VNS Study
(1995)Objective
To evaluate the efficacy and safety of chronic intermittent vagus nerve stimulation (VNS) in adults with medically intractable partial seizures.
Study Summary
• VNS significantly reduced seizure frequency compared to low-level stimulation and was well tolerated in patients with refractory partial epilepsy.
Intervention
Adjunctive vagus nerve stimulation using an implanted programmable device delivering high-level or low-level stimulation to the left vagus nerve.
Inclusion Criteria
Adults ≥12 years old with ≥6 partial seizures/month, refractory to ≥2 AEDs, on ≤3 AEDs at baseline, with stable drug levels and no seizure-free interval >14 days during baseline.
Study Design
Arms: High-level VNS vs Low-level VNS (sham-like subtherapeutic control)
Patients per Arm: High: 54; Low: 60
Outcome
• Mean seizure reduction: −24.5% (high) vs −6.1% (low), p=0.01. • ≥50% reduction in seizures: 31% (high) vs 13% (low), p=0.02. • No patient became seizure-free during the 12-week stimulation phase. • Most common adverse event: hoarseness during stimulation (37.2% high vs 13.3% low). • One myocardial infarction and one generator malfunction with left vocal cord paralysis occurred in the high group. • AED levels remained stable across groups; no cardiac or EEG rhythm changes observed.