Resective surgery for intractable focal epilepsy in patients with low IQ: predictors for seizure control and outcome with respect to seizures and neuropsychological and psychosocial functioning

PURPOSE: To investigate possible predictive factors for seizure control in a group of children and adults with low IQs (IQ, < or =70) who underwent resective surgery for intractable focal epilepsy and to study outcome with respect to seizures and neuropsychological functioning. We also studied psychosocial outcome in the adult patients. METHODS: Thirty-one patients (eight children younger than 18 years) with a Wechsler Full Scale IQ of 70 or less underwent comprehensive neuropsychological assessments before and 2 years after surgery. Adults also completed the Washington Psychosocial Seizure Inventory (WPSI). Univariate analyses were used to identify variables differentiating between patients who became seizure free and those who did not. Pre- and postoperative test results were compared by t test for dependent samples. RESULTS: Forty-eight percent of the patients became seizure free, 52% of those with temporal lobe resection and 38% of those with extratemporal resection. Only one variable was predictive for seizure outcome: duration of epilepsy. In one third of the patients, who had the shortest duration of epilepsy (<12 years), 80% became seizure free. Significant improvement was seen regarding vocational adjustment in adults (WPSI). Seizure-free adults improved their Full Scale IQ scores. No cognitive changes were found in seizure-free children or in patients who did not become seizure free. CONCLUSIONS: A good seizure outcome was obtained after resective surgery in patients with intractable focal epilepsy and low IQ, provided that treatment was done relatively shortly after onset of epilepsy. No adverse effects were seen on cognitive and psychosocial functioning.