See Applied Behavioral Analysis.

Absence Seizure

An absence seizure (formerly known as a petit mal seizure) is a type of generalized seizure that typically occurs without warning and causes lapses of attention lasting from 5 to 30 seconds. Most children with absence seizures experience what physicians call typical absence seizures, which may involve eye blinking, head bobbing, or jerky movements of the face or lips, in addition to the characteristic lapses of attention. Atypical absence seizures are similar but involve a distinctive EEG pattern of slow spike and wave discharges. Atypical absence seizures are usually associated with Lennox-Gastaut syndrome. Absence seizures are often called staring seizures.


Acetoacetate is a by-product produced by the liver during the process of fat metabolism. The liver makes acetoacetate during periods of fasting, starvation, or prolonged physical exertion, or when an individual's epilepsy treatment involves a high-fat dietary therapy such as the ketogenic diet. It is theorized that betahydroxybuterate and acetoacetate (known as ketones or ketone bodies) may accumulate in the brain and be an important factor in seizure control associated with dietary therapies.


Acidosis is a condition in which there is an increased amount of acid in the blood, resulting in a drop in blood pH.

Activating Procedure

An activating procedure is a practice used during an EEG to provoke a clinical seizure or epileptiform discharge. Activating procedures include hyperventilation and photic stimulation, during which a strobe light is flashed at various frequencies while an individual opens and closes his or her eyes.


See Attention Deficit Hyperactivity Disorder.

Aicardi Syndrome

Aicardi syndrome is a very rare neurological disorder that affects only girls (doctors think Aicardi syndrome is lethal to male embryos in utero). The disorder is thought to be genetic, although the gene has yet to be identified. Aicardi syndrome is diagnosed based on the presence of three clinical features: coloboma, or absence of normal tissue in the retinas of the eyes; partial or complete absence of the corpus callosum in the brain; and a serious type of seizure called infantile spasms.


The amygdala is a structure of the brain located in the mesial, or middle, of the temporal lobe. As part of the brain's limbic system, the amydala functions in integrating the senses, including sight and hearing, as well as processing and controlling emotion. The amygdala, along with the hippocampus, also functions in transferring information into memory.

Angelman Syndrome (AS)

Angelman syndrome (AS) is a genetic disorder characterized by seizures, ataxia (unsteady gait), language problems (most individuals with AS are nonverbal), cognitive impairment (which is often severe), and a happy demeanor. Because of the way Angelman children walk and their generally joyful disposition, AS is often referred to as the "happy puppet" syndrome.

Anticonvulsant Medication

An anticonvulsant medication is a drug prescribed to help manage seizures by controlling excessive electrical activity in the brain. It is sometimes referred to as an antiepileptic drug (AED).

Applied Behavioral Analysis (ABA)

Applied behavioral analysis (ABA) is a therapeutic educational intervention that has been used successfully with children on the autism spectrum and children with other types of severe learning disorders. The method employs structure and repetition to modify behaviors and introduce new skills.

Atonic Seizure

An atonic seizure is an abnormal discharge of electrical activity in the brain that causes a sudden complete loss of muscle tone or posture. All large muscle groups relax, the limbs go limp, and the individual falls to the floor or ground in what experts generally refer to as a "drop attack."

Attention Deficit Hyperactivity Disorder (ADHD)

Attention deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder that makes learning and social interactions difficult, even for those with normal cognitive abilities, by causing individuals to be easily distracted and frustrated, fidgety, impulsive, and forgetful.

Atypical Absence Seizure

See Absence Seizure.


An aura is a simple partial seizure, which serves as a warning sign occurring seconds or minutes before a complex partial seizure or a partial seizure with secondary generalization. An aura is typically an unusual physical sensation such as a smell, a sound, a feeling of fear, or a sick feeling in the stomach.


Autism is a spectrum disorder, or symptom complex, characterized by deficits in verbal and nonverbal communication skills, severe social dysfunction, and repetitive behaviors. Also known as autism spectrum disorder.


Automatisms are small, repetitive movements during a seizure. Automatisms are involuntary and may include, for example, movements of the mouth or limbs, blinking of the eyes associated with absence seizures, or picking at one's buttons. Automatisms occur most often with absence or complex partial seizures, or after tonic-clonic seizures. Because consciousness is lost, individuals are typically not aware that these movements have occurred.

Autonomic Nervous System

The autonomic nervous system is the part of the nervous system responsible for regulating the involuntary vital functions of the body, including digestion, breathing, heartbeat, and blood flow.

Autosomal Dominant Nocturnal Frontal Lobe Epilepsy

Autosomal dominant nocturnal frontal lobe epilepsy is caused by a single gene mutation in one of three genes. This type of epilepsy produces shaking movements mostly during sleep.


Axons are the long nerve fibers through which nerve cells transmit signals.

Benign Epilepsy Syndromes

Seizures associated with benign syndromes are typically well controlled with medications, are not associated with other neurological symptoms such as learning disabilities, and are often outgrown.

Benign Familial Neonatal Convulsions

Benign familial neonatal convulsions is a type of epilepsy caused by the mutation of a single gene. It usually begins prior to the third day of life and typically goes into remission after two or three weeks.

