Epilepsy Glossary

Reviewed by: HU Medical Review Board | Last reviewed: November 2021


Absence seizure
An absence seizure is named for the brief, blank stare common to these seizures. Absence seizures are more common in children. These used to be called petit mal seizures.1

Atonic seizure
Atonic seizures cause muscles to relax. These seizures are also known as drop attacks, since the person having them often falls to the ground.2

An aura is a type of seizure that serves as a warning that another seizure may take place soon. People describe their auras in a variety of ways. It can be a sense of doom or a change in vision, smell, taste, or sound.3


Catamenial epilepsy
Catamenial epilepsy is a type of epilepsy triggered by hormonal changes during the menstrual cycle. These may also be called menstrual seizures.4

Clonic seizure
Clonic seizures cause rhythmic, repeated jerking on both sides of the body.2

A type of seizure symptom that may include jerking motions, falling, grunting, drooling, and abnormal eye movements.3


Drug-resistant epilepsy
This is also called refractory, uncontrolled, or intractable epilepsy. Someone has drug-resistant epilepsy if they tried 2 anti-seizure drugs and did not become and stay seizure-free. These 2 drugs may be tried 1 after another or both at the same time.5


EEG stands for electroencephalogram. An EEG is a test that measures electrical activity in the brain. It is one of the most important tests used to diagnose epilepsy or rule it out.6

Epilepsy is a neurological (brain) disease that causes people to have seizures.7


Focal seizure
Focal seizures are seizures caused by abnormal electrical activity in part of the brain. These are the most common seizures. You may hear them called partial seizures.2


Generalized seizure
Generalized seizures are seizures that happen on both sides of the brain. The seizure may also start on 1 side of the brain and then spread to the whole brain. The 2 main types of generalized seizures are tonic-clonic (grand mal) and absence (petit mal).7

Grand mal seizure
"Grand mal" is an old term for a generalized tonic-clonic seizure.2


Intractable epilepsy
"Intractable epilepsy" is another name for drug-resistant epilepsy.4


Keto diet
A high-fat, low-carbohydrate diet that helps control seizures in some people with epilepsy. It is often used in children with certain types of epilepsy.8


Myoclonic seizure
Myoclonic seizures cause occasional, brief jerking. The person having them remains aware of their surroundings. The jerking usually happens on both sides of the body.2


A type of treatment that uses a device to send small electric currents to the nervous system. There are several types of neuromodulation devices used to stop or reduce seizures.9

A neuropsychologist is a psychologist specially trained in diagnosing and treating behavioral and thinking problems. They conduct a series of tests to look at how the brain is working. These tests are used to guide a neurologist in understanding what part of the brain is affected during seizures.9


Partial seizure
"Partial seizure" is an old term for focal seizures.2

Petit mal seizure
"Petit mal" is an old term for an absence seizure.7


Refractory epilepsy
"Refractory epilepsy" is another name for drug-resistant epilepsy.4


A seizure is the body’s reaction to abnormal electrical activity in the brain. Nerve cells in the brain, called neurons, normally create tiny electrical signals in a regular rhythm. These signals tell other parts of the brain and body what to do. With epilepsy, neurons create too many electrical signals, too quickly, and this causes seizures.7,8

Status epilepticus
There are 2 kinds of status epilepticus. The first is 1 seizure lasting more than 5 minutes. The second is more than 1 seizure within 5 minutes without recovery in-between. Status epilepticus is a medical emergency.1,2

SUDEP stands for sudden unexpected death in epilepsy. Most of these deaths occur during or soon after a seizure. Because the causes of SUDEP are unknown, the best way to prevent it is to have as few seizures as possible.13,14


Tonic seizure
Tonic seizures cause muscle stiffness and, in many cases, unconsciousness.15

Tonic-clonic seizure
This is a generalized seizure in which the person stiffens (tonic phase) and then begins jerking (clonic phase).15

Traumatic brain injury
A violent blow or jolt to the head that affects or damages the brain. These injuries may be caused by falls, car crashes, combat, or sports. Seizures that develop after a brain injury are called post-traumatic epilepsy.16


Unknown onset seizure
A seizure that happens when no one else is around to witness it. This may happen if a seizure takes place at night or if the person having the seizure lives alone.15


Vagus nerve
The vagus nerve controls body functions such as heart rate and breathing. It carries information from the brain to the body and back. Stimulating this nerve can help reduce seizures. The vagus nerve is targeted in some anti-seizure devices to help control seizures.17

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