Quantifying Vagus Nerve Stimulation Outcomes in Multifocal Refractory Epilepsy: A Model Across Multiple Surgeries

Objective This study aims to develop a quantifiable model for evaluating the outcomes of vagus nerve stimulation (VNS) in patients with multifocal refractory epilepsy, particularly focusing on those who have undergone multiple surgeries. By adopting a patient-centered approach, the study seeks to provide a robust framework for assessing VNS efficacy across various patient demographics, including both adult and pediatric patients, and those with impaired cognitive and communicative abilities. Methods We conducted a retrospective analysis of 49 patients with multifocal refractory epilepsy who underwent at least one VNS surgery. The cohort was divided into two groups: adults (≥16 years) and a combined pediatric group that included patients under 16 years of age and patients with impaired cognitive and communicative skills. The Liverpool Seizure Severity Scale (LSSS) was used for adults, while the Hague Seizure Severity Scale (HASS) was employed for the pediatric group. Key outcome measures, including changes in seizure frequency, quality of life (QoL), number of hospitalizations, and other clinical metrics, were quantified using our proposed model. The iterative use of the mentioned scales was also assessed for validity by comparison with the Engel Outcome Scale (EOS). A total of 96 procedures were assessed. Results The results indicated a significant reduction in seizure severity post-surgery across both groups, as quantified by the LSSS for adults and HASS for pediatric and cognitively impaired patients. The model also demonstrated a consistent decrease in seizure frequency and an improvement in QoL metrics over successive surgeries. Minimal major side effects were reported, supporting the effectiveness of our quantification approach in capturing VNS outcomes. Conclusions This study introduces a novel, quantifiable model for evaluating VNS outcomes, providing a comprehensive tool for clinicians to assess the effectiveness of VNS in managing multifocal refractory epilepsy. By integrating multiple outcome measures into a cohesive framework, our model can aid in better understanding VNS therapy's impact and contribute to more informed clinical practice.