissues back into the veins. The capillaries are thus a central component in the circulatory system, essentially between the arteries and the veins. When pink areas of skin are compressed, this causes blanching because blood is pressed out of the capillaries. The blood is the fluid in the body that contains, among other elements, the red blood cells (erythrocytes) that carry the oxygen and give the blood its red color.
Capillary: One of the tiny blood vessels that connect the arterioles (the smallest divisions of the arteries) and the venules (the smallest divisions of the veins). The capillaries form a fine network in many parts of the body.
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Cardiovascular: The circulatory system comprising the heart and blood vessels which carries nutrients and oxygen to the tissues of the body and removes carbon dioxide and other wastes from them.
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Catheter: A thin, flexible tube . For example, a catheter placed in a vein provides a pathway for giving drugs, nutrients, fluids, or blood products. Samples of blood can also be withdrawn through the catheter.
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Cerebellum: The portion of the brain in the back of the head between the cerebrum and the brain stem. The cerebellum controls balance for walking and standing and other complex motor functions.
Cerebral: Pertaining to the brain, the cerebrum or the intellect.
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Cerebral cortex: A thin mantle of gray matter about the size of a formal dinner napkin covering the surface of each cerebral hemisphere. The cerebral cortex is crumpled and folded, forming numerous convolutions ( gyri ) and crevices ( sulci ). It is made up of six layers of nerve cells and the nerve pathways that connect them. The cerebral cortex is responsible for the processes of thought, perception and memory and serves as the seat of advanced motor function, social abilities, language, and problem solving.
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Cerebrospinal fluid: CSF. A watery fluid, continuously produced and absorbed, which flows in the ventricles (cavities) within the brain and around the surface of the brain and spinal cord.
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Cerebrum: The largest part of the brain. It is divided into two hemispheres, or halves.
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Childhood: (1) The time for a boy or girl from birth until he or she is an adult. (2) The more circumscribed period of time from infancy to the onset of puberty .
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Chromosome: A visible carrier of the genetic information.
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Circulatory: Having to do with the circulation, the movement of fluid in a regular or circuitous course. Although the adjective "circulatory" need not necessarily refer to the circulation of the blood, for all practical purposes today it does. A circulatory problem is taken usually to be a problem with the blood circulation, for example with heart failure.
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Circulatory system: The system that moves blood throughout the body. The circulatory system is composed of the heart, arteries, capillaries, and veins. This remarkable system transports oxygenated blood from the lungs and heart throughout the body via the arteries. The blood goes through the capillaries which are situated between the arteries and veins. And the blood that has been depleted of oxygen by the body is then returned to the lungs and heart via the veins.
Complication: In medicine, an additional problem that arises following a procedure, treatment or illness and is secondary to it. A complication complicates the situation.
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Compress: 1. As a noun, a cloth or another material applied under pressure to an area of the skin and held in place for a period of time. A compress can be any temperature (cold, luke warm, or hot) and it can be dry or wet. It may also be impregnated with medication or, in traditional medicine, an herbal remedy. Most compresses are used to relieve inflammation.
2. As a verb, to squeeze or press together. An injury can compress the spinal cord.
Condition: The term "condition" has a number of biomedical meanings including the following: - An unhealthy state, such as in "this is a progressive condition."
- A state of fitness, such as "getting into condition."
- Something that is essential to the occurrence of something else; essentially a "precondition."
- As a verb: to cause a change in something so that a response that was previously associated with a certain stimulus becomes associated with another stimulus; to condition a person, as in behavioral conditioning.
Congestive heart failure : Inability of the heart to keep up with the demands on it and, specifically, failure of the heart to pump blood with normal efficiency. When this occurs, the heart is unable to provide adequate blood flow to other organs such as the brain, liver and kidneys. Heart failure may be due to failure of the right or left or both ventricles. The signs and symptoms depend upon which side of the heart is failing. They can include shortness of breath (dyspnea), asthma due to the heart (cardiac asthma), pooling of blood (stasis) in the general body (systemic) circulation or in the liver's (portal) circulation, swelling ( edema ), blueness or duskiness (cyanosis), and enlargement (hypertrophy) of the heart.
