What is an absence seizure?
An absence seizure causes a short period of “blanking out” or staring into space. Like other kinds of seizures, they are caused by brief abnormal electrical activity in a person’s brain.
- An absence seizure is a generalized onset seizure, which means it begins in both sides of the brain at the same time.
- An older term is petit mal seizures.
- Absence seizures usually affect only a person’s awareness of what is going on at that time, with immediate recovery.
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What do absence seizures look like?
There are two types of absence seizures that may look a bit different. Both types of seizures are short, and people often don’t notice them at first. They may come and go so quickly that no one notices anything wrong. Or observers may mistake the symptoms for simple daydreaming or not paying attention.
Typical Absence Seizures
- These seizures are the most common.
- The person suddenly stops all activity. It may look like he or she is staring off into space or just has a blank look.
- The eyes may turn upwards and eyelids flutter.
- The seizures usually last less than 10 seconds.
- These absence seizures are called atypical because they may be longer, have a slower onset and offset, and involve different symptoms.
- The seizure still starts with staring into space, usually with a blank look.
- There is usually a change in muscle tone and movement. You may see
- Blinking over and over that may look like fluttering of the eyelids
- Smacking the lips or chewing movements
- Rubbing fingers together or making other hand motions
- An atypical absence seizure lasts longer, up to 20 seconds or more.
"Absence seizures are so brief they are often missed."
Who’s at risk for absence seizures?
Absence seizures are most common in children from age 4 to 14. However, older teens and adults may also have absence seizures.
Some people have absence seizures for many months or years before it’s recognized as a problem.
What causes this delay?
- It’s very common for people to mistake absence seizures for daydreaming or not paying attention.
- Absence seizures are most likely to affect children, and paying attention is a common problem for children. Since daydreaming can happen often in school for many different reasons, it may be hard to know if the staring is a seizure or not.
- Often the first clue that a child may be having absence seizures is when he or she starts having trouble in school.
What’s it like to have an absence seizure?
- When people have absence seizures, they are not aware of what is happening around them. For example, they will not notice if someone tries to speak to them during a seizure.
- If a person is speaking when their seizure begins, they will stop talking, often in the middle of a sentence. It may seem like a pause to an observer.
- Often a child may have many absence seizures in a row.
- An observer may not see the beginning or end of a seizure. The person may just look confused and not know what has happened.
What happens after an absence seizure?
When an absence seizure ends, the person usually continues doing whatever they were doing before the seizure. They are almost always wide awake and able to think clearly. Generally, no first aid is needed for this type of seizure.
When absence seizures happen close together or a person has many in a day, the person may look or act confused and lose track of what has been going on. For children in school, they may not be aware of what has happened in the classroom, miss instructions from the teacher, or have incomplete work.
If someone has absence seizures, how often will they happen?
- The number of absence seizures a person may have varies a lot.
- Seizure medicines can control absence seizures in many children so they have rare seizures or none at all.
- Other people may have hundreds of brief absence seizures a day.
How are absence seizures diagnosed?
Absence seizures may be diagnosed by:
- A good written description of what happened is important. Usually this description comes from people who have seen the seizures: a parent, teacher, or other family member.
- An EEG (electroencephalogram) will be done if the events sound like seizures or other symptoms have happened. The EEG checks the electrical activity in the brain for patterns usually seen in absence seizures.
- During the EEG, you may be asked to breath fast or close your eyes while lights are flashed fast. These things may make it easier to see absence seizure patterns on an EEG.
How are absence seizures treated?
Certain seizure medicines can help prevent absence seizures. Usually these are recommended for most children. The medicines most commonly used for absence seizures include ethosuximide (Zarontin), lamotrigine (Lamictal), valproic acid (Depakene), or divalproex sodium (Depakote).
In about 7 out of 10 children with absence seizures, the seizures may go away by age 18. If this happens, medicines may not be needed as an adult. Children who start having absence seizures before age 9 are much more likely to outgrow them than children whose absence seizures start after age 10.
For other children, seizure medication may be needed long-term. A neurologist can help you learn about the risks, treatments, and outlook for the future.
What should I do if I think my child may have absence seizures?
If you think your child may be having absence seizures, talk to your child’s doctor about your concerns right away. Absence seizures may be confused with other types of seizures. That’s another reason why it’s so important that your child see a doctor for a correct diagnosis. If the diagnosis is not clear or your child continues to have problems, see an epilepsy specialist (called an epileptologist).
Kids who have absence seizures aren’t usually in danger during a seizure. However, absence seizures may cause your child to
- Have trouble learning at school
- Have social problems
- Misbehave more often
How can I tell the difference between absence seizures and daydreaming?
If you’re wondering whether your child is daydreaming or having absence seizures, here are a few key differences to look for.
- It is more likely to happen when your child is bored (for example, during a long class at school)
- Usually comes on slowly
- Can be interrupted
- Tends to continue until something stops it (for example, the teacher, a friend, or parent getting the child’s attention)
- Can happen anytime, including during physical activity
- Usually come on very suddenly, without warning
- Cannot be interrupted
- End on their own, typically within 10-20 seconds
How can I tell the difference between absence seizures and focal impaired awareness seizures?
Seizures that involve staring and a change in awareness are sometimes mislabeled as absence seizures. People often confuse absence seizures with focal impaired awareness seizures.
There are some key signs that happen before and after a seizure that help us to decide which type of seizure a person is having. The length of a seizure and the frequency of seizures are also helpful observations to keep track of. All of this information, along with the results of EEG testing, can help to accurately diagnose which type of seizure a person is having.
The following features are more suggestive of focal impaired awareness seizures:
- Warning (aura) prior to the seizure
- Confusion and sleepiness after the seizure (postictal state)
- Duration longer than 30-45 seconds
- Frequency is less often than daily
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