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Neurology Glossary

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Absence seizures.The type of seizure seen in absence epilepsy, in which the person experiences a momentary loss in consciousness. The person may stare into space for several seconds and may have some twitching or jerking of muscles.

Acetylcholine.A neurotransmitter that is important for the formation of memories. Studies have shown that levels of acetylcholine are reduced in the brains of people with Alzheimer's disease.

Activities of daily living (ADL). The tasks of everyday life. These activities include eating, dressing, getting into or out of a bed or chair, taking a bath or shower, and using the toilet. Instrumental activities of daily living are activities related to independent living and include preparing meals, managing money, shopping, doing housework, and using a telephone.

Adjunctive therapy. A treatment combined with the primary treatment. Its purpose is to assist the primary treatment. Also called adjunct therapy.

Advance directive. A legal document that states the treatment or care a person wishes to receive or not receive if he or she becomes unable to make medical decisions (due to being unconscious or in a coma). Some types of advance directives are living wills and Do Not Resuscitate (DNR) orders.

Adverse effect. An unwanted side effect of treatment.

Ambulatory EEG monitoring. A system for recording the electroencephalogram for a prolonged period (typically 18 to 24 hours) in an outpatient; the electrodes are connected to a small cassette tape recorder.

Amyloid plaques. Collections of a protein called beta amyloid along that are a hallmark of Alzheimer's disease.

Aneurysm. A blood-filled sac formed by disease related stretching of an artery or blood vessel.

Angiography. A procedure to X-ray blood vessels. The blood vessels can be seen because of an injection of a dye that shows up in the X-ray. The film or image of the blood vessels is called an angiograph, or angiogram.

Anhedonia. Failure to enjoy positive emotional experiences.
Anoxia. An absence of oxygen supply to an organ's tissues leading to cell death.
Anterograde memory. The ability to form new memories; memories for events occurring after a problem such as a head trauma or seizure.

Antibodies. Proteins made by the immune system that bind to structures (antigens) they recognize as foreign to the body.

Anticoagulant. A drug that helps prevent blood clots from forming. Also called a blood thinner.

Anticholinergic drugs. Drugs that interfere with production or uptake of the neurotransmitter acetylcholine.

Anticonvulsant. A drug or other substance used to prevent or stop seizures or convulsions. Also called an antiepileptic.

Antidepressant. A drug used to treat depression.

Antigen. A structure foreign to the body, such as a virus. The body usually responds to antigens by producing antibodies.

Antiepileptic drug (AED). A medication used to prevent or stop seizures or convulsions. Also called an anticonvulsant.

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

Aphasia, Fluent. A condition in which patients display little meaning in their speech even though they speak in complete sentences. Also called Wernicke's or motor aphasia.

Aphasia, Global. A condition in which patients suffer severe communication disabilities as a result of extensive damage to portions of the brain responsible for language.

Aphasia, Nonfluent. A condition in which patients have trouble recalling words and speaking in complete sentences. Also called Broca's or motor aphasia.

Apolipoprotein E. A gene that has been linked to an increased risk of Alzheimer's disease. People with a variant form of the gene, called apoE epsilon 4, have about ten times the risk of developing Alzheimer's disease.

Assistive device. A tool that helps a person with a disability to do a certain task. Examples include a cane, wheelchair, scooter, walker, hearing aid, or special bed.

Assistive technology. Any device or technology that helps a disabled person. Examples include special grips for holding utensils, computer screen monitors to help a person with low vision read more easily, computers controlled by talking, telephones that make the sound louder, and lifters to help a person rise out of a chair.

Asthenia. Weakness; lack of energy and strength.

Astrocyte. A star-shaped cell that helps nerve cells in the brain and spinal cord work the way they should. An astrocyte is a type of glial cell.

Astrocytoma. A tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes.

Ataxia. Loss of muscle coordination.

Ataxic gait. Awkward, uncoordinated walking.

Atonic seizure. An epileptic seizure characterized by sudden loss of muscle tone; may cause the head to drop suddenly, objects to fall from the hands, or the legs to lose strength, with falling and potential injury; usually not associated with loss of consciousness.

Aura. Unusual sensations or movements that warn of an impending, more severe seizure. These auras are actually simple focal seizures in which the person maintains consciousness.

Autoimmune disease. A condition in which the body recognizes its own tissues as foreign and directs an immune response against them. Examples include multiple sclerosis and lupus.

Automatisms. Strange, repetitious behaviors that occur during a seizure. Automatisms may include blinks, twitches, mouth movements, or even walking in a circle.

Autonomic nervous system (ANS). The part of the nervous system that controls muscles of internal organs (such as the heart, blood vessels, lungs, stomach, and intestines) and glands (such as salivary glands and sweat glands). One part of the autonomic nervous system (parasympathetic) helps the body rest, relax, and digest food, and another (sympathetic) helps a person fight or take flight in an emergency. Also called involuntary nervous system.

Autosomal dominant. A mode of biological inheritance in which a gene is passed on by either parent; in most cases, the child has a 50% chance of inheriting the gene; the expression of the gene (that is, the development of the physical trait or the disorder) can vary considerably among different individuals with the same gene.

Autosomal recessive. A mode of inheritance in which an individual has two copies of a gene that requires both copies for expression, or development, of the trait. Both parents must be carriers (that is, they have only one copy of the gene and, therefore, do not have the physical trait that the gene confers) or have the trait (that is, have two copies of the same gene).

Axon. The part of the nerve cell (neuron) that communicates with other cells, similar to a telephone wire; the axon is often covered with myelin, an insulating fatty layer, which functions similarly to plastic around a copper wire.

