Urethral sensitivity and impact on urinary continence in patients with ileal bladder substitute after cystectomy

Purpose: After cystectomy and ileal bladder substitution, sensitivity in th e membranous urethra correlates with postoperative urinary continence. We d etermine whether sensitivity is decreased only in the most proximal part of the urethra or also more distally in the bulbar urethra, which would give some indication as to which nerves may be injured during radical. cystopros tatectomy. Materials and Methods: The sensory threshold for electrical stimulation was measured with double ring electrodes in the membranous urethra, and 2.5 cm . distally to it in 41 men after cystectomy and ileal bladder substitution, and in a control group of 29 men. Results: The mean sensory threshold plus or minus standard deviation of the membranous urethra was 9 +/- 2 mA. in the control group compared to 26 +/- 11 mA. in the postoperative group (p <0.001). Mean sensory threshold 2.5 c m. distal to the membranous urethra was 8 +/- 3 versus 9 +/- 3 mA, in the c ontrol and postoperative groups, respectively inot significant). Patients w ith daytime continence had a mean threshold of 22 +/- 8 mA, in the membrano us urethra compared to 38 +/- 11 mA. in those who were incontinent (p <0.00 4) and a threshold of 8 +/- 3 mA, 2.5 cm, distal to the membranous urethra compared to 8 +/- 2 mA. in those who were incontinent (not significant). Conclusions: After cystectomy and ileal bladder substitution, urethral sens itivity 2.5 cm, distal to the membranous urethra is unaffected by surgery a nd does not correlate with postoperative continence. In contrast, a decreas ed sensitivity ill the membranous urethra correlates with an increased risk of postoperative incontingence. Preservation of sensitivity in the membran ous urethra seems to be an important factor for achieving continence after cystectomy and ileal bladder substitution, and does not seem to be dependen t on the extrapelvic portion of the pudendal nerve.