Both childhood absence epilepsy and juvenile absence epilepsy are associated with typical absence seizures. These syndromes may also cause other types of seizures.
Childhood absence epilepsy usually begins between ages four and 11 and goes away within a few years, usually by the team the child enters their teens.
Juvenile absence epilepsy starts when the child is around 12 years old and may continue for the rest of their life.
What are other terms for absence epilepsy?
Other terms for absence epilepsy include:
- absence seizure disorder
- petit mal seizures or epilepsy
- pyknolepsy
What are the features of childhood absence epilepsy?
Childhood absence epilepsy usually begins when the child is between four and 11 years old, with a peak age of onset at five or six years. It is unusual for childhood absence epilepsy to begin after age 11. About 10% of children with childhood absence epilepsy had febrile seizures at some point before the onset of absence seizures.
The child has several typical absence seizures every day. They may have dozens or even hundreds of seizures per day. Because absence seizures are often confused with daydreaming, the child and their parents may not notice them right away. Sometimes teachers notice them occurring during school and will report them to parents.
It is rare for children to have other seizure types at first, but about 40% of children with childhood absence epilepsy may develop tonic-clonic seizures at some point. These often begin near puberty but can begin earlier or later. Myoclonic seizures (brief jerks mostly upon awakening) are usually not seen, although some children may have twitching or jerking movements with their absence seizures.
Rarely, children with childhood absence epilepsy may have absence status epilepticus, characterized by prolonged loss of awareness, where the child may appear dazed or confused for several minutes to hours. As there are no abnormal movements, this condition can only be diagnosed if an EEG is performed.
Most children have normal intelligence and a normal neurological exam, but a small percentage may have some learning or intellectual disabilities.
What are the features of juvenile absence epilepsy?
We know less about juvenile absence epilepsy than about childhood absence epilepsy. If a child starts having absence seizures at age 10 or 11, it may be difficult to tell if they have childhood or juvenile absence epilepsy.
Children with juvenile absence epilepsy begin having absence seizures near or after puberty, usually between the ages of 10 and 17, with a peak age of onset at around 12 years old. They usually have normal intelligence. They usually have no abnormalities on their neurological exam.
Children with juvenile absence epilepsy have fewer seizures than in childhood absence epilepsy. They may also have other types of seizures.
- About 80% of children with juvenile absence epilepsy also have tonic-clonic seizures. These may begin later than the absence seizures.
- About 15% of children with juvenile absence epilepsy also have myoclonic seizures , although they do not happen very often and may not be very obvious.
- Absence status epilepticus is also fairly common in children with juvenile absence epilepsy.
What causes absence epilepsy?
Both childhood and juvenile absence epilepsy are generalized epilepsy syndromes presumed to have a genetic cause. The age of onset (when a seizure first occurs) and the seizure types are slightly different between these two groups of patients. In both childhood and juvenile absence epilepsies, the child’s brain will likely appear normal on imaging (MRI).
There is a strong but complex genetic predisposition to childhood absence epilepsy. It does not mean that the child inherited this directly from parents, even though it is not rare to see a family history for seizures. There is probably more than one gene that causes childhood absence epilepsy, and other factors likely play a role as well.
Although we know less about it, genetic factors are also important in juvenile absence epilepsy.
How many other children have absence epilepsy?
Between 2% and 8% of children with epilepsy have absence epilepsy. Usually, slightly more girls than boys have absence epilepsy.
Juvenile absence epilepsy seems to be less common than childhood absence epilepsy. In most studies, about 20% of children with absence seizures begin having them after age 10. The syndrome may be more common than we realize, because children and their families do not always realize that a child is having absence seizures, especially if they are not having very many per day.
How do you know that a child has absence epilepsy?
Absence epilepsy is usually easy to diagnose, although some absence seizures may be confused with focal onset impaired awareness seizures.
Your child’s health-care provider will look for:
- information from you or your child’s teacher about staring spells or other symptoms of absence seizures
- a typical EEG pattern during the absence seizures
Typical absence seizures can often be induced in the health-care provider’s office. The health-care provider will ask your child to hyperventilate (breathe fast and deeply) for two to five consecutive minutes.
It is usually not necessary to do any neuroimaging studies (MRI) if the child has typical absence seizures and an EEG pattern that supports the diagnosis.
How is absence epilepsy treated?
Anti-seizure medications usually control the seizures in childhood absence epilepsy very well. Any one of several possible drugs can be used, and probably fewer than 5% of cases do not respond to treatment. If a child with childhood absence epilepsy has seizures that cannot be controlled, their health-care provider may try a combination of two anti-epileptic drugs.
Juvenile absence epilepsy can often be controlled with anti-seizure medications as well. Because juvenile absence epilepsy usually affects teenagers, who are becoming more independent, it is especially important to educate them about the disorder and engage them to take their medications as prescribed. A teenager with juvenile absence epilepsy needs to take responsibility for their treatment, which includes taking their medication at the right time, getting enough sleep and not drinking alcohol until legal age and after having a conversation with their health-care provider.
What is the outlook for a child with absence epilepsy?
Childhood absence epilepsy
Childhood absence epilepsy often goes away two to five years after the seizures begin or when the child is a teenager. Some researchers believe that early treatment and good response to anti-epileptic drugs improve the chances that the seizures will go away permanently.
If a child has been free of seizures for at least two or three years, their health-care provider may try to gradually discontinue their anti-epileptic drugs. The decision to stop medication will depend on the individual child and on factors such as their EEG, their activities and whether they want to start driving. Medication should only be stopped gradually and with a health-care provider’s supervision, since sudden or early withdrawal may trigger seizures.
If the child has tonic-clonic seizures along with absence seizures, these are less likely to go away. However, they are usually easy to control.
Juvenile absence epilepsy
Less is known about the long-term outcome of juvenile absence epilepsy than childhood absence epilepsy. The seizures usually respond well to medication, but children with this syndrome may need to take medication to control seizures for their entire lives. As in childhood absence epilepsy, uncontrolled seizures may lead to poorer social and academic outcomes.