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Behavior modificationA technique used to help people change the way they react to certain triggers in the environment that cause a negative reaction. In cancer treatment, behavior modification may be used to help patients who have become nauseous during previous cancer treatments cope with nausea they feel when they enter the therapy room to begin a new round of treatment.

Biofeedback. A method of learning to voluntarily control certain body functions such as heartbeat, blood pressure, and muscle tension with the help of a special machine. This method can help control pain.

Blood-brain barrier. A protective network of blood vessels and tissue that protects the brain from harmful substances; it can also prevent medications from reaching the brain.

Bradykinesia. Gradual loss of spontaneous movement.

Brain death. An irreversible cessation of measurable brain function.

Brain metastasis. Cancer that has spread from the original (primary) tumor to the brain.

Brain stem. The part of the brain that is connected to the spinal cord. It controls breathing, heartbeat, blood pressure, and other basic body functions.

Brain stem glioma. A tumor located in the part of the brain that connects to the spinal cord (the brain stem). It may grow rapidly or slowly, depending on the grade of the tumor.

Brand-name drug. Medication manufactured by a major pharmaceutical company; the drugs are often expensive, but tend to be uniform in the amount of drug and the method of preparation.

Breakthrough pain. Intense increases in pain that occur with rapid onset even when pain-control medication is being used. Breakthrough pain can occur spontaneously or in relation to a specific activity.

Breath-holding spells. Episodes in children in which intense crying or an emotional upset is followed by interruption of breathing and sometimes loss of consciousness; the episodes are not harmful, but when prolonged, slight jerking movements may occur.

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Caffeine A substance found in coffee, tea, yerba mate, guarana berries, and in small amounts in cocoa. It can also be made in a laboratory and is added to some soft drinks, foods, and medicines. Caffeine increases brain activity, alertness, attention, and energy. It may also increase blood pressure, heart rate, breathing rate, and the loss of water through urine.

Catamenial. Referring to the menses or to menstruation; with regard to women with epilepsy, a tendency for seizures to occur around the time of the menses.

Catheter. A flexible tube used to deliver fluids into or withdraw fluids from the body.

Central nervous system (CNS). The brain and spinal cord. Cerebellar hemangioblastomaA benign, slow-growing tumor in the cerebellum (part of the brain at the back of the head) made up of abnormal blood vessel growth. People with von Hippel-Landau disease have an increased risk of developing hemangioblastomas.

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, as well as other complex motor functions.

Cerebral hemisphere. One half of the cerebrum, the part of the brain that controls muscle functions and also controls speech, thought, emotions, reading, writing, and learning. The right hemisphere controls the muscles on the left side of the body, and the left hemisphere controls the muscles on the right side of the body.

Cerebrospinal fluid (CSF). The fluid that flows in and around the hollow spaces of the brain and spinal cord, and between two of the meninges (the thin layers of tissue that cover and protect the brain and spinal cord). Cerebrospinal fluid is made by tissue called the choroid plexus in the ventricles (hollow spaces) in the brain. Also called cerebral spinal fluid.

Cerebrum. The largest part of the brain, located at the top of the brain. It is divided into two hemispheres, or halves, called the cerebral hemispheres. The right hemisphere controls the muscles on the left side of the body and vice versa. Areas within the cerebrum control muscle functions and also control speech, thought, emotions, reading, writing, and learning.

Cholinesterase inhibitors. Medications that slow the breakdown of the neurotransmitter acetylcholine. May be prescribed for people with Alzheimer's and other forms of dementia.

Choroid plexus tumor. A rare type of cancer that occurs in the ventricles of the brain. It usually occurs in children younger than 2 years.

Chronic. Describes a disease or condition that persists or progresses over a long period of time (the opposite of acute).

Clonic seizure. An epileptic seizure characterized by jerking movements and involving muscles on both sides of the body.

Closed head injury. An injury that occurs when the head suddenly and violently hits an object but the object does not break through the skull.

Cognition. The mental process of thinking, learning, remembering, being aware of surroundings, and using judgment (as opposed to physical functions).

Cognitive training. A type of training in which patients practice tasks designed to improve mental performance. Examples include memory aids, such as mnemonics, and computerized recall devices.

Coma. A condition in which a patient is in a state of deep sleep and cannot be awakened. A coma may be caused by many things, including trauma, drugs, toxins, or certain diseases.

Comfort care. Activities that ease the symptoms of a disease or the side effects of treatment for a disease. Comfort care does not cure the disease. It is aimed at improving quality of life and it addresses the psychological, social, and spiritual needs of patients and their families. Also called palliative therapy, palliative care, supportive care, and symptom management.

Complementary and alternative medicine (CAM). Forms of treatment that are used in addition to (complementary) or instead of (alternative) standard treatments. These practices generally are not considered standard medical approaches. Standard treatments go through a long and careful research process to prove they are safe and effective, but less is known about most types of CAM. CAM may include dietary supplements, megadose vitamins, herbal preparations, special teas, acupuncture, massage therapy, magnet therapy, spiritual healing, and meditation.

Complex focal seizures. Seizures in which only one part of the brain is affected, but the person has a change in or loss of consciousness.

Complex partial seizure. An epileptic seizure that involves only part of the brain and impairs consciousness; often preceded by a simple partial seizure (aura, or warning).

Concussion. Injury to the brain caused by a hard blow or violent shaking, causing a sudden and temporary impairment of brain function, such as a short loss of consciousness or disturbance of vision and equilibrium.

Consciousness. State of awareness; if consciousness is preserved during a seizure, the person can respond (either in words or actions, such as raising a hand on command) and recall what occurred during the spell.

Contusion. A distinct area of swollen brain tissue mixed with blood released from broken blood vessels.

Convulsion. An older term for a tonic-clonic seizure.

