Electrical activity of corpus cavernosum during flaccidity and erection of the human penis: a new diagnostic method?

Evaluation of electrophysiological changes after radical prostatectomy and their relationship with erectile function recovery

Erectile dysfunction (ED) is a common complication of radical prostatectomy (RP), mostly due to cavernous nerve (CN) injury. Despite improved surgical techniques and tools, ED rates are still high. Electrophysiological studies help to understand the functional effects of RP on CN and cavernous smooth muscles. The aim of this study is to evaluate the clinical reflection of changes on corpus cavernosum electromyography (CC-EMG) parameters caused by RP. A total of 44 patients were included in this prospective cohort study who underwent RP. The patients were divided into three groups based on nerve-sparing status: bilateral nerve-sparing (Group A) (n = 21), unilateral nerve-sparing (Group B) (n = 12), and non-nerve-sparing (Group C) (n = 11). All patients underwent CC-EMG one month before the operation and at the postoperative third month and were administered the International Index of Erectile Function (IIEF)-5 one month before the operation and at the postoperative third and 12th months. The postoperative third-month CC-EMG showed that the degree of cavernous smooth muscle relaxation in Group A was significantly higher than in Group B and Group C (p = 0.010 and p = 0.032, respectively). In the regression analysis, it was determined that patients with a postoperative IIEF-5 score of 12 or higher at the 12th month had a significantly greater degree of relaxation on the postoperative third-month CC-EMG (p = 0.034). In conclusion, a greater relaxation degree on postoperative third-month CC-EMG correlates with better long-term recovery of erectile function in patients who underwent RP.

Artificial Intelligence-Based Clinical Decision-Making in Erectile Dysfunction: a Narrative Review

PURPOSE OF REVIEW

Artificial Intelligence (AI) has great potential in erectile dysfunction (ED) diagnosis and treatment. This review aims to summarize AI-based clinical decision-making in ED.

RECENT FINDINGS

Based on the literature search, forty-seven articles related to AI and ED were analyzed and their findings were summarized. AI may help diagnose ED and offer treatment for it. Developing AI chatbots may also be beneficial for ED patients who are embarrassed to seek treatment. However, there are deficiencies in AI programs and a lack of accuracy in offering precise diagnoses and treatments for ED. AI technology integrates positively into ED clinical decision-making processes and needs progressive research to gain precision and efficiency.

A possible mechanism of erectile dysfunction in coronavirus disease-19: Cavernosal smooth muscle damage: A pilot study

INTRODUCTION

Studies have reported that coronavirus disease 2019 (COVID-19) may cause erectile dysfunction (ED), however, its role in the pathophysiology of ED has not yet been fully elucidated. We aimed to elucidate COVID-19's effects on cavernosal smooth muscle, which has a pretty important role in erection physiology, by corpus cavernosum electromyography (cc-EMG).

MATERIALS AND METHODS

Twenty-nine male patients aged 20-50 years who applied to the urology outpatient clinic due to ED were included in the study. Nine patients that had COVID-19 and were treated as outpatients were classified as group 1, 10 patients who were hospitalized due to COVID-19 were classified as group 2, and 10 patients who did not have COVID-19 were classified as the control group (group 3). Patients underwent diagnostic evaluation including International Index of Erectile Function (IIEF)-5 form, penile color Doppler ultrasonography (CDUS), cc-EMG, and fasting serum levels of reproductive hormones (07-11am).

RESULTS

According to penile CDUS and hormonal values results, there was no significant difference between the groups. According to cc-EMG results, amplitudes and relaxation capacities of the cavernosal smooth muscle of patients in group 3 were significantly higher than those in the other groups.

CONCLUSIONS

COVID-19 can cause ED not only by psychogenic and hormonal factors but also with cavernosal smooth muscle damage.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04980508.

A new diagnostic definition for patients with lower urinary tract symptoms evaluated by corpus cavernosum electromyography: 'Pelvic autonomic dysfunction'

This study investigates the use of corpus cavernosum electromyography (CC-EMG) recording as a diagnostic tool for identifying the presence of pelvic autonomic dysfunction (PAD) in patients with LUTS and concurrent ED. Fifty patients were included in the study, and the electromyographic and urodynamic findings were compared. The 50% relaxation degree was accepted as a threshold value for PAD. According to relaxation degree in CC-EMG recordings, patients were grouped as; Group 1 (with PAD) = 23 patients with a relaxation degree of less than 50%. Group 2 (without PAD) = 27 patients with a relaxation degree greater than 50%. The mean age of the patients was 58 ± 3.2 (50-71) years. The comparison of the urodynamic parameters and transrectal ultrasound revealed that the postvoiding residual urine volume (PVR) (p = 0.0007), P det Q_max (p = 0.0005), and P det compliance (0.003) values were statistically significantly lower in Group 2. The mean IIEF-5 and IIEF-15 scores of the patients in Group 1 were 2.5 ± 0.7 and 8.1 ± 1.1 respectively. In Group 2, mean IIEF-5 and IIEF-15 scores were 7.2 ± 2.9, and 17.2 ± 3.5 (p: 0.00023 and p: 0.0009). The mean I-PSS score was 22.8 ± 3 in Group 1 and 16 ± 2.3 in Group 2 (p = 0.001). The mean relaxation degree (RD) in Group I was 30.73 ± 6.8%, and in Group 2 was 66.3 ± 5.1%. The mean amplitude values of the patients in Group I were 261.41 ± 112.97 before papaverine injection, and in Group 2 were 246 ± 101.28 respectively. The inter-group difference was statistically significant (p < 0.05). The mean amplitude value of the patients in Group I after papaverine injection was 182.73 ± 60.71, and in Group 2, that value was 83.2 ± 29.19. The inter-group difference was also significant (p < 0.05). Increased electrical bursts and decreased relaxation responses on CC-EMG indirectly indicated an increase in the contractility of the bladder sphincter. Therefore, we concluded that CC-EMG could be a diagnostic tool for PAD and cavernous autonomic dysfunction.

