SEATTLE — Most children with epilepsy who become seizure free with antiepileptic drug therapy are able to stop taking the drugs without developing intractable seizures, according to findings from a population-based cohort study.
Dr. Katherine C. Nickels said that about a third of children with epilepsy experience a recurrence after becoming seizure free on antiepileptic drugs (AEDs) and stopping therapy. More than half of those who resume AEDs are rapidly able to regain seizure control.
To put the findings in perspective, she noted the 20% rate of intractable seizures is similar to that seen among children with a new diagnosis of epilepsy.
“Children who achieve seizure freedom on antiseizure medications can be considered for antiseizure medication withdrawal without high risk of intractable epilepsy,” Dr. Nickels reported at the annual meeting of the American Epilepsy Society. Dr. Nickels said she had no disclosures to report in association with the study.
“Antiepileptic medications may have serious side effects, including cognitive slowing, weight change, fatigue, and hepatotoxicity,” she said.
Children who become seizure free while taking AEDs are often weaned off of them, but there is a concern that seizures will recur and—most worrisome—that they will be intractable when they do.
“The current data regarding the risk of recurrence of seizures as well as the risk of intractable seizures following medication withdrawal varies widely from one study to the next,” said Dr. Nickels, a pediatric neurologist at the Mayo Clinic, Rochester, Minn. Moreover, “many of them are not population based.”
Using data from the Rochester Epidemiology Project, she and her coinvestigators reviewed the medical charts of all children aged 1 month to 16 years who received a new diagnosis of epilepsy while living in Olmsted County during 1990-2000 and had follow-up of at least 5 years after their first seizure. To be included in the study, children were required to have had two or more unprovoked seizures in the absence of any progressive neurologic disorder and to be receiving AEDs daily.
The investigators focused on the group who became seizure free and discontinued their AEDs. They reviewed the medical charts of these children through their last follow-up to assess seizure recurrence (defined as occurrence of at least one seizure) and the development of intractable seizures (defined as occurrence of at least one seizure every 3 months during the last year of follow-up and failure of at least two AEDs to control the seizures at maximum tolerated doses).
A total of 152 children fit the study criteria. Some 56 (37%) became seizure free and were weaned off of the drugs. Their mean duration of seizure freedom while on treatment had been 2.3 years.
After a mean follow-up of 8 years, 20 (36%) of this group had a recurrence of seizures. Among these children, 15 restarted AEDs, 4 remained off AEDs with rare or no additional seizures, and 1 died of sudden unexpected death in epilepsy.
After a mean follow-up of 5.7 years in the 15 children who restarted AEDs, 10 again became seizure free within 2 years, whereas 5 never did. Of those five children, three—5% of the total stopping AEDs or 20% of the total restarting them—had intractable seizures.
An analysis of the time until seizures recurred among the children with this outcome showed that 55% had their recurrence within 1 year of stopping AEDs, said Dr. Nickels. But 20% had their recurrence more than 5 years after stopping.
Finally, an analysis of the time until regaining freedom from seizures among the 15 children who had a recurrence and restarted AEDs showed that 8 became seizure free within 1 year and another 2 achieved this status within 2 years. The remaining five children never regained freedom from seizures.