Corpus callosotomy. Surgery that severs the corpus callosum, or network of neural connections between the right and left hemispheres of the brain.

Cortical atrophy. Degeneration of the brain's cortex (outer layer). Cortical atrophy is common in many forms of dementia and may be visible on a brain scan.

CT (computed tomography). A type of brain scan that reveals the structure of the brain.

Cytokines. Powerful chemical substances secreted by T cells. Cytokines are an important factor in the production of inflammation and show promise as treatments for MS.

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Daily dose. The average amount of medication taken over the course of the day to achieve a therapeutic blood level of the drug, usually measured in milligrams (mg) per kilogram (kg) of the patient's body weight (1 kg = 2.2 pounds).

Deep brain stimulation (DBS). A therapy that uses a surgically implanted, battery-operated medical device called a neurostimulator to deliver electrical stimulation to targeted areas in the brain that control movement, blocking the abnormal nerve signals that cause tremor and other movement symptoms.

Deep vein thrombosis. Formation of a blood clot deep within a vein.

Deja vu. Feeling as if one has lived through or experienced this moment before; may occur in people without any medical problems or immediately before a seizure (i.e., as a simple partial seizure).

Delirium. A mental state in which a person is confused, disoriented, and not able to think or remember clearly. The person may also be agitated and have hallucinations, and extreme excitement.

Dementia. A condition in which a person loses the ability to think, remember, learn, make decisions, and solve problems. Symptoms may also include personality changes and emotional problems. There are many causes of dementia, including Alzheimer’s disease, brain cancer, and brain injury. Dementia usually gets worse over time.

Dementia pugilistica. Brain damage caused by cumulative and repetitive head trauma. Common in professional sports that experience significant head trauma, such as boxing or football.

Demyelination. Damage caused to myelin by recurrent attacks of inflammation. Demyelination ultimately results in nervous system scars, called plaques, which interrupt communications between the nerves and the rest of the body. Multiple sclerosis is the most well-known of demyelinating disorders.

Do Not Resuscitate order (DNR). A type of advance directive in which a person states that healthcare providers should not perform cardiopulmonary resuscitation (restarting the heart) if his or her heart or breathing stops. Also called a DNR.

Dopamine. A chemical messenger, deficient in the brains of Parkinson's disease patients, that transmits impulses from one nerve cell to another.

Drug interaction. A change in the way a drug acts in the body when taken with certain other drugs, herbals, or foods, or when taken with certain medical conditions. Drug interactions may cause the drug to be more or less effective, or cause effects on the body that are not expected.

Drop attacks. Seizures that cause sudden falls; another term for atonic seizures.

Dura. A tough, fibrous membrane lining the brain; the outermost of the three membranes collectively called the meninges.

Dysphagia. Difficulty swallowing.

Dysarthria. Inability or difficulty articulating words due to emotional stress, brain injury, paralysis, or spasticity of the muscles needed for speech.

Dysesthesias. Abnormal sensations such as numbness, prickling, or "pins and needles."

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EEG(electroencephalogram). A recording of electrical activity in the brain. It is made by placing electrodes on the scalp (the skin covering the top of the head), and impulses are sent to a special machine. An EEG may be used to diagnose brain and sleep disorders.

Early Seizures. Seizures that occur within 1 week after a traumatic brain injury.

Electrode. In medicine, a device such as a small metal plate or needle that carries electricity from an instrument to a patient for treatment or surgery. Electrodes can also carry electrical signals from muscles, brain, heart, skin, or other body parts to recording devices to help diagnose certain condition.

Embolism. A block in an artery caused by blood clots or other substances, such as fat globules, infected tissue, or cancer cells.

Enteral nutrition. A form of nutrition that is delivered into the digestive system as a liquid. Drinking nutrition beverages or formulas and tubefeeding are forms of enteral nutrition. People who are unable to meet their needs with food and beverages alone, and who do not have vomiting or uncontrollable diarrhea may be given tubefeedings. Tubefeeding can be used to add to what a person is able to eat or can be the only source of nutrition. A small feeding tube may be placed through the nose into the stomach or the small intestine, or it may be surgically placed into the stomach or the intestinal tract through an opening made on the outside of the abdomen, depending on how long it will be used.

Ependymoma. A tumor that arises from cells that line the ventricles or the central canal of the spinal cord. They are most commonly found in children and young adults.

Epidural. The space between the wall of the spinal canal and the covering of the spinal cord. An epidural injection is given into this space.

Epidural block. An injection of an anesthetic drug into the space between the wall of the spinal canal and the covering of the spinal cord. Also called saddle block.

Epidural hematoma. Bleeding into the area between the skull and the dura.

Epileptiform. Resembling epilepsy or its manifestations; may refer to a pattern on the EEG associated with an increased risk of seizures.

Epileptologist. A neurologist with specialty training in epilepsy.

Epilepsy syndromes. Disorders with a specific set of symptoms that include epilepsy.

Exacerbation. A sudden worsening of symptoms or the appearance of new symptoms that lasts for at least 24 hours.

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First-degree relative. The parents, brothers, sisters, or children of an individual.

Febrile seizures. Seizures in infants and children that are associated with a high fever.

Flattened affect. Decreased emotional range. Also called flat affect or blunted affect.

Focal Seizures. An older term for a partial seizure that occur in just one part of the brain.

Frontotemporal dementias. A group of dementias characterized by degeneration of nerve cells, especially those in the frontal and temporal lobes of the brain.

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Gadolinium. A chemical compound given during MRI scans that helps distinguish new lesions from old.

