Abstracts

RATIONALE:_ To determine seizure control, side effects (SE), and additional benefits for patients (pts) implanted with the vagus nerve stimulator (VNS). METHODS: Prospective review of pts ?18yrs, implanted with VNS from 6/98 - 5/99. All pts had medically intractable epilepsy. Prior to VNS, all pts were evaluated with EEG and/or long-term video EEG monitoring, and brain MRI's. VNS settings were adjusted monthly for tolerance. Pts with < 3mos follow-up were excluded. RESULTS: 15 pts (5-female, 10-male)were followed between 3-20mos (mean=7.9). Age at implantation was 4-18 yrs (mean=11.3 yrs). Age of epilepsy onset was 3 wks-16yrs (mean=3yrs). 13 pts(87%) had cognitive disability, and 9(60%) had cerebral palsy. Previous AEDs attempted ranged from 5-14 (mean=7), and 1 pt had previous surgery (corpus callosotomy). 8(53%) pts had Lennox-Gastaut Syndrome, 4(27%) had other generalized epilepsies, and 3(20%) had mixed or partial epilepsy. Etiologies included: 5(33%) history of infantile spasms, 3(20%) metabolic/chromosomal disorders, 3(20%) encephalitis, and 5(33%) idiopathic epilepsy. 8(56%)pts were on regular cycle settings(on/off time=30sec/5min), 3(19%) were on fast cycle (14sec/0.5min or 14sec/0.8min), and 4(19%) were on intermediate settings. Amplitude settings ranged from 0.25-2.25mA (mean=1mA). Concurrent AEDs ranged from 1-3(mean=2). Seizure frequency was: 7 pts(47%)?75% reduction, 4pts(27%)?50% reduction, 4 pts(27%)<50%reduction. 9(60%) pts reported additional benefits: 5(33%) decreased seizure duration, 5(33%) decreased seizure clusters, 6(43%)improved altertness, 4(27%) improved verbal communication. All pts reported mild SE after adjustment of settings (hoarseness, coughing). 3 pts had reversible SE (insomnia, agitation, hiccups). 10 pts (67%) noted persistent, but tolerable, vocal changes with stimulation. CONCLUSIONS: For pediatric patients with medically intractable epilepsy, who are not candidates for focal resections, VNS provides an alternative means of therapy, that is effective, well-tolerated and may provide additional therapeutic benefits.