Benign Rolandic Epilepsy (BRE)

Benign rolandic epilepsy (BRE) is an epilepsy syndrome that typically arises after three years of age and is considered benign because children usually outgrow it by adolescence. In most children with BRE, seizures are infrequent and sometimes do not require medication. Characteristic manifestations of the seizures associated with this syndrome begin with a sensation at the corner of the mouth and drooling, followed by jerking of the mouth that can progress to the rest of that side of the face, and sometimes to that entire side of the body. Although children remain conscious during this type of seizure, they usually are unable to speak for a period of time during and after the seizure. Seizures occur more commonly at night, especially during particular stages of sleep.


Betahydroxybuterate is a by-product produced by the liver during the process of fat metabolism. The liver makes betahydroxybuterate during periods of fasting, starvation, or prolonged physical exertion, or when an individual's epilepsy treatment involves a high-fat dietary therapy such as the ketogenic diet. It is theorized that betahydroxybuterate and acetoacetate (known as ketones or ketone bodies) may accumulate in the brain and be an important factor in seizure control associated with dietary therapies.

Brain Stem

The brain stem is the lowest part of the brain. It connects the midbrain to the spinal cord. The brain stem is comprised of the pons located in the upper portion of the brain stem and the medulla oblongata located in the lower portion of the brain stem. The pons is a bundle of nerve fibers linking the left and right sides of the cerebellum. The medulla oblongata's main function is to relay nerve signals between the brain and the spinal cord. The medulla oblongata also functions to help control autonomic functions including breathing and heart contractions, as well as reflex activities such as swallowing and coughing.

Brain Mapping

See Electrocorticography.

Catastrophic Epilepsy Syndrome

Seizures associated with catastrophic syndromes are often refractory to treatment and are often associated with developmental sequelae.


The cerebellum is the part of the brain located at the back of the head, below the cerebrum and behind the brain stem. The cerebellum is responsible for coordination and balance.

Cerebral Cortex

The cerebral cortex is the highly folded, neuron-rich outer layer of the cerebrum that is referred to as gray matter.


The cerebrum is the largest and most recognizable of the brain's structures. It is made up of a highly folded outer layer, called the cerebral cortex, and an inner layer rich in nerve fibers, which carry signals from the cortex to targets in other parts of the body. The cerebrum is divided into right and left hemispheres, with a bundle of fibers called the corpus callosum connecting and aiding in communication between the two halves. Each hemisphere can be divided further into four functionally distinct lobes: frontal,parietaloccipital, and temporal.

Childhood Absence Epilepsy (CAE)

Childhood absence epilepsy (CAE) is an epilepsy syndrome characterized by absence seizures that occur from one to dozens—and sometimes hundreds—of times per day. Seizures typically arise during childhood between the ages of four and eight years. Tonic-clonic seizures may precede absence seizures and may recur periodically after absence seizures have begun. Most children with childhood absence epilepsy outgrow the propensity for seizures by adolescence. Because of this, CAE is considered a benign epilepsy syndrome.


Chromosomes are structures located in the nucleus of a cell that contain our genetic material (genes). Humans have 23 pairs of chromosomes: Half of each pair is inherited from our mother, and the other half from our father.


The term cognitive refers to the collective mental processes through which knowledge is acquired. It involves, among other things, perception, memory, reasoning, and intuition.

Complex Partial Seizures

Complex partial seizures begin in one area, or focus, of the brain, and then progress, or spread, to other areas of the brain, where they affect consciousness or cause staring, confusion, or loss of alertness. In some cases, they also cause aimless movements called automatisms, such as lip smacking or picking at clothes, the repetition of words or phrases, or inappropriate laughter. See also Partial Seizure.

Computed Tomography (CT)

Computed tomography (CT) is a procedure that uses x-rays and computer technology to produce cross-sectional images of the internal structures of the body, including the brain. The images produced are more detailed than traditional x-ray images. Also known as a CAT scan.


Consciousness is the state of being aware. If consciousness is preserved during a seizure, the individual is aware that the seizure is happening and can respond. If consciousness is lost during a seizure, the individual may appear unresponsive for a short period of time and may not remember the seizure.

Corpus Callosotomy

A corpus callosotomy is a surgical procedure to sever the corpus callosum, the thick band of nerve fibers connecting the right and left sides of the brain. The procedure is done to stop the spread of seizures from one hemisphere to the other.

Corpus Callosum

The corpus callosum is the thick band of nerve fibers connecting the right and left sides of the brain.

Déjà Vu

Déjà vu is a French phrase that translates as "already seen." Déjà vu refers to a sensation or feeling that something being experienced for the first time has actually happened before. Déjà vu is a frequent type of aura for temporal lobe seizures.


Dendrites are branchlike projections through which nerve cells receive signals.

Deoxyribonucleic Acid (DNA)

Deoxyribonucleic acid (DNA) is made up of molecules that encode all the instructions necessary for a living organism to grow. Two long strands of DNA make up the familiar double helix shape.


A dietitian is a medical professional who specializes in diet and metabolism. A dietitian who is knowledgeable about epilepsy and has had specialized training in administering the ketogenic diet and other dietary therapies can instruct patients on how to implement these treatments.

