May 2014

Study Probes Diet-Related Seizure Freedom

Story9_Seizure Freedom

Most children with epilepsy lead active and fulfilling lives, with the help of modern therapies. Yet 20 to 30 percent of children with epilepsy do not respond to medications, which physicians call medication-resistant or intractable epilepsy.

Researchers at The Children’s Hospital of Philadelphia are continually looking into ways to lower the frequency of seizures that children with medication-resistant epilepsy experience on a sometimes daily basis. Alternative treatment options may include the ketogenic diet, vagal nerve stimulator, or epilepsy surgery.

The ketogenic diet, which is low in carbohydrates and high in fat, achieves seizure freedom in 15 to 20 percent of patients and greater than 90 percent seizure reduction in one-third of children with medication-resistant epilepsy; however, few studies have considered its long-term outcomes. Katherine S. Taub, MD, an epileptologist at CHOP and assistant professor of neurology at the Perelman School of Medicine, published a study in the journal Epilepsia that provides evidence to support the continued use of the ketogenic diet in patients with initial seizure freedom even after breakthrough seizures.

“For children who are seizing daily, it has a big impact on their lives,” Dr. Taub said. “Physicians should encourage patients to continue the diet as treatment even if they have seizure recurrence because they can still have a meaningful reduction in their total number of seizures.”

Epilepsy is a brain disorder that affects 1 percent of children in the U.S. Many types of epilepsy exist, each with its own seizure types and frequent neurological comorbidity. Children are diagnosed with epilepsy if they have had more than two unprovoked (no precipitating cause) seizures. Seizures occur when clusters of nerve cells, or neurons, in the brain have a burst of abnormal electrical signals that temporarily interrupts normal electrical brain function.

Researchers are unsure of exactly how the ketogenic diet inhibits epileptic seizures. The diet consists of 90 percent fats, 7 percent protein, and 3 percent carbohydrates, and it requires precise measuring and steadfast adherence.

In this retrospective cohort study, participants were patients at CHOP between 1991 and 2009 who had been unsuccessfully treated with four or more antiepileptic drugs prior to ketogenic diet initiation. The majority had daily seizures. Sixty-five participants achieved seizure freedom for a minimum of one month during ketogenic diet treatment. When Dr. Taub examined the probability of their sustained seizure freedom, the average time to seizure recurrence was three months or less, and the likelihood of remaining seizure-free at 18 months was 3 percent.

“A high number of patients on the diet did have breakthrough seizures, but none of our patients returned to their baseline seizure frequency,” Dr. Taub said.

Another significant finding that Dr. Taub discovered while comparing this data to previous studies is that a consistent definition of sustained seizure freedom is lacking in the medical literature. Such a consensus would facilitate future studies, such as a head-to-head study comparing the ketogenic diet versus other antiepileptic medications.

“If we’re going to be sharing comparative data between centers, then we should establish an agreed upon definition for seizure freedom, so we can evaluate institutions’ success of the diet,” Dr. Taub said.

The study’s co-authors included Sudha Kilaru Kessler, MD, an attending physician at CHOP, and Christina Bergqvist, MD, an attending physician and director of CHOP’s Ketogenic Diet Program, which is one of the largest of its kind in the country providing resources and training for families.

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