Micturition and the male genitourinary response to sacral root stimulation

The sacral roots, because of their anatomic and functional organization, are well suited to chronic stimulation. Data from our previous experiments on female dogs suggested that effective voiding responses to stimulation could be obtained by using the ventral root of S2, the sacral nerve in canines with the greatest detrusor representation. Elimination of dorsal root afferents from the stimulus field was essential to the minimization of spinal reflex activity. A selective somatic neurotomy was also necessary to attenuate maximally sphincter activity. In the male, the presence of the prostate gland, the greater urethral length, and the erectile response to stimulation might result in compression of the urethra, compromising micturition. Sacral root stimulation was thus studied using both spinalized and nonspinalized male dogs; the results are discussed with a view toward the applicability of sacral root stimulation to effect micturition in male paraplegics, who comprise the largest percentage of this group of patients.