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Contrast: Short for "contrast media." Contrast media are X-ray dyes used to provide contrast, for example, between blood vessels and other tissue.
Cortex: The outer portion of an organ.
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Dementia : Significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning.
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Disease: Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.
Dizziness : Painless head discomfort with many possible causes including disturbances of vision, the brain, balance (vestibular) system of the inner ear, and gastrointestinal system. Dizziness is a medically indistinct term which laypersons use to describe a variety of conditions ranging from lightheadedness, unsteadiness to vertigo.
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Drain: A device for removing fluid from a cavity or wound. A drain is typically a tube or wick.
Dura: The outermost, toughest, and most fibrous of the three membranes ( meninges ) covering the brain and the spinal cord . Dura is short for dura mater (from the Latin for hard mother). Also called the pachymeninx (singular) or pachymeniges (plural).
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Dura mater: Literally, hard mother (in Latin). The outermost, toughest, and most fibrous of the three membranes (meninges) covering the brain and the spinal cord. See: Dura.
Dural: Pertaining to the dura.
Embolization: A treatment that clogs small blood vessels and blocks the flow of blood, such as to a tumor.
Embolus: Something that travels through the bloodstream, lodges in a blood vessel and blocks it. Examples of emboli are a detached blood clot, a clump of bacteria , and foreign material such as air.
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Eye: The organ of sight. The eye has a number of components. These components include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.
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Familial: A condition that is tends to occur more often in family members than expected by chance alone. A familial disease may be genetic (such as cystic fibrosis ) or environmental (such as tuberculosis ).
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Fistula: An abnormal passageway in the body. The fistula may go from the body surface into a blindpouch or into an internal organ or go between two internal organs.
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Frontal: In anatomy, pertaining to the forehead. As, for example, the frontal bone, frontal sinus, and frontal nerve. From the Latin "frons" meaning the forehead or brow.
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Frontal lobe: The part of each hemisphere of the brain located behind the forehead that serves to regulate and mediate the higher intellectual functions. The frontal lobes have intricate connections to other areas of the brain. In the frontal lobes, we meld emotions, cognition, error detection, volition, a sense of self, and more to create our social brain.
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Gait: A manner of walking. Observation of the gait can provide clues to a number of diagnoses including Parkinson disease, cerebral palsy, congenital dislocation of the hip, and stroke.
Galen: Greek physician and philosopher (born about 129 AD, died about 210 AD) known among other things for his discovery of blood in human arteries and for his dissection of the human cranial nerves, the nerves that supply key areas of the head, face, and upper chest.
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Genetic: Having to do with genes and genetic information.
Headache : A pain in the head with the pain being above the eyes or the ears, behind the head (occipital), or in the back of the upper neck. Headache, like chest pain or back ache, has many causes.
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Health: As officially defined by the World Health Organization, a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity.
Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest.
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Heart failure : Inability of the heart to keep up with the demands on it and, specifically, failure of the heart to pump blood with normal efficiency. When this occurs, the heart is unable to provide adequate blood flow to other organs such as the brain, liver and kidneys. Heart failure may be due to failure of the right or left or both ventricles. The signs and symptoms depend upon which side of the heart is failing. They can include shortness of breath (dyspnea), asthma due to the heart (cardiac asthma), pooling of blood (stasis) in the general body (systemic) circulation or in the liver's (portal) circulation, swelling ( edema ), blueness or duskiness (cyanosis), and enlargement (hypertrophy) of the heart.
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Hemorrhage: Bleeding or the abnormal flow of blood.
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Hemorrhagic: Pertaining to bleeding or the abnormal flow of blood.
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Hereditary hemorrhagic telangiectasia: Abbreviated HHT. A genetic disease characterized by the presence of arteriovenous malformations (AVMs) which involve direct connections between arteries and veins without the usual intervening capillaries. These AVMs can vary in size from a pinhead to a pea. The tiniest AVMs are called telangiectases. Those telangiectases that are close to the surface of skin and mucous membranes tend to rupture easily and bleed after even slight trauma. Recurrent nosebleeds are common, particularly at night, beginning at about the age of 12, due to the rupture of telangiectases within the nose. Large AVMs can bleed in the gastrointestinal (GI) tract, brain, spine, lung, liver and other sites and create major, sometimes life-threatening, problems.
