Absence seizures involve brief, sudden lapses of consciousness. They're more common in children than in adults.
A person having an absence seizure may stare blankly into space for a few seconds. Then the person typically returns quickly to being alert. This type of seizure usually doesn't lead to physical injury. But injury can result during the period when the person loses consciousness. This is particularly true if someone is driving a car or riding a bike when the seizure happens.
Absence seizures usually can be controlled with anti-seizure medicines. Some children who have them also develop other seizures, such as generalized tonic-clonic seizures or myoclonic seizures. Many children outgrow absence seizures in their teens.
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A simple absence seizure causes a vacant stare, which may be mistaken for a brief lapse in attention. The seizure lasts about 10 seconds, though it may last as long as 30 seconds. There's no confusion, headache or drowsiness after the seizure.
Symptoms of absence seizures include:
- A sudden stop in activity without falling.
- Lip smacking.
- Eyelid flutters.
- Chewing motions.
- Finger rubbing.
- Small movements of both hands.
Afterward, there's usually no memory of the incident. But if the seizure is longer, the person may be aware of missed time. Some people have many episodes daily. When it happens, it can interfere with school or daily activities.
A child may have absence seizures for some time before an adult notices them. This is because the seizures are so brief. A decline in a child's learning ability may be the first sign of the seizure disorder. Teachers may say the child has trouble paying attention or that a child is often daydreaming.
When to see a doctor
Contact your child's pediatrician:
- If you're concerned that your child may be having seizures.
- If your child has epilepsy but develops symptoms of a new type of seizure.
- If the seizures continue to occur despite taking anti-seizure medicine.
Contact 911 or emergency services in your area:
- If you observe prolonged automatic behaviors lasting minutes to hours. This may include activities such as eating or moving without awareness. It also might include prolonged confusion. These are possible symptoms of a condition called status epilepticus.
- After any seizure lasting more than five minutes.
Absence seizures usually have a genetic cause.
In general, seizures occur as a result of a burst of electrical impulses from nerve cells in the brain, called neurons. Neurons typically send electrical and chemical signals across the synapses that connect them.
In people who have seizures, the brain's usual electrical activity is altered. During an absence seizure, these electrical signals repeat themselves over and over in a three-second pattern.
People who have seizures also may have altered levels of the chemical messengers that help the nerve cells communicate with one another. These chemical messengers are called neurotransmitters.
Certain factors are common to children who have absence seizures, including:
- Age. Absence seizures are more common in children between the ages of 4 and 14.
- Sex. Absence seizures are more common in females.
- Family members who have seizures. Nearly a quarter of children with absence seizures have a close relative who has seizures.
While most children outgrow absence seizures, some:
- Must take anti-seizure medicines throughout life.
- Eventually have full convulsions, such as generalized tonic-clonic seizures.
Other complications can include:
- Learning problems.
- Behavior problems.
- Social isolation.
- Injury during the seizure.