Cavernosal nerve mapping: current data and applications

Abstract

There are four reviews in this month's section, two relating to the technical aspects of treating prostate cancer, one to genetic instability and bladder cancer, and the final one about continence surgery in urogenital prolapse. The authors are from Canada, the USA, and the UK. The messages from all of the reviews are clear, and provide interesting reading. The contributions to this section continue to give considerable information, and there are many more to follow.Although nerve‐sparing prostatectomy is widely practised, the results with respect to preserving potency often do not meet expectations. The concept of intraoperative cavernosal nerve stimulation is reasonable. Data that link the response to sildenafil after prostatectomy with bilateral nerve sparing has increased the importance of optimizing nerve sparing. The cavernosal nerves are often difficult to visualize and may have a variable course. A tumescent response to nerve stimulation can be shown consistently; the response may be subtle, and characterized by a minimal increase in penile circumference and blood flow. Immediately after prostatectomy, proximal nerve stimulation identifies whether neural continuity has been maintained, and is predictive of recovery of erectile function. The CavermapTM system (Uromed Corporation, Boston, MA, USA) was developed to permit intraoperative nerve stimulation with tumescence monitoring. An initial phase 2 and subsequent phase 3 single‐blinded, randomized, multicentre study that compared Cavermap‐assisted prostatectomy with conventional nerve sparing showed a significant benefit in terms of the duration of nocturnal tumescence at 1 year. Other approaches are being explored, including incorporating the device into sural or genito‐femoral nerve grafting, use of nerve stimulation during cystectomy or abdominal‐perineal resection, and direct corpus cavernosal pressure monitoring during nerve stimulation. These approaches warrant further evaluation.

Effects of hyperglycemia on rat cavernous nerve axons: A functional and ultrastructural study

“…ED may stem from deficits in the vascular system, penile smooth muscles and autonomic nerves (Hecht et al, 2001). The integrity of cavernous nerve (CN) is critical for normal erectile function; even minor surgical impairment of this nerve can lead to impotence (Klotz, 2004; Walsh and Donker, 2002). The CN is principally composed of unmyelinated axons with a few scattered myelinated fibers (Schaumburg et al, 2007).…”

The Effects of Cavernous Nerve Grafting following Surgically Induced Loss of Erectile Function in a Large-Animal Model

“…A number of studies have supported the clinical efficacy of the CaverMap system to assist in cavernous nerve preservation. [42][43][44][45][46] However, other studies have questioned the usefulness of direct electrical stimulation and have recommended further refinements to the system. 47,48 In this study, direct stimulation was limited by anatomical restrictions associated with the sensor placement on the canine penis and an inability to quantify the erectile response with sequential ablation or at the time of cavernous nerve harvest.…”

Hope springs eternal: cavernosal nerve regeneration

“…The Cavermap TM device has been used as an adjunct to aid in identifying and preserving the cavernosal nerves. In a trial reported in 2000 [21], of 61 patients randomized to conventional nerve‐sparing or Cavermap‐assisted nerve‐sparing procedure there tended to be better potency after its use, with a significant difference in potency outcomes as assessed by nocturnal Rigiscan TM testing. However, others have reported less satisfaction with the device and its outcomes, citing difficulties with the reliability of the technique and its poor correlation with long‐term potency outcomes as problems with its implementation [22–24].…”