Flat electrode contacts for vagus nerve stimulation

Abstract

The majority of available systems for vagus nerve stimulation use helical stimulation electrodes, which cover the majority of the circumference of the nerve and produce largely uniform current density within the nerve. Flat stimulation electrodes that contact only one side of the nerve may provide advantages, including ease of fabrication. However, it is possible that the flat configuration will yield inefficient fiber recruitment due to a less uniform current distribution within the nerve. Here we tested the hypothesis that flat electrodes will require higher current amplitude to activate all large-diameter fibers throughout the whole cross-section of a nerve than circumferential designs. Computational modeling and in vivo experiments were performed to evaluate fiber recruitment in different nerves and different species using a variety of electrode designs. Initial results demonstrated similar fiber recruitment in the rat vagus and sciatic nerves with a standard circumferential cuff electrode and a cuff electrode modified to approximate a flat configuration. Follow up experiments comparing true flat electrodes to circumferential electrodes on the rabbit sciatic nerve confirmed that fiber recruitment was equivalent between the two designs. These findings demonstrate that flat electrodes represent a viable design for nerve stimulation that may provide advantages over the current circumferential designs for applications in which the goal is uniform activation of all fascicles within the nerve.

ASCENT (Automated Simulations to Characterize Electrical Nerve Thresholds): A pipeline for sample-specific computational modeling of electrical stimulation of peripheral nerves

“…We applied ASCENT’s extensive set of features to quantify the change in fiber responses across cuff rotations for a multifascicular nerve, to implement previously published models of rabbit sciatic [ 11 ] and human vagus [ 39 ] nerve stimulation, and to reproduce findings from an in vivo study of dog VNS [ 40 ].…”

“…Computational modeling can be leveraged to achieve translation between preclinical and clinical studies and to optimize application-specific parameters. Prior modeling studies used generalized representations of nerve morphology [ 9 – 11 ] or patient-specific models of peripheral nerve stimulation [ 12 , 13 ], but these were bespoke implementations by experts; a standardized platform to enable the research community to implement and use such models has not been developed. The field needs a “completely customizable and modular framework … to interpret the results of stimulation experiments in terms of quantities of common use in neuro-prosthetics” [ 14 ].…”

Use of a physiological reflex to standardize vagal nerve stimulation intensity improves data reproducibility in a memory extinction assay

“…Technical variability will occur due to electrode placement or damage to axonal fibres. Electrode placement is an important consideration because minor alterations in cuff dimensions can increase the current required to recruit the same proportion of fibres by over 1 mA [43]. These factors likely have therapeutic consequences.…”

Assessment of the Use of Multi-Channel Organic Electrodes to Record ENG on Small Nerves: Application to Phrenic Nerve Burst Detection

“…Here, the technology proposed in this paper allow us to record from the rat PHR nerve with a higher averaged SNR ( dB). Helical, cuffs or flat electrodes, with mono-, bi-, or tri-polar characteristics have been mainly tested for neurostimulation [ 57 , 58 , 59 ]. Further investigations are needed to compare the performances of those electrodes with multicontact OE in ENG recording.…”