COMPARISON IN YOUNG HEALTHY-VOLUNTEERS OF 3 DIFFERENT PARAMETERS OF CONSTANT-CURRENT STIMULATION USED TO DETERMINE SENSORY THRESHOLDS IN THE LOWER URINARY-TRACT

Purpose: We compared different parameters of constant current stimulat ion used for evaluation of sensation in the lower urinary tract. Mater ials and Methods: In 24 healthy male and 9 healthy female volunteers ( mean age 24 years) sensory thresholds were determined at the same site on the bladder, urethra and skin with 3 different parameters of const ant current stimulation (2.5, 20 and 95 Hz. at pulses 1, 1 and 0.5 mse c., respectively) given at random. Results: Thresholds were highly rep roducible at all sites and with the 3 currents. Thresholds obtained wi th 2.5 Hz. were significantly greater than those obtained with 20 Hz. at all sites or 95 Hz. at the bladder and male urethra. No significant difference was found between thresholds in the bladder or urethra wit h 20 and 95 Hz. In 2 volunteers no bladder sensation was elicited with 2.5 Hz. even at 33 mA. A reproducible elevated threshold was found wi th 20 and 95 Hz. No intravesical pressure increase occurred during sti mulation. Conclusions: Absolute values of sensory thresholds vary in r elation to the site of stimulus and stimulation parameters in healthy young subjects. Low frequency current (2.5 Hz.) is less easily perceiv ed and, therefore, would seem less suitable for evaluation of electric al sensation in the lower urinary tract. Thresholds obtained with freq uences of 20 and 95 Hz. were not statistically different.