A prospective, multicenter study of cardiac-based seizure detection to activate vagus nerve stimulation
Introduction from Dr Markus Reuber, editor-in-chief of Seizure
It seems a long time ago that the monitoring of physiological functions such as respiratory or heart rate was something reserved to high intensity medical care environments, astronauts, deep-sea divers or performance athletes. Now everybody seems to be busy monitoring their body’s physiological adjustment, not only to exercise, but also to quite ordinary activities such as the different phases of sleep.
The plethora of ever smaller, wearable devices available to carry out and make sense of these measurements may well reduce the sense of wonder about the research which underpins this months’ editor’s choice by Paul Boon et al. (1). However, what this editor’s choice article describes is a first in man study of a device which attempts to detect the physiological build-up to an epileptic seizure and to disrupt this process. Admittedly, this study, in which a vagus nerve stimulator (VNS) sensitive to heart-rate changes was tested, is not the first major clinical trial involving a device designed to “scramble” emerging electrical changes in the brain to stop or shorten epileptic seizures. The first such study was the SANTE trial which demonstrated that a closed loop system is capable of reading local electroencephalographic (EEG) changes and responding to them by stimulating the anterior thalamic nucleus.
However, VNS treatment and the monitoring of electrocardiographic (ECG) rather than EEG activity is considerably less invasive than the intracranial system tested in the SANTE trial and has a well-documented safety profile.
The study described by Boon et al. demonstrates that the heart-rate sensitive VNS device is capable of picking up heart rate changes and responding to them by delivering a triggered stimulation pulse. The study also demonstrates how hard it is to study seizure disruption or prevention devices. Some seizures recorded during by video-EEG during the study appeared to have been cut short by an ECG-triggered stimulation pulse, but this study was not powered to prove the superiority of cardiac-responsive VNS over traditional VNS. Future studies will have to examine how much of an improvement the new device represents. However, the combination of VNS with an ECG-based automated seizure-detection system holds promise for the many patients with epilepsy whose seizures occur without warning or from sleep.
 P Boon et al. A Prospective, Multicenter Study of Cardiac-based Seizure Detection to Activate Vagus Nerve Stimulation. Seizure 2015;32:52-61.
 Fisher R, Salanova V, Witt T, Worth R, Henry T, Gross R, et al, SANTE Study Group. Electrical stimulation of the anterior nucleus of thalamus for treatment of refractory epilepsy. Epilepsia 2010;51:899-908.