Glossary

This glossary includes common medical terms, abbreviations, and concepts you may encounter when learning about epilepsy.

A

Absence seizure: A type of generalized seizure characterized by brief episodes of staring and impaired awareness, typically lasting 3-10 seconds. Most common in children.
Acute symptomatic seizure: A seizure that occurs as a direct result of an acute brain insult or systemic condition (e.g., during a fever, head injury, or metabolic disturbance). Also called a provoked seizure.
AED: Anti-Epileptic Drug — an older term for seizure medications. Now more commonly called ASMs (Anti-Seizure Medications).
Afebrile: Without fever.
Aura: A focal aware seizure that may precede a larger seizure. The person experiences unusual sensations, emotions, or perceptions while remaining conscious. Often serves as a warning that a bigger seizure is coming.
ASM: Anti-Seizure Medication — the current preferred term for medications used to prevent seizures.
Atonic seizure: A seizure characterized by sudden loss of muscle tone, causing the person to collapse or drop. Also called a “drop attack.”
Atypical absence: A type of absence seizure with a slower onset and offset than typical absence seizures, often with more pronounced motor features.
Automatisms: Repetitive, purposeless movements during a seizure, such as lip smacking, chewing, picking at clothes, or fumbling with objects.

B

Benign: In epilepsy, this term describes syndromes that typically resolve on their own without long-term consequences, though the term is being used less frequently.
Bilateral: Affecting both sides of the brain or body.
Breakthrough seizure: A seizure that occurs despite being on anti-seizure medication.

C

Catamenial epilepsy: Epilepsy in which seizures are related to the menstrual cycle, often occurring more frequently around menstruation.
CBZ: Abbreviation for carbamazepine, a commonly used ASM.
Clonic: Rhythmic jerking movements.
Cognitive: Related to thinking, learning, memory, and mental processing.
Comorbidity: A condition that occurs alongside epilepsy, such as ADHD, anxiety, or autism.
Complex partial seizure: An older term for what is now called a focal impaired awareness seizure.
Convulsion: A seizure with prominent motor features, especially jerking movements. Often used to describe tonic-clonic seizures.
Cryptogenic: An older term meaning the cause of epilepsy is hidden or unknown. Now more commonly called “unknown etiology.”

D

DBS: Deep Brain Stimulation — a treatment involving implanted electrodes that deliver electrical stimulation to specific brain areas to reduce seizures.
Developmental delay: When a child doesn’t reach developmental milestones at the expected age.
Dravet syndrome: A severe genetic epilepsy syndrome that typically begins in infancy with prolonged febrile seizures.

E

EEG: Electroencephalogram — a test that records the brain’s electrical activity using electrodes placed on the scalp.
Electrographic seizure: Seizure activity seen on EEG without obvious clinical symptoms. Also called a subclinical seizure.
EMU: Epilepsy Monitoring Unit — a specialized hospital unit where patients stay for continuous video-EEG monitoring to capture and analyze their seizures.
Encephalopathy: A general term for brain dysfunction or disease. Some epilepsy syndromes are called “epileptic encephalopathies” because the seizures and abnormal brain activity interfere with brain development.
Epileptiform: EEG patterns (such as spikes or sharp waves) that suggest an increased risk of seizures.
Epileptogenic zone: The area of brain tissue responsible for generating seizures. The target for surgical removal in epilepsy surgery.
Etiology: The cause or origin of a disease or condition.

F

Febrile seizure: A seizure that occurs in a young child (typically 6 months to 5 years) during a fever, without evidence of brain infection or other definable cause.
Focal: Starting in or affecting one area of the brain. Previously called “partial.”
Focal to bilateral tonic-clonic: A seizure that starts in one area of the brain (focal) and then spreads to involve both sides (bilateral). Previously called “secondarily generalized.”

G

GABA: Gamma-aminobutyric acid — the main inhibitory neurotransmitter in the brain. Many ASMs work by enhancing GABA activity.
Generalized: Involving both sides (hemispheres) of the brain from the beginning of the seizure.
Grand mal: An older term for a tonic-clonic seizure.

H

Hemispheric: Related to one hemisphere (half) of the brain.
Hippocampal sclerosis: Scarring and cell loss in the hippocampus (a brain structure important for memory), often found in temporal lobe epilepsy.
Hyperventilation: Rapid, deep breathing. Sometimes used during EEG to try to provoke absence seizures.

I

Ictal: During a seizure. Ictal symptoms are what happens during the seizure itself.
Idiopathic: Of unknown cause, though often implying a genetic basis. This term is being replaced by “genetic” or “unknown etiology.”
IEP: Individualized Education Program — a legal document that outlines special education services and accommodations for a student with disabilities.
ILAE: International League Against Epilepsy — the leading international organization dedicated to epilepsy research and education.
Interictal: Between seizures. Interictal EEG abnormalities occur between seizure events.
Intractable epilepsy: Epilepsy that doesn’t respond adequately to medication. Now more commonly called drug-resistant epilepsy or refractory epilepsy.

J

JME: Juvenile Myoclonic Epilepsy — a common genetic epilepsy syndrome that typically begins in adolescence with myoclonic jerks, often occurring in the morning.

K

Ketogenic diet: A high-fat, low-carbohydrate medical diet used to treat epilepsy, particularly in children with drug-resistant epilepsy.

