Neuropsychological Outcome of Dominant Frontal Topectomy in Children and Adolescents

RATIONALE: Adult studies suggest that dominant frontal topectomy (DFT) results in diminished language functions, including verbal fluency and verbal reasoning. This study was aimed at assessing cognitive outcome following DFT in a pediatric epilepsy population. METHODS: Patients included eight children and adolescents ranging in age from 7 to 16 years (mean = 12) at the time of surgery. Six evidenced cryptogenic epilepsy and two experienced seizures secondary to low grade tumor. In four patients with cryptogenic seizures, the frontal region anterior to language was resected, and in two patients resection spared the inferior frontal gyrus and frontal pole. Surgery was limited to tumor resection in one patient. In the second tumor patient surgery also involved multiple subpial transection (MST) over language cortex and resection of the epileptogenic region anterior to the language area. All patients underwent cortical mapping of language and motor areas via stimulation of a subdural electrode array prior to resection. Patients underwent neuropsychological testing prior to and four to 13 months following DFT (mean = 9 months). Changes in confrontation naming, verbal fluency, verbal intelligence, and problem solving were analyzed. RESULTS: Both tumor patients evidenced stable or improved verbal IQ, verbal fluency, and problem-solving post-operatively; one experienced a mild (.5 SD) decline in confrontation naming. A 1-2 SD decline in verbal fluency was noted in five of six patients with cryptogenic epilepsy. A 1-2 SD decline was noted on at least one of two indices of problem solving in two of these patients. Two cryptogenic seizure patients evidenced mild decline in VIQ and two displayed decline in confrontation naming. By parent report, cryptogenic seizure patients who experienced decreased problem-solving on formal testing were nonetheless described as having improved self-awareness or social judgment postoperatively. No patient was reported by parents to have experienced an adverse behavioral change. CONCLUSION: Neuropsychological outcome in pediatric patients is similar to that observed in adults. Diminished verbal fluency and, less frequently, diminished problem-solving, confrontation naming and verbal IQ, were observed primarily in patients undergoing extensive frontal topectomy for cryptogenic epilepsy. Patients undergoing resection for tumor removal experienced minimal cognitive changes and often improved verbal functioning, even in the patient who underwent MST and extensive frontal topectomy of the epileptogenic region. Parent report suggests that improved seizure control may result in nonspecific improvements in mental efficiency and social behavior that may offset mild declines in executive abilities and language observed on formal testing. There …