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High blood pressure : Also known as hypertension, high blood pressure is, by definition, a repeatedly elevated blood pressure exceeding 140 over 90 mmHg -- a systolic pressure above 140 with a diastolic pressure above 90.
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Hippocampus: An area buried deep in the forebrain that helps regulate emotion and memory. Functionally, the hippocampus is part of the olfactory cortex, that part of the cerebral cortex essential to the sense of smell. Certain antidepressants (such as fluoxetine, or Prozac) influence the birth of new neurons in the hippocampus. The hippocampus is so-called because its shape suggests that of a seahorse. From the Greek hippos (horse) = kampos (a sea monster).
Hydrocephalus : Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain.
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Indicate: In medicine, to make a treatment or procedure advisable because of a particular condition or circumstance. For example, certain medications are indicated for the treatment of hypertension during pregnancy while others are contraindicated.
Injury: Harm or hurt. The term "injury" may be applied in medicine to damage inflicted upon oneself as in a hamstring injury or by an external agent on as in a cold injury. The injury may be accidental or deliberate, as with a needlestick injury. The term "injury" may be synonymous (depending on the context) with a wound or with trauma.
Intervention: The act of intervening, interfering or interceding with the intent of modifying the outcome. In medicine, an intervention is usually undertaken to help treat or cure a condition. For example, early intervention may help children with autism to speak. "Acupuncture as a therapeutic intervention is widely practiced in the United States," according to the National Institutes of Health. From the Latin intervenire, to come between.
Irradiation: The use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy) or from materials called radioisotopes. Radioisotopes produce radiation and can be placed in or near the tumor or in the area near cancer cells. This type of radiation treatment is called internal radiation therapy, implant radiation, interstitial radiation, or brachytherapy. Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. Irradiation is also called radiation therapy, radiotherapy, and x-ray therapy.
Lesion: Pronounced "lee-sion" with the emphasis on the "lee," a lesion can be almost any abnormality involving any tissue or organ due to any disease or any injury.
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Lobe: Part of an organ that appears to be separate in some way from the rest. A lobe may be demarcated from the rest of the organ by a fissure (crack), sulcus (groove), connective tissue or simply by its shape. For example, there are the frontal, parietal, temporal, and occipital lobes of the brain.
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Lungs: The lungs are a pair of breathing organs located with the chest which remove carbon dioxide from and bring oxygen to the blood. There is a right and left lung.
Malformation: A structural defect in the body due to abnormal embryonic or fetal development. There are many types of malformations. For example, cleft lip and cleft palate. See also Congenital malformation.
Medical school: A school with a curriculum leading to a medical degree. The mission of every medical school includes medical teaching, research, and patient care. All medical schools share the goal of preparing students in the art and science of medicine, and providing them with the background necessary to enter the period of graduate medical education. The years of medical school preceding graduate medical education are typically divided into a preclinical phase and a clinical phase.
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Medication: 1. A drug or medicine. 2. The administration of a drug or medicine. (Note that "medication" does not have the dangerous double meaning of "drug.")
Membrane: A very thin layer of tissue that covers a surface.
Memory: 1. The ability to recover information about past events or knowledge. 2. The process of recovering information about past events or knowledge. 3. Cognitive reconstruction. The brain engages in a remarkable reshuffling process in an attempt to extract what is general and what is particular about each passing moment.
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Microscopic: So small it cannot be seen without the aid of microscope. As opposed to macroscopic (large enough to be seen with naked eye). A tiny tumor is microscopic while a big tumor is macroscopic.
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Mortality: A fatal outcome or, in one word, death. The word "mortality" is derived from "mortal" which came from the Latin "mors" (death). The opposite of mortality is, of course, immortality. Mortality is also quite distinct from morbidity (illness).
