Types of Seizures & Syndromes
Not all seizure disorders are alike. They can differ in the way they affect the brain and in the symptoms they produce. Here is a summary of different types of seizures:
Partial seizures
Partial seizures begin in just one part of the brain. About 60% of people with epilepsy have partial seizures. There are two types of partial seizures:- Simple partial seizures may cause unusual feelings or sensations that can take many forms, such as sudden, unexplained feelings of joy, anger, sadness, or nausea. It's not uncommon to hear, smell, taste, see, or feel things that are not real. During simple partial seizures, you may remain alert and aware.
- Complex partial seizures cause a change in or loss of consciousness. Altered consciousness can produce a dreamlike experience. Strange, repetitious behaviors such as blinks, twitches, mouth movements, or even walking in a circle occur. Throwing objects or striking walls or furniture, as if in anger or fear, may also occur.
- Secondary generalized seizures occur when simple or complex seizures spread to involve your entire brain. They may begin as a complex partial seizure with staring and nonpurposeful movements. The seizure then becomes more intense, leading to generalized convulsions characterized by stiffening and shaking of your extremities and your body with loss of consciousness.
Symptoms of partial seizures can be mistaken for other disorders. For example, the dreamlike experience of partial seizures may be mistaken for migraine headaches. In people with partial seizures, the progression of symptoms tends to be similar every time.
Generalized seizures
Generalized seizures affect areas of both sides of the brain, usually with loss of consciousness. There are four main types of generalized seizures:- Tonic-clonic seizures (formerly called "grand mal" seizures) can cause a person to become stiff, lose consciousness, and jerk repetitively. The person may fall to the ground, bite his/her tongue, and/or lose bladder control. Serious injury including bone fractures can occur. These are the most common generalized seizures.
- Absence seizures (formerly called "petit mal" seizures) can cause brief periods of staring, blinking, and/or twitching. They occur mainly in children, who are often mistaken to be daydreaming.
- Myoclonic seizures cause limbs to jerk suddenly, and often happen just after waking.
- Atonic seizures (formerly called "drop attacks") cause sudden loss of muscle tone. This type of seizure can literally cause a person to drop to the ground.
Defining seizure type can sometimes be difficult. Seizure patterns can change, and some people experience more than one type of seizure, with no clear pattern.
Does having a seizure mean you have epilepsy?
Not necessarily. Sometimes a single seizure is due to a one-time event (such as drug use or a high fever). In this case, your doctor may not diagnose epilepsy. In epilepsy, a person has recurrent seizures due to a chronic (ongoing), underlying brain disturbance.
Epilepsy syndromes
There are hundreds of epilepsy syndromes. Syndromes are defined by shared characteristics such as type of seizure, seizure triggers, behavior during a seizure, hereditary factors, and brain wave patterns.
Doctors look at the type(s) of seizures you experience, along with other factors, to determine whether you have a known epilepsy syndrome. If your symptoms fit a known epilepsy syndrome, it provides useful information about your prognosis and which treatments are likely to be most effective.
Some of these syndromes develop in children and are outgtrown by adulthood.
Some epilepsy syndromes include:- Benign rolandic epilepsy - Seizures that begin as partial - often affecting the face and tongue, causing drooling and speech problems - and then progress to tonic-clonic seizures.
- Absence epilepsy - Momentary lapses of consciousness, or staring spells, often accompanied by jerking arms, lip-smacking and rapidly blinking eyes.
- Juvenile myoclonic epilepsy - Seizures that usually appear at puberty and involve sudden jerking of the arms and legs.
- Lennox-Gastaut syndrome - Severe epilepsy that usually develops before age 6; involves several different types of seizures; and includes mental retardation.
- Temporal lobe epilepsy - Partial seizures that often are preceded by a warning sensation (called an aura) that can cause a wide range of thoughts and emotions, including deja vu, anxiety, panic, joy, or strange sensations that are impossible to describe.