Rationale:
Epilepsy with eyelid myoclonia (EEM) is a rare, generalized epilepsy syndrome that is often resistant to pharmacologic treatment. Given the subtle nature of its seizures and the limited available therapeutic options, managing EEM remains challenging. Vagus nerve stimulation (VNS) represents a neuromodulatory alternative for drug-resistant epilepsy, yet its efficacy specifically in EEM has not been well established. This study aims to evaluate seizure outcomes, side effects, and adjustments in concurrent therapies following VNS implantation in patients with EEM.
Methods:
We conducted a retrospective chart review of 250 patients who underwent VNS placement at a single tertiary pediatric epilepsy center between 2013 and 2025 and identified patients with EEM. Diagnosis was based on electroclinical criteria consistent with the ILAE classification of idiopathic generalized epilepsies. Collected data included demographics, seizure characteristics, VNS programming, complications, and concurrent antiseizure medication (ASM) adjustments. Seizure outcomes were categorized by patient and family reports as no improvement, < 50% improvement, >50% improvement, or seizure freedom.
Results:
The cohort included 8 patients with a mean age at VNS placement of 13.6 years; 88% were female. Median follow-up was 24 months. At any point during therapy, 50% of patients experienced >50% seizure reduction, 12.5% had < 50% improvement, and 37.5% had no benefit. No patients achieved seizure freedom. In some responders, initial efficacy diminished over time. VNS became effective at 0.75 mA in one patient, at 1.0 mA in two patients, and at 1.5 mA in one additional patient—yielding a 50% response rate at or below 1.5 mA. No patients gained additional benefit from current increases beyond 1.5 mA. Rapid cycling was trialed in 62.5% of patients and was effective in 40% of those. Three patients (38%) discontinued VNS after a mean of 20 months: one due to lack of efficacy, one due to side effects despite perceived benefit, and one due to parental preference although VNS was not trialed for a full course in this patient. At last follow-up, 25% of patients continued to report sustained benefit. ASM or therapy adjustments were common, particularly during VNS titration or in response to suboptimal efficacy. Adverse effects were reported in 75% of patients and included cough, vocal modulation, throat tingling, pain at the generator site, and worsening of seizures.
Conclusions:
VNS was associated with meaningful seizure reduction in half of patients with EEM, although efficacy fluctuated over time and no patients achieved seizure freedom. Clinical benefit was generally achieved at or below 1.5 mA, with no added efficacy from higher current. Rapid cycling appeared helpful in select patients. VNS discontinuation was common due to variable response or adverse effects. These findings suggest VNS may be a useful adjunctive therapy in EEM, although its benefit may be time-limited.
Funding: None.