Gamma Knife therapy. A treatment using gamma rays, a type of high-energy radiation that can be tightly focused on small tumors or other lesions in the head or neck, so very little normal tissue receives radiation. The gamma rays are aimed at the tumor from many different angles at once and deliver a large dose of radiation exactly to the tumor in one treatment session. This procedure is a type of stereotactic radiosurgery. Gamma Knife therapy is not a knife and is not surgery. Gamma Knife is a registered trademark of Elekta Instruments, Inc.

Generalized seizure. A seizure that involves both sides of the brain and causes tonic and clonic movements (primary or secondary generalized) or another type of primary generalized epilepsy (e.g., absence or atonic seizure).

Generic drug. A drug that is not sold under a brand name; for example, carbamazepine can be obtained as a generic drug or as Tegretol or Carbatrol, its brand names.

Genetic analysis. The study of a sample of DNA to look for mutations (changes) that may increase risk of disease or affect the way a person responds to treatment.

Genetic counseling. A communication process between a specially trained health professional and a person concerned about the genetic risk of disease. The person's family and personal medical history may be discussed, and counseling may lead to genetic testing.

Genetic marker. Alteration in DNA that may indicate an increased risk of developing a specific disease or disorder.

Glasgow Coma Scale. A clinical tool used to assess the degree of consciousness and neurological functioning - and therefore severity of brain injury - by testing motor responsiveness, verbal acuity, and eye opening.

Glioblastoma multiforme (GBM). A fast-growing type of central nervous system tumor that forms from glial (supportive) tissue of the brain and spinal cord and has cells that look very different from normal cells. Glioblastoma multiforme usually occurs in adults and affects the brain more often than the spinal cord. Also called grade IV astrocytoma and glioblastoma.

Glioma. A cancer of the brain that begins in glial cells (cells that surround and support nerve cells).

Gliosarcoma. A type of glioma (cancer of the brain that comes from glial, or supportive, cells).

Glutamate. An excitatory neurotransmitter that may play a role in some types of epilepsy.

Grand mal. An older term for a tonic-clonic seizure.

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Half-life. The time required for the amount of a drug in the blood to decline to half its original value, measured in hours; a drug with a longer half-life lasts longer in the body and, therefore, generally needs to be taken less often than a drug with a shorter half-life.

Healthcare proxy (HCP). A type of advance directive that gives a person (such as a relative, lawyer, or friend) the authority to make healthcare decisions for another person. It becomes active when that person loses the ability to make decisions for himself or herself.

Hematoma. Heavy bleeding into or around the brain caused by damage to a major blood vessel in the head.

Hemorrhagic Stroke. A s troke caused by bleeding out of one of the major arteries leading to the brain.

Hydrocephalus. An abnormal accumulation of cerebrospinal fluid within the skull.

Hypoxic. Having too little oxygen. Referring to the period during a sudden attack, such as a seizure or stroke.

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Idiopathic. Describes a disease of unknown cause.

Idiopathic epilepsy. Epilepsy with an unknown cause.

Idiosyncratic. Pertaining to an abnormal susceptibility to some drug or other agent, peculiar to the individual.

Immunoglobulin G (IgG). An antibody-containing substance produced by human plasma cells in diseased central nervous system plaques. Levels of IgG are increased in the cerebrospinal fluid of most MS patients.

Implantable pump. A small device installed under the skin to administer a steady dose of drugs.

Incontinence. Inability to control the flow of urine from the bladder (urinary incontinence) or the escape of stool from the rectum (fecal incontinence).

Inflammation. Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

Informed consent. A process in which a person is given important facts about a medical procedure or treatment, a clinical trial, or genetic testing before deciding whether to participate. It also includes informing the patient when there is new information that may affect his or her decision to continue. Informed consent includes information about the possible risks, benefits, and limits of the procedure, treatment, trial, or genetic testing.

Infusion. A method of putting fluids, including drugs, into the bloodstream. Also called intravenous infusion.

Inherited. Transmitted through genes that have been passed from parents to their children.

Insomnia. Difficulty in going to sleep, staying asleep, or getting enough sleep.

Interictal. Referring to the period between seizures.

Intractable. Difficult to alleviate, remedy, or cure; for example, intractable seizures are difficult to control with the usual antiepileptic drug therapy. About 20 percent of people with epilepsy will continue to experience seizures even with the best available treatment.

Investigational drug. A drug available only for experimental purposes because its safety and effectiveness have not yet been proven.

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Ketogenic diet. A high-fat, low-carbohydrate diet for children whose seizures are difficult to control with medications.

Kindling. A process in which electrical abnormalities become more intense over time; for example, small electrical shocks are delivered to the brain once a day to cause a progressive tendency toward seizures; eventually, seizures may occur without the electrical shocks.

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Lesion. A damaged or dysfunctional part of the brain or other parts of the body due to disease or injury. Also referred to as a "plaque".

Lewy body dementia. One of the most common types of progressive dementia, characterized by the presence of abnormal structures called Lewy bodies in the brain. In many ways the symptoms of this disease overlap with those of Alzheimer's disease.

Lobectomy. Removal of a lobe of the brain.

Locked-in Syndrome. A rare condition in which a patient is aware and awake, but cannot move or communicate due to complete paralysis of the body.

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Magnetic resonance imaging (MRI ). A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. Magnetic resonance imaging makes better images of organs and soft tissue than other scanning techniques, such as computed tomography (CT) or X-ray. Magnetic resonance imaging is especially useful for imaging the brain, the spine, the soft tissue of joints, and the inside of bones. Also called nuclear magnetic resonance imaging and NMRI.

Magnetic resonance perfusion imaging. A special type of magnetic resonance imaging (MRI) that uses an injected dye in order to see blood flow through tissues. Also called perfusion magnetic resonance imaging.

