Post-vagus nerve stimulation mood and cognitive burden in dual epileptic-functional seizure patients

To evaluate neuropsychiatric burden in the understudied population of patients with dual diagnoses of epileptic seizures (ES) and functional seizures (FS) who have received vagus nerve stimulation (VNS).

In this retrospective study, adults with dual diagnoses of ES and FS who underwent VNS at a tertiary care center between 2015 and 2024 were identified via ICD-10 codes and confirmed by video-electroencephalography (VEEG). Propensity score matching generated two control groups: (1) patients with ES only with VNS, and (2) patients with dual ES and FS without VNS. Longitudinal patient-reported outcomes, including seizure frequency, NDDI-E, and the QOLIE-31 Cognitive subscale, were analyzed using time-weighted averaging and nonparametric statistics.

Eight patients with dual ES and FS who received VNS were matched to eight in each control group. The dual-diagnosis patients with VNS implants had significantly higher seizure frequency than those without VNS implants (median seizure frequency = 14.1 vs. 2.2, p = 0.001). Among patients with VNS implants, those with dual diagnoses had significantly greater depressive symptoms (median NDDI-E = 16.4 vs. 8.8, p = 0.015) compared to those with ES alone. Significant differences in cognitive quality of life were not observed.

Dual-diagnosis patients exhibited higher seizure reporting after VNS therapy compared to those without VNS and higher depressive burden compared to patients with ES alone, patterns that may reflect the underlying severity of FS-related comorbidity. These exploratory results support careful pre-implant counselling and highlight the need for prospective studies with baseline assessments to clarify outcomes in this complex population.