Progress in corpus cavernosum electromyography (CC-EMG)-third international workshop on corpus cavernosum electromyography (CC-EMG)

Establishment of Novel Intraoperative Monitoring and Mapping Method for the Cavernous Nerve During Robot-assisted Radical Prostatectomy: Results of the Phase I/II, First-in-human, Feasibility Study

BACKGROUND

Potency preservation often does not meet expectation despite nerve-sparing prostatectomy.

OBJECTIVE

To set the protocol for intraoperative cavernous nerve monitoring and mapping during robot-assisted radical prostatectomy (RARP), and to evaluate its safety and clinical feasibility.

DESIGN, SETTING, AND PARTICIPANTS

A prospective phase I/II, feasibility study was performed. A total of 30 patients with prostate cancer who underwent RARP at a high-volume tertiary academic hospital were enrolled.

SURGICAL PROCEDURE

Pudendal somatosensory evoked potential, bulbocavernosus reflex, spontaneous corpus cavernosum electromyography (CC-EMG), median nerve stimulation evoked CC-EMG, and neurovascular bundle (NVB)-triggered CC-EMG with various stimulation protocols were assessed during conventional RARP under total intravenous anesthesia with controlled muscle relaxation.

MEASUREMENTS

The primary endpoint was the completion rate of planned surgery and assessment. Adverse events, and erectile and urinary functions were evaluated within 1 yr. CC-EMGs were graded and correlated with functional outcomes.

RESULTS AND LIMITATIONS

The completion rate was 100%. Only one patient experienced adverse events, which were not related to study intervention. Grades of CC-EMGs including NVB-triggered CC-EMG before prostate removal were associated with baseline five-item International Index of Erectile Function (IIEF-5) score (grades 0-1, 4.6±2.7; grade 2, 13.2±6.8; grades 3-4, 16.6±5.9; p=0.003). Furthermore, grades of CC-EMGs including NVB-triggered CC-EMG after prostate removal were significantly associated with potency recovery (grade 0, 12.5%; grade 1, 0%; grade 2, 33.3%; grades 3-4, 100% at 12 mo; p=0.005) and postoperative IIEF-5 scores at all evaluation time points (grades 0-1, 2.6±2.8; grade 2, 4.3±5.8; grades 3-4, 15.7±11.0 at 12 mo; p=0.003).

CONCLUSIONS

We successfully established the protocol for safe intraoperative cavernous nerve monitoring and mapping using CC-EMG during RARP. Its grades were well correlated with erectile function.

PATIENT SUMMARY

In this first-in-human feasibility study, we successfully established the protocol for safe intraoperative cavernous nerve monitoring and mapping method during robot-assisted radical prostatectomy. The results were significantly associated with erectile function. Evaluation of clinical efficacy to preserve potency seems worthy of further optimization and investigation in confirmatory clinical trials.

Evoked cavernous activity: measuring penile autonomic innervation following pelvic surgery

To assess cavernous nerve integrity, we measured evoked cavernous activity (ECA) in 16 men who underwent nerve sparing radical prostatectomy (NS group) and 11 men who underwent non-nerve-sparing surgery (non-NS group). The right median nerve was electrically stimulated and ECA was recorded with two concentric electromyography needles placed into the right and left cavernous bodies. We simultaneously recorded hand and foot sympathetic skin responses (SSRs) as controls. All subjects had recordable SSR, and all subjects following nerve-sparing radical prostatectomy had reproducible ECA. Of the 11 non-NS subjects, eight had no response, indicating interrupted corporal innervation. Three subjects had reproducible ECA, one of whom had a very late latency, suggesting residual innervation was present. The mean latencies of ECA were similar to foot SSR mean latencies (P>0.05), but not to hand SSR latencies. The non-NS group was significantly different from the NS group for the presence of ECA (P<0.001). ECA is a viable method of evaluating the autonomic innervation of the penis.

Evaluation of autonomic innervation of the clitoris and bulb

PURPOSE

Female sexual dysfunction is a common disorder but there are few objective measures of female genital function. We present a novel technique to record electrical activity of the female genital erectile tissue.

MATERIALS AND METHOD

We placed concentric needle electrodes in the right clitoral crus and the bulb of 22 healthy women. Following spontaneous activity recording we stimulated the median nerve to activate the sympathetic nervous system. We simultaneously measured evoked activity in the clitoris and bulb, and hand sympathetic skin responses (SSRs).

RESULTS

Spontaneous electrical activity of the clitoris and bulb was present in 13 subjects. A total of 21 subjects had evoked activity in the bulb, while 18 had evoked activity in the clitoris. All subjects had hand SSRs. Evoked genital response latencies were similar to hand SSR latency (p > 0.05). Evoked electrical activity was recordable in the clitoris and bulb but it was more easily performed in the bulb.

CONCLUSIONS

Evoked electrical activity is more consistently obtained than spontaneous activity. These tests represent possible objective measures of female genital autonomic innervation, which may have relevance to female sexual function.

The value of corpus cavernosum electromyography in erectile dysfunction: current status and future prospect

In the last decade, several investigators have tried to develop corpus cavernosum electromyography (CC-EMG) as a direct clinical method to evaluate the state of the penile autonomic innervation and the cavernous smooth muscle. Both basic and clinical studies have shown promising results. However, its application as a diagnostic tool with clinical relevance was hindered by insufficient knowledge of cavernous smooth muscle electrophysiology, lack of standardization, technical and practical difficulties and problems in the interpretation of the results. Recently, the European Commission created the so-called COST Action B18 (corpus cavernosum EMG in erectile dysfunction), aiming to strengthen the coordination of the European research groups and give the development of CC-EMG a new impetus. This review presents an overview of the physiological background, the current status of CC-EMG, and discusses possibilities for further developments.

Central inhibition of sexual response in the male: a theoretical perspective

A theoretical model for central inhibition of sexual response is proposed, postulating individual variability in the propensity for such inhibition. Whereas such inhibition is typically adaptive, individuals with high propensity may be vulnerable to sexual dysfunction, and those with low propensity to high risk sexual behavior. Evidence of the existence and localization of such inhibitory mechanisms from both the animal and human literature is reviewed. Evidence of central neurotransmitters with sexual inhibitory effects is substantial, though in most cases the inhibition is not specific to sexual response or behavior. Recent studies have identified centers in the brain stem and lateral hypothalamus which appear to have specific inhibitory effects on sexual response. A variety of adaptive mechanisms involving inhibition of sexual response are considered, some involving perception of threat, others occurring more directly as consequences of previous sexual activity. These different adaptive functions may well involve different inhibitory mechanisms. This theoretical model opens a new agenda for experimental research into adaptive sexual behavior, both human and animal.

Evaluation and nonsurgical management of erectile dysfunction

The addition of oral drugs to the armamentarium of therapies for erectile dysfunction promises to dramatically increase the number of men seeking treatment for this condition. It is important to have a rational approach to the diagnostic evaluation of erectile dysfunction and to tailor the evaluation to each patient's goals for his sexual function. It is important also to offer each patient the full array of therapeutic options for erectile dysfunction. This article reviews the outpatient diagnostic work-up and current treatment possibilities for erectile dysfunction. The article also discusses clinical research experience with new forms or oral and topical therapies now being developed for future treatment of erectile dysfunction.