Applications of artificial intelligence in the diagnosis and prediction of erectile dysfunction: a narrative review

Despite the high prevalence of erectile dysfunction, patients are reluctant to seek medical advice, which leads to low diagnostic rates in clinical practice. Artificial intelligence has been widely applied in the diagnosis of many diseases and may alleviate the situation. However, the applications of artificial intelligence in erectile dysfunction have not been reviewed to date. Therefore, the assistance from artificial intelligence needs to be summarized. In this review, 418 publications before January 10, 2021, regarding artificial intelligence applications in diagnosing and predicting erectile dysfunction, were retrieved from five databases, including PubMed, EMBASE, the Cochrane Library, and two Chinese databases (WANFANG and CNKI). In addition, the reference lists of the included studies or relevant reviews were checked to avoid bias. Finally, 30 articles were reviewed to summarize the current status, merits, and limitations of applying artificial intelligence in diagnosing and predicting erectile dysfunction. The results showed that artificial intelligence contributed to developing novel diagnostic questionnaires, equipment, expert systems, classifiers by images and predictive models. However, most of the included studies were not subjected to external validations, resulting in doubt on the generalizability. In the future, more rigorously designed studies with high-quality datasets for erectile dysfunction are required.

Fast voltage-dependent sodium (NaV ) currents are functionally expressed in mouse corpus cavernosum smooth muscle cells

BACKGROUND AND PURPOSE

Corpus cavernosum smooth muscle (CCSM) exhibits phasic contractions that are coordinated by ion channels. Mouse models are commonly used to study erectile dysfunction, but there are few published electrophysiological studies of mouse CCSM. We describe, for the first time, voltage-dependent sodium (Na_V ) currents in mouse CCSM and investigate their function.

EXPERIMENTAL APPROACH

Electrophysiological, pharmacological, and immunocytochemical studies on isolated CCSM cells. Tension measurements in whole tissue.

KEY RESULTS

A fast, voltage-dependent sodium current was induced by depolarising steps. Steady-state activation and inactivation curves revealed a window current between -60 and -30 mV. Two populations of Na_V currents, ('TTX-sensitive') and ('TTX-insensitive'), were distinguished. TTX-sensitive current showed 48% block with the Na_V -subtype-specific blockers ICA-121431 (Na_V 1.1-1.3), PF-05089771 (Na_V 1.7), and 4,9-anhydro-TTX (Na_V 1.6). TTX-insensitive current was insensitive to A803467, a Na_V 1.8 blocker. Immunocytochemistry confirmed the expression of Na_V 1.5 and Na_V 1.4 in freshly dispersed CCSM cells. Veratridine, a Na_V activator, reduced time-dependent inactivation of the current and increased the duration of evoked action potentials. Veratridine induced phasic contractions in CCSM strips. This effect was reversible with TTX and nifedipine but not by KB-R7943.

CONCLUSION AND IMPLICATIONS

We report, for the first time, a fast voltage-dependent sodium current in mouse CCSM. Stimulation of this current increases the contractility of corpus cavernosum in vitro, suggesting that it may contribute to the mechanisms of detumescence, and potentially serve as a clinically relevant target for pharmaceutical intervention in erectile dysfunction. Further work will be necessary to define its role.

Histologic and physiologic analysis of the relationship between the dorsal nerve of the penis and the corpus cavernosum on a rat model. A complementary pathway on the innervation of penile erection?

AIM

The dorsal nerve of the penis (DNP) is the terminal branch of the pudendal nerve which is responsible for the somatic innervation of the penis. This study aims to outline any direct role of the DNP in the hemodynamics of erection histologically and physiologically.

MATERIALS AND METHODS

Fifteen Wistar albino rats were sorted into the electrical activity (n = 6), intracavernous pressure (n = 4), and control (n = 5) groups. The dorsal nerve was electrostimulated and the simultaneous changes in intracavernous pressure and smooth muscle activity were recorded. Penile tissues were collected, fixed, and sectioned, the slides were stained with either hematoxylin-eosin for morphological evaluation or using the indirect immunoperoxidase technique to analyze the distributions of eNOS, iNOS, and nNOS.

RESULTS

During electrostimulation, there was a simultaneous statistically significant decrease in the electrical activity inside the corpora in electromyography and an increase in intracavernous pressure. eNOS and iNOS immunoreactivities were higher in the study group than in the control group. nNOS immunoreactivity was moderate in both study and control groups.

CONCLUSION

Some fibers in the dorsal nerve of penis continue into the corpora cavernosa through the tunica albuginea and have an active, direct role in the hemodynamic process of erection, which may be complementary to the main route of innervation.

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.

Relaxant mechanisms of 3, 5, 7, 3', 4'-pentamethoxyflavone on isolated human cavernosum

We have investigated effects and mechanisms responsible for the activity of 3, 5, 7, 3', 4'-pentamethoxyflavone (PMF) on isolated human cavernosum. PMF is the major flavone isolated from Kaempferia parviflora claimed to act as an aphrodisiac. PMF caused relaxation of phenylephrine precontracted human cavernosal strips, and this effect was slightly inhibited by N(G)-nitro-l-arginine, a nitric oxide synthase inhibitor, but not by ODQ (soluble guanylate cyclase inhibitor), TEA (tetraethylammonium, blocker of voltage-dependent K(+) channels) or glybenclamide (blocker of ATP-dependent K(+) channels). PMF did not significantly inhibit the relaxant activity of glyceryltrinitrate or acetylcholine on human cavernosal strips precontracted with phenylephrine. In contrast, sildenafil (phosphodiesterase inhibitor) potentiated the relaxant activity of glyceryl trinitrate but not of acetylcholine. In normal Krebs solution with nifedipine (blocker of l-type Ca(2+) channels), or in Ca(2+)-free Krebs solution, PMF caused a further inhibition of human cavernosum contracted with phenylephrine. In human cavernosum treated with thapsigargin (inhibitor of sarcoplasmic reticulum Ca(2+)-ATPase) in Ca(2+)-free medium, PMF suppressed the concentration-response curve of human cavernosum to phenylephrine and a further suppression was found when SKF-96365 (a blocker of store-operated Ca(2+) channels and Y-27632 (inhibitor of Rho-kinase)), but not nifedipine, were added sequentially. Thus, PMF had only a weak effect on the release of nitric oxide, and had no effect as a K(ATP)- or K(Ca) channel opener, a phosphodiesterase inhibitor, a store-operated Ca(2+) channel blocker or a Rho-kinase inhibitor. Therefore, these studies suggest that PMF causes relaxation of human cavernosum through voltage-dependent Ca(2+) channels and other mechanisms associated with calcium mobilization.