Magnetic resonance spectroscopic imaging (MRSI ). A noninvasive imaging method that provides information about cellular activity (metabolic information). It is used along with magnetic resonance imaging (MRI) which provides information about the shape and size of the tumor (spatial information). Also called 1H-nuclear magnetic resonance spectroscopic imaging and proton magnetic resonance spectroscopic imaging.

Magnetoencephalography (MEG). Recording the brain's magnetic activity, which is generated by its electrical activity.

Medulloblastoma. A malignant brain tumor that begins in the lower part of the brain and that can spread to the spine or to other parts of the body. Medulloblastomas are a type of primitive neuroectodermal tumor (PNET).

Meninges. The three thin layers of tissue that cover and protect the brain and spinal cord.

Meningioma. A type of slow-growing tumor that forms in the meninges (thin layers of tissue that cover and protect the brain and spinal cord). Meningiomas usually occur in adults.

Meningitis. Inflammation of the meninges (three thin layers of tissue that cover and protect the brain and spinal cord). Meningitis is usually caused by a bacterial or viral infection, but sometimes is caused by cancer, drug allergies, or inflammatory diseases.

Mild cognitive impairment. A condition associated with impairments in understanding and memory not severe enough to be diagnosed as dementia, but more pronounced than those associated with normal aging.

Mini-Mental State Examination. (MMSE). A test used to assess cognitive skills in people with suspected dementia. The test examines orientation, memory, and attention, as well as the ability to name objects, follow verbal and written commands, write a sentence spontaneously, and copy a complex shape.

Monotherapy. Treatment with a single medication.

Multi-infarct dementia. Atype of vascular dementia caused by numerous small strokes in the brain.

Muscle tone. The level of muscle contraction present during the resting state. With increased tone there is stiffness and rigidity. With decreased tone there is looseness or floppiness of the limbs and trunk.

Musculoskeletal. Having to do with muscles, bones, and cartilage.

Myalgia. Pain in a muscle or group of muscles.

Myelin. A fatty covering insulating nerve cell fibers in the brain and spinal cord, myelin facilitates the smooth, high-speed transmission of electrochemical messages between these components of the central nervous system and the rest of the body. In MS, myelin is damaged through a process known as demyelination, which results in distorted or blocked signals.

Myelin basic protein (MBP). A major component of myelin. When myelin breakdown occurs (as in MS), MBP can often be found in abnormally high levels in the patient's cerebrospinal fluid.
Myelogram. An X-ray of the spinal cord after an injection of dye into the space between the lining of the spinal cord and brain.

Myoclonic jerk . Brief muscle jerk; may involve muscles on one or both sides of the body; may be normal (e.g., as one falls asleep) or caused by a seizure or other disorders.

Myoclonic seizures. Seizures that cause sudden jerks or twitches, especially in the upper body, arms, or legs.

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Neocortical epilepsy. Epilepsy that originates in the brain's cortex, or outer layer. Seizures can be either focal or generalized, and may cause strange sensations, hallucinations, or emotional changes.

Nerve A bundle of fibers that receives and sends messages between the body and the brain. The messages are sent by chemical and electrical changes in the cells that make up the nerves.

Nerve block . A procedure in which medicine is injected directly into or around a nerve or into the spine to block pain.

Nervous system. The organized network of nerve tissue in the body. It includes the central nervous system (the brain and spinal cord), the peripheral nervous system (nerves that extend from the spinal cord to the rest of the body), and other nerve tissue.

Neurofibrillary tangles. Bundles of twisted filaments found within neurons, and a characteristic feature found in the brains of Alzheimer's patients. These tangles are largely made up of a protein called tau.

Neuro-oncologist. A doctor who specializes in diagnosing and treating brain tumors and other tumors of the nervous system.

Neurobehavioral. Having to do with the way the brain affects emotion, behavior, and learning. Some cancers or their treatment may cause neurobehavioral problems.

Neuroblastoma. Cancer that arises in immature nerve cells and affects mostly infants and children.

Neurocognitive. Having to do with the ability to think and reason. This includes the ability to concentrate, remember things, process information, learn, speak, and understand.

Neuroectodermal tumor. A tumor of the central or peripheral nervous system.

Neuroendocrine. Having to do with the interactions between the nervous system and the endocrine system. Neuroendocrine describes certain cells that release hormones into the blood in response to stimulation of the nervous system.

Neurofibroma. A benign tumor that develops from the cells and tissues that cover nerves.

Neuroglia. Any of the cells that hold nerve cells in place and help them work the way they should. The types of neuroglia include oligodendrocytes, astrocytes, microglia, and ependymal cells. Also called glial cell.

Neurological exam. A series of questions and tests to check brain, spinal cord, and nerve function. The exam checks a person’s mental status, coordination, ability to walk, and how well the muscles, sensory systems, and deep tendon reflexes work.

Neurologist. A doctor who specializes in the diagnosis and treatment of disorders of the nervous system.

Neuroma. A tumor that arises in nerve cells.

Neuron. A nerve cell. A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current.

Neuropathologist. A pathologist who specializes in diseases of the nervous system. A pathologist identifies disease by studying cells and tissues under a microscope.

Neuropathy. A nerve problem that causes pain, numbness, tingling, swelling, or muscle weakness in different parts of the body. It usually begins in the hands or feet and gets worse over time. Neuropathy may be caused by physical injury, infection, toxic substances, disease (such as cancer, diabetes, kidney failure, or malnutrition), or drugs, including anticancer drugs. Also called peripheral neuropathy.

Neuropeptide. A member of a class of protein-like molecules made in the brain. Neuropeptides consist of short chains of amino acids, with some functioning as neurotransmitters and some functioning as hormones.

Neuropsychology. The study of how the brain and central nervous system are related to behavior.

