Abstracts

Rationale: Corpus callosotomy (CC) had been the only procedure of palliation for medically refractory epilepsy before vagus nerve stimulation (VNS) was introduced in 1990s. CCs were commonly indicated for epileptic falls in Lennox-Gastaut syndrome (LGS), tonic seizures in symptomatic generalized epilepsy, and secondary generalization in localization-related epilepsy. However, VNS is now more frequently indicated for these seizure types or epileptic syndromes. It depends on each institution which procedure is the first choice. Effectiveness especially for seizure reduction by CC was reviewed as compared to VNS in our series, and then our principle of surgical indication was reconsidered. Methods: Thirty cases of CC were carried out from 2008 through the end of 2013 for medically refractory epilepsy. Ages at surgery ranged from 6 months to 53 years old. The mean age was 23.8 years old. The follow-up period varies from 9 months through 66 months. The mean follow-up period was 38.4 months. Seizure reduction by CC, the difference of seizure reduction by seizure types or epileptic syndromes, the difference of seizure reduction by the extent of CC, and additional seizure reduction by VNS after unsatisfied results of CC were examined in medical records of our hospital. Results: Epileptic diagnoses or syndromes in patients who underwent CC showed LGS (40%), West syndrome (3%), symptomatic generalized epilepsy (30%), and symptomatic localization-related epilepsy (27%). Regarding combination with VNS, only CC was performed in 17 out of 30 patients. VNS was added on to unsatisfied CC in 11 patients. Conversely, VNS was followed by CC in 2 patients. Extent of CC was well discussed at the multidisciplinary presurgical conference and determined in terms of severity of seizures, ability in communication and language, and quality of life. Partial CCs were 5 cases of anterior two thirds of disconnection and 13 cases of anterior four fifths. Complete sectioning was carried out in 11 patients. Additional sectioning of the splenium (posterior one fifth) was performed in 2 patients. Seizure freedom was achieved in 20% of patients. More than 80% seizure reduction was observed in 13%. Twenty percent of patients showed 50-79% seizure reduction. Less than 50% seizure reduction was demonstrated in 40%. Seven percent of them did not show any changes in seizure frequency. CC was most effective in epileptic falls with seizure freedom in 40% of patients. Extent of CC did not affect the results of seizure reduction. Complete sectioning was not necessarily most effective. Eleven patients were treated by VNS because CC was not satisfactory and revealed improvement by VNS in 10 patients. Conclusions: VNS is considered as the first choice more than ever for certain types of epilepsy such as generalized epilepsy and multifocal epilepsy, particularly because VNS is much safer than CC. However, CC is still important and works well for epileptic falls in LGS. Then we must possess and keep both of them as palliation, since most difficult cases sometimes need both for seizure control.