Epilepsy Glossary

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Epilepsy Glossary

Learn How Getting to Know These Epilepsy Terms Can Help You Or Someone Who Has Epilepsy

 Getting familiar with these terms will help discussions with your doctors

epilepsy calming seizures

Absence seizure: (also know as “dialeptic seizure” or “petit mal seizure”) a seizure that causes a brief loss of awareness. During an absence seizure, the patient stops any activity and stares blankly. Rarely, there may be some blinking.

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

Anticonvulsant: an antiepileptic drug used to control both convulsive and nonconvulsive seizures.

Atonic seizure: a seizure that causes a sudden loss of muscle tone, particularly in the arms and legs, and often causes the patient to fall.

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 or initial symptom at the beginning of a seizure, experienced by the patient, but not visible to observers. Auras may progress to become focal or even generalized seizures, or they may exist alone.

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 the 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 from 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 occurring 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 drugs 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).

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

Clonic seizure: Repetitive, rhythmic jerks that involve all or part of the body.

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 occurred 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.

Complex partial seizure: a seizure that includes impairment of awareness, for example, patients seem to be “out of it” or “staring into space.” Unintentional movements or other movements are frequently a part of the seizure.

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.

Corpus callosum: a band of nerve fibers located deep in the brain that connects the two halves (hemispheres) of the brain. The corpus callosum helps the hemispheres share information.

Corpus callosotomy: an operation that cuts the corpus callosum and interrupts the spread of seizures from one hemisphere of the brain to the other. Callosotomy may be complete or may involve only a portion of the corpus callosum. Although seizures generally do not completely stop after this procedure, they usually become less severe.

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

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 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.

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

EEG-video monitoring: Continuous simultaneous recording of brainwaves and video observation of the behavior accompanying the EEG. This technique, carried out at comprehensive epilepsy centers, is employed to diagnose epilepsy and localize the seizure focus. The results are used to determine therapy — medical or surgical.

Epilepsy: a chronic medical condition marked by recurrent epileptic seizures. Patients may have single seizures as a result of fever, medication withdrawal, etc., but are not labeled as having epilepsy if seizures do not recur.

Epileptogenic zone: the region of the brain responsible for the abnormal electrical signals that cause seizures.

Electrode: a conductive disk (usually metal) attached to the scalp which conveys the electrical activity of the brain through a wire to an EEG machine. During an electroencephalogram, typically around 20 electrodes are temporarily pasted to the scalp.

Electroencephalogram (EEG): a diagnostic test that measures brainwaves, the electrical impulses in the cerebral cortex. This test helps a doctor to diagnose epilepsy.

Epilepsy surgery: a neuro-surgical procedure to prevent further seizures, usually accomplished by resecting the epileptogenic zone. Successful in eliminating seizures in a large majority of patients, depending on the type of epilepsy identified during EEG-video monitoring.

Extratemporal cortical resection: an operation to cut out (resect) brain tissue that contains a seizure focus. “Extratemporal” means the tissue is located in an area of the brain other than the temporal lobe, most often the frontal lobe. 

Functional hemispherectomy: a procedure in which portions of one hemisphere of the brain which is not functioning normally are removed, and the corpus callosum is split. This interrupts the communications among the various lobes and between the two hemispheres and prevents the spread of seizures.

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.

Hemisphere: one half of the cerebrum, the largest part of the brain.

Generalized seizure: a seizure that occurs all through the brain.

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 seizure: an older term for a seizure in which the patient loses consciousness and collapses. The patient also has body stiffening and violent jerking, and then often goes into a deep sleep. Also known as a generalized convulsion.

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.

Ketogenic diet: a treatment for epilepsy intended to maintain the starvation or fasting metabolism for a long period in order to create ketones, byproducts of fat-burning metabolism. Seizures often lessen or disappear during periods of fasting. The diet is very high in fat and low in carbohydrates and is most often recommended for children ages 2 through 12 who have been diagnosed with a generalized type of epilepsy, and who have failed to respond to a variety of medications.

Lesionectomy: surgery to remove isolated brain lesions that are responsible for seizure activity.

Lobe: one of the sections of the cerebrum, the largest part of the brain. The lobes are divided into four paired sections (frontal, parietal, occipital, and temporal). The seizure focus is usually located in one of the lobes.

Lumbar puncture: a diagnostic procedure in which the fluid surrounding the spinal cord (cerebrospinal fluid) is withdrawn through a needle and examined in a laboratory. Also known as a spinal tap.

Multiple subpial transections: a surgical procedure to help control seizures that begin in areas of the brain that cannot be safely removed (areas that control movements or speech). The surgeon makes a series of shallow cuts (transections) in the brain tissue to interrupt the movement of seizure impulses.

Myoclonic seizure: a seizure that consists of sporadic jerks, usually on both sides of the body. Patients with these seizures may drop or involuntarily throw objects.

Neurologist: a doctor who specializes in the treatment of epilepsy and other disorders of the brain and nervous system.

Neuron: a single nerve cell. The brain is made up of billions of neurons. Many neurons malfunctioning together are necessary to produce a seizure.

Nonepileptic event: an event that resembles a seizure but is actually produced by another condition, such as Tourette syndrome or heart rhythm disturbances (arrhythmias). Certain psychological conditions can also bring on a nonepileptic event.

Partial seizure: (also know as a “focal seizure”) a seizure that occurs in a limited area in only one hemisphere of the brain. This type of seizure is more amenable to treatment with surgery than are generalized seizures. 

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: an event of altered brain function caused by abnormal or excessive electrical discharges in the brain. Most seizures cause sudden changes in behavior or motor function.

Seizure focus: the area of the brain in which a seizure starts.

Status epilepticus:  a prolonged seizure (usually defined as lasting longer than 30 minutes) or a series of repeated seizures without regaining consciousness. Status epilepticus is a medical emergency, and medical help should be obtained immediately.

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.

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 blink, 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.

Temporal lobe resection: a surgical procedure in which brain tissue in the temporal lobe is cut away (resected) to remove the seizure focus.

Tonic seizure: a seizure that is characterized by stiffening of the muscles, sustained for more than a few seconds.

Tonic-clonic seizure: a seizure marked by loss of consciousness, falling, stiffening, and jerking. This is the hallmark of a generalized motor seizure, which used to be called a “grand mal seizure.”

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 stimulation: a surgical treatment for epilepsy involving implantation in the neck of an electrode on the vagus nerve. The electrode is connected to a pacemaker that is placed under the skin in the chest. While the VNS is usually programmed to cycle continuously, the patient can turn the stimulator on, using a small magnet placed over the pacemaker, if he or she feels a seizure coming on.

Vagus nerve: a small cranial nerve that passes through the neck and is connected to various areas of the brain and other organs in the body, including the stomach, heart, and lungs. 

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.