Corpus callosotomy for childhood-onset drug-resistant epilepsy unresponsive to vagus nerve stimulation

Corpus callosotomy and vagus nerve stimulation are common palliative options for people with drug-resistant epilepsy when resective epilepsy surgery is not feasible. Because most of the published corpus callosotomy experience comes from a period before vagus nerve stimulation was approved and widely used, there is a paucity of data about efficacy of corpus callosotomy in patients with inadequate response to vagus nerve stimulation.

We report seven patients who had complete corpus callosotomy after an inadequate response to vagus nerve stimulation. At the time of surgery, these patients had failed a median of six antiseizure medications, three patients also had failed a trial of ketogenic diet, and all the patients had a vagus nerve stimulation implanted for a mean duration of 2.5 years with maximal tolerated settings.

There was a decrease in total daily seizure frequency of 34.7% (± 94.7; median, 71.4%; interquartile range, 55.3) after corpus callosotomy at a mean follow-up of 2.6 years (± 1.4). One patient achieved complete seizure freedom and five patients had ≥ 50% reduction in seizure frequency. Six patients continued to have partial-onset seizures though the frequency was decreased. Drop attacks and tonic seizures stopped in all the patients.

Seizure outcomes after corpus callosotomy in our series are most likely a result of complex dynamic interaction between the natural history of epilepsy, the effect of the surgery, ongoing vagus nerve stimulation modulation, and modification in antiseizure drugs. Our study supports the clinical decision to try corpus callosotomy in patients having nonlateralizing drug-resistant epilepsy with inadequate response to vagus nerve stimulation.