Neuroradiologist. A doctor trained in radiology who specializes in creating and interpreting pictures of the nervous system. The pictures are produced using forms of radiation, such as X-rays, sound waves, or other types of energy.

Neurosurgeon. A doctor who specializes in surgery on the brain, spine, and other parts of the nervous system.

Neurotoxicity. The tendency of some treatments to cause damage to the nervous system.

Neurotoxin. A substance that is poisonous to nerve tissue.

Neurotransmitter. A chemical that is made by nerve cells and used to communicate with other cells, including other nerve cells and muscle cells. Neurotransmitters include serotonin, dopamine, glutamate and acetylcholine.  People with Alzheimer's disease have reduced supplies of acetylcholine. Medications may be prescribed to alter levels of neurotransmitters in the brain. For instance, some antidepressants called "SSRIs" increase levels of serotonin. Others increase levels of dopamine.

Nonconvulsive seizure. Any type of seizure that does not include violent muscle contractions.

Nonepileptic events. Any phenomena that look like seizures but do not result from abnormal brain activity. Nonepileptic events may include psychogenic seizures or symptoms of medical conditions such as sleep disorders, Tourette syndrome, or cardiac arrythmia.

Nursing home. A place that provides care for people who have physical or mental disabilities and need help with activities of daily living (such as taking a bath, getting dressed, and going to the bathroom) but do not need to be in the hospital.

Nutritionist. A health professional with special training in nutrition who can help with dietary choices. Also called a dietitian.

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Off-label. Describes the legal use of a prescription drug to treat a disease or condition for which the drug has not been approved by the U.S. Food and Drug Administration.

Oligoastrocytoma. A brain tumor that forms from both oligodendrocytes and astrocytes, which are types of glial cells (cells that cover and protect nerve cells in the brain and spinal cord and help them work the way they should). An oligoastrocytoma is a type of mixed glioma.

Oligodendrocyte. A cell that forms the myelin sheath (a layer that covers and protects nerve cells) in the brain and spinal cord. An oligodendrocyte is a type of glial cell.

Oligodendroglioma. A rare, slow-growing tumor that begins in oligodendrocytes (cells that cover and protect nerve cells in the brain and spinal cord). Also called oligodendroglial tumor.

Optic nerve. The nerve that carries messages from the retina to the brain.

Optic neuritis. An inflammatory disorder of the optic nerve that usually occurs in only one eye and causes visual loss and sometimes blindness. It is generally temporary.

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Palliative care. Activities that ease the symptoms of a disease or the side effects of treatment for a disease. Palliative care does not cure the disease. It is aimed at improving quality of life and it addresses the psychological, social, and spiritual needs of patients and their families. Also called palliative therapy, comfort care, supportive care, and symptom management.

Parenteral nutrition. A form of nutrition that is delivered into a vein. Parenteral nutrition does not use the digestive system. It may be given to people who are unable to absorb nutrients through the intestinal tract because of vomiting that won't stop, severe diarrhea, or intestinal disease. It may also be given to those undergoing high-dose chemotherapy or radiation and bone marrow transplantation. It is possible to give all of the protein, calories, vitamins and minerals a person needs using parenteral nutrition. Also called hyperalimentation, total parenteral nutrition, and TPN.

Paresthesias. Abnormal sensations such as numbness, prickling, or "pins and needles."

Paroxysmal hemicrania. Arare form of headache that usually begins in adulthood and is marked by one-sided attacks that typically occur 5 to 40 times a day.

Parkinson's dementia. A type of  dementia that sometimes occurs in people with advanced Parkinson's disease, which is primarily a movement disorder. Many Parkinson's patients have the characteristic amyloid plaques and neurofibrillary tangles found in Alzheimer's disease, but it is not yet clear if the diseases are linked.

Parkinsonism. A term referring to a group of conditions that are characterized by four typical symptoms—tremor, rigidity, postural instability, and bradykinesia.

Partial seizures. Another term used to describe focal seizures, those that occur in just one part of the brain.

Pathologist. A doctor who identifies diseases by studying cells and tissues under a microscope.

Pathology report. The description of cells and tissues made by a pathologist based on microscopic evidence, and sometimes used to make a diagnosis of a disease.

Persistent vegetative state (PVS). An ongoing state of severely impaired consciousness, in which the patient is incapable of voluntary motion.

PET scan (positron emission tomography scan) . A procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body.

Petit mal seizures. An older term for absence seizures.

Photophobia . A condition in which the eyes are more sensitive than normal to light.

Photosensitive epilepsy. Epilepsy with seizures triggered by flickering or flashing lights. It also may be called photic epilepsy or photogenic epilepsy.

Physiatrist (physical medicine specialist) . A doctor who specializes in physical medicine (the prevention and treatment of disease or injury with physical methods, such as exercise and machines).

Physical therapist. A health professional who teaches exercises and physical activities that help condition muscles and restore strength and movement.

Physical therapy (PT). The use of exercises and physical activities to help condition muscles and restore strength and movement. For example, physical therapy can be used to restore arm and shoulder movement and build back strength after breast cancer surgery.

Pituitary tumor. A tumor that forms in the pituitary gland. The pituitary is a pea-sized organ in the center of the brain above the back of the nose. It makes hormones that affect other glands and many body functions, especially growth. Most pituitary tumors are benign (not cancer).

Plasmapheresis. The process of taking blood out of the body and removing components in the blood’s plasma that are thought to be harmful before transfusing the blood back into the body (also called plasma exchange).

Plasticity. Ability of the brain to adapt to deficits and injury.

Plaques.  Patchy areas of inflammation and demyelination typical of MS, plaques disrupt or block nerve signals that would normally pass through the regions affected by the plaques.

