Effect of functional continuous magnetic stimulation on urethral closure in healthy volunteers

Abstract

Objectives. To study urodynamically the effect of functional continuous magnetic stimulation on urethral closure in normal volunteers. Methods. Ten volunteers (6 men and 4 women, 20 to 29 years old, mean age 24.5) were recruited for the study. Seven subjects were assigned to an active group and 3 to a sham group. An 8F transducer was inserted transurethrally, and the urethral pressure profile was monitored. Then the catheter was fixed so that the transducer could be positioned at the portion at which the highest pressure was recorded (maximum intraurethral pressure). In the active group, the stimulating intensity was gradually increased up to the tolerable limit. A 15-minute single session of stimulation was carried out at 20 Hz in an intermittent manner with 1-minute-on/30-second-off cycles. After stimulation, the urethral pressure profile was repeated. Results. In the active group, the greatest pressure difference between the on and off phases of the maximum intraurethral pressure was 62.4 ± 37.6 cm H 2O at 35% to 55% of maximum output (46 to 113 J). In the urethral pressure profile, the maximum urethral closure pressure increased significantly after stimulation ( P = 0.0280). In the sham group, no changes in these parameters were noted. All subjects tolerated the functional continuous magnetic stimulation well, and none experienced any adverse effect. Conclusions. Functional continuous magnetic stimulation safely and significantly increased maximum intraurethral pressure during stimulation and maximum urethral closure pressure after stimulation.