Doose Syndrome or Myoclonic-Astatic Epilepsy (MAE)

Doose syndrome, also called myoclonic-astatic epilepsy (MAE), is an epilepsy syndrome that typically arises in children between the ages of one and five years. The seizures that result are generalized, and there is no known cause for this syndrome. In addition, seizures associated with Doose syndrome are often resistant to anticonvulsant medications, and other treatment options are often considered. Children with Doose syndrome typically experience mixed seizure types.

Drop Attack

A drop attack is a seizure that causes an individual to suddenly fall to the ground. Although many seizure types can cause drop attacks, they are most commonly associated with atonic seizures during which a child experiences a sudden loss of all muscle tone. Also referred to as drop seizure.

Early Intervention

Early Intervention programs vary from state to state, but are generally designed to provide services for infants and young children who are at risk for developmental delays. Services include occupational, speech, and physical therapy.

Educational Psychologist

An educational psychologist is a licensed psychologist who evaluates children with learning difficulties and advises educators and parents on the child's development and educational progress.

EEG Technologist

An EEG technologist is a person who administers the EEG test and who is trained to recognize the abnormal patterns that are characteristic of epileptic seizures.

Electrical Status Epilepticus of Sleep (ESES)

Electrical status epilepticus of sleep (ESES) is near-constant epileptiform activity during as much as 80 percent of sleep in the form of continuous spike and slow wave discharges. ESES is associated with childhood syndromes involving cognitive dysfunction and epilepsy, such as Landau-Kleffner syndrome.

Electrocorticography (EcoG)

Electrocorticography (EcoG) is a diagnostic test in which an electrode is placed onto the brain to record electrical activity. The test is performed in the operating room, typically during epilepsy surgery, and may show or confirm where in the brain seizures are coming from. The procedure is also used to define eloquent cortex, or regions of sensory function such as the areas of the brain that control motor function and speech. This is done by stimulating various parts of the brain with electrical current and then monitoring the effect in the body. Also known as brain mapping.

Electroencephalogram (EEG)

An electroencephalogram (EEG) is a noninvasive diagnostic test used to measure and record the electrical activity of the brain. An EEG is used to help locate the origins of seizures and help diagnose epilepsy.


Encephalitis is a brain inflammation often caused by a viral infection. Encephalitis can cause seizures.


Epilepsy, sometimes called "seizure disorder," is a neurological condition that manifests itself as a susceptibility to seizures. Individuals diagnosed with epilepsy have typically experienced two or more seizures as a result of factors other than preventable conditions, such as fever or low blood sugar levels, which can cause seizures but are not necessarily indicative of epilepsy.

Epilepsy Syndrome

An epilepsy syndrome is defined by patterns of recurrent seizures that follow a similar course from one individual to the next, including age of onset, seizure type, and, often, characteristic EEG patterns. Importantly, individuals with a particular epilepsy syndrome also respond in a predictable manner to medications, and such syndromes may relate to underlying genetic factors and point to a family history of or predisposition to this form of epilepsy.

Epilepsy syndromes are sometimes grouped into two classes: benign and catastrophic. Seizures associated with benign syndromes are typically well controlled with medications and are often outgrown. In contrast, seizures associated with catastrophic syndromes often persist despite medication or the age of the child, and typically result in more extensive developmental problems.


An epileptiform change is a pattern on an electroencephalogram (EEG) that shows abnormal electrical activity in the form of spike wavessharp waves, and slow waves, which may be suggestive of seizures.


Epileptogenic means to cause seizures or epilepsy.


An epileptologist is a neurologist who specializes in treating epilepsy.


Etiology is the cause of a disease or disorder.


Excitation refers to the processes through which brain electrical activity is increased, causing nerve cells to fire. Healthy brain function relies on a balance of excitation and inhibition of nerve cells. Seizures are thought to occur when there is too much excitation, or too little inhibition, in the nerve cells of the brain.

Executive Functioning

Executive functioning, or executive control, describes the processes of developing and applying systematic approaches to solving problems and challenges. This is one of the most complex functions that our brains perform. It involves planning, self-regulation, and the ability to think flexibly or creatively. This allows us to consider more than one option, choose one, and then create a plan of action based on past experience, rather than acting on impulse or emotion.


Extensor refers to muscles that are involved in straightening or extending the joints in the body.

Febrile Seizure

A febrile seizure is a seizure that occurs in young children during rapid elevation of temperature. Febrile seizures are common in children under five years of age, often run in families, and are not considered epilepsy.


Flexor refers to muscles that are involved in bending the joints in the body.


The focus is the place in the brain from which the seizure originates. Foci refers to more than one place of seizure origin.

Frontal Lobe

The frontal lobe makes up the largest portion of the cerebrum. Located just behind the forehead, this area of the brain is responsible for emotions, personality, memory, and skills associated with executive functioning, including problem solving, planning, and self regulation. The frontal lobe also includes the motor strip, which controls muscles in the limbs and face.