Polysomnogram. A group of recordings taken during sleep that shows brain wave changes, eye movements, breathing rate, blood pressure, heart rate, and the electrical activity of the heart and other muscles. A polysomnogram may be used to help diagnose sleep disorders.

Post-concussion syndrome (PCS) . A complex, poorly understood problem that may cause headache after head injury; in most cases, patients cannot remember the event that caused the concussion and a variable period of time prior to the injury.

Postdrome. The period following the headache.

Post-traumatic amnesia (PTA). A state of acute confusion due to a traumatic brain injury, marked by difficulty with perception, thinking, remembering, and concentration; during this acute stage, patients often cannot form new memories.

Post-traumatic dementia. A condition marked by mental deterioration and emotional apathy following trauma.

Post-traumatic epilepsy. Recurrent seizures occurring more than 1 week after a traumatic brain injury.

Post-traumatic stress disorder (PTSD ). An anxiety disorder that develops in reaction to physical injury or severe mental or emotional distress, such as military combat, violent assault, natural disaster, or other life-threatening events. Having cancer may also lead to post-traumatic stress disorder. Symptoms interfere with day-to-day living and include reliving the event in nightmares or flashbacks; avoiding people, places, and things connected to the event; feeling alone and losing interest in daily activities; and having trouble concentrating and sleeping.

Premonitory (meaning before). Some individuals with migraine experience premonitory symptoms up to 24 hours prior to headache pain.

Presenilin 1 and 2. Proteins produced by genes that influence susceptibility to early-onset Alzheimer's disease.

Primary dementia. A dementia, such as Alzheimer's disease, that is not the result of another disease.

Primary exertional headache. Headache brought on by fits of coughing or sneezing, or by intense physical activity such as running or lifting.

Primary headaches. Headaches that occurs on their own with no detectable underlying cause, such as migraine, tension-type headache, and the trigeminal autonomic cephalgias.

Progressive epilepsy. Epilepsy in which seizures and/or the person's cognitive abilities get worse over time.

Prophylactic. In medicine, something that prevents or protects.

Prophylaxis. An attempt to prevent disease.

Prosthesis. A device, such as an artificial leg, that replaces a part of the body.

Psychiatrist. A medical doctor who specializes in the prevention, diagnosis, and treatment of mental, emotional, and behavioral disorders.

Psychogenic seizure. A type of non-epileptic event that is caused by psychological factors.

Psychological. Having to do with how the mind works and how thoughts and feelings affect behavior.

Psychologist. A specialist who can talk with patients and their families about emotional and personal matters, and can help them make decisions.

Psychosis. A severe mental disorder in which a person loses the ability to recognize reality or relate to others. The person is not able to cope with the demands of everyday life. Symptoms include being paranoid, having false ideas about what is taking place or who one is, and seeing, hearing, or feeling things that are not there.

Psychostimulant. A drug that causes a sense of well-being, decreases fatigue and depression, and increases the desire to eat. These drugs can also cause mood changes and trouble with sleeping.

Psychotherapy. Treatment of mental, emotional, personality, and behavioral disorders using methods such as discussion, listening, and counseling. Also called talk therapy.

Ptosis. Drooping of the upper eyelid.

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Quality of life (QOL). The overall enjoyment of life. Many clinical trials assess the effects of cancer and its treatment on the quality of life. These studies measure aspects of an individual’s sense of well-being and ability to carry out various activities.

Reflexes. Automatic movements the body makes in response to a stimulus.

REM sleep (rapid eye movement sleep). One of the five stages of sleep. During rapid eye movement sleep, the eyes move rapidly while closed and dreams occur. Rapid eye movement sleep is the lightest stage of sleep, during which a person may wake easily. During several hours of normal sleep, a person will go through several sleep cycles that include rapid eye movement sleep and the 4 stages of non-rapid eye movement (light to deep sleep).

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Schwannoma. A tumor that arises from a Schwann cell, which a type of cell that helps separate and insulate nerves.

Secondary dementia. A dementia that occurs as a consequence of another disease or an injury.

Secondary headaches. Headaches that are caused by an underlying condition or disease.

Seizure. A sudden, excessive discharge of nervous-system electrical activity that usually causes a change in behavior.

Seizure focus. An area of the brain where seizures originate.

Seizure threshold. Minimal conditions necessary to produce a seizure.

Seizure triggers. Phenomena that trigger seizures in some people. Seizure triggers do not cause epilepsy but can lead to first seizures or cause breakthrough seizures in people who otherwise experience good seizure control with their medication.

Selective serotonin reuptake inhibitor (SSRI). A type of drug that is used to treat depression. Selective serotonin reuptake inhibitors slow the process by which serotonin (a substance that nerves use to send messages to one another) is reused by nerve cells that make it. This increases the amount of serotonin available for stimulating other nerves.

Senile dementia. An outdated term that reflects the formerly widespread belief that dementia was a normal part of aging. The word senile is derived from a Latin term that means, roughly, "old age. "

Sensory. Pertaining to the senses (touch, vision, hearing, taste, smell).

Serotonin. A neurotransmitter present throughout the body and brain that plays an important role in headache and migraine, mood disorders, regulating body temperature, sleep, vomiting, sexuality, and appetite.

Sharp wave. An EEG pattern indicating the potential for epilepsy; “benign” sharp waves are not associated with seizures.

Sleep apnea A sleep disorder that is marked by pauses in breathing of 10 seconds or more during sleep, and causes unrestful sleep. Symptoms include loud or abnormal snoring, daytime sleepiness, irritability, and depression.

Sleep disorder. A disturbance of normal sleep patterns. There are a number of sleep disorders that range from trouble falling asleep, to nightmares, sleepwalking, and sleep apnea (problems with breathing that cause loud snoring). Poor sleep may also be caused by diseases such as heart disease, lung disease, or nerve disorders.

