Mayo Clinic researchers studied more than 200 children with epilepsy and found that even if the cause of focal-onset seizures cannot be identified and they do not fit into a known epilepsy syndrome, long-term prognosis is still excellent. This study was presented at the American Epilepsy Society's annual meeting in San Antonio on Dec. 4.
Epilepsy is a disorder characterized by the occurrence of two or more seizures. It affects almost 3 million Americans, and approximately 45,000 children under age 15 develop epilepsy each year in the U.S.
"This study is important because even if we cannot identify a cause of focal seizures in children and they do not fit into a known epilepsy syndrome, most of the children outgrow the seizures, and very few have seizures that are unable to be controlled by medication," says Elaine Wirrell, M.D., a Mayo Clinic epileptologist and an author of this study.
Mayo Clinic researchers identified all children in Olmsted County, Minn., ages 1 month through 17 years from 1980 to 2004 with newly-diagnosed focal-onset epilepsy. They found 215 children with newly-diagnosed focal-onset epilepsy that was non-idiopathic, meaning that they did not have benign rolandic or benign occipital epilepsy. Focal-onset means that the seizures are produced in a small part of the brain, not the entire brain. The team reviewed medical records, imaging, EEG studies, treatments used and long-term outcomes. They also reviewed follow-up information for more than 12 months for 206 of the children. Children were categorized as having "symptomatic" epilepsy if they had a known genetic or structural/metabolic cause for their seizures, and they were categorized as "cryptogenic" if they did not. The researchers found that more than half of the children had cryptogenic epilepsy, and that this group had a significantly better long-term outcome than those with symptomatic epilepsy. For example, of those who achieved seizure freedom at final follow-up, 68 percent of the cryptogenic group versus only 46 percent of the symptomatic group were off medications.
"This study shows us that it is important to distinguish cryptogenic epilepsy from those children with symptomatic causes, as the prognosis can differ," says Dr. Wirrell. "We will continue to look at the data to see if we can identify specific genes responsible for some of these conditions in order to help us predict which children may have intractable epilepsy, or epilepsy that cannot be controlled by medications."
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