Outcomes/Effectiveness Research

Certain clinical features are associated with seizure frequency after epilepsy surgery

Epilepsy surgery is used to treat people whose seizures do not respond to medication. About 60 to 80 percent of patients become seizure-free after surgery. Some patients suffer rare seizures after surgery. Others continue to suffer from monthly or more frequent seizures, which are associated with increased risk of injury, lower quality of life, higher medical costs, and increased mortality. A new study, supported in part by the Agency for Healthcare Research and Quality (HS09986), identifies clinical factors that can predict seizure frequency after surgery, which may help set realistic goals for surgery and affect treatment decisions and postoperative management.

Researchers placed patients who underwent surgery for epileptic seizures in 2 categories in the second postoperative year: rare postoperative seizures (2 or fewer per year) and frequent postoperative seizures (12 or more a year). They examined the relationship between numerous characteristics and postoperative seizure frequency. Characteristics ranged from preoperative seizure frequency, age of first risk (for example, due to head trauma or convulsions due to high fever), and age at first seizure due to certain defects seen on magnetic resonance imaging (MRI) or computerized tomography (CT), and family history of epilepsy.

Nearly one-fourth of 475 patients who had epilepsy surgery had rare or frequent seizures in the second postoperative year, despite increased dosage of existing medication or prescribing of new medication in an effort to stop all seizures. After anterior temporal lobectomy (ATL), age of first risk at 5 years or younger and presence of mesial temporal sclerosis on MRI were associated with rare seizures (66 percent of patients), whereas lack of these risk factors was associated with frequent seizures (75 percent of patients). For non-ATL operations, preoperative seizure frequency of 20 or more seizures per month was associated with frequent postoperative seizures. No other factors affected postoperative seizure frequency.

See "Predicting seizure frequency after epilepsy surgery," by John S. Khoury, Ronald S. Winokur, Joseph I. Tracy, and Michael R. Sperling, in Epilepsy Research 67, pp. 89-99, 2005.

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