Functional Magnetic Resonance Imaging (fMRI)

Functional MRI is a noninvasive procedure that uses a special magnetic resonance imaging scanner to look at blood flow in the brain to determine which areas of the brain are activated during such physical activities as seeing, hearing, and touching.

Gelastic Epilepsy

Gelastic epilepsy is a type of epilepsy characterized by inappropriate laughter known as laughing seizures, though people with gelastic epilepsy may also experience other seizure types. Gelastic comes from the Greek word gelos, which means "laughter."


A gene is a unit of DNA that codes for the formation of a specific protein. Genes are the fundamental units of heredity. Genes come in pairs: One half of each pair is inherited from our mother, and the other half from our father.

Gene Mutation

A gene mutation is a permanent change in the DNA of a gene. Mutations can be inherited or can occur spontaneously.

Generalized Epilepsy with Febrile Seizures Plus (GEFS+)

Generalized epilepsy with febrile seizures plus (GEFS+) is a type of epilepsy caused by the mutation of a single gene. GEFS+ arises in childhood, with seizures occurring during episodes of fever, and then progresses to generalized seizures.

Generalized Seizures

Generalized seizures are thought to involve both sides of the brain spontaneously at seizure onset. Specialists recognize two classes of generalized seizures based on how they manifest themselves. Nonconvulsive generalized seizures alter consciousness but do not cause convulsions; convulsive generalized seizures also alter consciousness and cause repetitive jerking and stiffening movements. Generalized epilepsy is when a person has more than one generalized seizure.


Gestation is the period of time from the fertilization of the egg by the sperm until the birth of a child, or the length of a pregnancy.

Glial Cell

A glial cell is a specialized cell that surrounds nerve cells and provides structural and metabolic support. It is estimated that glial cells outnumber neurons by as much as 50 to 1. Also known as neuroglia or glia.

Glycemic Index

The glycemic index is a measure of a particular food's effect on the body's blood-sugar level. Foods that contain simple sugars, such as sucrose (table sugar), have a high glycemic index because they rapidly raise blood sugar after consumption. Conversely, many grains and legumes have a low glycemic index because they affect blood-sugar levels more slowly.

Grand Mal Seizure

See Tonic-Clonic Seizure.


Hemiparesis is a weakness or partial paralysis of one side of the body.


Hemiplegia is paralysis on one side of the body.


A hemispherectomy is a surgical procedure in which half of the brain, or one hemisphere, is removed. Hemispherectomy is used most often to treat intractable epilepsy where the epileptogenic region involves most of one cerebral hemisphere, such as in Sturge-Weber syndrome.


The hippocampus is a structure of the brain located in the mesial, or middle, of the temporal lobe. As part of the brain's limbic system, the hippocampus is important for learning and memory. The hippocampus functions in transferring information, including sensory inputs like tastes and sounds, into memory. The hippocampus, along with the amygdala, also functions in integrating and recalling spatial memory, as well as processing and controlling emotion.


Hydrocephalus is a buildup of cerebrospinal fluid in the ventricles of the brain, causing increased intracranial pressure. Hydrocephalus may present at birth or result from a head injury or tumor, and can cause seizures.


Hyperventilation is increased rapid and deep breathing. Hyperventilation is often used as an activating procedure during an EEG because it can sometimes provoke abnormal brain wave activity, helping doctors make a diagnosis or identify an individual's seizure type.


Hypoxia is a condition in which there is a deficiency or inadequate amounts of oxygen reaching the tissues. An insufficient supply of oxygen to the brain can cause seizures.


Hypsarrhythmia is a markedly abnormal and chaotic EEG pattern characterized by multifocal spike and slow wave discharges, very high amplitudes, and lack of organization. Hypsarrhythmia is a characteristic of West syndrome.


Ictal refers to the period of time during a seizure.


The word ictus comes from Latin and means "sudden attack." In epilepsy, an ictus is a seizure.


The word idiopathic refers to a disorder or symptom of unknown cause, as in idiopathic epilepsy or idiopathic seizures. Approximately 65 to 70 percent of epilepsy cases are idiopathic.

Individualized Educational Plan (IEP)

An Individualized Education Plan (IEP) is a written education plan for a student with learning disabilities that is developed by a team of professionals (teachers, therapists, etc.) and the student's parents. An IEP is based on a multidisciplinary evaluation of the student, describing how the student is currently doing, what the student's learning needs are, and what services will be needed to optimize the student's learning potential.

Infantile Spasms

Infantile spasms is an epilepsy syndrome that affects infants and very young children. The syndrome is characterized by a form of myoclonic seizures, which may be identified by a sudden jerking of the body, in which the child flexes or extends at the trunk. The indication may also be more subtle, such as staring or blinking. Infantile spasms commonly appear in clusters, typically occurring as the child is going to sleep or soon after waking.

Although not all spasms are immediately obvious, parents are still likely to pick up on the subtle clues that suggest something may be out of the ordinary with their child. Acting quickly on these suspicions by seeking the advice of a pediatrician or epilepsy specialist is critical to controlling infantile spasms. Appropriate treatment may in turn reduce the incidence and severity of learning disabilities and behavioral disorders associated with these seizures. See also West Syndrome.