L

Lamotrigine (LTG): A commonly prescribed ASM, brand name Lamictal.
Lennox-Gastaut syndrome (LGS): A severe epilepsy syndrome characterized by multiple seizure types, cognitive impairment, and slow spike-wave pattern on EEG.
Levetiracetam (LEV): A commonly prescribed ASM, brand name Keppra.
Lorazepam: A benzodiazepine medication (brand name Ativan) used to stop active seizures.

M

MEG: Magnetoencephalography — a neuroimaging technique that measures magnetic fields produced by electrical activity in the brain, used in presurgical evaluation.
Mesial temporal sclerosis: Another term for hippocampal sclerosis, a common cause of temporal lobe epilepsy.
Monotherapy: Treatment with a single medication, as opposed to using multiple medications.
MRI: Magnetic Resonance Imaging — a scan that creates detailed images of the brain structure.
Myoclonic: Brief, shock-like muscle jerks.

N

Neocortex: The outer layer of the brain, involved in higher functions like conscious thought, language, and sensory perception.
Neurologist: A doctor who specializes in diseases of the nervous system, including epilepsy.
Neuropathy: Damage to peripheral nerves, which can be a side effect of some ASMs.
Neurostimulation: Treatment using electrical stimulation to modulate brain activity, such as VNS, RNS, or DBS.
Neurosurgeon: A surgeon who operates on the brain and nervous system.

O

Occipital lobe: The back part of the brain, responsible for processing vision.
Oxcarbazepine (OXC): A commonly prescribed ASM, brand name Trileptal.

P

Parietal lobe: The upper-middle part of the brain, involved in processing sensory information and spatial awareness.
Partial seizure: An older term for focal seizure.
Petit mal: An older term for absence seizure.
Phenobarbital: One of the oldest ASMs, a barbiturate medication.
Phenytoin (PHT): An older ASM, brand name Dilantin.
Photosensitivity: Sensitivity to flashing lights or patterns, which can trigger seizures in some people with epilepsy.
Polypharmacy: The use of multiple medications together.
Postictal: The period immediately after a seizure, during which the brain is recovering. May include confusion, fatigue, or other symptoms.
Prophylactic: Preventive. ASMs are prophylactic medications that work to prevent seizures from occurring.
Provoked seizure: A seizure caused by an immediate, reversible factor (fever, low blood sugar, head injury, etc.). Does not meet criteria for epilepsy diagnosis. Also called acute symptomatic seizure.

R

Refractory epilepsy: Epilepsy that doesn’t respond to two or more appropriately chosen ASMs. Also called drug-resistant epilepsy.
Rescue medication: Fast-acting medication (usually a benzodiazepine) given to stop a prolonged seizure or cluster of seizures.
RNS: Responsive Neurostimulation — an implanted device that detects seizure activity and delivers electrical stimulation to stop seizures.

S

Secondary generalization: Old term for when a focal seizure spreads to become generalized. Now called “focal to bilateral tonic-clonic.”
Seizure disorder: Another term for epilepsy, though less precise.
Seizure threshold: The level of stimulation needed to trigger a seizure. A lower threshold means seizures occur more easily.
Simple partial seizure: An older term for focal aware seizure.
Status epilepticus: A medical emergency defined as a seizure lasting longer than 5 minutes, or multiple seizures without full recovery in between.
SUDEP: Sudden Unexpected Death in Epilepsy — a rare but serious risk in epilepsy where a person dies suddenly without a clear cause, often related to seizures.
Symptomatic epilepsy: Epilepsy with an identified structural or metabolic cause. Now more commonly described by the specific etiology (structural, genetic, infectious, etc.).
Syncope: Fainting due to temporary reduced blood flow to the brain. Can be mistaken for a seizure but is not epileptic.

T

Temporal lobe: The side part of the brain, involved in memory, emotion, hearing, and language. The most common site of focal epilepsy.
Therapeutic range: The blood level range of a medication considered most likely to be effective with acceptable side effects.
Todd’s paralysis: Temporary weakness on one side of the body after a focal seizure, lasting minutes to hours.
Tonic: Stiffening of muscles.
Tonic-clonic: A type of generalized seizure with two phases: stiffening (tonic) followed by rhythmic jerking (clonic). Previously called “grand mal.”
Topiramate (TPM): A commonly prescribed ASM, brand name Topamax.
TLE: Temporal Lobe Epilepsy — the most common type of focal epilepsy in adults.

U

Unprovoked seizure: A seizure that occurs without an immediate, reversible cause. Two or more unprovoked seizures typically meet the definition of epilepsy.

V

Valproic acid (VPA): A commonly prescribed ASM, brand names Depakote, Depakene, Epilim.
Vagus nerve: A major nerve running from the brain to the abdomen.
Video-EEG: Simultaneous video recording and EEG monitoring to capture and analyze seizures.
VNS: Vagus Nerve Stimulation — a treatment involving an implanted device that sends electrical pulses to the vagus nerve to reduce seizures.

W

Wean: Gradually reduce the dose of a medication, typically to discontinue it safely.
West syndrome: An epilepsy syndrome occurring in infancy, characterized by infantile spasms, developmental regression, and a chaotic EEG pattern called hypsarrhythmia.

Z

Zonisamide (ZNS): An ASM, brand name Zonegran.

Don’t See a Term?

If you encounter a term not listed here that you feel I should add, let me know! :::