Alternative Paradigm of Selective Vagus Nerve Stimulation Tested on an Isolated Porcine Vagus Nerve

Abstract

Alternative paradigm for spatial and fibre-type selective vagus nerve stimulation (VNS) was developed using realistic structural topography and tested in an isolated segment of a porcine cervical left vagus nerve (LVN). A spiral cuff (cuff) containing a matrix of ninety-nine electrodes was developed for selective VNS. A quasitrapezoidal stimulating pulse (stimulus) was applied to the LVN via an appointed group of three electrodes (triplet). The triplet and stimulus were configured to predominantly stimulate the B-fibres, minimizing stimulation of the A-fibres and by-passing the stimulation of the C-fibres. To assess which fibres made the most probable contribution to the neural response (NR) during selective VNS, the distribution of conduction velocity (CV) within the LVN was considered. Experimental testing of the paradigm showed the existence of certain parameters and waveforms of the stimulus, for which the contribution of the A-fibres to the NR was slightly reduced and that of the B-fibres was slightly enlarged. The cuff provided satisfactory fascicle discrimination in selective VNS as well as satisfactory fascicle discrimination during NR recording. However, in the present stage of development, fibre-type VNS remained rather limited.

An improved method of crafting a multi-electrode spiral cuff for the selective stimulation of peripheral nerves

“…The design of the cuff was based on the realistic structural topography of a porcine cervical vagus nerve and the published models of activation for different types of nerve fibres within a specific superficial region of the nerve 7 , 40 – 50 . The functionality paradigm of the cuff was tested recently intra-operatively in humans, where the vagus nerves were stimulated selectively to modulate the function of the heart as well as in “ ex vivo ” experiments where the left porcine vagus nerves were selectively stimulated under simulated physiological conditions 51 , 52 . In the latter, the paradigm for spatial and fibre-type selective vagus nerve stimulation was developed using the realistic structural topography of a porcine cervical left vagus nerve.…”

Measurement of bio-impedance on an isolated rat sciatic nerve obtained with specific current stimulating pulses

“…The feasibility of the stimulating paradigm, where the specific stimulus waveform was used to selectively stimulate different types of nerve fibres within the cervical segment of porcine vagus nerve, has already been published. 19 In the last two decades, particular attention has been paid to vagus nerve stimulation techniques that are used to treat, among others, a number of nervous-system disorders, neuropsychiatric disorders, eating disorders, sleep disorders, cardiac disorders, endocrine disorders, and pain. [22][23][24][25] Considerable scientific and technological efforts have been devoted to developing systems of electrodes that interface the human vagus nerve with electronic implantable devices.…”

“…An aforementioned waveform of the stimulating pulse was adopted from a recent study where this waveform was tested by selective nerve stimulation of the isolated porcine left cervical vagus nerve segment. 19 Afterwards, driving pulses were delivered to the VCCS, where they were converted into constant current pulses by means of the high-output-impedance current generator. To avoid a measurement error in developing the presented Z measurement set-up, it was essential that a high-output Z was maintained over the operating frequency range so that the injected current was constant and that the current source did not load the sample.…”

MicroCT optimisation for imaging fascicular anatomy in peripheral nerves

“…This is undertaken by electrical stimulation of autonomic nerves (Famm et al, 2013;Kollewe, 2017;Mishra, 2017). A prime target for intervention is the cervical vagus nerve (Blount, 2015;Ekmekçi and Kaptan, 2017;Guiraud et al, 2016;Koopman et al, 2016;Pečlin and Rozman, 2014;Smucny et al, 2015), as it innervates the majority of the visceral organs and muscles (Câmara and Griessenauer, 2015;Rea, 2014). However, surprisingly, the organisation of fascicles within the nerve remains almost completely unknown.…”