Inhibition refers to the processes through which brain electrical activity is slowed, causing nerve cells to stop firing. Healthy brain function relies on a balance of excitation and inhibition of nerve cells. Seizures are thought to occur when there is too much excitation or too little inhibition in the nerve cells of the brain.


Interictal refers to the period of time between seizures.


Intractable seizures are seizures that are difficult to control with anticonvulsant medications. If an individual's epilepsy is intractable, it typically means that two or more appropriate medications have failed to adequately control seizures. Also known as refractory.


An ion is an electrically charged atom or group of atoms. The atoms become electrically charged by gaining or losing one or more electrons. For example, sodium, potassium, and calcium all gain an electron and become positively charged, while chloride loses an electron and becomes negatively charged.

Ion Channels

Ion channels are the proteins that allow for and regulate the flow of ions across cell membranes.

Juvenile Myoclonic Epilepsy (JME)

Juvenile myoclonic epilepsy (JME) is an epilepsy syndrome that typically begins in late childhood or early adolescence. It is characterized by myoclonic jerks as the individual is going to sleep or waking, though typically in the morning. Children describe intense feelings of jumpiness that generally subside after about 30 minutes. In addition to the myoclonic seizures, children with juvenile myoclonic epilepsy also have periodic tonic-clonic seizures.

Ketogenic Diet

The ketogenic diet is a dietary therapy used to treat epilepsy. The ketogenic diet consists mostly of fats, with limited carbohydrates and the recommended daily allowance of protein. Dietitians carefully calculate individualized meal plans for patients based on their calorie and protein needs for growth and development, and their ketogenic diet ratio. The prescribed ratio refers to grams of fat to grams of protein and carbohydrates combined. The higher the ratio, the larger the percentage of fat in the diet.

Ketones or Ketone Bodies

Ketones are the by-products of fat metabolism. Ketones are typically present in the blood, urine, and breath when the body uses fat as its primary energy source, as in the ketogenic diet. Ketones may be an important factor in seizure control associated with dietary therapies. See also Betahydroxybuterate and Acetoacetate.


Ketosis is the metabolic state in which ketones are present in the body as a result of burning fat as the primary energy source.

Landau-Kleffner Syndrome

Landau-Kleffner syndrome is a rare epilepsy syndrome characterized by a loss of speech thought to be related to abnormal electrical activity in the child's brain during sleep. Typically, an otherwise normally developing child experiences mild seizures and then slowly loses the ability to understand language and the ability to speak, as well as an interest in communicating. All individuals show electrical status epilepticus of sleep, or near continuous epileptiform activity during as much as 80 percent of their sleep. The syndrome frequently causes lifelong language deficits. Unfortunately, a deeper understanding of the syndrome's cause and possible treatment remains elusive.

Learning Disability

A learning disability is a condition that either prevents or hinders somebody from learning basic skills or information at the same rate as most people of the same age.

Lennox-Gastaut Syndrome

Lennox-Gastaut syndrome is an epilepsy syndrome that often arises between the ages of two and six and is common among children who experienced infantile spasms. The syndrome has no single cause but typically results from some developmental brain disorder or brain injury. Children with Lennox-Gastaut syndrome have two or more seizure types, one of which is the atonic type of seizure, which causes loss of muscle tone and a sudden collapse to the ground.

Lennox-Gastaut is considered a mixed seizure disorder and shows characteristic EEG patterns of slow spike and wave activity. Treatment of the syndrome typically requires multiple medications, sometimes with little improvement. Because Lennox-Gastaut syndrome is difficult to treat and often comes with a poor prognosis, it is considered a catastrophic epilepsy syndrome. Fortunately, some children with Lennox-Gastaut respond well to medications and/or other anticonvulsant therapies, such as the ketogenic diet, and experience a great reduction or cessation of their seizures.


A lesion is a wound, injury, destructive change, or area of dysgenesis (abnormal development). The term lesion is sometimes used as another word for tumor, but does not always mean tumor.

Limbic System

The limbic system is a group of structures in the mesial, or middle, brain and is responsible for regulating such autonomic functions as heart rate, blood pressure, and temperature, as well as generating and controlling emotional response and storing memories. The limbic system includes such structures as the amygdala, the hippocampus, and the thalamus.

Low Glycemic Index Treatment (LGIT)

The low glycemic index treatment (LGIT) is a new dietary therapy currently being studied to treat epilepsy. LGIT attempts to reproduce the positive effects of the ketogenic diet. The treatment allows a more generous intake of carbohydrates than the ketogenic diet, but is restricted to foods that have a low glycemic index, meaning foods that have a relatively low impact on blood-glucose levels.

Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is a noninvasive procedure that uses radio waves and magnetic fields to produce images of body tissue. The images produced are more detailed than traditional x-ray images and computed tomography (CT) scans. The MRI is particularly important in identifying brain abnormalities that are small or only subtly different from normal tissue.

Magnetic Resonance Spectroscopy (MRS)

Magnetic resonance spectroscopy (MRS) is a diagnostic tool that provides information about metabolism in the brain and may be able to detect biochemical abnormalities. The MRS is often used in conjunction with structural imaging such as the MRI.