Mechanisms of penile erection and basis for pharmacological treatment of erectile dysfunction

Erection is basically a spinal reflex that can be initiated by recruitment of penile afferents, both autonomic and somatic, and supraspinal influences from visual, olfactory, and imaginary stimuli. Several central transmitters are involved in the erectile control. Dopamine, acetylcholine, nitric oxide (NO), and peptides, such as oxytocin and adrenocorticotropin/α-melanocyte-stimulating hormone, have a facilitatory role, whereas serotonin may be either facilitatory or inhibitory, and enkephalins are inhibitory. The balance between contractant and relaxant factors controls the degree of contraction of the smooth muscle of the corpora cavernosa (CC) and determines the functional state of the penis. Noradrenaline contracts both CC and penile vessels via stimulation of α₁-adrenoceptors. Neurogenic NO is considered the most important factor for relaxation of penile vessels and CC. The role of other mediators, released from nerves or endothelium, has not been definitely established. Erectile dysfunction (ED), defined as the "inability to achieve or maintain an erection adequate for sexual satisfaction," may have multiple causes and can be classified as psychogenic, vasculogenic or organic, neurologic, and endocrinologic. Many patients with ED respond well to the pharmacological treatments that are currently available, but there are still groups of patients in whom the response is unsatisfactory. The drugs used are able to substitute, partially or completely, the malfunctioning endogenous mechanisms that control penile erection. Most drugs have a direct action on penile tissue facilitating penile smooth muscle relaxation, including oral phosphodiesterase inhibitors and intracavernosal injections of prostaglandin E₁. Irrespective of the underlying cause, these drugs are effective in the majority of cases. Drugs with a central site of action have so far not been very successful. There is a need for therapeutic alternatives. This requires identification of new therapeutic targets and design of new approaches. Research in the field is expanding, and several promising new targets for future drugs have been identified.

Corpus cavernosum electromyography: could it be a parameter to predict ageing?

In this study, we investigated whether electromyography of corpus cavernosum (CC-EMG) results vary with age and whether CC-EMG could be a parameter to predict ageing of cavernous smooth muscle. Recordings of electrical activity of corpus cavernosum (EACC) were retrospectively investigated in 134 patients with erectile dysfunction. Penile colour Doppler ultrasonography and cavernosometry were also performed for all of the patients. The total number and duration of EACC and amplitudes between positive and negative peaks were compared between the flask state for 10 min and after intracavernosal papaverine injection. The mean age of the 47 patients in group 1 was 35.2 ± 6.3 years (range, 23-44), the mean age of the 45 patients in group 2 was 51.1 ± 3.1 years (range, 45-56) and the mean age of the 42 patients in group 3 was 61.8 ± 4.6 years (range, 57-77). Total IIEF-5 score was 7.6 ± 2.1 in group 1, 7.9 ± 2.4 in group 2 and 7.9 ± 2.1 in group 3. There were no statistically significant differences among the groups regarding electrical potential frequencies, durations and amplitudes of electromyographic recordings.

CONCLUSION

We do not think that CC-EMG findings could be used efficiently as a predictor of ageing.

Brain potentials related to corpus cavernosum electromyography

The aim of this study was to elucidate the relation between electrical activity in the corpus cavernosum (CC), penile responses and brain processes. EEG potentials, penile circumference and electrical activity of the CC (CC-EMG) were recorded simultaneously while male subjects were exposed to visual sexual stimuli. The trials were sorted by the penile response of the subjects (erection, maintenance or detumescence). The corresponding EEG recordings were subjected to independent component analysis (ICA) and then correlated with CC activity. We found that CC activity was decreased in the case of erection. EEG activity was found to be correlated with CC activity in most cases at the same instant or with subsequent CC activity. EEG activity at early time points after stimulus onset (<300 ms) was found to be correlated with CC activity, indicating penile response preparation at a pre-attentive processing level. These data indicate that (i) CC activity is under the control of brain processing and (ii) autonomous input reaches the CC in fractions of a second after sexual stimulus onset. Our experimental paradigm should be used for the study of psychogenic erectile dysfunctions and could help in the development of an objective measurement of this disturbance.

ELECTROCAVERNOSOGRAM IN ERECTILE DYSFUNCTION: A DIAGNOSTIC TOOL

Corpora cavernosa (CC) evoke electric waves that appear to be of diagnostic significance in evaluation of erectile dysfunction (ED). We investigated the hypothesis that electrocavernosography (ECG) exhibits different patterns in the various types of ED: neurogenic, vasculogenic, and psychogenic. Electrocavernosography was performed in the flaccid phase in 16 neurogenic, 28 vasculogenic (15 arteriogenic, 13 venogenic), and 24 psychogenic patients with ED, and in 15 healthy volunteers (controls). Two needle electrodes were introduced into the CC and the EMG activity was recorded in each of the 2 CCs of the same subject. Two 20 minute recording sessions were performed for each subject. The controls recorded slow waves (SWs) with regular rhythm and identical frequency, amplitude and conduction velocity from the 2 electrodes of the same subject. Random action potentials (APs) were superimposed on or followed the SWs. The ECG in the neurogenic ED recorded no waves in 14/16 patients and occasional irregular waves in 2. The SWs of the arteriogenic ED had irregular rhythm and variable and low parameters compared to those of the controls. The ECG of the patients with venogenic ED was similar to that of the controls, while the ECG of the psychogenic ED exhibited SWs with irregular rhythm and higher parameters than the controls. The study has revealed various ECG patterns in ED: "silent" in neurogenic. "bradyarrhythmic" in arteriogenic, "normal" in venogenic, and "overactive" in psychogenic ED. We suggest that electrocavernosography has the potential to function as an investigative tool in diagnosing the type of ED provided further studies are performed to verify the described findings.

Clinical autonomic neurophysiology and the male sexual response: an overview

INTRODUCTION

Clinical neurophysiology is the study of the human nervous system through the recording of bioelectrical activity. In the realm of male sexual functioning, this includes using electrophysiologic techniques to study the nerves subserving erection, emission, ejaculation, and orgasm.

AIM

To introduce the reader to the principles of clinical neurophysiology as they relate to the male sexual response, particularly erection.

METHODS

We review the pertinent autonomic neuroanatomy and neurophysiology of reflexes relevant to the male sexual response, as well as summarize the genital electrodiagnostic tests that are being used to interrogate the autonomic innervation pertinent to male sexual functioning.