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MRA:The magnetic resonance angiogram, or MRA, is a noninvasive test that has demonstrated usefulness in defining the anatomy of blood vessels of certain size in the head and neck. MRA serves as a complement to traditional MRI scanning in evaluation of the brain and neck.
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MRI: Abbreviation and nickname for magnetic resonance imaging. For more information, see: Magnetic Resonance Imaging; Paul C. Lauterbur; Peter Mansfield.
Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."
Mutation: A permanent change, a structural alteration, in the DNA or RNA . In humans and many other organisms, mutations occur in DNA. However, in retroviruses like HIV , mutations occur in RNA which is the genetic material of retroviruses.
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Nerve: A bundle of fibers that uses chemical and electrical signals to transmit sensory and motor information from one body part to another. See: Nervous system.
Neurological: Having to do with the nerves or the nervous system.
Nidus: The Latin word for "nest", nidus is used in medicine to refer to any structure that resembles a nest in appearance or function. Just as a nest is a repository for the eggs of birds, insects and other animals, a nidus is a breeding place where bacteria, parasites and other agents of a disease lodge and develop. This is a nidus of infection, a focus of infection.
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NIH: The National Institutes of Health. The NIH is an important U.S. health agency. It is devoted to medical research. Administratively under the Department of Health and Human Services (HHS), the NIH consists of 20-some separate Institutes and Centers. NIH's program activities are represented by these Institutes and Centers.
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NINDS: Stands for the National Institute of Neurological Disorders and Stroke, one of the National Institutes of Health in the U.S., whose mission is to "support and conduct research and research training on the normal structure and function of the nervous system and on the causes, prevention, diagnosis, and treatment of more than 600 nervous system disorders including stroke, epilepsy, multiple sclerosis, Parkinson's disease, head and spinal cord injury, Alzheimer's disease, and brain tumors."
Occipital: 1. Pertaining to the occiput, the back of head.
2. Located near the occipital bone as, for example, the occipital lobe of the brain.
Onset: In medicine, the first appearance of the signs or symptoms of an illness as, for example, the onset of rheumatoid arthritis . There is always an onset to a disease but never to the return to good health. The default setting is good health.
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Optic: Having to do with vision.
Optic nerve: The optic nerve connects the eye to the brain. The optic nerve carries the impulses formed by the retina, the nerve layer that lines the back of the eye and senses light and creates impulses. These impulses are dispatched through the optic nerve to the brain, which interprets them as images. Using an ophthalmoscope, the head of the optic nerve can be easily seen. It can be viewed as the only visible part of the brain (or extension of it).
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Oxygen: A colorless, odorless and tasteless gas that makes up about 20% of the air we breathe (and at least half the weight of the entire solid crust of the earth) and which combines with most of the other elements to form oxides. Oxygen is essential to human, animal and plant life.
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Pain: An unpleasant sensation that can range from mild, localized discomfort to agony. Pain has both physical and emotional components. The physical part of pain results from nerve stimulation. Pain may be contained to a discrete area, as in an injury, or it can be more diffuse, as in disorders like fibromyalgia . Pain is mediated by specific nerve fibers that carry the pain impulses to the brain where their conscious appreciation may be modified by many factors.
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Papilledema: Swelling of the head of the optic nerve, a sign of increased intracranial pressure. The optic nerve head, also called the optic disk or papilla, is the area where the optic nerve (the nerve that carries messages from the eye to the brain) enters the eyeball.
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Paralysis: Loss of voluntary movement (motor function). Paralysis that affects only one muscle or limb is partial paralysis, also known as palsy; paralysis of all muscles is total paralysis, as may occur in cases of botulism.
Parenchyma: The key elements of an organ essential to its functioning, as distinct from the capsule that encompasses it and other supporting structures. The parenchyma is thus opposed to the connective tissue framework, or stroma, of an organ. The parenchyma of the testis consists of what are called the seminiferous tubules.
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Parenchymal: Pertaining to the parenchyma of an organ. See: Parenchyma.
Paresthesia: An abnormal sensation of the skin, such as numbness, tingling, pricking, burning, or creeping on the skin that has no objective cause. Paresthesia is the usual American spelling and paraesthesia the preferred English spelling.