Magnetoencephalogram (MEG)

The magnetoencephalogram (MEG) is a noninvasive diagnostic test that detects and records the magnetic fields produced by the electrical activity in the brain and helps doctors determine and monitor brain function.


Meningitis is an inflammation of the meninges, the membranes surrounding the brain and spinal cord, typically caused by a bacterial or viral infection. Meningitis can cause seizures.


Metabolic refers to metabolism, which is the physical and chemical processes through which the body produces energy.

Modified Atkins Diet

The modified Atkins diet is a dietary therapy used to treat epilepsy. The diet was first developed in 2003 as an alternative to the classic ketogenic diet. The modified Atkins diet is also high in fat and low in carbohydrates. Families following this treatment regimen no longer have to weigh and measure foods or follow specific meal plans. Daily carbohydrates are restricted to 10 grams per day for the first month and subsequently liberalized to 15-20 grams per day if 10 grams is too restrictive.

Motor Strip

The motor strip is a part of the brain located in the frontal lobe, near the border of the parietal lobe. The motor strip is responsible for movement in parts of the body such as the face, hands, arms, and legs.

Myelin Sheath

The myelin sheath is a fatty, protein-rich covering on the axons of many neurons that aids in the transmission of electrical signals from one neuron to another, from one side of the brain to the other, and directly to the tissues such as the muscles.

Myoclonic-Astatic Epilepsy (MAE)

See Doose Syndrome.

Myoclonic Seizures

Myoclonic seizures are generalized seizures characterized by single, intense muscular contractions that may result in a powerful jerk of the limbs, trunk, or face. They are thought to result from abnormal activity in an area of the brain responsible for muscle tone and posture. When myoclonic seizures cause the contraction of large muscle groups, such as the flexor or extensor muscles of the trunk, an individual may be thrown forward or backward powerfully, often causing injury.


Neurocircuit refers to the extensive network of pathways created by neurons in the brain.

Neurodevelopmental Evaluation

See Neuropsychological Evaluation.


Neurofibromatosis is a genetic disorder caused by a mutation in the NF1 or NF2 gene. Neurofibromatosis 1 (NF1) is characterized by multiple benign tumors and patches of skin pigmentation called cafe au lait spots. Neurofibromatosis 2 (NF2) is characterized by tumors of the hearing and balance nerve.


Neurological refers to the nerves and nervous system, including the brain.


A neurologist is a physician who specializes in disorders of the nervous system. A neurologist who treats people with epilepsy is trained to recognize abnormal patterns of brain activity in EEGs and brain abnormalities. A pediatric neurologist is a neurologist who specializes in treating children affected by disorders of the nervous system. An epileptologist is a neurologist who specializes in the treatment of epilepsy.


A neuron is a specialized cell that transmits electrical and chemical signals in the body's nervous system. Also known as a nerve cell. The term neuronal refers to the neuron. The term neural refers to the nerves and the nervous system.

Neuropsychological Evaluation

A neuropsychological evaluation involves a battery of tests used to assess cognitive and behavioral functions and identify areas of cognitive impairment. Also known as neurodevelopmental evaluation.


A neuropsychologist is a licensed psychologist with specialized training in brain-behavior relationships and the evaluation of cognitive functions. Neuropsychologists use a battery of standardized tests to assess specific cognitive and behavioral functions and identify areas of cognitive strengths and impairment as they relate to brain functioning.


A neuroradiologist is a physician who interprets images, including x-rays, ultrasounds, CT scans, and MRIs, of the central nervous system, including the brain. A neuroradiologist is trained to recognize abnormalities in brain structure.


A neurosurgeon is a surgeon who specializes in performing surgery on the nervous system, including the brain. A neurosurgeon who treats people with epilepsy is trained in the identification and resection (surgical removal) of brain regions where seizures originate. Neurosurgeons are often also qualified to treat epilepsy with implants such as the vagus nerve stimulator (VNS).


Neurotransmitters are specialized chemicals released at the synapse that act as messengers between nerve cells.

Occipital Lobe

The occipital lobe is located at the back of the cerebrum, behind the temporal and parietal lobes. One of the most important functions of this lobe is the processing of visual stimuli.

Parietal Lobe

The parietal lobe is located at the top of the cerebrum, behind the frontal lobe. This lobe receives much of the body's sensory stimuli and is responsible for integrating and interpreting information related to touch, sound, smell, and vision. The area of the parietal lobe most involved in sensation is the sensory strip, portions of which have been linked to specific body parts and/or functions.


Paroxysmal refers to the sudden occurrence of a symptom, like an attack or a seizure.

Partial Seizures

Partial seizures are seizures that begin in one area, or focus, of the brain. They may or may not affect consciousness, depending on where in the brain they occur and the specialized brain structures they might involve. A partial seizure that does not affect consciousness is called a simple partial seizure. A partial seizure that alters consciousness is called a complex partial seizure.

Partial Seizure with Secondary Generalization

A partial seizure with secondary generalization is a seizure that begins focally, meaning in one area, and progresses very rapidly to involve the entire brain. Sometimes referred to as secondary generalized seizure.

Petit Mal Seizure

See Absence Seizure.


