Your brain contains billions of nerve cells, also known as neurons. These neurons use electrical activity to communicate and send signals.
If there’s an abnormal change in this electrical activity, it can produce a seizure. Epilepsy is a condition in which seizures repeatedly occur.
Traditionally, epilepsy was defined as a type of disorder. It was sometimes referred to as an “epilepsy disorder.” However, epilepsy is now officially known as a disease rather than a disorder.
The classification of epilepsy types has also changed. This was done to help people better understand epilepsy and improve diagnosis.
Learn about these changes, along with the different types of epilepsies.
The International League Against Epilepsy (ILAE) is an organization that studies epilepsy. They publish reports that provide updated classifications of epilepsies and seizures that are agreed upon by the leading organizations.
In 2005, epilepsy was defined as a brain disorder characterized by seizures. However, in 2014, the ILAE released an
According to the report, the term “disorder” suggests a disruption that isn’t necessarily long-term. The word “disorder” could also diminish the seriousness of epilepsy and is often misunderstood.
The ILAE stated that “disease” is a more accurate term to describe epilepsy. “Disease” generally implies more long-term disruptions.
In 2017, the ILAE published another report announcing new classifications of epilepsies and seizures. These guidelines introduced new terms and removed some older ones.
The new classification system categorized epilepsy according to its type of seizure. The goals of this new system include:
- easier classification
- easier, more accurate diagnosis
- better guidance for medical and surgical treatments
These changes make it easier to understand and classify different epilepsies, as well as the seizures involved in each one.
There are four types of epilepsies. Each type includes different types of seizures, which cause different symptoms and have different onset (begin in different parts of the brain).
Identifying the type of seizure and where it begins in the brain guides treatment because medications used for one type can sometimes worsen another type.
Epilepsy types include:
Focal onset epilepsy involves focal seizures, or seizures that begin on one side of the brain.
Focal epilepsies are common. About
Seizures in this category include:
Simple focal seizures
A simple focal seizure can be similar to a seizure aura and it is sometimes called a seizure aura. You stay conscious and aware of your surroundings but sometimes unable to fully respond during the seizure. It might also cause:
- muscle jerking
- feeling of déjà vu
- strange sensations, like odd smells
Complex focal seizures
A complex focal seizure causes altered consciousness, but not necessarily complete loss of consciousness. Other symptoms include:
- blank staring
- repetitive movements, like blinking or gulping
A simple focal seizure can progress to a complex focal seizure. A simple or complex focal seizure that progresses to a generalized seizure is called a secondarily generalized seizure.
Generalized epilepsy involves generalized onset seizures. These seizures begin on both sides of the brain and cause impaired consciousness or loss of consciousness. Approximately 23 to 35 percent of epilepsies are generalized.
It includes the following seizures:
An absence seizure, formerly called a petit mal seizure, lasts for about 15 seconds and affects the whole brain.
- lack of awareness and lack of responsiveness while appearing conscious
- suddenly stopping movement
- appearance of daydreaming
- slight muscle twitching
- usually not remembering what happened during the seizure
Myoclonic seizures are brief, lasting a few seconds or less. You might have multiple myoclonic seizures within a short time.
Other symptoms include:
- staying fully or partially conscious
- increase in muscle tone of some muscles
- possible altered sensations, such as a sensation of an electric shock
Generalized tonic-clonic (GTC) seizures were previously called grand mal seizures. Symptoms include:
- loss of consciousness
- muscle stiffening (tonic phase) and jerking (clonic phase)
- crying out
A tonic seizure causes muscle stiffening, but it doesn’t have a clonic phase. You might stay conscious or experience a brief change in awareness.
A clonic seizure causes muscle spasms and jerking for several minutes. You may lose awareness.
Also called drop attacks, atonic seizures cause a sudden loss of muscle tone. This might cause:
- staying aware or briefly losing consciousness
- head dropping
- injury due to fall
Combined generalized and focal epilepsy
If both generalized onset and focal onset seizures occur, it’s called combined generalized and focal epilepsy.
This type of epilepsy causes a combination of various seizures, including one or more of:
- generalized tonic-clonic seizures
- myoclonic seizures
- absence seizures
- tonic seizures
- atonic seizures
The seizures can occur together or separately. One type of seizure can occur more frequently than others. The exact symptoms depend on the seizures involved.
Unknown if generalized or focal epilepsy
Sometimes, it’s not possible to determine the type of seizures. This might happen if there isn’t enough medical information to classify the seizure onset. One example is an electroencephalogram (EEG) with normal results.
In this case, the epilepsy is categorized as “unknown” until there is more information.
An epilepsy syndrome refers to a set of medical features that usually appear together. This includes seizure types, along with:
- age when seizures typically start
- EEG results
- common triggers
- genetic factors
- response to antiepileptic drugs
- other symptoms, such as physical or cognitive problems
This is different from an epilepsy type. An epilepsy type only indicates the types of seizures. An epilepsy syndrome describes the types of seizures (and therefore, epilepsy type), plusother characteristics.
To date, there are more than 30 known epilepsy syndromes. Examples include:
- Dravet syndrome
- childhood absence epilepsy
- gelastic epilepsy
- Laundau Kleffner syndrome
- Lennox-Gastaut syndrome
- Doose syndrome (myoclonic astatic epilepsy)
- West syndrome (infantile spasms)
Epilepsy syndromes often appear in childhood. The most common childhood syndromes include:
- benign rolandic epilepsy
- childhood idiopathic occipital epilepsy
- childhood absence epilepsy
- juvenile myoclonic epilepsy
A doctor will use several tests to determine what type of epilepsy you might have. These include:
- Physical exam. A doctor will check if you have physical problems in addition to your seizures. They’ll also test your motor skills.
- Medical history. Since epilepsy is often inherited, a doctor will want to learn more about your family’s history.
- Blood tests. Your doctor will test markers that might be related to seizures. Examples include low blood sugar or inflammatory markers.
- Neuropsychological exam. A specialist will test your cognition, speech, and memory. This helps them determine where the seizures are happening in your brain and if there are other associated problems.
- Electroencephalogram. An electroencephalogram (EEG) measures your brain’s electrical activity and it can help identify where the seizure is starting, and whether it is focal onset or generalized onset.
- Imaging tests. An imaging tests lets your doctor check for lesions or structural abnormalities that may be causing seizures. Examples include a computerized tomography (CT) scan or magnetic resonance imaging (MRI).
An epilepsy syndrome is treated based on its clinical features. This includes the type of epilepsy and seizures involved.
Treatment may include:
- Antiepileptic drugs. Antiepileptic drugs (AEDs) reduce the frequency or severity of seizures. The type of seizure will determine the most effective option.
- Surgery. Surgery for epilepsy involves cutting or removing part of the brain where seizures are happening and it can control some types of epilepsy.
- High-fat diet. If AEDs don’t work or you can’t get surgery, your doctor might suggest a high-fat, low-carb diet for certain types of epilepsy. This might include a ketogenic diet or modified Atkins diet.
- Vagus nerve stimulation. A small electrical device is implanted under the skin to stimulate the vagus nerve, which controls some of your brain activity. The device helps control certain seizures by stimulating the nerve.
Types of epilepsy are classified by the types of seizures involved. The main epilepsy types include focal onset epilepsy, generalized onset epilepsy, combined generalized and focal epilepsy, and unknown onset.
A doctor can use various tests to determine what type of epilepsy you might have. This may include a physical exam, blood tests, imaging scans, and an EEG. Depending on the type, epilepsy might be treated with drugs, surgery, vagus nerve stimulation, and/or a high-fat diet.