Electrodiagnostic artifacts due to neurostimulation devices for drug resistant epilepsy

Background: Neurostimulation devices including vagus nerve stimulation (VNS), deep brain stimulation (DBS), and responsive neurostimulation (RNS) are approved therapeutic options for drug resistant epilepsy (DRE). As these devices are increasingly used in clinical practice, it is of importance to recognize their artifacts in electrodiagnostic studies. Methods: This is a retrospective study of all adult DRE patients treated with neuromodulation devices for epilepsy at our center between 2012 and 2021. Available EEGs were reviewed for neurostimulator-related artifacts. Results: Fifty-two patients were included. 37% of patients had neurostimulation related electrophysiological artifacts (20% of VNS, 75% of DBS, all patients with dual VNS-DBS treatment, and in the single patient with RNS). Artifacts were intermittent, appearing most commonly simultaenously in the EEG and ECG. VNS artifacts were monomorphic appearing mostly in the lower temporal EEG electrodes, whereas DBS artifacts were with variable morphology, amplitude, and scalp distribution. At times, the artifacts resembled electrographic seizures in the EEG and mimicked extrasystole or asystole in the ECG. Conclusions: With the increasing use of neurostimulation treatments for DRE, and the need for frequent electrodiagnostic studies in this patient population, it is important clinicians recognize these electrophysiological findings as artifacts, to avoid misdiagnosis and facilitate accurate interpretation.