Abstracts

Rationale: Anterior corpus callosotomy (ACC) is a procedure that involves transecting the anterior two-thirds of the corpus callosum performed as a palliative measure for refractory epilepsy. In some cases, this procedure can unmask focal epilepsy previously thought to be generalized, or may help to further lateralize and localize the seizure focus in cases in whom the seizures rapidly spread. The purpose of this study is to characterize outcome results of focal resection of these unmasked foci for epilepsy following ACC. Methods: All patients in the Jefferson epilepsy surgery database who had an ACC followed by a focal resection were included (n=23). Those with missing data, bilateral focal resection, hemispherectomy and prior epilepsy surgery were excluded (n=7). Statistical analysis was done via Chi-Square and Kruskal-Wallis test.Results: Of the patients who had an ACC followed by a focal resection (n=16), 14 had frontal lobe epilepsy, 1 had parietal lobe epilepsy, and 1 had a focus involving the unilateral frontal and parietal lobe. The mean days from ACC to focal resection was 138 days (SD: 233.59, Range: 7 681). 15 out of 16 patients had intracranial monitoring. The mean pre-op seizure frequency was 149.75 seizures per month (SD: 236.57, Range: 2 - 903). After the first surgery, 5 achieved Class I outcome (no seizures with alteration of mental status), 9 achieved Class III outcome (greater than or equal to 80% seizure reduction), and 2 were Class IV outcome (worse or no different). 5 of the Class III result patients went on to have additional resection and of those, 3 achieved Class I result and 2 stayed in Class III. Overall, after the second surgery, 50% (n=8) achieved Class I result, 37.5% (n=6) achieved Class III and 12.5% (n= 2) achieved class IV. There was a trend toward better outcome when surgery was performed at a younger age but this did not reach statistical significance. The mean age at ACC for those achieving Class I result was 26.5 years old (SD: 7.57, Range: 16.87 40.01), Class III was 31.48 years old (SD: 8.67, Range: 14.79 38.21), and Class IV was 19.72 (SD: 1.26, Range: 18.83 20.62). Conclusions: ACC with subsequent focal resection can significantly reduce seizure frequency in selected patients with highly refractory epilepsy and seizure foci which are difficult to localize non-invasively. 87.5% of patients had improvements in seizure frequency after the focal resection. Furthermore, a second resection can be considered in selected patients should the first resection not adequately control the seizure. There was also a trend towards better result in having the surgery performed earlier in life but statistical significance was not achieved due to small sample size.