EMBARGOED FOR RELEASE UNTIL 4 PM ET, January 27, 2003
Positive Response to Epilepsy Medication Does Not Ensure Good Prognosis
St. Paul, Minn. -
Contrary to common belief, early successful treatment and control of epileptic seizures with appropriate medications does not necessarily guarantee that seizures will always be controlled by those medications in the future, according to a study published in the January 28 issue of Neurology, the scientific journal of the American Academy of Neurology. The study examined 333 adults with epilepsy who underwent surgery for partial epilepsy occurring in a localized area of the brain. The study found that the patients went an average of nine years from the onset of the epilepsy to the point when their epilepsy was intractable, or could no longer be controlled by medication. Intractable epilepsy was defined as the failure of two medications to control seizures. The study also found that 26 percent of the patients had a remission period without any seizures of at least a year before having surgery. Remission periods of five years or more were reported by 8.5 percent of the patients. The younger patients were when their epilepsy started, the more likely they were to have had a remission period and the longer the time was between when the epilepsy started and when it became intractable. Study author Anne T. Berg, PhD, of Northern Illinois University in DeKalb, part of a large, multi-center team led by Susan Spencer, MD, of Yale University in New Haven, CT, noted that the results need to be confirmed by additional studies. "The possibility that an early positive response to treatment may not necessarily guarantee a good long-term outcome is sobering news," Berg said. "But it''''s possible that we could learn to identify those patients who will develop intractable epilepsy in the future, identify the mechanisms involved and eventually develop treatments that might prevent some forms of epilepsy from becoming intractable." The study was supported by a grant from the National Institute of Neurological Disorders and Stroke. In another study on epilepsy published in this issue of Neurology, researchers examined brain tissue from children who had undergone surgery for intractable epilepsy occurring in the temporal lobe of the brain. Temporal lobe epilepsy has been linked to the occurrence in childhood of atypical febrile seizures, or multiple, prolonged seizures that occur when the child has an illness with fever. Researchers believe these seizures cause injury to the temporal lobe, leading to what is called mesial temporal sclerosis, a lesion or area of damage to the temporal lobe or hippocampal areas of the brain. MRI scans are used to determine the cause of temporal lobe epilepsy and decide whether surgery is likely to be effective in controlling the seizures, according to study author and neurologist Lionel Carmant, MD, of the University of Montreal in Canada. "The problem is that often the mesial temporal sclerosis won''''t show up on an MRI for children, but there are always concerns about operating on a temporal lobe when a child has a normal MRI," Carmant said. The study found that 12 of the 15 children tested had mesial temporal sclerosis, even those with normal MRI scans. "These results suggest that, in children, a normal MRI doesn''''t mean that there are no abnormalities and should not be a limiting factor when considering children for epilepsy surgery when all other findings point to temporal lobe epilepsy," Carmant said. Of the 12 children with mesial temporal sclerosis, eight were also found to have an abnormal development of the brain called cortical dysplasia. These children were younger when they developed epilepsy and had more severe cases than those without both abnormalities. Researchers hypothesize that this abnormality could make the children more likely to have febrile seizures and then develop mesial temporal sclerosis and epilepsy.