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Pia mater: One of the meninges, the pia mater is the delicate innermost membrane enveloping the brain and spinal cord. It is known informally as the pia.
Pregnancy: The state of carrying a developing embryo or fetus within the female body. This condition can be indicated by positive results on an over-the-counter urine test, and confirmed through a blood test, ultrasound, detection of fetal heartbeat, or an X-ray. Pregnancy lasts for about nine months, measured from the date of the woman's last menstrual period (LMP). It is conventionally divided into three trimesters, each roughly three months long.
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Primary: First or foremost in time or development. The primary teeth (the baby teeth) are those that come first. Primary may also refer to symptoms or a disease to which others are secondary.
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Radiation: 1. Rays of energy. Gamma rays and X-rays are two of the types of energy waves often used in medicine. 2. The use of energy waves to diagnose or treat disease. See also: Irradiation.
Range: In medicine and statistics, the difference between the lowest and highest numerical values. For example, if five premature infants are born weighing two, three, four, four, and five pounds respectively, the range of their birth weights is two to five pounds.
Regress: To return or go back, particularly to return to a pattern of behavior or level of skill characteristic of a younger age. For example, if a three-year-old child begins to regress by losing the ability to control his bowels or speak, that is a cause for medical concern. In reference to a disease, to "regress," means tending to worsen.
Resolution: In genetics , resolution refers to the degree of molecular detail on a physical map of DNA , ranging from low to high.
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Seizure: Uncontrolled electrical activity in the brain, which may produce a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms.
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Sensory: Relating to sensation , to the perception of a stimulus and the voyage made by incoming ( afferent ) nerve impulses from the sense organs to the nerve centers.
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Sign: Any objective evidence of disease. Gross blood in the stool is a sign of disease. It can be recognized by the patient, doctor, nurse, or others. In contrast, a symptom is, by its nature, subjective. Abdominal pain is a symptom. It is something only the patient can know.
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Sleep : The body's rest cycle.
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Spinal cord: The major column of nerve tissue that is connected to the brain and lies within the vertebral canal and from which the spinal nerves emerge. Thirty-one pairs of spinal nerves originate in the spinal cord: 8 cervical , 12 thoracic , 5 lumbar, 5 sacral, and 1 coccygeal. The spinal cord and the brain constitute the central nervous system ( CNS ). The spinal cord consists of nerve fibers that transmit impulses to and from the brain. Like the brain, the spinal cord is covered by three connective-tissue envelopes called the meninges . The space between the outer and middle envelopes is filled with cerebrospinal fluid ( CSF ), a clear colorless fluid that cushions the spinal cord against jarring shock. Also known simply as the cord.
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Stenosis: A narrowing, as in: - aortic stenosis (narrowing of the aortic valve of the heart),
- pulmonary stenosis (narrowing of the pulmonary valve of the heart),
- pyloric stenosis (narrowing of the outlet of the stomach), and
- spinal stenosis (narrowing of the vertebral canal).
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Stroke : The sudden death of some brain cells due to a lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain. A stroke is also called a cerebrovascular accident or, for short, a CVA.
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Sturge-Weber syndrome: A congenital, but not inherited, disorder that affects the skin, the neurological system, and sometimes the eyes and internal organs. The main sign of Sturge-Weber syndrome is a port wine stain birthmark. Neurological symptoms may include seizures and developmental delay. Also known as encephelotrigeminal angiomatosi.
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Subarachnoid: Literally, beneath the arachnoid, the middle of three membranes that cover the central nervous system. In practice, subarachnoid usually refers to the space between the arachnoid and the pia mater, the innermost membrane surrounding the central nervous system.
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Subarachnoid hemorrhage: Bleeding within the head into the space between two membranes that surround the brain. The bleeding is beneath the arachnoid membrane and just above the pia mater. (The arachnoid is the middle of three membranes around the brain while the pia mater is the innermost one.)
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Subdural: Below the dura, the outermost, toughest, and most fibrous of the three membranes (meninges) covering the brain and the spinal cord. An subdural hematoma is a collection of blood beneath the dura.