Pharmacological refers to pharmacology, which is the study of drugs and their properties, interactions, and reactions on living organisms.


Plasticity is the brain's astounding capacity to create new connections and relearn information or behaviors that were lost due to seizures or other insults to the brain. The developing brain does this by creating new functional neuronal networks. The brain has the greatest plasticity in childhood, and the potential for plasticity diminishes over time.

Polypharmacy or Polytherapy

Polypharmacy or polytherapy is the use of more than one anticonvulsant medication simultaneously for the treatment of epilepsy. Polytherapy may also be the use of an anticonvulsant medication in combination with a dietary therapy or the vagus nerve stimulator. Also known as combination therapy.

Positron Emission Tomography (PET)

Positron emission tomography (PET) is a neuroimaging technique in which a small amount of short-lived radioactive tracer is injected into the body and a scanner is used to determine where in the body the tracer is being metabolized. PET can be used to look at metabolic activity in the brain and determine the source of seizure activity (often an area of reduced metabolism in comparison to surrounding tissue) in preparation for seizure surgery.


Postictal refers to the period of time after a seizure during which an individual may be recovering from the effects of the seizure, including feelings of drowsiness and disorientation. Postictal also refers to the changes on an EEG following a seizure.


Pruning is the process by which unused or unnecessary portions of the brain's complex network of neural connections are periodically eliminated. This natural process improves the efficiency of brain's neurocircuitry.


A pseudoseizure is a nonepileptic event resembling a seizure, which results from subconscious mental activity. May also be referred to as a nonepileptic event.


A psychiatrist is a medical doctor who specializes in the diagnosis and treatment of mental and behavioral disorders. A psychiatrist who treats people with epilepsy is familiar with the cognitive and behavioral issues that are common to the disorder and knows what treatment options are most effective for these issues, including medication options.


A psychologist is a licensed professional who specializes in the diagnosis and treatment of mental, emotional, and behavioral problems, and may be involved in evaluation, testing, counseling, and/or psychotherapy.

Rasmussen's Syndrome

Rasmussen's syndrome is a rare and progressive neurological disorder that is characterized by intractable partial seizures and inflammatory changes affecting one cerebral hemisphere. Treatment for Rasmussen's syndrome often involves a hemispherectomy, or removal of half of the brain.


The term refractory refers to a medical condition or disease that does not respond to treatment. Also known as intractable.


A resection is the surgical removal of tissue or a portion of a structure or organ.


In education, scaffolding refers to teaching strategies designed to provide students with the appropriate supports so they can build on what they are learning and move to the next level.

Secondary Generalized Seizure

See Partial Seizure with Secondary Generalization.


A seizure is a sudden abnormal burst of electrical activity in the brain that causes an alteration of sensation, behavior, or consciousness.

Seizure Threshold

Seizure threshold is the minimal conditions required to produce a seizure. Seizure threshold varies from individual to individual.

Selective Serotonin Reuptake Inhibitor (SSRI)

A selective serotonin reuptake inhibitor (SSRI) is a type of antidepressant drug that blocks or slows the removal of serotonin from synapses, preventing it from being absorbed by nerve cells that make it. Serotonin is a neurotransmitter thought to be responsible for many functions including appetite and mood. By blocking the uptake of serotonin, SSRIs can help regulate mood.

Sensory Strip

The sensory strip is a part of the brain located in the parietal lobe, near the border of the frontal lobe. The sensory strip is involved in registering sensations, which are linked to specific body parts and/or functions.


Sequelae are conditions that result from an injury, disease, or treatment.

Serum Lipids

Serum lipids refer to insoluble fats, fatty acids, or fat compounds in the blood. Lipids are fats. Serum is the clear liquid part of the blood.

Sharp Waves

On an EEG, sharp waves are deviations from a normal brain wave activity and are distinguished by more sharply contoured waveforms of varying amplitude, or voltage. The duration of each sharp wave is 70 to 200 milliseconds. Spike waves, sharp waves, or distinct patterns of spike and sharp waves or spike and slow waves may be indicative of seizure activity.

Simple Partial Seizures

See Partial Seizures.

Single Photon Emission Spectroscopy (SPECT)

Single Photon Emission Spectroscopy (SPECT) is a special type of computed tomography (CT) scan during which a small amount of radioactive dye is injected, allowing doctors to make detailed images of the brain and get information about blood flow in the brain.

Slow Waves

On an EEG, slow waves have a much slower frequency than do normal brain waves and can also vary in amplitude, or voltage. Spike wavessharp waves, or distinct patterns of spike and sharp waves or spike and slow waves may be indicative of seizure activity. Additionally, slowing of brain waves may suggest a structural or functional abnormality, such as a tumor or an area of the brain that developed abnormally, that could be associated with seizures.

Social Worker

A social worker is a licensed professional who provides support to families and children with medical or psychological issues. A social worker may provide counseling pertaining to emotional, social, and physical needs, and facilitate access to services and organizations.

Spike Waves

On an EEG, spike waves are deviations from a normal brain wave activity and are distinguished by more sharply contoured waveforms of varying amplitude, or voltage. The duration of each spike wave is less than 70 milliseconds. Spike waves, sharp waves, or distinct patterns of spike and sharp waves or spike and slow waves may be indicative of seizure activity.

