Faculty Bibliography

PURPOSE: Functional mapping of eloquent cortex with electrical neurostimulation is used both intra- and extraoperatively to tailor resections. In pediatric patients, however, functional mapping studies frequently fail to localize language. Wada testing has also been reported to be less sensitive in children. METHODS: Thirty children (4.7 - 14.9 years) and 18 adult controls (18-59 years) who underwent extraoperative language mapping via implanted subdural electrodes at the NYU Comprehensive Epilepsy Center were included in the study. Ten children and 14 adults underwent preoperative Wada testing. Success of the procedures was defined as the identification of at least one language site by neurostimulation mapping and determination of hemispheric language dominance on the Wada test. RESULTS: In children younger than 10.2 years, cortical stimulation identified language cortex at a lower rate than was seen in children older than 10.2 years and in adults (p<0.05). This threshold, demonstrated by survival and chi2 analysis, was sharply defined in our data set. Additionally, Wada testing was more likely to be successful than was extraoperative mapping in this younger age group (p<0.05). CONCLUSIONS: Analysis of our series demonstrates that language cortex is less likely to be identified in children younger than 10 years, suggesting that alternatives to the current methods of cortical electrical stimulation, particularly the use of preoperative language lateralization, may be required in this age group

OBJECTIVE: Tuberous sclerosis complex (TSC) is associated with medically refractory epilepsy and developmental delay in children and usually results from cortical tubers. Seizures that begin in young patients are often refractory and may contribute to development delay. Functional outcome is improved when seizures are controlled at an early age. Previous reports have shown modest benefit from surgical resection of single tubers/seizure foci in older children; however, many children with TSC develop uncontrolled seizures before age 1. To identify patients who might benefit from surgery and to maximize outcome, we used a novel surgical approach in young children that consists of invasive intracranial monitoring, which is typically 3-staged and often bilateral. METHODS: Of 110 consecutive children who underwent epilepsy surgery by a single surgeon in the past 6 years, 25 patients (9 boys and 16 girls) had TSC. At the time of their first surgery at our institution, they were a median age of 4.0 years. A total of 31 separate admissions for epilepsy surgery in these 25 patients were identified. Bilateral electrode placement was performed in 13 children whose seizures could not be lateralized definitively preoperatively, and 22 patients underwent 3-stage surgeries. RESULTS: At 6 months or longer after the initial resection, 21 (84%) children were class I, 2 (8%) children were class II, and 2 (8%) children were class IV. At a mean follow-up of 28 months, 17 (68%) children were class I, 6 (24%) were class II, and 2 (8%) were class III. Four of the 5 children who initially were rejected as surgical candidates because of multifocality and who required initial bilateral electrode study are now seizure-free. CONCLUSIONS: This approach can help to identify both primary and secondary epileptogenic zones in young TSC patients with multiple tubers. Multiple or bilateral seizure foci are not necessarily a contraindication to surgery. Long-term follow-up will determine whether this approach has durable effects