Childhood Absence Epilepsy

Childhood absence epilepsy (CAE) is a type of epilepsy characterized by recurrent seizures in young children. 1 These seizures, known as absence seizures, briefly impair the consciousness of the affected child, causing them to stare blankly into space and become unresponsive, among other reactions. Immediately after the seizure, which will usually last for around 10 seconds, the child will return to normal and may not even realize that the seizure has taken place. 2 Seizures typically occur often, sometimes up to 200 times per day. ref1

While a person of any age can experience absence seizures, childhood absence epilepsy is specific to children and will usually first occur in children of between five and eight years old. 1 Most children affected by the condition will cease to experience seizures by mid-adolescence. However, for some, seizures may continue into adolescence and other types of seizures may also develop, such as tonic-clonic seizures. ref1

The cause of childhood absence epilepsy is thought to be largely genetic, with one in three affected children having a family history of similar seizures. 2 Treatment involves the use of medication and is generally effective at controlling seizures.

The key symptom of childhood absence epilepsy is absence seizures, formerly known as petit mal seizures. Absence seizures may cause the affected child to: 3 4

• Stare blankly into space
• Stop talking or interacting
• Suddenly stop moving
• Become unresponsive
• Repeatedly move their fingers, hands or mouth without apparent purpose
• Repeatedly flutter or flicker their eyelids

Seizures last for an average of 5 to 15 seconds. 3 Following a seizure, the affected child will typically resume normal activity and may be unaware that the seizure has taken place.

Seizures can first appear in children of between three and eleven years old, but most often occur in children of between three and eight. 2 They are marginally more common in girls than boys.

Without treatment, seizures tend to occur frequently, sometimes up to 200 times per day. 1 They are more likely to occur when a child is bored, tired or not engaged in an activity and become less likely when a child is concentrating. 3

Seizures are unlikely to impact upon the development of the affected child. However, children who experience a high frequency of seizures may develop some learning difficulties. 3

Good to know: It is possible for children to be affected by atypical absence seizures. This less common type of seizure tends to begin and end more gradually than a typical absence seizure. Generally, they also last longer, though they can last anywhere between 5 and 30 seconds. 5

Children experiencing possible symptoms of childhood absence epilepsy should see a doctor for evaluation. In addition, parents and carers can use the free Ada app to carry out a symptom assessment.

Childhood absence epilepsy is a type of epilepsy. The seizures associated with epilepsy occur as a result of uncontrollable bursts of electrical activity in the brain.

The underlying cause of the condition is generally genetic, though environmental factors may contribute to its onset in some cases. 1 The genetic element is complex and not fully understood, with several genes and genetic changes thought to play a role. ref1

The complexity of the genetics behind childhood absence epilepsy means, that its inheritance pattern is also not straightforward.

When associated with some genes, GABA receptors or calcium channel genes, for example, the condition follows an autosomal dominant inheritance pattern, meaning that a faulty gene from just one parent could be enough to pass on the condition. 1 When associated with other genes, however, the inheritance pattern may be different.

Roughly one in three children with childhood absence epilepsy have a family history of similar seizures. The siblings of affected children have an estimated 1 in 10 chance of also developing the condition. 5

The diagnosis will usually be based upon a detailed description of the symptoms being experienced and a physical examination.

A hyperventilation test may be performed. This involves asking the child to hyperventilate, or breathe quickly, for three to four minutes, sometimes while counting aloud and with their eyes closed. In 90 percent of cases, this will cause the child to experience an absence seizure. 3

Doctors may also order an electroencephalogram (EEG). During this test, which can be performed in a doctor’s office or hospital, the child will be asked to lie flat while disk-shaped electrodes are attached to the scalp. Connected to a monitoring device, these electrodes are able to monitor the electrical activity of the brain. Those affected by childhood absence epilepsy tend to present a distinctive pattern of brain activity, making this test an important step in confirming a diagnosis of childhood absence epilepsy. 4 5 Often, doctors will record an EEG at the same time as performing a hyperventilation test.

In most cases, no further tests will be necessary. However, if the condition does not improve following treatment, a number of additional tests may be ordered. These include: 1 3

• A ct scan or MRI scan to check the location of the problem in the brain
• Genetic testing to help identify the gene or genes responsible for the condition

Childhood absence epilepsy can be effectively managed using medication. The two most commonly prescribed medications are ethosuximide and sodium valproate, also known as valproic acid. 5 6 Both have been shown to be effective at controlling absence seizures in 80 percent of cases. ref6 Sodium valproate may be preferred in instances where the child also experiences other types of seizures, such as clonic-tonic seizures.

Lamotrigine has also been proven to be effective in some cases. It may also produce fewer side-effects than ethosuximide and sodium valproate. 5 Although other medications have been used to control absence seizures, most of these medications have not had their efficacy proven through controlled trials. ref5

If the use of a single type of medication proves ineffective, a combination may be used. This has shown to be effective in half of all cases where the affected child does not respond to a single medication. Persisting with a single type of medication until the maximum possible dose has been prescribed is generally recommended, however. 6

The prognosis for childhood absence epilepsy is very good. 7 Through the use of medication, approximately 70 percent of children with the condition will have their seizures completely controlled by mid-adolescence. 2 3

In around 10 percent of cases, children with CAE will develop other types of seizures in adolescence, most commonly clonic-tonic seizures. Similarly to CAE, these seizures can usually be controlled effectively through the use of medication. 3

• absence seizures
• petit mal seizures

Q: How common is childhood absence epilepsy?
A: Childhood absence epilepsy affects around 2 to 8 in 100,000 children each year. 1 Around 8 percent of children with epilepsy have CAE, making it one of the more common types of epilepsy in children. 8

Q: What is the difference between childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE)?
A: Childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE) are similar conditions, both involving the presence of absence seizures and both typically responding well to medication. However, whereas CAE usually first presents between the ages of 3 and 8, JAE presents later, generally between the ages of 10 and 17. 1 9 Compared to CAE, people with JAE also tend to experience fewer absence seizures. They are, however, more likely to experience additional types of seizures: an estimated 80 percent of those with JAE also experience clonic-tonic seizures, and around 15 percent also experience myoclonic seizures. 9