Responsive brain stimulation in epilepsy

Abstract

Stimulation devices are considered in patients with drug-resistant epilepsy and who are not surgical candidates. Responsive neurostimulation (RNS) is a cortically based stimulator activated by electrocorticography (ECoG) patterns. Stimulation is applied directly to the seizure focus. The vagal nerve stimulator AspireSR 106 is also a responsive device which, in addition to basal stimulation, is activated by tachycardia. Deep brain stimulation of the anterior nucleus of the thalamus is used in Europe for intractable epilepsy and yields similar response rates to RNS using duty cycle stimulation. Chronic subthreshold cortical stimulation is an experimental form of constant, low-level stimulation applied to a seizure focus. These modalities are discussed and compared in this review.

Time-evolving controllability of effective connectivity networks during seizure progression

“…For patients with medication-resistant epilepsy, RNS as a means of seizure suppression is a relatively new option that provides an alternative to more permanent and invasive choices such as cortical resection or laser ablation. While the majority of patients improve over the course of months to years with treatment, the current trial and error routine for selecting stimulation parameters is far from ideal, and only rarely do patients achieve seizure freedom ( 1 , 2 , 37 ). We completed this study to introduce a control-theory framework for dynamic controllability that could provide support for clinical treatment decisions and highlight the regions and time points for stimulation that require the least input.…”

“…Although current RNS technology is limited by a restricted number of seizure detection criteria and stimulation response patterns ( 2 ), our methodology could enrich a number of model-based control approaches that could be adapted to improve seizure suppression in future implantable devices. For example, model predictive control (MPC) is a multivariable control algorithm that periodically reassesses the control function every few time steps along the planned trajectory ( 44 ).…”

“…Responsive neurostimulation (RNS) is a nonresective treatment for medication-resistant epilepsy that aims to suppress seizures by delivering an electrical stimulus through intracranial electrodes in response to abnormal electrographic activity. Despite the fact that the first implantable RNS device was approved in 2013, the mechanism of action and optimal patient-specific stimulation settings remain unknown ( 1 , 2 ). A better understanding of the cortical locations and patterns of brain activity that are most responsive to stimulation would improve treatment efficacy and efficiency.…”

Putative novel neuromodulatory treatments for affective disorders – What might emerge?

“…In epilepsy, responsive closed-loop cortical DBS is approved in the US since 2013 and represents a personalized approach providing ondemand stimulation responding to intracranial patterns of electrocorticography [33]. Additionally, vagal nerve stimulation (VNS) has been developed as an adaptive treatment for epilepsy, too.…”

“…Additionally, vagal nerve stimulation (VNS) has been developed as an adaptive treatment for epilepsy, too. The VNS system is responsive to tachycardia because heart rate changes precede electrographic and clinical changes during seizure [33]. Closed-Loop systems have successfully been implemented in the treatment of pain syndromes with spinal cord electrical stimulation sensing the patient's body activity and position [28].…”