Abstracts

Rationale: Vagus nerve stimulation (VNS) is an established adjunctive treatment for drug-resistant epilepsy.  Early VNS models provided cyclical stimulation as well as on-demand stimulation with magnet activation, which is most effective when delivered early in the course of the seizure.  The newest VNS model, Aspire SR model 106, also has the additional capability to provide stimulation in response to ictal tachycardia, which is an early sign in the majority of seizures (Autostim feature).  There are insufficient data on the incremental efficacy provided by this added stimulation.  Methods: We evaluated seizure frequency before and after conversion from an older VNS model to the Aspire SR model 106 in the same subjects.  We included subjects 18 years or older who had at least 3 months of seizure frequency data prior to converting to the newest device and at least 3 months of seizure frequency data after activation of the Autostim feature.  We compared the seizure frequencies to evaluate the incremental benefit of the Autostim feature. The study was approved by the Vanderbilt Institutional Review Board.  Results: Six patients qualified for inclusion in the study at the time at the time of this abstract. Their age ranged from 31 to 45 years. Four had focal epilepsy and two had structural/metabolic generalized epilepsy. Their baseline monthly seizure frequency ranged from 7-90. After activation of the Autostim feature, there was an average 36% reduction in seizure frequency. Four patients (two with focal and two with generalized epilepsy) improved, with 33%, 50%, 70% and 80% seizure reduction. Of the remaining two patients (both with focal seizures) one had no change and the other a 14% increase in seizures.     Conclusions: The Autostim feature may provide additional benefit in VNS efficacy for some patients. This should be confirmed with a larger number of patients. Funding: None