Substance: 1. Material with particular features, as a pressor substance.
2. The material that makes up an organ or structure. Also known in medicine as the substantia.
3. A psychoactive drug as, for example, in substance abuse.
Superficial: In anatomy, on the surface or shallow. As opposed to deep. The skin is superficial to the muscles. The cornea is on the superficial surface of the eye.
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Superior: In antomy, above or over top of. As opposed to inferior. The heart is superior to the stomach. The superior surface of the tongue rests against the palate.
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Surgeon: A physician who treats disease, injury, or deformity by operative or manual methods. A medical doctor specialized in the removal of organs, masses and tumors and in doing other procedures using a knife (scalpel). The definition of a "surgeon" has begun to blur in recent years as surgeons have begun to minimize the cutting, employ new technologies that are "minimally invasive," use scopes, etc.
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Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office.
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Symptomatic: 1 With symptoms, as a symptomatic infection. 2 Characteristic, as behavior symptomatic of Huntington disease. 3 Directed at the symptoms, as symptomatic treatment.
Syndrome: A set of signs and symptoms that tend to occur together and which reflect the presence of a particular disease or an increased chance of developing a particular disease.
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Taste: Taste belongs to our chemical sensing system, or the chemosenses. The complicated process of tasting begins when molecules released by the substances stimulate special cells in the mouth or throat. These special sensory cells transmit messages through nerves to the brain where specific tastes are identified.
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Therapeutic: Relating to therapeutics , that part of medicine concerned specifically with the treatment of disease . The therapeutic dose of a drug is the amount needed to treat a disease.
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Therapy: The treatment of disease .
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Tissue: A tissue in medicine is not like a piece of tissue paper. It is a broad term that is applied to any group of cells that perform specific functions. A tissue in medicine need not form a layer. Thus, - The bone marrow is a tissue;
- Connective tissue consists of cells that make up fibers in the framework supporting other body tissues; and
- Lymphoid tissue is the part of the body's immune system that helps protect it from bacteria and other foreign entities.
Tomography: The process for generating a tomogram , a two-dimensional image of a slice or section through a three-dimensional object. Tomography achieves this remarkable result by simply moving an x-ray source in one direction as the x-ray film is moved in the opposite direction during the exposure to sharpen structures in the focal plane, while structures in other planes appear blurred. The tomogram is the picture; the tomograph is the apparatus; and tomography is the process.
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Vascular: Relating to the blood vessels of the body. The blood vessels of the body, as a group, are referred to as the vascular system.
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Vein: A blood vessel that carries blood low in oxygen content from the body back to the heart. The deoxygenated form of hemoglobin (deoxyhemoglobin) in venous blood makes it appear dark. Veins are part of the afferent wing of the circulatory system which returns blood to the heart.
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Ventricles: 1, The right ventricle and the left ventricle, the lower two chambers of the heart. 2. Two or more of the four connected spaces within the central portion of the brain.
Vertebrae: The preferred plural of vertebra. (The alternate plural is vertebras.) See also: Cervical vertebrae; Coccygeal vertebrae; Lumbar vertebrae; Sacral vertebrae; and Thoracic vertebrae.
Vessel: A tube in the body that carries fluids: blood vessels or lymph vessels.
Visual field: The entire area that can be seen when the eye is directed forward, including that which is seen with peripheral vision.
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Vital: Necessary to maintain life. Breathing is a vital function.
Voluntary: Done in accordance with the conscious will of the individual. The opposite of involuntary.
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- CT Scan (Computerized Axial Tomography) - CT Scan (Computerized Axial Tomography, CAT scan) is a procedure that assists in diagnosing tumors, fractures, bony structures, and infections in the organs and tissues of the body.
- Headache - Learn about the different types of headaches, migraine, tension, cluster, menstrual, and spinal headaches; and their causes, symptoms, diagnosis and treatment.
- MRI (Magnetic Resonance Imaging Scan) - Medical information on magnetic resonance imaging (MRI) used in detecting structural abnormalities of the body. Learn uses, risks, and how to prepare for an MRI scan
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