Abstracts

Rationale: Developmental and epileptic encephalopathy (DEE) is characterized often by both frequent seizures and severe developmental delay. The main issues for these patients are how the seizure frequency is reduced as much as possible and how they can make more development in their cognitive function because these severe seizures can affect lifestyles of themselves and even their care givers. Recently there are several reports demonstrating that vagus nerve stimulation (VNS) therapy with auto-stimulation (Auto-stim) induced by ictal tachycardia gives additional seizure reduction as compared to the outcomes by the previous VNS models. However, it is unknown exactly when is the best timing for implantation and introduction of VNS with Auto-stim to obtain better outcomes in patients with DEE, although previous reports showed earlier initiation of VNS is better for patients with drug-resistant epilepsy. We reviewed seizure outcomes by VNS with Auto-stim in DEE patients with special reference to their age of implantation and the timing after their seizure onset.


Methods: Twenty-four patients with DEE who underwent VNS therapy by Model 106 (Aspire SR^TM) or Model 1000 (SenTiva^TM) for more than two years at the Seirei Mikatahara General Hospital or the Seirei Numazu Hospital were assessed retrospectively. 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 seizure onset was 1.9 years old. The mean age of the first VNS implantation was 19.5 years old. Regarding the seizure frequency, 21 patients had daily seizures and 3 patients had weekly seizures. The mean period of follow-up after VNS with Auto-stim was 50.4 months.
As compared to the baseline before VNS therapy, a more than 50% seizure reduction was achieved in 21 patients (88%, responders) and a more than 90% seizure reduction in 12 patients. In 14 patients who underwent implantation and started VNS in younger than 16 years old, 13 patients (93%) were considered responders and 9 patients (64%) achieved even more than a 90% seizure reduction. On the other hand, 8 patients (80%) were considered responders and 3 (30%) achieved a more than 90% seizure reduction in ten patients with VNS introduction in older than 17 years old. Final VNS parameters showed that the mean normal output current was 2.375mA, the mean duty cycle was 21.4% and the mean rate of the total daily stimulation with Normal and Auto-stim Modes was 24.8%.


Conclusions: Earlier implantation and initiation of VNS with Auto-stim, especially in younger than 16 years old, demonstrated better seizure outcomes for DEE than patients whose introduction of VNS was delayed after adolescence in our series. Earlier commencement of VNS with Auto-stim presumably has expectation to contribute to better seizure control for patients with DEE. Treatment for patients with DEE is always challenging, however, VNS with the Auto-stim Mode would be one of the effective options for these patients.


Funding: No funding was received in support of this abstract.