CONCLUSIONS

The male sexual response is a coordinated series of interactions between the somatic and the autonomic nervous systems. Measurement of the autonomically mediated portions of the sexual reflexes is of great clinical interest, particularly in relation to erection. Advances in clinical electrodiagnostics now allow for consistent recording of evoked and spontaneous intrapenile electrical activity. However, before broad and widespread use of these techniques is possible, more investigations are needed.

Study of the response of the penile corporal tissue and cavernosus muscles to micturition

BACKGROUND

The reaction of the corpora cavernosa (CC), the corpus spongiosum (CS), the bulbocavernosus (BCM) and ischiocavernosus (ICM) muscles to passage of urine through the urethra during micturition is not known. We investigated the hypothesis that the passage of urine through the urethra stimulates the corporal tissue and cavernosus muscles.

METHODS

In 30 healthy men (mean age 42.8 +/- 11.7 years), the electromyographic activity (EMG) of the CC, CS, BCM, and ICM were recorded before and during micturition, and on interruption of and straining during micturition. These tests were repeated after individual anesthetization of urethra, corporal tissue, and cavernosus muscles.

RESULTS

During micturition, the slow wave variables (frequency, amplitude, conduction velocity) of the CC and CS decreased while the motor unit action potentials of the BCM and ICM increased; these EMG changes were mild and returned to the basal values on interruption or termination of micturition. Micturition after individual anesthetization of urethra, corporal tissue and cavernosal muscles did not effect significant EMG changes in these structures, while saline administration produced changes similar to those occurring before saline administration.

CONCLUSION

The decrease of sinusoidal and increase of cavernosus muscles' EMG activity during micturition apparently denotes sinusoidal relaxation and cavernosus muscles contraction. Sinusoidal muscle relaxation and cavernosus muscles contraction upon micturition are suggested to be mediated through a 'urethro-corporocavernosal reflex'. These sinusoidal and cavernosus muscle changes appear to produce a mild degree of penile tumescence and stretch which might assist in urinary flow during micturition.

Electrophysiologic Activity of the Tunica Albuginea and Corpora Cavernosa: Possible Role of Tunica Albuginea in the Erectile Mechanism

INTRODUCTION

It is claimed that the tunica albuginea (TA) shares in the erectile mechanism by compressing the emissary veins passing through it. However, the TA does not contain smooth muscle fibers.

AIM

We investigated the hypothesis that TA lacks a contractile activity on the emissary veins passing through it.

METHODS

Fourteen healthy male volunteers (mean age 35.2 +/- 4.3 years) were studied. The electromyographic (EMG) activity of the TA and corpora cavernosa (CC) was individually recorded in the flaccid and erectile phases by EMG needle electrodes. Recording was performed in the upper, middle, and lower third of the TA and CC on one and then on the contralateral side.

MAIN OUTCOME MEASURES

The TA lacks a contractile activity on the emissary veins passing through it.

RESULTS

The EMG of the CC in the flaccid phase recorded regular slow waves and random action potentials. The wave variables in the erectile phase exhibited a significant decrease (P < 0.01) compared with the variables in the flaccid phase of the same subject. The TA EMG showed no electric waves in the flaccid or erectile phases. These recordings were similar from the upper-, middle-, and lower-third of the penis, and were reproducible from the contralateral CC.

CONCLUSIONS

Electric waves were recorded from the CC in the flaccid phase; wave variables decreased at erection. In contrast, the TA showed no electric waves in the flaccid or erectile phases. It appears that the TA acts as a CC covering sheet which expands passively at erection, and shares in compressing the subtunical venular plexus between it and the tumescent CC.

ORIGINAL RESEARCH—ERECTILE DYSFUNCTION: A Reproducibility Study of Corpus Cavernosum Electromyography in Young Healthy Volunteers Under Controlled Conditions

INTRODUCTION

Although the corpus cavernosum electromyography (CC-EMG) has been studied already for 16 years, doubts regarding its reproducibility have remained.

AIM

To assess the reproducibility of CC-EMG under controlled conditions and the influence of confounding factors.

METHODS

Three CC-EMG recording sessions were performed in 13 healthy young men under the same conditions. Furthermore, the effects of potentially confounding factors, such as intake of caffeine, alcohol and smoking, and sexual activity, were investigated in the same population. Using auto- and cross-correlation techniques, CC-potentials were characterized with parameters amplitude (A), duration (D), dominant frequency (DF), maximum cross-correlation coefficient of longitudinal and bilateral CC-potential pairs (Rmax-lon. and Rmax-bi.), and propagation velocity (PV ).

MAIN OUTCOME MEASURES

Comparison of CC-EMG parameters A, D, DF, Rmax-lon., and Rmax-bi. between three recording sessions and assessment of the impact of confounding factors on these parameters.

RESULTS

DF, D, A, and Rmax-lon. showed significant correlations among three sessions; PV showed significant correlations between two sessions performed within the same day but not between those performed on different days; Rmax-bi. did not show significant correlations between any two sessions. Intake of caffeine, alcohol, and smoking did not affect CC-potentials, while the recordings shortly after ejaculation showed more irregular oscillations and less CC-potentials with smaller A.

CONCLUSIONS

CC-potential parameters DF, D, A, and Rmax-lon. have been demonstrated to be reproducible. The results provide a basis for the clinical and scientific application of CC-EMG. CC-potentials are not sensitive to confounding factors such as intake of caffeine, alcohol, and smoking, while measurements shortly after ejaculation should be avoided.

Corpus Cavernosum Electromyography with Revised Methodology: An Explorative Study in Patients with Erectile Dysfunction and Men with Reported Normal Erectile Function

INTRODUCTION

A lack of standardization of the recording techniques of corpus cavernosum electromyography (CC-EMG) and objective criteria to characterize the recorded signals (CC-potentials) are the main difficulties hindering the clinical application of this method. These difficulties have been recently overcome by revising the recording and interpretation methodology of CC-EMG AIM: To assess if CC-EMG performed with the revised methodology is discriminative for well-defined clinical conditions in patients with erectile dysfunction (ED).

METHODS

Based on blinded clinical diagnosis, ED patients were catalogued into five subgroups: severe penile fibrosis, cavernous arterial insufficiency (CAI), cardio-vascular comorbidity (CVCM) without proven CAI, post-radical retropubic prostatectomy (RRP), and psychogenic ED. With four electrodes placed on the penile shaft bilaterally, CC-EMG was recorded monopolarly for 30 minutes during flaccidity. After evaluation of the recordings by visual inspection, CC-potentials were analyzed using cross- and autocorrelation techniques. The parameters evaluated were amplitude, duration, dominant frequency (DF), and maximum cross-correlation coefficient (Rmax) of CC-potentials recorded from proximal and distal parts of the CC.

