A Complete Model for the Evaluation of the Magnetic Stimulation of Peripheral Nerves

Abstract

In this paper, a numerical procedure for the analysis of peripheral nerve excitation through magnetic stimulation is presented and used to investigate the physical parameters influencing stimulation. The finite difference technique is used to evaluate the electric field distribution induced inside an arm by the current flowing through a coil, and a nonlinear cable model is used to describe the response of the nerve fiber to the induced electric field. The comparison among several forearm structures has evidenced that the heterogeneous non dispersive forearm model is a good reference condition. With this model, the lowest charging voltage on the stimulator capacitance, able to produce the nerve stimulation, is achieved when the coil is shifted, with respect to the nerve, of a quantity slightly lower than the coil radius but it is also possible to excite the nerve fiber by applying a shift equal to zero. The charging voltage increases when the coil radius is increased and when a three-dimensional coil geometry is considered. Moreover, this voltage is strongly dependent on the nerve position inside the forearm and on the kind of tissue surrounding the nerve.

Prediction of peripheral nerve stimulation thresholds of MRI gradient coils using coupled electromagnetic and neurodynamic simulations

“…In work toward a more predictive model of the field/body/nerve interactions, simulations have been recently performed to assess the interaction between the electric field and the nerve to inform nerve response (31, 32, 33, 28, 34, 35, 36, 37). These investigations were begun as simplified straight nerve segments placed in small body models (approximately 10 cm) to evaluate the effect of the electric field on the neurodynamics and extended by Neufeld and colleagues to study segments of the ulnar and sciatic nerves within a detailed body model (38, 39).…”

Investigation of the mechanisms for wireless nerve stimulation without active electrodes

“…Modeling the nerve tissue and surrounding tissue is another issue which needs to be addressed. Results from Pisa et al (2014). found that the best trade-off between accuracy and computational expense was achieved by modeling surrounding tissue using an anatomically correct model with heterogeneous but non-dispersive tissue characteristics.…”

A Computational Model for Real-Time Calculation of Electric Field due to Transcranial Magnetic Stimulation in Clinics

“…The analysis domain is divided into homogeneous cells (Δ × Δ × Δ ) centered at the point of coordinates ( , , ) in a Cartesian grid that can be represented as a network of lumped electrical elements (see Figure 2 of [45] for a simplified 2D representation) [45,49,50].…”