The ictal EEG as a predictive factor for outcome following corpus callosum section in adults.

Unlabelled: Published reports have indicated that after callosotomy half or more of all patients will experience a 50% or greater reduction in seizure frequency. Those callosotomy patients whose seizures produce falls appear to have the best results. We studied the value of ictal EEG in 41 patients 18 years or older who had undergone either a total or partial callosotomy at our program. Ictal EEG's were separated into two categories: Type I: generalized slow spike wave, electrodecrement, non-evolving low amplitude fast activity; Type II: all other patterns. Types I and II were then compared to a defined one-year outcome for the targeted seizure type using Chi-square or Fishers Exact Test. Previously identified predictors of good or worthwhile outcome as defined by the literature were also evaluated.

Results: A significant association was noted for presence of specifically defined EEG patterns and a 90% reduction in seizure frequency but not for other factors analyzed.

Conclusion: The ictal EEG but not other factors is able to identify a group of patients who have a better than 90% chance for total or nearly total resolution of seizures causing sudden falls.