Dynamic changes in comorbid conditions following vagus nerve stimulation for epilepsy.

Abstract

Background: Vagus nerve stimulation (VNS) has been widely used in the clinical treatment of epilepsy, while its effects on comorbidities in epilepsy remain incompletely elucidated. This study aimed to evaluate the impact of VNS on comorbidities and quality of life in adult patients with epilepsy.

Methods: A longitudinal, multicenter cohort study was conducted from 2021 to 2024 among adult patients with epilepsy who underwent VNS implantation. We enrolled 128 participants from 83 hospitals. The inclusion criteria were patients over 18 years old, diagnosed with epilepsy according to the 2014 International League Against Epilepsy guidelines, and having complete data from at least two follow-up visits. Standard assessment tools, including diagnosis according to International Classification of Diseases, 10th Edition (ICD-10), Neurological Disorders Depression Inventory for Epilepsy (NDDI-E), Generalized Anxiexy Disorde-7 (GAD-7), Pittsburgh Sleep Quality Index (PSQI), and Quality of Life in Epilepsy-31 (QOLIE-31) were used to evaluate comorbidities and quality of life. Statistical analysis was performed using SPSS 26.0. The major clinical measurements were changes in the scales above before and after VNS implantation during follow-up. Generalized estimation model was applied to illustrate the effect over time an its relation to seizure control.

Results: A total of 113 participants met the inclusion criteria. Baseline characteristics were comparable between the comorbidity and non-comorbidity groups in terms of gender, seizure onset, age at VNS implantation, seizure types, or the number of antiseizure medications used. Significant improvements were observed from the implantation to the end of follow-up. The PSQI score decreased from 5.43 ± 3.60 to 4.44 ± 3.14 (P < 0.01), indicating better sleep quality. Depressive symptoms (NDDI-E) and anxiety symptoms (GAD-7) decreased significantly, with scores dropping from 6.49 ± 4.67 to 4.83 ± 4.37 (P < 0.01) and from 7.15 ± 5.06 to 4.95 ± 3.69 (P < 0.01), respectively. The QOLIE-31 score increased from 54.40 ± 15.70 to 61.33 ± 16.19 (P < 0.01), suggesting improved quality of life. Further analysis indicated that in the early second postoperative follow-up (1 month after implantation), the scales had already improved significantly (P < 0.001 for PSQI and QOLIE-31, P = 0.006 for NDDI-E and GAD-7). We did not find any statistically significant difference between patients with comorbidity and those without on the efficacy of any scales in this study. The efficacy of VNS on the four scales above was related to follow-up time, with a slightly rebound at the last two follow-ups. The NDDI-E as well as the GAD-7 scores were related to better seizure control according to the GEE model. Higher stimulation currents over 1 mA did not improve the efficacy of VNS on the comorbid conditions.

Conclusions: VNS implantation significantly improved sleep quality, mental health, and overall quality of life in adult patients with epilepsy. Such effects could be observed shortly after the implantation and were mostly long-lasting. Further research is needed to validate its long-term effects.