Treatment of refractory epilepsy in adult patients with right-sided vagus nerve stimulation

Vagus nerve stimulation (VNS) was introduced as a novel method for the treatment of patients with medically and/or surgically refractory epilepsy. VNS typically involves placement of the electrode on the left vagus nerve. However, there are some patients who cannot be implanted on this side because of complications related to the surgical procedure or side effects or infections forcing the left side VNS (L-VNS) explant. Because right side VNS (R-VNS) implants have shown similar effectiveness compared to L-VNS in reducing the frequency of seizures in animal models, treatment with R-VNS should be considered in patients who may not tolerate L-VNS. We present two adult patients who underwent R-VNS. One of the patients improved dramatically after L-VNS, but the device had to be removed because of mechanical malfunction. This patient was thought to be at high risk for nerve injury if L-VNS reimplantation was done, thus R-VNS was chosen. In the other patient, L-VNS was first attempted, but the operation had to be stopped due to significant bleeding caused by the accidental tearing of an ectopic vein. Both patients had a marked reduction in their seizure activity and none of them had cardiac side effects from therapeutic R-VNS. We conclude that R-VNS therapy is an alternative, promising therapy for reducing seizure activity in those patients who cannot undergo L-VNS implantation. Close follow-up and frequent ECG monitoring is required to detect the presence of cardiac side effects.