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Below is a glossary of many of the terms used on the epilepsy.com website. Please feel free to browse the terms below or you will see them highlighted the first time they appear on any page on the site.

Absence seizure: A primary generalized epileptic seizure, usually lasting less than 20 seconds, characterized by a stare sometimes associated with blinking or brief automatic movements of the mouth or hands; formerly called petit mal seizure. Absence seizures usually begin in childhood, are usually easily controlled with medication, and are outgrown by approximately 75% of children. See Atypical absence seizure.

Accommodation (or Reasonable accommodation): Any change in the work environment or in the way things are customarily done that enables an individual with a disability to have equal employment opportunities.

ADHD: Attention deficit hyperactivity disorder.

Adjunct: Something added to another thing in a subordinate position or use; for example, an adjunct drug is one used in addition to another drug, not alone (add-on therapy).

Adverse effects: side effect; negative effect from medication or therapy

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.

Americans with Disabilities Act: A law that makes discrimination against people with disabilities illegal; the act applies to employment, access to public places, and places of accommodation.

Anhedonia: Failure to enjoy positive emotional experiences

Anterograde memory: The ability to form new memories; memories for events occurring after a problem such as a head trauma or seizure.

Anticholinergic : Drugs that block the cholinergic neurotransmitter system

Antiepileptic drug: A medication used to control both convulsive and nonconvulsive seizures; sometimes called an anticonvulsant.

Apathy: Lack of interest and motivation

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.

Attention deficit disorder (ADD): An impairment in the ability to focus or maintain attention.

Atypical absence seizure: A staring spell characterized by partial impairment of consciousness; often occurs in children with the Lennox-Gastaut syndrome; the EEG shows slow (less than 3 per second) spike-and-wave discharges.

Aura: A warning before a seizure; a simple partial seizure occuring within seconds before a complex partial or secondarily generalized tonic-clonic seizure, or it may occur alone; also a warning before a migraine headache.

Autoinduction (of metabolism): A process in which continued administration of a drug leads to an increase in the rate at which the drug is metabolized.

Automatism: Automatic, involuntary movement during a seizure; may involve mouth, hand, leg, or body movements; consciousness is usually impaired; occurs during complex partial and absence seizures and after tonic-clonic seizures.

Autonomic: Pertaining to the autonomic nervous system, which controls bodily functions that are not under conscious control (e.g., heartbeat, breathing, sweating); some partial seizures may cause only autonomic symptoms; changes in autonomic functions are common during many seizures.

Autosomal dominant: A mode of 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.

Benign: Favorable for recovery.

Benign rolandic epilepsy: An epilepsy syndrome of childhood characterized by partial seizures occuring at night and often involving the face and tongue; the seizures may progress to tonic-clonic seizures, have a characteristic EEG pattern, are easily controlled with medications but may not require treatment, and are outgrown by age 16 years.

Blood drug level: The concentration, or amount, of circulating drug in the bloodstream, measured in micrograms (µg) or nanograms (ng) per milliliter (mL). The concentration may be measured as the free or total level because some of the drug is bound to the protein in the blood and some is not; the free level is the amount of drug that is "free" (unbound); the total level is the amount of drug that is both bound and unbound to the blood protein; the drug that is free (unbound) is the portion that reaches the brain and exerts an effect on the disorder.

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.

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.

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.

Cerebral hemisphere: One side of the cerebrum (upper brain); each hemisphere contains four lobes (frontal, parietal, occipital, and temporal).

Cerebral palsy: A condition with various combinations of impaired muscle tone and strength, coordination, and intelligence.

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

Cognitive: Pertaining to the mental processes of perceiving, thinking, and remembering; used loosely to refer to intellectual functions as opposed to physical functions.

Comorbid: A disorder that is present in association with another

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).

Comprehensive epilepsy centers : Comprehensive epilepsy centers are clinics staffed by epileptologists and other experts in epilepsy treatment. They are valuable resources for anyone who has unresolved problems related to definite or suspected epilepsy. Patients may be referred to a comprehensive epilepsy center for a single outpatient visit to assess their diagnosis and therapy, or they may receive long-term follow-up and treatment, including epilepsy surgery or the use of new medications that are still being investigated.

