Vagus nerve stimulation (VNS) is an adjunctive antiepileptic treatment for
patients with refractory epilepsy. Limited information on long-term treatme
nt with VNS is available. The purpose of this paper is to present our exper
ience with VNS with a follow-up of up to 4 years.
Twenty-five patients (13 females and 12 males) with refractory partial epil
epsy were treated with VNS. The first 15 patients with a mean age of 30 yea
rs and a mean duration of epilepsy of 17.5 years have sufficient follow-up
for analysis.
Mean post-implantation follow-up was 29 months and mean stimulation output
2.25 mA. There was a mean seizure frequency reduction from 14 complex parti
al seizures (CPS) per month before implantation to 8 CPS per month after im
plantation (P = 0.0016; Wilcoxon signed-rank rest (WSRT)). The mean maximum
CPS-free interval changed from 9 to 312 days (P = 0.0007; WSRT). Six patie
nts were Gee of CPS for at least one year. In one patient, one antiepilepti
c drug (AED) was tapered; in 10 patients, AEDs remained unchanged; in four,
one adjunctive AED was administered. Side effects occurred in six patients
, three of whom required a temporary reduction of output current. Nine pati
ents reported no side effects at all.
Treatment with VNS remains effective in the long-term. In this series 4/15
(27%) patients with highly refractory epilepsy experienced entirely seizure
-free intervals of 12 months or more. (C) 1999 BEA Trading Ltd.