MAIN OUTCOME MEASURES

Comparison of the values of parameters amplitude, duration, DF, and Rmax between patient and control groups.

RESULTS

A total of 119 patients with ED and 43 men with reported normal erectile function were studied. Thirteen out of 14 patients with severe penile fibrosis did not show any distinguishable CC-potential. Patients with CAI had significantly decreased amplitude compared with the potent controls, as well as the patients with CVCM but without proven CAI. Significantly decreased amplitude and Rmax were detected in ED patients following RRP compared with the controls.

CONCLUSIONS

Corpus cavernosum electromyography performed with the revised methodology is able to discriminate ED patients with conditions that are associated with cavernous smooth muscle degeneration and/or autonomic neuropathy from men with reported normal erectile function.

The hypoactive corpora cavernosa with degenerative erectile dysfunction: a new syndrome

BACKGROUND

In a group of 22 patients with erectile dysfunction, vasculogenic, neurogenic, endocrinologic or psychogenic investigations failed to find a cause for their erectile dysfunction. The electro-cavernosograms of these patients recorded a diminished activity. We investigated the hypothesis that diminished corpus cavernosum electromyography activity was the cause of erectile dysfunction in these patients.

METHODS

The study comprised the above mentioned 22 patients (study group, 43.8 +/- 5.9 SD years) and 15 healthy volunteers (control group, 41.8 +/- 5.1 SD years). The electro-cavernosograms were recorded in the flaccid, erectile and detumescent phases by 2 electrodes inserted into the corpus cavernosum.

RESULTS

The electro-cavernosogram of the healthy volunteers registered in the flaccid phase regular slow waves and random action potentials. The wave variables declined significantly in the erectile phase (p < 0.01). In the study group, the slow wave variables in the flaccid phase exhibited a significant decrease (p < 0.05) compared to the healthy volunteers, and the rhythm was irregular. Erection did not occur with sildenafil administration or intracavernosal papaverine injection, and penile implant was performed. Biopsy examination showed degenerated muscle fibers, and fragmented collagen and elastic fibers with areas of fibrosis.

CONCLUSION

A novel concept of the cause of erectile dysfunction was presented. Corpora cavernosa showed degenerative changes on histopathologic examination and exhibited diminished electromyography activity. They did not respond to sildenafil administration or intracavernosal papaverine injection. Penile implants were the only treatment. The condition is given the name 'hypoactive corpus cavernosum'. The cause of corpus cavernosum degenerative changes needs further study.

Corpus cavernosum electromyography during morning naps in healthy volunteers: further evidence that corpus cavernosum potentials reflect sympathetically mediated activity

PURPOSE

We assessed the practicability of corpus cavernosum (CC) electromyography (EMG) in volunteers during morning naps in the laboratory and further validated this method.

MATERIALS AND METHODS

A total of 11 healthy volunteers with a mean age of 23.8 years (range 19 to 31) were included. CC-EMG was started between 6:30 a.m. and 7 a.m. Two surface electrodes were placed at the base of the penis bilaterally and a reference electrode was placed on 1 kneecap. A strain gauge or Barlow gauge (Behavioral Technology, Salt Lake City, Utah) was used to monitor changes in penile circumference. Subjects were asked to sleep. Recording duration was 2 to 3 hours. Two recordings were performed per subject.

RESULTS

Full erection was observed on 17 of the 22 recordings (77%), partial erection was noted on 3 (14%) and no tumescence was observed on the other 2 (9%). CC potentials consistently disappeared during tumescence and erection, while continuous CC potential oscillations reappeared during detumescence. During flaccidity bursts of CC potentials and electrical silence were recorded. Penile shrinkage was observed to accompany CC potentials but not to accompany electrical silence.

CONCLUSIONS

CC-EMG during morning naps is a practical and valid method for investigating CC electrophysiology. CC-EMG signal patterns during tumescence, detumescence and flaccidity fit the existing theory that CC potentials reflect cavernous smooth muscle sympathetically mediated activity.

Diagnosing erectile dysfunction: instruments for the study of smooth muscle relaxation

Complete cavernosal smooth muscle relaxation is the pre-requisite for the reliability of every evaluation of the integrity of the corporal veno-occlusive system. Such evaluation is needed whenever reaching a diagnostic conclusion on the haemodynamic status of a given patient is clinically relevant. Clinical challenges that a laboratory evaluation of veno-occlusive integrity face comprise both the induction of complete smooth muscle relaxation, and the possibility to monitor it. This article will review the relevant aspects of normal range values of veno-occlusive function, existing strategies aimed to promote complete smooth muscle relaxation, and available techniques to monitor the cavernosal smooth muscle status.

TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY: A TOOL FOR RECORDING THE ELECTROMYOGRAPHIC ACTIVITY OF THE CORPORA CAVERNOSA

PURPOSE

The electric activity of the corpora cavernosa (CC) is recorded by needle electrodes introduced into the CC. We investigated the hypothesis that transcutaneous electrocavernosography (ECG) would register electric waves similar to those recorded by the needle ECG but noninvasively.

MATERIALS AND METHODS

The ECG was recorded transcutaneously in 35 healthy volunteers (mean age 37.6 +/- 4.8 SD years). Two silver-silver chloride electrodes were applied on the dorsum of the penis over 1 of the CC. A reference electrode was applied to the thigh. Intracavernosal ECG using 2 needle electrodes introduced into the CC was performed in the same subjects. At least two 20 minutes sessions were recorded for each subject.

RESULTS

Slow waves (SWs) were registered transcutaneously. The waves from the 2 electrodes in each individual had the same frequency, amplitude and conduction velocity. They had a regular rhythm and were reproducible. The SWs were followed or superimposed by action potentials which occurred randomly. The transcutaneously recorded SWs were confirmed by the intracavernous route. Both routes had similar ECG recordings.

CONCLUSIONS

The study demonstrated that the transcutaneous ECG recorded electric waves similar to those registered by the intracavernosal route. The transcutaneous ECG is simple, easy, non-invasive, and may be included as an investigative tool in the diagnosis of erectile dysfunction.

