Abstracts

Rationale: Early data defining the extent of division of the corpus callosum in treating medically intractable atonic seizures showed no significant difference in seizure outcomes with full versus anterior two-thirds callosotomy. Several recent studies have shown improved seizure outcomes with complete callosotomy, and no significant difference in cognitive outcomes or morbidity. We describe a series of sixteen patients who underwent partial or total callosotomy and compare results under the care of a single surgeon. Methods: Sixteen patient with medically intractable atonic seizures (drop attacks) presented to Beth Israel Medical Center in New York. Video EEG monitoring demonstrated generalized and bisynchronous discharges in all patients, whose major semiology involved injurious drops. All children had significant cognitive impairment, with IQ less than 30 in all patients. Results: Sixteen patients (11 M, 5 F, ages 8-24) presented with medically intractable atonic seizures of extended duration (3-24 years, mean 96 months). Nine of16 children had undergone prior placement of a vagal nerve stimulator, which did not confer lasting improvements in seizure control. Partial callosotomy (anterior 2/3) was performed in 5 children, while complete callosotomy was performed in 11. Seizure control was measured as a greater than 90% reduction in drop attacks in all 11 children treated with complete callosotomy. Only 2/5 children in the partial callosotomy had a similar reduction in atonic seizures. Of the three patients in the partial callosotomy group who did not have an adequate reduction in drop attacks, two children underwent completion of the callosotomy resulting in a cessation of drop attacks. There was no difference in cognitive outcome or operative morbidity between the two groups. Conclusions: Complete corpus callosotomy appears to provide better seizure control without cognitive change or operative morbidity when compared to partial callosotomy. We advocate complete corpus callosotomy when medically intractable drop attacks occur in the setting of severe mental retardation.