Frequency of Types
Seizures can be divided into two main types: Focal (partial) seizures and generalized seizures.
Focal seizures can be further divided into two types: simple focal seizures and dyscognitive focal seizures.
Simple focal seizures
Simple focal seizures, also called simple partial seizures, affect only one area of the brain. Memory and cognitive abilities remain unimpaired, but a partial seizure might lead to temporary paralysis, visual changes, or difficulty with simple movements. Less than 15 percent of people with epilepsy have simple focal seizures.
A dyscognitive focal seizure
A dyscognitive focal seizure only affects a specific part of the brain. Unlike focal seizures, a dyscognitive focal seizure can cause mental confusion, loss of memory, and loss of awareness during the seizure. People having a complex focal seizure may appear unaware or dazed. More than a third of patients with epilepsy have dyscognitive partial seizures.
The second main type of seizure is generalized seizures. Generalized seizures divide into several subtypes. These include:
- Tonic seizure
- Clonic seizure
- Myoclonic
- Absence seizure
- Atonic seizure
- Tonic-clonic seizure
More than 30 percent of people with epilepsy experience generalized seizures.
Types
The area of the brain that is affected by a seizure will determine the symptoms and sensations the seizure causes.
Focal Seizures
This type of seizure affects only a portion of the brain. For that reason, it’s also sometimes called a partial seizure. Focal seizures have two main categories: simple focal seizures and dyscognitive focal seizures.
Simple focal seizures typically cause few symptoms. The symptoms that this type of seizure causes can be easily mistaken for another condition and overlooked. People may experience slightly shifted emotions or moods, involuntary jerking and twitching in body parts, and unusual sensory experiences, such as seeing flashing lights. Simple focal seizures do not cause memory loss.
Dyscognitive focal seizures cause a loss of consciousness or awareness. People who experience this type of seizure will not be aware of what occurred during the seizure. This type of seizure often causes unusual, repetitive movement. These movements might include hand rubbing, swallowing, walking in circles, or chewing.
Generalized Seizures
All types of generalized seizures affect both sides of the brain. Generalized seizures can be divided into six groups:
- Absence seizures. This type of seizure leaves a person briefly unaware of their surroundings and actions. Most people who experience an absence seizure stare blankly until the seizure is over. Some will produce a subtle, repetitive body movement. Absence seizures are also called “petit mal” seizures.
- Atonic seizures. This type of seizure causes loss of muscle control. A person experiencing an atonic seizure may suddenly fall or collapse. That’s why this type of seizure is sometimes called a drop seizure.
- Clonic seizures. People who have clonic seizures will routinely experience rhythmic, repeated jerking movements. The neck, face, and arms are commonly affected.
- Myoclonic seizures. This type of seizure causes sudden jerking movements or twitches. These movements commonly happen in the arms and legs.
- Tonic seizures. When this seizure begins, the muscles in the affected area of the body will tighten and stiffen. The arms, legs, and back are commonly affected. Most people who experience a tonic seizure will fall to the ground because of their muscle rigidity.
- Tonic-clonic seizures. Commonly called “grand mal” seizures, this type of seizure causes loss of consciousness, as well as violent shaking and body stiffening. Some people will lose control of their bladder and may bite their tongue during the seizure.