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 the child has 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.
Childhood absence epilepsy (CAE)
This is a common epilepsy syndrome starting in early childhood. Absence seizures can happen in many different epilepsy syndromes occurring in childhood and adolescence. This information refers specifically to the syndrome of childhood absence epilepsy.
The seizures of childhood absence epilepsy usually start between the ages of 4 to 7 years of age; rarely the seizures may start under 4, and as late as 8 years of age. They happen slightly more often in girls than boys. They can also happen many times a day, from 10 and up to over 100. They are sometimes divided into ‘typical’ and ‘atypical’ absence seizures.
A typical absence seizure consists of a sudden loss of awareness. The child will suddenly stop talking or what they are doing and stare blankly into space. They will not respond to people talking to them. The seizure is sometimes associated with repetitive, purposeless movements of the fingers, hands or mouth, such as some lip-smacking. These are called automatisms. There may also be eyelid flickering or fluttering.
A seizure usually lasts between 5 and 15 seconds and usually stops as suddenly as it starts, with the child resuming their normal activities.
Absences that last longer than 15 or 20 seconds or that have a lot of automatisms or brief jerks of the head are usually called ‘atypical’ absences.
Absence seizures tend to happen more commonly when the child is bored, sitting quietly or when they are tired or unwell. They happen less often when the child is busy or focused on an activity that they enjoy.
Children with CAE usually develop and learn normally, although uncontrolled absence seizures that happen many times a day may cause some learning difficulties. Sometimes a child’s concentration and memory are thought to be poor before the diagnosis of the childhood absence epilepsy is made – and improves after treatment is started.
The diagnosis is usually suggested by the history. The doctor may ask the child to hyperventilate (over-breathe) for 3 to 4 minutes while counting out loud and sometimes with the eyes shut. If an absence seizure occurs, the child will stop hyperventilating and will open their eyes. Hyperventilation will trigger an absence seizure in over 90 per cent of children with typical CAE, and is important in making the diagnosis.
An EEG test is useful in confirming the diagnosis. The EEG may also be used to monitor response to treatment. No other tests such as a brain scan are required in CAE. If the absences are not controlled with treatment and continue to happen may times a day, children may need to have a magnetic resonance imaging (MRI) brain scan or genetic tests to make sure the diagnosis of CAE is the right one.
Epilepsy Action has more information about diagnosis.
CAE usually responds very well to treatment. The epilepsy medicines of choice are sodium valproate (Epilim), ethosuximide (Zarontin) and lamotrigine (Lamictal). Occasionally a combination of two of these medications may be required to completely control absences. Rarely, the medicines topiramate (Topamax) and zonisamide (Zonegran) might be helpful. Some children may also benefit from the ketogenic diet if their absences are not controlled by any combination of epilepsy medicines.
Epilepsy Action has more information about epilepsy treatment.
The outlook of typical CAE is excellent, with the majority of children becoming seizure free as they pass through puberty.
About 70 per cent of children with CAE will have their absence seizures completely controlled with one or two epilepsy medicines.
Approximately 10 per cent of children will develop other seizure types in adolescence, usually generalised tonic-clonic seizures. However these seizures are infrequent and usually respond to treatment with sodium valproate (Epilim) or lamotrigine (Lamictal).
Some children with CAE may also develop other seizure types such as myoclonic seizures (sudden, brief jerks of the head, limbs or body). When looked at in more detail these children will almost certainly not have CAE but instead have a different epilepsy syndrome such as juvenile absence epilepsy, juvenile myoclonic epilepsy, epilepsy with myoclonic absences or an ‘atypical’ absence epilepsy.
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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.