Authors :
Presenting Author: Tomohiro Yamazoe, MD, PhD – Seirei Mikatahara General Hospital
Hiroshi Kawaji, MD, PhD – Seirei Mikatahara General Hospital
Ayumi Yoshimura, MD – Seirei Mikatahara General Hospital
Katsuhiko Nishimura, MD – Seirei Mikatahara General Hospital
Naoto Ando, MD – Seirei Numazu Hospital
Takamichi Yamamoto, MD, PhD – Seirei Mikatahara General Hospital
Rationale:
Vagus nerve stimulation (VNS) is a popular palliative option for patients with drug-resistant epilepsy (DRE). It is well recognized that around 50% of the patients implanted with previous VNS models achieved more than 50% seizure reduction. Recently, the auto-stimulation mode responding to ictal tachycardia (AutoStim), closed-looped stimulation, established as a therapeutic option of VNS because tachycardia is associated with ictal events in about 80% of patients with epilepsy. However, seizure outcomes of VNS therapy with AutoStim are not well understood. We assessed seizure outcomes of VNS therapy with AutoStim for patients with DRE followed up at our two hospitals.
Methods:
Seventy-five patients with DRE who underwent VNS implantation with Model 106 (Aspire SRTM) or Model 1000 (SenTivaTM) were followed up and assessed at the Seirei Mikatahara General Hospital or the Seirei Numazu Hospital for more than a year. In all cases, the Auto-stim Mode has been active in addition to the conventional modes including the Normal Mode and the Magnet Mode.
Results:
The mean age of the seizure onset was 8.0 years old. The mean age of the first VNS implantation was 25 years old. In the epilepsy classification, 42 patients had focal epilepsy and 33 patients had generalized epilepsy. In the frequency of seizures before the VNS therapy, 39 patients had daily seizures, 22 patients had weekly, 13 patients had monthly and one patient had yearly seizures. The mean periods of the follow-up of VNS therapy with AutoStim were 51.3 months. Thirty-nine patients underwent switching from the previous models to the new models with AutoStim.
As compared to the baseline before VNS therapy, a more than 50% seizure reduction was achieved in 52 patients (69.3% responders) and a more than 90% seizure reduction in 19 patients (25.3%). Final VNS parameters showed that the mean normal output current was 2.29mA and the mean duty cycle was 20.5%.
Conclusions:
Almost 70% of the patients with DRE underwent VNS therapy with AutoStim achieved a more than 50% seizure reduction in our series. Although there are differences between our report and previous reports in patients background or follow-up periods, VNS therapy with AutoStim could provide more patients with seizure reduction in the number of responders than previous models. In addition, 25% of the patients achieved a more than 90% seizure reduction, as compared with 11 out of 104 patients (10.6%) with the traditional VNS modes in our previous series. Therefore, VNS therapy with AutoStim could offer more favorable seizure outcomes than previous models without AutoStim.
Funding: No funding that was received in support of this abstract.