NATIONAL HARBOR, MD—Parents of children with epilepsy tend to have three main questions for neurologists about outcomes after epilepsy surgery. They want to know whether their children will be seizure-free, whether their children will be able to stop taking antiepileptic drugs (AEDs), and how surgery will affect their children’s overall function.
“Ideal outcomes are always the goal. However, in the real world, sometimes the ideal outcome is not possible,” said Ajay Gupta, MD, Head of the Pediatric Epilepsy Section at Cleveland Clinic’s Epilepsy Center. “In fact, in many children who have severe and catastrophic epilepsy, the outcome goals could be a specific target—for example, eliminating grand mal seizures, episodes of status epilepticus, nocturnal seizures, or falls. Therefore, what you actually get in each child after epilepsy surgery is usually a unique outcome for that patient … and sometimes that outcome is dynamic over the years.”
Ajay Gupta, MD
Realistic family counseling is possible, however, with the available data, Dr. Gupta said in a presentation at a symposium he directed at the 2015 Child Neurology Society Annual Meeting. The same factors that predict seizure freedom in children after epilepsy surgery also predict neurologists’ ability to reduce or wean medications postoperatively and to deliver cognitive and behavioral improvement for the child, he said.
Seizure Freedom
The only Class I study in epilepsy surgery included 80 adults with intractable temporal lobe epilepsy. “There was no question that surgery was superior to long medical therapy in adult patients with temporal lobe epilepsy,” said Dr. Gupta. In pediatric epilepsy surgery, data are limited to retrospective series, but neurologists have enough experience and consistently meaningful data to counsel patients and their families before surgery, he said.
Dr. Gupta reviewed six series of children with epilepsy who had hemispherectomy, including three published series with more than 100 patients each. In two studies with longitudinal follow-up, approximately 76% of the patients were seizure-free at one to two years. At year five, 58–60% were seizure-free.
The seizure freedom outcomes in hemispherectomy are representative of most of the outcome curves for epilepsy surgery in children, where over time the number of children who relapse with seizures increases, he said. In one series, the researchers reviewed seizure outcomes for 170 children who underwent hemispherectomy between 1997 and 2009 at Cleveland Clinic’s Epilepsy Center. Initially, there was a steep decline in the percentage of patients who were seizure-free. Most surgical failures occur very early, said Dr. Gupta. “In fact, many occur right in the acute postoperative period or shortly thereafter,” he said. In this series, 78% of patients were seizure-free six months after surgery. At two years, 70% were seizure-free. At five years, about two-thirds remained seizure-free.
In studies of temporal lobe surgery in adults and children, the seizure freedom rate is about 80% at one year and approximately 60% at five years. For frontal lobe surgeries, the seizure freedom rate is somewhat lower—two-thirds at one year and 44% at five years.
“All the curves are saying [that] you have early failures, which are probably your incomplete resections,” said Dr. Gupta. “And then you have late failures, which could be a combination of incomplete resections and failure to localize.”
For posterior quadrant surgery, seizure freedom is in the range of 60% to 70% at one year. At five years, 55% of patients are seizure-free. Surgical treatment of occipital pathology seems to produce better outcomes than treatment of parietal pathology, said Dr. Gupta. “The best predictor of long-term seizure outcome is really a brain MRI lesion that is concordant with the electrophysiologic data, and that complete resection of the lesion was feasible,” he said. Considering etiology, surgeries to remove low-grade tumors, well-circumscribed remote encephaloclastic lesions, and vascular substrates are the most successful, followed by cortical dysplasias, type 2 or higher. Patients with focal cortical dysplasias, type 1, are the most difficult to treat surgically.
In summary, child neurologists who are referring or thinking of referring children for epilepsy surgery can use the data from these studies to counsel families in the clinic. “You can use these median numbers: the median seizure freedom that you can expect of all surgeries in the pediatric population is about 60–70% at one year and about 50–60% at five years. Obviously some children will do much better. Some will not.”
Tapering AEDs
In children who are seizure-free one year after surgery, reducing AEDs “appears to be safe and reasonable and therefore should be considered,” said Dr. Gupta. In the series of 170 patients, approximately two-thirds of patients were not taking any AEDs at five years. In the other patients, medications were reduced, continued, or restarted because the patient failed to achieve seizure freedom. “The mean number of [AEDs] that these patients have after surgery is much lower than that would be otherwise,” he said.
