Juvenile absence epilepsy (JAE) is a relatively common epilepsy syndrome. The main seizure type in JAE is absence seizures. These can happen in other childhood and adolescent epilepsy syndromes, including childhood absence epilepsy (CAE) and juvenile myoclonic epilepsy (JME).
The seizures of JAE usually start between the ages of 9 and 12 years, but may start earlier, at 5 or 6 years of age. They may also start in the late teenage years. They happen slightly more often in girls than boys.
A typical absence seizure consists of a sudden loss of awareness. The child will suddenly stop their activities and stare blankly into space. They will be unresponsive to voices or other types of stimulation. The seizure is sometimes associated with repetitive, purposeless movements of the mouth or eyes (called automatisms). These movements can include eyelid flickering or fluttering and lip smacking. A seizure usually lasts between 5 and 20 seconds. However, children with JAE can also have longer absence seizures (atypical absences) lasting up to 45 seconds. In these seizures, the child may still be partly able to continue doing certain things (automatic behaviour) and because of this the seizure may be wrongly diagnosed as a focal (partial) seizure. The seizure usually stops as suddenly as it starts, with the child resuming their normal activities. Absence seizures usually happen many times a day, every day. But they are usually not as frequent as in CAE.
Absence seizures tend to happen more commonly when the child or young person is tired or unwell. They usually happen less frequently when they are doing something.
Up to 8 out of every 10 children with JAE can have generalised tonic-clonic seizures, particularly just after waking, or if they are very tired. These are far more likely to happen before treatment is started. A small proportion of children may also experience some brief myoclonic seizures. These are also more likely to happen when the child is tired. The myoclonic seizures happen far less frequently than in JME.
Children with JAE usually have normal learning ability, although uncontrolled absence seizures may have an impact on their ability to learn at school. Sometimes a child’s concentration or memory is said to be poor before the diagnosis of epilepsy is made.
The diagnosis is usually made based on the child’s history. As part of the diagnosis, the doctor may ask them to hyperventilate (over-breathe) for 3 to 4 minutes in the clinic. This will trigger an absence seizure in just a few children with typical JAE. Hyperventilation is far more likely to trigger an absence in CAE.
An EEG test will usually show a pattern called generalised spike and slow wave activity, particularly if the child or young person is tired or has been sleep-deprived before the test. One in 10 to 20 children with JAE may also be photosensitive, and this can be seen during the EEG. However, photosensitivity is far more commonly seen in children and young people with JME. No other tests, such as a brain scan or blood tests, are required in the vast majority of children with JAE.
Epilepsy Action has more information about diagnosing epilepsy.
JAE usually responds very well to treatment. The medicines of choice are sodium valproate (Epilim), ethosuximide (Zarontin) and lamotrigine (Lamictal). However, ethosuximide would not be the treatment of choice if the child has had generalised tonic-clonic seizures as well as absence seizures. Sometimes a combination of 2 of these medicines may be required. Occasionally the seizures can be resistant to treatment with epilepsy medicines. Where this is the case, a referral should be made to a paediatric neurologist, and other investigations may be needed, such as a magnetic resonance imaging (MRI) scan and genetic tests.
There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.
Information about treatments for children can be found on the Medicines for Children website.
The outlook for typical JAE is rather mixed. The seizures will stop with treatment in over 3 out of 4 children and young people, but the epilepsy is usually life-long. This means that if the epilepsy medicine was withdrawn, the seizures would happen again. These seizures could either be absences, or tonic-clonic seizures.
About 7 out of 10 children with JAE will have their absence seizures completely controlled with one or two epilepsy medicines. If the epilepsy remains poorly controlled and carries on into adult life, the usual seizure type will be tonic-clonic rather than absences.
Some children with what initially appears to be JAE, go on to have more frequent myoclonic seizures. Myoclonic seizures are sudden, brief jerks. If the EEG also shows photosensitivity (where seizures are triggered by flickering or flashing lights) at this stage, the more likely epilepsy syndrome will be JME and not JAE. It is important to have an accurate diagnosis, because it may make a difference for the outlook for these children.
What is a syndrome?
A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.
If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.
Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.