Objectives. To determine if intraoperative stimulation of the cavernous nerves while monitoring changes in penile tumescence to map the course of these nerves would result in an improvement in nerve sparing and erectile function after radical prostatectomy.

Methods. Patients were eligible for this pilot study if they were undergoing a radical prostatectomy and were candidates for a nerve-sparing approach. Erectile function was assessed by patient self-reporting and questionnaire before surgery and by patient self-reporting periodically 12 months after surgery. A cavernous nerve stimulator and tumescence-monitoring device was used during radical prostatectomy to identify the course of the cavernous nerves and guide the surgeon in avoiding nerve damage. Patients were monitored for any evidence of complications and/or adverse events for 1 year from time of surgery.

Results. Twenty-six patients were recruited to the trial. Nerve stimulation and tumescence monitoring was performed in 23 patients. Twenty-one of 23 patients demonstrated a tumescence response to intraoperative nerve stimulation. Nineteen of 21 patients reported erectile function preoperatively. Seventeen (89%) of 19 patients demonstrated a tumescence response during surgery. Sixteen (94%) of the 17 patients who demonstrated a response to nerve stimulation and for whom the surgery was guided by the tumescence response reported the ability to have erections after surgery. No side effects due to the use of the device were reported. Only 3 (12%) of 25 patients had positive margins confined to the lateral margin and/or apex whose modifications associated with nerve sparing could conceivably have altered margin status.

Conclusions. These clinical data suggest that an intraoperative tumescence response to cavernous nerve stimulation may guide the surgeon in preserving cavernous nerves and improving erectile function after radical prostatectomy.