2005 年 43 巻 1 号 p. 58-67
Magnetic stimulation has been reported to be effective for eliminating urinary incontinence. Magnetic stimulation can be applied as a low invasive technique without requiring the removal of clothes. However clinical applications of this treatment are uncommon because little physiological and technical information is available. Stimulation focused on the target is highly desirable from a safety perspective. The effect of magnetic stimulation for the treatment of urinary incontinence has been explained as a re-activation of lost functions of the pelvic floor muscles. A model study was used to investigate how electric current is distributed in the body during the application of magnetic stimulation. Current distribution induced in a homogeneous model (infinite conductor) is easy to understand. However, current distribution in an in-homogeneous model displays a much more complicated distribution than current distribution using a homogeneous model. This study investigated current distribution in the female abdomen using experimental and computer models of magnetic stimulation for the treatment of urinary incontinence. The influence of tissue in-homogeneity on current distribution was reported. In the region of the pelvic floor muscles, at depths of 20 and 50 mm above the stimulation coil, the analysis of eddy current distribution could not be performed as a homogeneous conductor due to large differences in angles and the summation of currents between inhomogeneous and homogeneous models. Within the region of the bladder and other organs at a depth of 100 mm above the stimulation coil, the pelvis and other tissues exerted little influence on current distribution.