Sleep stages. Five parts or stages of the sleep cycle, each defined by the type of brain activity that occurs during that stage. During stages 1 to 4, a person will feel drowsy, fall asleep, and move into a deep, dreamless sleep. Stage 5 is called rapid eye movement (REM) sleep, and it is during this stage that dreams occur. During several hours of normal sleep, a person will go through several sleep cycles that include REM sleep and the 4 stages of non-REM sleep (light to deep sleep).

Social Security Disability Income (SSDI). A federal assistance program for disabled people who have paid Social Security taxes or are dependents of people who have paid.

Social worker. A professional trained to talk with people and their families about emotional or physical needs, and to find them support services.

Spasticity. Abnormal, involuntary stiffness or contraction of the body's muscles. In MS, this condition primarily affects the lower limbs.

SPECT (single-photon emission computed tomography). A special type of computed tomography (CT) scan in which a small amount of a radioactive drug is injected into a vein and a scanner is used to make detailed images of areas inside the body where the radioactive material is taken up by the cells. SPECT can give information about blood flow to tissues and chemical reactions (metabolism) in the body.

Spell. A period, bout, or episode of illness or indisposition; refers to seizures or other disorders that produce brief episodes of behavioral change.

Spike. An EEG pattern strongly correlated with seizures; “benign” spikes are not associated with seizures.

Spinal cord. A column of nerve tissue that runs from the base of the skull down the back. It is surrounded by three protective membranes (spinal meninges) and is enclosed within the vertebrae (back bones). The spinal cord and the brain make up the central nervous system, and spinal cord nerves carry most messages between the brain and the rest of the body.

Spinal tap. A procedure in which a needle is put into the lower part of the spinal column to collect cerebrospinal fluid (CSF) or to give drugs. Also called lumbar puncture.

Staging. Performing exams and tests to learn the extent of the cancer within the body, especially whether the disease has spread from the original site to other parts of the body. It is important to know the stage of the disease in order to plan the best treatment.

Stereotactic external-beam radiation therapy. A type of external radiation therapy that uses special equipment to position the patient and precisely deliver radiation to a tumor. The total dose of radiation is divided into several smaller doses given over several days. Stereotactic external-beam radiation therapy is used to treat brain tumors and other brain disorders. It is also being studied in the treatment of other types of cancer, such as lung cancer. Also called stereotactic radiation therapy and stereotaxic radiation therapy.

Supportive care. Activities that ease the symptoms of a disease or the side effects of treatment for a disease. Supportive care does not cure the disease. It is aimed at improving quality of life and it addresses the psychological, social, and spiritual needs of the patient.

Simple focal seizures. seizures that affect only one part of the brain. People experiencing simple focal seizures remain conscious but may experience unusual feelings or sensations.

Status epilepticus. A potentially life-threatening condition in which a seizure is abnormally prolonged. Although there is no strict definition for the time at which a seizure turns into status epilepticus, most people agree that any seizure lasting longer than 5 minutes should, for practical purposes, be treated as though it was status epilepticus.

Status migrainosus. A migraine lasting more than 72 hours.

Stereotyped.  Similar every time. In epilepsy this refers to the symptoms an individual person has, and the progression of those symptoms.

Subdural hematoma. Bleeding between the brain and its protective membrane covering.
Sudden unexplained death (SUDEP). Death that occurs suddenly for no discernible reason. Epilepsy increases the risk of sudden explained death about two-fold.

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T cells. Immune system cells that develop in the thymus gland. Findings suggest that T cells are implicated in myelin destruction.

Temporal lobe epilepsy (TLE). The most common epilepsy syndrome with focal seizures.

Temporal lobe resection. A type of surgery for temporal lobe epilepsy in which all or part of the affected temporal lobe of the brain is removed.

Tension-type headache. A primary headache that is band-like or squeezing and does not worsen with routine activity. It may be brought on by stress.

Thrombosis or thrombus. The formation of a blood clot at the site of an injury.

Tonic seizures. Seizures that cause stiffening of muscles of the body, generally those in the back, legs, and arms.

Tonic-clonic seizures. Seizures that cause a mixture of symptoms, including loss of consciousness, stiffening of the body, and repeated jerks of the arms and legs. In the past these seizures were sometimes referred to as grand mal seizures.

Transcranial magnetic stimulation (TMS). A procedure which uses a strong magnet held outside the head to influence brain activity. This is an experimental treatment for seizures.

Transient ischemic attack (TIA). A stroke that last only a few minutes but signals a subsequent and more severe stroke.

Transverse myelitis. An acute spinal cord disorder causing sudden low back pain and muscle weakness and abnormal sensory sensations in the lower extremities. Transverse myelitis often remits spontaneously; however, severe or long-lasting cases may lead to permanent disability.

Trigger. Something that brings about a disease or condition.

Triptans. A family of drugs used to treat migraines and cluster headaches by preventing or stopping nerve tissue inflammation and resulting changes in blood vessels.

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Vascular. Refers to blood vessels or the flow of blood.

Vascular dementia. A type of dementia caused by brain damage from cerebrovascular or cardiovascular problems - usually strokes. It accounts for up to 20 percent of all dementias.

Vasospasm. Exaggerated, persistent contraction of the walls of a blood vessel.

Venous sinus thrombosis. A form of stroke caused by a clot that blocks blood flow in the brain's veins.

Ventriculostomy. A surgical procedure that drains cerebrospinal fluid from the brain by creating an opening in one of the small cavities called ventricles.

White matter. Nerve fibers that are the site of many MS lesions and that connect areas of gray matter in the brain and spinal cord.


Reference: National Institute of Neurological Disorders and Stroke (NINDS)