The methodology of corpus cavernosum electromyography revisited

OBJECTIVE

The methodology of corpus cavernosum electromyography (CC-EMG) was revisited, in order to overcome current methodological difficulties that hinder its clinical application.

MATERIALS AND METHODS

Using an 8-channel device, CC-EMG was performed in 12 healthy volunteers. Surface electrodes were placed bilaterally on the penile shaft and the kneecap (reference electrode), the pubis region and the anterior superior iliac spine (ASIS). A band pass filter with cut-off frequencies of 0.1 and 20 Hz was used. At least 2 sessions of recordings were performed in each subject.

RESULTS

Thirty-five of 46 recordings were interpretable. Significant time delays between potentials recorded from different sites of the CC were detected. Clear spatial voltage gradients related to CC-potentials were observed on the pubis region. No voltage changes related to CC-potentials, but electrical activity from other sources were recorded from the ASIS. In contrast to frequency, a clear correlation could be demonstrated between amplitude, duration and polyphasity of CC-potentials recorded in 2 different sessions in the same individual.

CONCLUSIONS

Multichannel monopolar recording of CC-EMG with surface electrodes is practical and has several advantages compared with bipolar recording. The results provide evidence that the recorded signals indeed reflect electrical activity of the CC and therefore offer a basis to pursue further clinical validation studies.

Role of penile electrodermal activity in the evaluation of autonomic innervation of corpus cavernosum

Electrodiagnostic tests measuring the activities of cavernous smooth muscle and sudomotor structures of penile skin are used in order to evaluate autonomic innervation of the penis. Owing to closeness of these tissues, the interference of sympathetic activity during recording is a possibility. In this study, we investigated this possibility in 10 patients whose cavernosal tissues were destroyed during penile prosthesis implantation by comparing the pre- and postoperative penile skin electrodermal activities. Penile electrodermal activities were recorded with surface electrodes before and after the operation. All of the patients had spontaneous and evoked penile electrodermal activity (EDA). The mean amplitude of evoked EDA decreased from 2159+/-700 to 1413+/-515 microV following penile prosthesis surgery (P=0.017). The decrease in the amplitude of penile-evoked EDA following penile prosthesis implantation suggests the contribution of cavernous smooth muscle activity to the sudomotor responses prior to operation. Although corpus cavernosum sympathetic activity contributes to the penile skin recordings, these recordings are mostly the result of penile skin sudomotor sympathetic activity. Therefore, surface potentials recorded from penile skin should not be used for the evaluation of autonomic innervation of corpus cavernosum.

Overactive corpus cavernosum: a novel cause of erectile dysfunction

Our recording of the electromyographic (EMG) activity of the corpus cavernosum (CC) in 59 patients with erectile dysfunction (ED) revealed 18 patients who had elevated electric activity, which presumably points to heightened tone of the CC smooth muscles. We investigated the hypothesis that this elevated EMG activity and muscular tone of the CC could be the cause of ED. The study comprised the said 18 subjects with the hypertonic CC muscles as study group (42.6 +/- 5.3 SD years), 15 healthy volunteers (41.8 +/- 5.1 SD years) and 15 patients (41.6 +/- 5.5 SD years) with ED who had not recorded elevated tone of the CC muscles as control group. The EMG activity was registered in the flaccid, erectile and detumescent phases by two electrodes inserted into the CC. Electrocavernosography (ECG) of healthy volunteers recorded in the flaccid phase showed regular slow waves (SW) and random action potentials (APs). The wave variables declined significantly in the erection phase (P < 0.01). In the study group, the SW variables in the flaccid phase increased significantly (P < 0.05) compared with the healthy volunteers and the rhythm was irregular. Erection did not occur with sildenafil but with intracavernosal injection of papaverine, which led to decline of the SW variables (P < 0.05). The control ED group exhibited in the flaccid phase diminished SW variables (P < 0.05) compared with the healthy volunteers. On erection with sildenafil administration, the SW variables showed significant reduction (P < 0.05). CC hypertonicity or 'overactive CC' was identified as a possible cause of ED. An elevated EMG activity of the CC muscle fibres in the flaccid phase presumably denotes hypertonicity of these fibres and their failure to relax to effect erection. The cause of elevated CCEMG activity and presumed muscle hypertonicity is unknown and could be functional or organic. Erection was produced by intracavernosus injection of papaverine and not by sildenafil. This condition of 'overactive CC' should be considered in the diagnosis of ED. However, further studies in the pathogenesis of the condition are warranted.

Nocturnal penile tumescence and rigidity (NPTR) findings in spinal cord injured men with erectile dysfunction

This prospective study aimed at determining whether nocturnal penile tumescence and rigidity (NPTR) findings correlate to the neurologic disorders in spinal cord injured (SCI) patients suffering from erectile dysfunction (ED). A total of 25 acute SCI male patients with post-traumatic ED underwent neurological, electrophysiological and urodynamic examinations, respectively, as well as NPTR recordings. The mean value for rigidity (R), tumescence (T) and duration (D) during NTPR tests were 83.3%, 3.3 cm, 6.4 min in patients with a complete lesion above the sacral (S2-S4) spinal cord (n=10), 46.1%, 1.6 cm, 5.5 min in patients with a complete lesion involving the sacral metameres (n=5) and 89.8%, 3.8 cm, 29 min in patients with an incomplete suprasacral lesion (n=7). The differences among these groups were statistically significant (P<0.05). Patients with lesions involving both sacral and thoracolumbar spinal cord showed no erections (n=3). We found four NTPR patterns: (1) normal R and T, short D; (2) weak R and T, short D; (3) normal R, T and D; and (4) no erections, which can be assigned to different levels and completeness of spinal cord lesions. Nocturnal erections of normal quality need preservation of thoracolumbar and sacral neuronal control as well as partially intact connections of the spinal erection centres with brain areas responsible for sexual arousal.

Investigations in erectile dysfunction

PURPOSE OF REVIEW

This is an update of recent developments in the investigation of erectile dysfunction in the period since March 2002.