Computed tomography (CT): A scanning technique that uses x-rays and computers to create pictures of the inside of the body; shows the structure of the brain; not as sensitive as MRI.

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 occured during the spell.

Controlled study: An experiment in which two groups are the same except that only one receives the drug, treatment, etc. being tested.

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

Convulsive syncope: A fainting episode in which the brain does not receive enough blood, causing a seizure; the episode is not an epileptic seizure, but a result of the faint.

Corpus callosotomy: A surgical technique that disconnects the cerebral hemispheres and is most effective in reducing atonic and tonic-clonic seizures.

Cortical dysplasia: An abnormality in the development and organization of the cerebral cortex that can cause seizures and other neurologic disorders. These disorders can result from abnormal migration of nerve cells during development or can occur with disorders such as tuberous sclerosis or Sturge-Weber syndrome.

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).

Deficit: A lack or deficiency of an essential quality or element; for example, a neurologic deficit is a defect in the structure or function of the brain.

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).

Development: The process of physical growth and the attainment of intelligence and problem-solving ability that begins in infancy; any interruption of this process by a disease or disorder is called developmental delay.

Dose-related effects: Adverse effects that are more likely to occur at times of peak blood levels of a drug.

EEOC: Equal Employment Opportunity Commission.

EF: Epilepsy Foundation.

Efficacy: Effectiveness

Electrode: A conductor through which electrical current enters or leaves. When used to record the electroencephalogram, a small metal disc attached to a wire is usually used.

Electroencephalogram (EEG): A diagnostic test of brain electrical activity; helpful in diagnosing epilepsy.

Elimination: The removal of waste products from the body.

Encephalitis: An inflammation of the brain, usually caused by a virus.

Epilepsia partialis continua: A continuous or prolonged partial seizure that causes contraction of the muscles; usually restricted to the muscles of the face, arm, or leg; usually not associated with impairment of consciousness.

Epilepsy: A disorder characterized by transient but recurrent disturbances of brain function that may or may not be associated with impairment or loss of consciousness and abnormal movements or behavior.

Epilepsy syndrome: A disorder defined by seizure type, age of onset, clinical and EEG findings, family history, response to therapy, and prognosis.

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

Epileptogenesis: The process(es) that lead to the development of epilepsy

Epileptogenic: Causing epilepsy.

Epileptologist: A neurologist with specialty training in epilepsy.

Equilibrium period: See Steady state.

Excitatory: Stimulating or increasing brain electrical activity; causing nerve cells to fire.

Febrile seizure: A seizure associated with high fever in children aged 3 months to 5 years, usually a tonic-clonic seizure; benign in most cases.

Fit: An older term for a seizure, usually a tonic-clonic seizure; still used in some places.

Flattened affect: Decreased emotional range.

Focal seizure: An older term for a partial seizure.

Focus: The center or region of the brain from which seizures begin; used in reference to partial seizures.

Frontal lobe seizure foci: A partial seizure arising in the frontal lobe area of the brain.

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.

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

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.

Hemispherectomy: A surgical procedure to remove a cerebral hemisphere (one side of the brain); the operation is now often modified to remove a portion of the hemisphere and to disconnect the remaining portions.

Hereditary: Passed from one generation to the next through the genes.

Hydrocephalus: A condition associated with obstruction of the cerebrospinal fluid pathways in the brain and accumulation of excess cerebrospinal fluid within the skull.

Hyperventilation: Increased rate and depth of breathing; may be done during the EEG to increase the chances of finding epileptiform or other abnormal activity.

Hypofunction: Diminished functional activity

Hypsarrhythmia: An abnormal EEG pattern of excessive slow activity and multiple areas of epileptiform activity; associated with infantile spasms.

Ictal: Referring to the period during a sudden attack, such as a seizure or stroke.

Idiopathic: Referring to a disorder of unknown cause.

Idiopathic generalized epilepsies: Epilepsy syndromes characterized by onset from both heispheres of the brain simultaneously;often genetic.

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

Incidence: The number of new cases of a disorder occurring in a population during a specified period.

Individuals with Disabilities Education Act (IDEA): A U.S. federal law ensuring that all handicapped children receive appropriate education at no cost and in the least restrictive environment.

