Abstracts

Rationale: Corpus callosotomy (CC) is a commonly indicated palliative surgery for Drug Resistant Epilepsy (DRE). The effectiveness of CC has been well documented, but there is a lack of evidence regarding long-term seizure outcomes. A study that evaluates seizure control on various points of follow-up is necessary to better understand the long-term effect of CC.


Methods: On this retrospective longitudinal cohort, we included patients operated by the epilepsy surgery service at the National Institute of Neurology and Neurosurgery, in Mexico City, who had CC between 1993-2023. We compiled epilepsy etiology, pre-operative seizure frequency, and post-operative seizure outcomes at < 1 year follow-up, 1-3 years follow-up, and >3 years follow-up. Our outcomes were seizure freedom and response rate (50% frequency decrease from pre-operative). We used the chi-square test for analysis of differences amongst categorical variables, and Mann-Whitney U test for analysis of differences between non-parametrical numerical variables.


Results: We analyzed data from 63 patients, from which 40 had a follow-up longer than 3 years (median 8.5 years, IQR 6-13). The most common indication for CC was DRE due to Lennox-Gastaut Syndrome (Table 1). Seizure frequency had a significant decrease from pre-operative (Median 70 seizures per month [spm], IQR=16-210) to the 1-year follow-up (Median 4spm, IQR=0-20, p=< 0.0001), 1-3 years follow-up (median 8spm, IQR=1-30, p=< 0.0001), and more than 3 years follow-up (7 spm, IQR 2.25-30, p=< 0.0001). There was no significant difference in seizure frecuency between short, medium, and long-term follow up (Figure 1). Seizure freedom at 1 year post-operative decreased from 25.4% to 9.7%, at 1-3 years (p=0.032), while the overall response rate of our sample remained consistent, being 55/63 patients (81%) at 1 year follow-up, 45/58 patients (77.6%) at 1-3 yeas of follow-up (p = 0.648), and 28/40 patients (70%) at the long-term follow-up (p=0.20)