Absence Seizures

What is an absence seizure?

Absence seizures cause a brief, temporary loss of awareness, usually for 5 to 30 seconds. They most commonly affect children. A child having an absence seizure may stare into space or look like they’re daydreaming. You may also hear them called petit mal seizures, which means “little illness” in French.

Absence seizures are a type of epilepsy, a condition that causes seizures. Absence seizures are a type of generalized seizure, meaning they start in both sides of the brain at the same time.

Absence seizures in children affect as many as 8 under age 15 every year. They typically start between ages 3 and 8. About with epilepsy experience absence seizures. Although uncommon, some children continue to have absence seizures into adulthood.

Absence seizures aren’t harmful or dangerous, but they can happen frequently — sometimes with multiple absence seizures every day. These recurrent seizures can affect a child’s behavior and ability to learn. There’s also a risk of injury when a child has a seizure and is unaware of their surroundings.

Our epilepsy expertise

As a Level 4 Epilepsy Center, Massachusetts General Hospital provides the highest level of epilepsy care available. Our team provides advanced neurodiagnostic monitoring, along with comprehensive medical, neuropsychological, and psychosocial treatment for even the most complex cases. We also offer full evaluations for epilepsy surgery, including intracranial monitoring and specialized surgical procedures that are not widely available at other institutions.

The Pediatric Epilepsy Program at Mass General Brigham for Children provides advanced diagnostic tests and treatments for epilepsy conditions that cause absence seizures in children.

Types and symptoms of absence seizures

Symptoms of absence seizures come and go quickly, making them easy to miss. A child having an absence seizure isn’t aware of their surroundings and may pause mid-activity without realizing it. After the seizure, they often resume what they were doing as if nothing happened. Some children may not notice anything unusual, while others may feel like they lost a moment in time.

There are two types of absence seizures, with slightly different symptoms.

Typical absence seizures

Typical absence seizures are the most common type. These seizures usually last between 5 to 20 seconds. Signs of a typical absence seizure include:

• Brief confusion or loss of awareness with a quick return to normal activities
• Eyes that roll
• Fluttering eyelids

Atypical absence seizures

Atypical absence seizures may last longer than 20 seconds and typically start with a child staring into space with a blank look. Other signs of an atypical absence seizure include:

• Changes in muscle tone and movement
• Chewing movements or lip smacking
• Hand motions, such as rubbing hands together
• Rapid blinking or fluttering eyelids

Causes of absence seizures

Absence seizures happen when nerve cells in the brain called neurons send an abnormal burst of electrical signals that cause a transient disruption of awareness or consciousness.

Triggers of absence seizures

Certain things may trigger an absence seizure:

• Bright, flashing lights
• Fast, deep breathing (hyperventilating)

Risk factors for absence seizures

Children assigned female at birth are slightly more likely to have absence seizures. Other risk factors include:

• Diagnosis of Lennox-Gastaut syndrome (LGS), a rare form of childhood epilepsy
• Family history of seizures
• Genetic changes (mutations) that are inherited (familial) or occur for no apparent reason (sporadic)
• History of other generalized seizure types, such as tonic and atonic seizures, febrile seizures, or grand mal seizures

Learn more about epilepsy symptoms, diagnosis, and treatments from a Mass General Brigham epilepsy specialist.

Diagnosis of absence seizures

To diagnose absence seizures, your child’s provider may perform a physical examination and ask about symptoms. These diagnostic tests help providers diagnose absence seizures:

• Electroencephalogram (EEG), to detect changes in the brain’s electrical activity that can indicate seizures
• Imaging tests, such as a brain MRI or CT scan to look for brain changes that can cause seizures
• Genetic testing, to look for gene changes that cause absence seizures

Treatment of absence seizures

Seizure medications are the main treatment. Absence seizure medications include:

• Ethosuximide
• Levetiracetam (Keppra)
• Lamotrigine (Lamictal)
• Valproic acid (Depakote)

FAQs about absence seizures