Infantile spasm: A sudden jerk followed by stiffening; spasms usually begin between age 3 and 12 months and usually stop by age 2 to 4 years, although other seizure types often develop; in some spells, the arms are flung out as the body bends forward ("jackknife seizures"), but in others the movements are more subtle.

Inhibitory: Shutting off or decreasing brain electrical activity; causing nerve cells to stop firing.

Intensive monitoring: See Video-EEG monitoring.

Interictal: Referring to the period between seizures.

Interictal epileptiform: Epilepsy waves recorded between seizures.

Interictal hypometabolism: Decreased metabolism of glucose or oxygen in a brain region measured between seizures.

Interictal psychosis: Thought disorder, often with delusions, halluciantions or emotional changes that are temporarily related to the occurence of seizures in people with epilepsy. Usually lasts 3-6 months.

Intractable: Difficult to alleviate, remedy, or cure; for example, intractable seizures are difficult to control with the usual antiepileptic drug therapy.

Intravenous infusion: Administering a drug or other substance as part of a liquid solution injected directly into a vein (usually in the arm) at a prescribed rate.

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

Juvenile myoclonic epilepsy (JME): A primary generalized epilepsy syndrome, usually beginning between ages 5 to 17 years, characterized by myoclonic (muscle-jerk) seizures and possibly also absence and tonic-clonic seizures; responds well to valproate.

Ketogenic diet: A high-fat, low-carbohydrate diet used to control seizures in some children with seizures, that are difficult to control with medications.

Kindling: A process (demonstrated by experiments using animals) 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.

Landau-Kleffner syndrome: A disorder of childhood characterized by the regression of language milestones in association with particular types of abnormalities on the EEG.

Left temporal seizure foci: Partial seizure dirsorder arising from the left temporal lobe.

Lennox-Gastaut syndrome: A disorder beginning in childhood, characterized by development delay or mental retardation, multiple seizure types that do not respond well to therapy, and slow spike-and-wave discharges on the EEG.

Magnetic resonance imaging (MRI): A scanning technique that creates pictures of the inside of the body and the brain; uses a strong magnet (does not use x-rays); more sensitive than CT.

Magnetic resonance spectroscopy (MRS): A scanning technique that examines the atoms hydrogen and phosphorus to glean information about chemical activity in small areas of the brain.

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

Medical history: The account of a patient's disorder.

Meningitis: A bacterial infection of the membranes surrounding the brain; often diagnosed by a spinal tap (lumbar puncture).

Metabolism: The physical and chemical processses by which substances are produced or transformed (broken down) into energy or products for the uses of the body.

Metabolite: Chemical product derived from breakdown (metabolism) of another chemical; may be biologically active or inactive; an active metabolite of an antiepileptic drug can be effective in controlling seizures or can cause or contribute to the drug's adverse effects.

Migraine: A headache characterized by throbbing head pain, often greater on one side; may be preceded by a warning (aura) and accompanied by nausea, vomiting, and sensitivity to light and sound; in rare cases, weakness, language problems, or other neurologic disorders are associated with migraine.

Minor (motor) seizure: An older term for seizures that cause contraction of muscles but do not become tonic-clonic seizures; mostly used in certain laws and acts.

Monotherapy: Treatment with a single medication.

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.

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 seizure: A brief muscle jerk resulting from an abnormal discharge of brain electrical activity; usually involves muscles on both sides of the body, most often the shoulders or upper arms.

Narcolepsy: A condition characterized by sudden and uncontrollable attacks of sleep.

Neuron: A nerve cell.

Neurotransmitter: A chemical substance produced by nerve cells, transported in the axon, and released at the synapse; causes chemical and electrical changes in adjacent cells.

Phonology: The study of speech sounds (phonemes) and how they are used.

Psychopharmocotherapy: Medication used to treat behavioral and psychiatric disorders

Ring Chromosome 20 Syndrome: Ring chromosome 20 syndrome (RC20) is one of a number of chromosomal disorders associated with refractory epilepsy. A ring chromosome is formed by the fusion of two arms of a chromosome during pre-natal development. Epilepsy appears to be the first and major clinical symptom of this syndrome, is a constant feature, and is often drug resistant.

Seizure threshold: Minimal conditions necessary to produce a seizure.

