Abstracts

Rationale: Current methods of neuromodulation have been shown to reduce seizures in patients with drug-resistant focal epilepsy (DRE), and in a small percentage of patients it has rendered them seizure-free when surgical resection is not feasible [1, 2]. Controlled clinical trials demonstrating efficacy include the responsive neurostimulator (RNS), deep brain stimulation of the anterior nucleus of the thalamus (DBS-ANT), and vagus nerve stimulator (VNS) [3, 4, 5]. While polytherapy with antiseizure medication is not uncommon, dual neurostimulation has received limited attention [4]. As newer forms of neuromodulation become available, the usage of poly-neuromodulation has increased. Therefore, we aimed to identify trends and changes in practice associated with dual neurostimulation to draw conclusions for device combinations.

Methods: We reviewed the Mayo Clinic database in Florida of patients who have undergone VNS, DBS, and RNS device implantation from 1/2011 through 8/2021. Review was supplemented from an industry-held database of neurostimulator placement. The prevalence of active VNS with DBS and RNS neuromodulation was assessed as dual therapy. In addition, we also focused on the management of VNS devices with RNS and DBS to detect changes in usage of maintaining VNS when an intracranial neuromodulatory device was implanted.

Results: 128 patients (67 females) underwent 157 VNS generator/lead placement or replacement for DRE. Most neuromodulation was performed for focal epilepsies, and 90% continued as VNS monotherapy. Dual neurostimulators with VNS-DBS (6 anterior thalamic; 2 centromedian) or VNS-RNS occurred in 13 patients. Active dual stimulation occurred in 5/28 patients with RNS and all 8 patients with thalamic DBS (p=0.006). There was an incremental trend toward continued use of active dual stimulation. There was a tendency for more patients with RNS to undergo invasive EEG monitoring compared to the DBS group prior to device implantation: 11/28 in the RNS group and 1/8 in the DBS group, though did not reach significance (p=0.129).

Conclusions: VNS surgery was the most common form of neuromodulation at our center. Most patients with DRE were managed with VNS monotherapy. Patients treated with DBS are more likely to maintain active VNS compared to those with RNS. Long-term dual neurostimulation is safe and feasible in patients with dual devices for DRE. Invasive EEG was more likely to be performed in patients who received VNS-RNS. Prospective multi-center studies are needed to determine the efficacy of dual device neurostimulation.

Funding: Please list any funding that was received in support of this abstract.: None.