RECENT FINDINGS

Three developments in the field of medical sexology redirected the approach towards the investigation of erectile dysfunction. First, the emergence of oral pharmacological therapy; second, the notion that sexual relationship issues have an important impact on the successful outcome of pharmacological therapy; and finally, the concept that erectile dysfunction is often a sequel or even a sentinel of cardiovascular disease. Consequently, the current evaluation of men with erectile dysfunction may be divided into two steps: a basic diagnostic evaluation for the majority of men, and specific diagnostic procedures for a small minority. The basic evaluation is aimed at the identification of the underlying pathological condition and erectile dysfunction-associated risk factors. Such screening may diagnose reversible causes of erectile dysfunction and also unmask medical and psychological conditions that manifest with erectile dysfunction. The basic evaluation consists of a comprehensive medical, sexual and psychosocial history and a physical examination. Patients who have failed first-line treatment or complicated cases qualify for specific diagnostic procedures, traditionally performed by urologists.

SUMMARY

Current research into the investigation of erectile dysfunction emphasizes the notion that erectile dysfunction is often a result of an interplay between medical and psychosexual conditions. Recognition of the underlying conditions and an estimation of their relative contribution to the patient's and his partner's sexual problem are key issues in the current evaluation of the man with erectile dysfunction.

Clinical value of combined electrophysiological and urodynamic recordings to assess sexual disorders in spinal cord injured men

AIMS

To assess the significance of combined neurophysiological and neurourological examinations for diagnosis of neurogenic male sexual dysfunction.

METHODS

This is a prospective study of 32 spinal cord injured men. Each underwent clinical and neurophysiological examinations (sympathetic skin responses (SSR), pudendal somato-sensory evoked potentials (P-SSEP), bulbocavernosus reflex (BCR)) and neuro-urological measurements (urodynamic examination (UE), reflex erections (RE), psychogenic erections (PE) and nocturnal penile tumescence recordings (NPTR)).

RESULTS

Erectile dysfunction due to impairment of RE was associated with loss of BCR and detrusor areflexia (P > 0.001), whereas that due to impairment of PE was associated with loss of perineal SSR (P < 0.001). P-SSEP corresponded in 94% with impairment of penile sensibility and duration of erections in NPTR. The NPTRs were less related to functional sexual impairment. NPTRs in complete and incomplete suprasacral (level > T10) spinal lesion showed sufficient erections despite strongly disturbed PE. NPTRs in lumbosacral lesion revealed significant reduction in or absent erections and underestimated the presence of well excitable PE.

CONCLUSIONS

Combined neurophysiologic and neurourologic testing provides highly relevant diagnostic informations about sexual dysfunction in men with spinal cord injury. Loss of the BCR and detrusor areflexia imply loss of somatic and parasympathetic reflex activity and correlate with loss of RE. Loss of PE correlates with loss of perineal SSR (sympathetic denervation).

Ca2+-activated K+ channels in the endothelial cell layer involved in modulation of neurogenic contractions in rat penile arteries

The present study was designed to investigate the functional K+ channels involved in contractions induced by electrical field stimulation in isolated rat penile arteries. Blockers of Ca2+-activated K+ channels (KCa), tetraethylammonium, and of large-conductance KCa channels, charybdotoxin and iberiotoxin, as well as a blocker of voltage-dependent K+ channels (KV), 4-aminopyridine, increased resting tension in penile small arteries. In the presence of propranolol and NG-nitro-L-arginine (L-NOARG), electrical field stimulation evoked prazosin-sensitive contractions. In endothelium-intact preparations, these latter contractions were enhanced in the presence of tetraethylammonium and charybdotoxin. However, these blockers did not enhance contractions evoked by exogenously added noradrenaline. Endothelial cell removal increased the neurogenic contractions but tetraethylammonium had no further potentiating effect in these preparations. In the presence of an inhibitor of cyclooxygenase, indomethacin, and inhibitor of nitric oxide (NO) synthase, L-NOARG, acetylcholine evoked relaxations, which were abolished in the presence of either tetraethylammonium or charybdotoxin. In phenylephrine-contracted arteries treated with guanethidine and atropine, electrical field stimulation evoked relaxations, which were partially inhibited by L-NOARG and tetraethylammonium, without any additive effect of these drugs. These observations suggest that both large-conductance KCa channels and KV channels sensitive to iberiotoxin/tetraethylammonium and 4-aminopyridine, respectively, are directly involved in the modulation of myogenic tone of rat penile arteries. Furthermore, activation of endothelial intermediate-conductance KCa channels sensitive to tetraethylammonium and charybdotoxin leads to release of a non-NO nonprostanoid factor, which inhibits release of the neurotransmitter, noradrenaline, but these channels do not appear to be involved in inhibition of contraction evoked by exogenously applied noradrenaline in rat penile arteries.

Priming the sexual system: implicit versus explicit activation

We investigated implicit versus explicit activation of the sexual system using a priming paradigm in which sexual slides were preceded by either sexual or neutral primes. In the first experiment, primes were made inaccessible to conscious cognitive elaboration. Identification of sexual targets was facilitated by sexual primes, indicating that sexual representations in memory can be activated automatically. In the second experiment, in which primes were presented at a conscious level, identification of sexual targets was decelerated by sexual primes. Primes elicited subjective sexual arousal in Experiment 2 only, demonstrating that the activation of subjective experience requires conscious cognitive elaboration. With the addition of a sexually specific physiological measure, to be constructed to measure initial genital responses, this paradigm may help elucidate activational mechanisms of sexual response.

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.

Clitoral electromyography

PURPOSE

The clitoris has several histomorphological and functional similarities to the penis. In this study we evaluated spontaneous and evoked electromyography activity in the clitoris.

MATERIALS AND METHODS

We evaluated 11 healthy female volunteers with clitoral electromyography using a concentric needle electrode placed intracorporeally. The hand, foot and genital sympathetic skin responses, and spontaneous electrodermal activity were simultaneously recorded with silver surface electrodes. Another concentric needle electrode was placed subdermally on the mons pubis to differentiate clitoral activity from possible artifact. After recording spontaneous electromyography and electrodermal activity the left median nerve was stimulated to record evoked clitoral activity, and the sympathetic skin response in the hand, foot and genital regions.

RESULTS

There was spontaneous electromyography activity in the corpus clitoris. All dermal sites, including the hand, foot and genital regions, showed spontaneous electrodermal activity. No spontaneous activity was recorded from the subdermal needle electrode. Distraction of attention and coughing increased the amplitude and frequency of spontaneous clitoral electromyography and electrodermal activity at all sites. After stimulating the left median nerve all sites except that of the subdermal needle electrode showed evoked activity.

CONCLUSIONS

The demonstrated evoked and spontaneous clitoral electromyography activity seems to indicate a sympathetic tonus of the corpus clitoris, as recorded from the corpus cavernosum of the penis in human males. Clitoral electromyography may be a useful objective assessment tool for evaluating female sexual dysfunction as well as genital autonomic innervation.

