Decreased sensitivity in the membranous urethra after orthotopic ileal bladder substitute

Purpose: The effect of cystoprostatectomy with orthotopic substitution on membranous urethral sensation and subsequent urinary continence is unknown. We determined the sensory threshold for electrical stimulation of the membranous urethra and correlated it with continence, nerve sparing surgical technique and potency. Materials and Methods: The sensory threshold was measured in a control group of 35 men before radical prostatectomy or cystoprostatectomy and in 47 men after cystoprostatectomy and ileal bladder substitution. Results: The sensory threshold of the membranous urethra was 9 +/- 2 in the control group compared to 27 +/- 11 mA. in the postoperative group (p < 0.001). Patients with daytime continence had a threshold of 24 +/- 9 compared to 39 +/- 10 mA. in incontinent patients (p < 0.001). We were unable to show any correlation between the sensory threshold in patients with (25 +/- 10 mA.) and without (31 +/- mA.) attempted nerve sparing surgery (p = 0.1) nor between potent (25 +/- 12 mA.) and impotent (27 +/- 11 mA.) patients (p = 0.4). Conclusions: Sensitivity in the membranous urethra decreased in patients after cystoprostatectomy and ileal bladder substitution. Urethral sensitivity in the sphincter area was better in continent than incontinent patients. Since we were unable to find any correlation between the sensory threshold and nerve sparing surgery or potency, it may be assumed that at least part of the sensory fibers to the membranous urethra pass through the pudendal nerve and/or the intrapelvic extrapudendal nerve fibers.