Staring Seizure

See Absence Seizure.

Status Epilepticus

Status epilepticus is a seizure lasting for 15 minutes or more, or back-to-back seizures without sufficient recovery time in between. Status epilepticus is considered a medical emergency, given that in some cases, if left untreated, it may cause long-lasting or permanent brain injury, or in rare cases, respiratory arrest and death.

Stevens Johnson Syndrome

Stevens Johnson syndrome is a severe immune system response caused by an allergic reaction to medication which can require hospitalization or be life threatening. Individuals with Stevens Johnson syndrome typically experience a full body rash, often involving mucous membranes such as the gums.

Sturge-Weber Syndrome

Sturge-Weber syndrome is a genetic disorder characterized by a port wine birthmark on one side of the face, glaucoma, and seizures.

Sudden Unexplained Death in Epilepsy (SUDEP)

Sudden unexplained death in epilepsy (SUDEP) is very rare, and experts think that most cases of SUDEP result from an abnormal heart rhythm and/or impaired respiration. However, little is known about this condition because it occurs in only about 1 in 3,000 people with epilepsy each year.


Symptomatic refers to medical conditions for which there is a known cause.


A synapse is the junction between two nerve cells through which signals pass, usually in the form of neurotransmitters.


Syncope is the temporary loss of consciousness, or fainting.

Temporal Lobe

The temporal lobe, as the name implies, is located near the temples, just below the center of the cerebrum. This area of the brain is responsible for language and memory, as well as speech and auditory perception.


The thalamus is a structure in the inner brain, located at the top of the brain stem. The thalamus is responsible for receiving sensory information (except smell) and relaying it to the rest of the brain.

Tonic Seizures

Tonic seizures are generalized seizures characterized by prolonged contraction of the large muscle groups involved in posture, as well as stiffening of the limbs. In contrast to many seizure types, tonic seizures do not produce rhythmic convulsions. They usually occur shortly before or after waking and usually involve most of the brain, typically resulting in a loss of consciousness.

Tonic-Clonic Seizures

Tonic-clonic seizures (formerly known as grand mal seizures) are the type most people imagine when they think about epilepsy, and they are a common type of seizure in children. These convulsive generalized seizures typically begin with a cry or sound caused by air being forced from the lungs, then progress to the tonic phase, which often involves a fall to the floor, stiffening of the limbs, clenching of teeth, and rolling back of the eyes. The tonic phase, which rarely lasts more than 30 seconds, is followed by the clonic phase, which presents itself as the rapid, rhythmic jerking of the limbs and torso. This phase is also characterized by shallow breathing, a bluish appearance to the skin, and loss of bladder and/or bowel control. The clonic phase typically lasts for a few minutes before it gradually begins to slow and eventually stops. After the seizure, individuals are typically difficult to rouse and, if awakened, will be sleepy and confused.

Tuberous Sclerosis Complex (TSC)

Tuberous sclerosis complex (TSC) is a genetic disorder that can affect most major organs, including the brain, and causes seizures in approximately 80 percent of patients. Approximately one-third of children with TSC experience infantile spasms.


The uncus is a structure of the brain located in the mesial, or middle, of the temporal lobe. The uncus functions in processing smells.

Vagus Nerve Stimulator (VNS)

The vagus nerve stimulator (VNS) is a therapy used to treat seizures. This technique relies on a pacemaker-like device that is implanted under the skin of the chest and supplies intermittent electrical impulses to the vagus nerve as it passes through the neck. The vagus nerve is a cranial nerve within the autonomic nervous system that influences motor functions in the larynx, diaphragm, stomach, and heart. Intermittent stimulation of this nerve with low-intensity electrical impulses may reduce seizures in some people. This therapy is most often used in conjunction with medications.

Video Electroencephalogram (vEEG)

The video EEG provides simultaneous recording of video and electrical activity in the brain. This enables physicians to relate any abnormal electrical patterns to any physical manifestations that a seizure might cause. This can help physicians identify the seizure focus, estimate seizure frequency, and differentiate seizures from nonepileptic events. See also Electroencephalogram.


The WADA test is typically performed before seizure surgery on the temporal lobe to test the temporal lobe functions of language and memory. During the WADA test, doctors put each half of the brain to sleep for a few minutes. This allows a neuropsychologist to test the language and memory functioning of each side of the temporal lobe in isolation. The results of the test show doctors how much of the language and memory functions are located in the right and left sides of the brain, and are used to determine how much of the temporal lobe can be removed. The Wada test is named after the neurologist Juhn A. Wada, MD, who first performed the test.

West Syndrome

West syndrome is a neurological disorder of infancy and early childhood, characterized by the presence of three features: a highly chaotic EEG pattern known as hypsarrhythmia, a type of seizure called infantile spasms, and intellectual disability.

Working Memory

Working memory is the ability to not only access information previously acquired, but also to make generalizations about this information and apply it to other types of situations. By accessing this prior knowledge, an individual acquires a deeper understanding by discovering how the original information fits within the context of other knowledge.