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

Selective Serotonin Reuptake Inhibitor (SSRI): A drug that blocks the removal of serotonin from the synapse; thereby prolonging and increasing the effects of serotonin.

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

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

Sibling: A brother or sister.

Simple partial seizure: An epileptic seizure that involves only part of the brain and does not impair consciousness.

Single-Photon Emission Computed Tomography (SPECT): A diagnostic test that uses a very low and safe dose of a radioactive compound to measure blood flow in the brain; not as sensitive as PET for baseline (interictal) studies but can more readily be obtained during a seizure.

Slowing: A term used to describe a group of brain waves on the EEG that have a lower frequency than expected for the subject’s age and level of alertness and the area of the brain recorded. Slow waves can result from drowsiness or sleep, drugs, or brain injuries and occur during or after seizures.

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.

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.

SSA: Social Security Administration

Status epilepticus: A prolonged seizure (usually defined as lasting longer than 30 minutes) or a series of repeated seizures; a continuous state of seizure activity; may occur in almost any seizure type. Status epilepticus is a medical emergency, and medical help should be obtained immediately.

Steady state: A state in which equilibrium has been achieved. In reference to antiepileptic drugs, steady state is achieved when a constant daily dose of a drug produces consistent blood levels of the drug (takes at least five times the half-life of the drug in question).

Structural lesion: Physical abnormality in the brain.

Sturge-Weber syndrome: A disorder of blood vessels affecting the skin of the face, eyes, and brain; brain involvement is associated with seizures.

Supplemental Security Income (SSI): A federal assistance program.

Symptomatic: Referring to a disorder with an identifiable cause; for example, severe head trauma can cause symptomatic epilepsy.

Synapse: The junction between one nerve cell and another nerve cell; the axon of one nerve cell releases a neurotransmitter, which diffuses across the synapse and causes changes in the membrane of the adjacent cell.

Syncope: (pronounced SIN-ko-pee) Fainting.

Syndrome: A group of signs and symptoms that collectively define or characterize a disease or disorder; signs are objective findings such as weakness, and symptoms are subjective findings such as a feeling of fear or tingling in a finger.

Temporal lobe epilepsy: An older term for partial epilepsy arising from the temporal lobe of the brain.

Temporal lobe seizure: A simple or complex partial seizure arising from the temporal lobe of the brain.

Therapeutic blood level: The amount of drug circulating in the bloodstream that brings about seizure control without troublesome adverse effects in most patients. “Subtherapeutic” (lower) levels are effective in some patients, and “supratherapeutic” or “toxic” (higher) levels are tolerated by others.

Threshold: The level at which an event or change occurs

Tic: Repeated involuntary contractions of muscles, such as rapid head jerks or eye blinks, as in Tourette’s syndrome; may be under partial voluntary control (for example, can be temporarily suppressed); nonepileptic.

Time to Peak Blood Level: The interval between the time a drug is taken and the time it reaches the highest concentration in the blood.

Todd’s paralysis: Weakness after a seizure; originally used to describe muscle weakness on the side of the body opposite the side in which the seizure

Tolerance: Decreased sensitivity to the effects of a substance such as a medication.

Tonic seizure: An epileptic seizure that causes stiffening; consciousness is usually preserved. The seizure involves muscles on both sides of the body, and electrical discharge involves all or most of the brain.

Tonic-clonic seizure: A convulsion; newer term for grand mal or major motor seizure; characterized by loss of consciousness, falling, stiffening, and jerking; electrical discharge involves all or most of the brain.

Trauma: An injury or wound caused by external force or violence.

Tuberous sclerosis: A disease in which benign tumors affect the brain, eyes, skin, and internal organs; associated with mental retardation and seizures; inherited as an autosomal dominant trait.

Vagus nerve stimulator (VNS): : A pacemaker-like device, implanted in the upper chest, which stimulates a nerve in the left neck and can reduce seizure activity.

Video-EEG monitoring: A technique for recording the behavior and the EEG of a patient simultaneously; changes in behavior can be correlated with changes in the EEG; useful for making the diagnosis of epilepsy and localizing the seizure focus.

West’s syndrome: An epileptic syndrome characterized by infantile spasms, mental retardation, and an abnormal EEG pattern (hypsarrhythmia); begins before 1 year of age.

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