Abstracts

Rationale: Due to the high case fatality in super-refractory status epilepticus (SRSE)  between 16-41.5%[1],[2], experimental treatments without evidence of acute efficacy in SRSE are often administered. Single case-reports and small case series summarized in a recent meta-analysis of 38 patients with acute vagus nerve stimulation (VNS) in SRSE report a cessation of the SRSE episode in 74% of cases[3]. To date it is unclear which titration approach and which stimulation parameters are most effective in SRSE and whether these differ from those used in VNS for seizure frequency and severity reduction in drug-resistant epilepsy. Here we present details on the stimulation parameters of all patients who received VNS for SRSE. [1] Kantanen et al Epilepsy Behav. 2015 Aug;49:131-4.[2] Leitinger et al Epilepsia. 2019 Jan;60(1):53-62[3] Dibué-Adjei et al Brain Stimulation 2019 May 14 Methods: We performed a sub-analysis for VNS programming parameters on all studies in our recently published meta-analysis. Details on search strategy have been reported previously 3. Results: Thirty-eight cases of acute implantations of VNS in SRSE were identified. Acute VNS was associated with cessation of SRSE in 74% (28/38) of cases3.  Information on VNS settings was reported in 50% (19/38) cases. Median output current was 1.5 mA (range 1-3 mA), median frequency was 30 Hz (range 20-30 Hz), median pulse-width 500 µsec (range 250 – 500µsec) and median duty cycle was 16 % (range 10-58%).  Full VNS parameters allowing for calculation of total charge applied to the vagus nerve per day were only reported in 9 cases, all in which acute VNS was associated with interruption of SE. The median charge per day in these successful cases was 688.5 mCb however the duration to achieving these final settings was not accurately reported throughout the studies and ranged from 0 days (immediate intra-operative titration to final setting) to 9 months. Conclusions: Considering the low sample size and highly anecdotal information, conclusions on optimal stimulation parameters or titration regimens in the treatment for SRSE are premature. Analysis of this small series suggests that VNS parameters associated with acute SRSE interruption (688.5 mCb/day) may be higher than those associated with response (>50% seizure reduction) to chronic VNS in patients with DRE at 24 months of therapy (345.8 mCb/day)[4]. [4] Orosz et al Epilepsia. 2014 Oct;55(10):1576-84 Funding: No funding