A simple and reliable monitoring system to confirm the preservation of the cavernous nerves

Background: It is important to establish a procedure with which to confirm the preservation of the cavernous nerves during nerve-sparing radical surgery. For this purpose, we examined changes in intracavernous pressure (ICP) following electrical stimulation of the neurovascular bundle (NVB) with respect to the continuity of the cavernous nerves. Methods: Six cases of radical prostatectomy and eight cases of radical cystoprostatectomy were examined. In all cases, prior to prostate removal, electrical stimulation of the site where the NVB was determined to run was performed and the changes in ICP measured. In eight cases, ICP changes were also measured following prostate removal. Results: Prior to prostate removal, ICP changes could be measured in all 28 sides of 14 cases. These changes were classified into two patterns: stimulation-related increases of convex waveform (t1) were observed in 24 sides (85.7%); and waveforms with reversed type (t2), which was thought to be an incomplete type tl, were observed in four sides (14.3%). There were no ICP changes following non-sparing or incomplete sparing of NVB macroanatomically. Of five sides where the NVB was supposedly completely preserved macroanatomically, ICP changes consisted of type t1 on three sides, t2 on one side and type t2 or no change on a single side. All measurements were obtained within 10 min. Neither electrical stimulation nor measurement of ICP caused any adverse effects. Conclusion: Intraoperative stimulation of the NVB while monitoring ICP changes provides a simple and reliable method of accurately evaluating the preservation of the cavernous nerves.