Page 231 - Computational Modeling in Biomedical Engineering and Medical Physics

220 Computational Modeling in Biomedical Engineering and Medical Physics

(Tsai et al., 2009), chronic back pain, motor function and posture in Parkinson’sdisease
(Hofstoetter et al., 2014; Yang et al., 2018) and to diagnose lumbar spondylosis or lumbo-
sacral motor radiculopathy (Krause et al., 2004). Moreover, LMS is used in neurology for
therapeutic purposes and in diagnosis, as it has been proven to help to identify and repair-
ing injured transmission ways in the central and peripheral nervous system, in stimulating
the expiratory muscles, in controlling neurogenic bowel dysfunctions, and posture in
Parkinson’sdisease.
In this chapter we present some of our FEM approaches to MS procedures based on
3D, image reconstructed, morphologically accurate computational domains combined with
CAD-generated models (applicator, coil geometries). These numerical tools are cost-
efficient, noninvasive, bioethics compliant, and easy-to-use for understanding the MS techni-
ques and optimize the associated magnetic field source to create patient-specific solutions.
Magnetotherapy (MT) is a basic physiotherapy procedure (Bednarˇ cík, 2019). In its static
form, using a permanent magnet (e.g., Aydin and Bezer, 2011),itwas used sincetime
immemorial as one of the natural healing sources. The interest in using it was reinvigo-
rated by the low-frequency pulsed magnet therapy (PMT) (e.g., Shupack, 2003; Assiotis
et al., 2012), whose effects are up to 100 times more effective than the application of a sta-
tionary magnetic field, which elicits PMT as one of the most common physiotherapy
methods at present. In chronic pains in degenerative articular diseases, PMT has proven
successful as therapy with long-term remedial effect even when other therapy methods
were less successful. MT may be recommended for usage in combination with pharmaco-
therapy, whose effects are, in general, supported by MT. These benefits features advocate
the usage of MT in case of a comprehensive approach to treatment, rather than mono-
therapy. The physiological response of the body to the EMF implies the analgesic, antie-
dematous, antiphlogistic, trophic, myorelaxant and spasmolytic, vasodilatation effects. A
glimpse in the EMF distribution used in MT and the associated heat transfer process is
touched through numerical simulation in this chapter too.

7.2 Magnetic stimulation of long cell fibers, a reduced mathematical
model

Cable theory and the activating function
Cable theory for cells similar to long cylindrical fibers (Plonsey and Barr, 1988;
Malmivuo and Plonsey, 1995; Morega, 1999) as the axons of peripheral nerves, pro-
vides a mathematical representation for the equivalent electrical circuit of the nerve
and the stimulus, with its active component, the so-called “activating function” (AF),
both for electrical stimulation and for MS. It is further intended to highlight the math-
ematical expressions of AF and to present an analytical calculation method for esti-
mates of AF in a simple concept of PMS, useful for quickly assessing the behavior of
different applicators and their effectiveness.