Childhood absence epilepsy (CAE) is the most common epilepsy syndrome found in children, and it usually starts between the ages of four and nine years. During an absence seizure, the child will suddenly lose awareness, stop all activity and stare blankly into space. He / she will be unresponsive to voices and may show automatic, repetitive movements of the mouth or eyes. This is associated with a characteristic change in the electrical activity in the brain.

Absence seizures typically last between five and 20 seconds, and they end as suddenly as they begin. Children with CAE usually develop normally, but because they may experience hundreds of seizures per day, if their seizures remain untreated, they risk falling behind at school (as their concentration and memory become more and more affected). Fortunately, the majority of children with this form of epilepsy become seizure-free when they reach puberty.

Approximately 70% of people with CAE have their seizures completely controlled with one or more anti-epileptic drugs (AEDs). The three AEDs that usually used to treat CAE are ethosuximide, valproic acid and lamotrigine; however, until now, no comparison between the three in terms of efficacy had been made.

Researchers in America, led by a team in Cincinnati, have now completed the first ever double-blind, randomized, controlled, clinical trial of these AEDs, in the treatment of CAE. They specifically looked at three aspects of the drugs - their efficacy, their tolerability and their neurological/psychological side-effects.

453 children who had been newly diagnosed with CAE were enrolled in the study over three years (beginning in 2004). Each child was randomly assigned treatment with either ethosuximide (total: 156 children), valproic acid (total: 148 children) or lamotrigine (total: 149 children). For each participant, the dosage of their allocated drug was increased until he/she was seizure-free, or until the maximum dose allowed or tolerated was reached.

Using the results obtained, the researchers established freedom-from-failure values for each of the AEDs. Freedom-from-failure refers to the percentage of cases in which a drug allows individuals to be seizure-free after 16 weeks of treatment, without causing intolerable side effects.

Finally, the group measured the impact of the three drugs on the children's ability to remain focused on every-day tasks.

The results showed that the freedom-from-failure values for ethosuximide and valproic acid were very similar (53% and 58% respectively), and approximately double that for lamotrigine (29%). However the older drug, ethosuximide, was considerably less likely than valproic acid to disrupt children's attention/concentration (33% and 49% respectively). There were no significant differences among the three AEDs with regards to how well they were tolerated/the percentage of cases in which they had to be discontinued due to side-effects.

These findings suggest that ethosuximide and valproic acid are more effective than lamotrigine in the treatment of childhood epilepsy, and that ethosuximide causes the least disruption in learning/attention.

Although further research is needed to confirm these results, this study is very helpful, because it will enable doctors and parents to make more informed treatment decisions for children with newly diagnosed CAE.

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