Neurophysiological testing to assess penile sensory nerve damage after radical prostatectomy

Radical prostatectomy (RP) can lead to erectile dysfunction due to surgical injury of the cavernous nerves. However, there is no simple, objective test to evaluate cavernous nerve damage caused by RP in clinical practice.

To assess the value of the measurement of penile thermal and vibratory sensory thresholds to reflect cavernous nerve damage caused by RP.

We included 42 consecutive patients who underwent RP with cavernous nerve sparing (laparoscopic approach, N = 12) or without cavernous nerve sparing (laparoscopic, N = 13; retropubic, N = 11; or transperineal, N = 6). Penile thermal (warm and cold) and vibratory sensory thresholds were measured twice, together with the Erectile Dysfunction Symptom Score (EDSS), 1 month before and 2 months after RP.

Penile sensory thresholds for warm, cold, and vibration sensations.

Penile sensory thresholds for warm (P < 0.0001) and cold (P < 0.0001) sensations significantly increased after non-nerve-sparing RP, but not after nerve-sparing RP. Vibration threshold only increased after transperineal non-nerve-sparing RP (P = 0.031). EDSS values were significantly increased in all groups of patients 2 months after surgery.

Sensory nerve fibers carrying penile skin sensations travel with the cavernous nerves in the pelvis. Therefore, testing these sensations may help to evaluate the extent of cavernous nerve damage caused by RP. In this series, post-operative changes in penile sensory thresholds differed with the surgical technique of RP, as the cavernous nerves were preserved or not. The present results support the value of quantitative penile sensory threshold measurement to indicate RP-induced cavernous nerve injury.