Evoked cavernous activity

PURPOSE

Corpus cavernosum electromyography has been widely done to evaluate autonomic dysfunction in patients with erectile dysfunction. We assessed the value of corpus cavernosum electromyography, evoked cavernous activity and penile sympathetic skin responses for their accuracy in determining autonomic involvement in cases of erectile dysfunction.

MATERIALS AND METHOD

We evaluated 75 men with erectile dysfunction by corpus cavernosum electromyography, evoked cavernous activity and penile sympathetic skin response tests at our neurourology laboratory. The etiology of dysfunction was vascular, neurogenic, psychogenic or mixed based on a detailed medical and sexual history, physical examination, electrophysiological and laboratory studies, penile color Doppler ultrasonography, and cavernosography and/or cavernosometry. Autonomic involvement was clinically assessed by systemic findings, such as orthostatic hypotension, impaired gastrointestinal motility, sinus dysrhythmia and secretomotor changes. A concentric electromyography needle placed in the right cavernous body was used to record corpus cavernosum electromyography and evoked cavernous activity. The right median nerve was stimulated electrically with 13 to 16 mA. to determine evoked cavernous activity and the penile sympathetic skin response. The latter response was recorded with silver disc electrodes placed on the left cavernous body. All tests were performed using an electromyography/evoked potential machine. We determined the relationships among corpus cavernosum electromyography, evoked cavernous activity and penile sympathetic skin response tests in respect to etiological factors.

RESULTS

The 56 patients with normal corpus cavernosum electromyography activity had also evoked cavernous activity and a penile sympathetic skin response except for 1 with no penile sympathetic skin response but evoked cavernous activity. None of these patients had autonomic neuropathy. Of the 19 patients without corpus cavernosum electromyography activity 11 had evoked cavernous activity, including 10 with no autonomic neuropathy. The remaining 8 patients had no evoked cavernous activity, of whom 7 had autonomic neuropathy. A penile sympathetic skin response was recorded in 18 men with absent corpus cavernosum electromyography.

CONCLUSIONS

Due to false-negative results on corpus cavernosum electromyography and penile sympathetic skin response testing evoked cavernous activity seems more reliable for determining autonomic involvement in the pathophysiology of erectile dysfunction.

New concept parameters of RigiScan in differentiation of vascular erectile dysfunction: is it a useful test?

BACKGROUND

The aim of this study is to investigate the value of new nocturnal penile tumescence recording parameters, such as tumescence activity unit and rigidity activity unit values, total erection number and erection times, in differentiating between psychogenic erectile dysfunction and organic erectile dysfunction. We also aimed to determine the role of these parameters in differentiating arterial erectile dysfunction from veno-occlusive dysfunction.

METHODS

Eighty-seven consecutive patients were allocated into three groups as psychogenic, arterial and venous erectile dysfunction after investigations. Nocturnal penile tumescence recording parameters between psychogenic and vascular erectile dysfunction and arterial and veno-occlusive dysfunction were compared. Mann-Whitney U-test, Pearson's chi2 test and correlation coefficient tests were used for statistical analysis.

RESULTS

Depending on intracavernous injection, penile Doppler ultrasonography and cavernosometry tests, 37 patients (43%) had psychogenic impotence while 50 (57%) had organic pathologies. Of the 50 patients diagnosed with vascular impotence, 29 (48%) had arterial failure and 21 (42%) had veno-occlusive dysfunction. Nocturnal penile tumescence recording revealed psychogenic erectile dysfunction in 34 patients (39%) and vascular erectile dysfunction in 53 patients (61%). Nocturnal penile tumescence recording has been regarded as the gold standard and, in our series, it showed 90.6% sensitivity and 88.2% specificity in differentiating the cause of erectile dysfunction. Values of rigidity activity unit and tumescence activity unit were significantly higher in patients with psychogenic impotence (P < 0.001), when compared with vascular impotence. In patients with a vascular cause, no difference was found between arterial failure and veno-occlusive dysfunction with regard to tip tumescence activity unit, base tumescence activity unit, tip rigidity activity unit, base rigidity activity unit and erection time (P > 0.001). However, patients with arterial failure had less erection than patients with veno-occlusive dysfunction (P < 0.001).

CONCLUSION

New recording parameters of nocturnal penile tumescence can differentiate organic and psychogenic erectile dysfunction more precisely. However, these recording parameters cannot distinguish subgroups with a vascular cause of erectile dysfunction.

Smooth muscle electromyography

This article addresses smooth muscle physiology, electromechanical and pharmacomechanical coupling, computed-based interpretations, and the role of electromyography in the diagnosis of erectile dysfunction.

The role of corpus cavernosum electromyography

Although corpus cavernosum electromyography presents great theoretical appeal as a possible direct clinical measure of penile neurogenic function, it has still not been adopted as a routine diagnostic test in the evaluation of patients with erectile dysfunction. This is because of the considerable technical and interpretative problems associated with the method. This review covers some of the more important research and clinical papers published since its first description in 1989, with a special focus on recent advances in this field.

The molecular basis of penile erection

Over the past two decades our understanding of the physiology and the various mediators involved in the pathway of penile erection has greatly increased. This has enabled us to develop effective pharmacological treatments for ED.

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.

Electrical activity of the corpus cavernosum in denervated rats

BACKGROUND

We evaluated the electrical activity of the corpus cavernosum after intracavernous papaverine injection in rats that had been denervated experimentally.

METHODS

Twenty-four male adult Sprague Dawley rats were divided into three groups: (i) controls (n=8) (ii) unilateral cavernous nerve resection on the right side (n=8); and (iii) bilateral cavernous nerve resection (n=8). Through a suprapubic incision, the urinary bladder was retracted laterally to locate the major pelvic plexus on the lateral surface of the prostate. The major branch of the cavernous nerve, running caudally from the pelvic plexus, was isolated and excised using an operating microscope. Three weeks later, recording of the electrical activity of the corpus cavernosum (EACC) was performed by using a Neuropack-2 EMG unit (Nihon Kohden, Tokyo, Japan) and coencentric needle electrode. Changes in amplitude were evaluated before and after intracavernosal papaverine injection. The results in the flaccid state and after papaverine injection were compared by using the Mann Whitney U-test in all three groups and paired t-test between groups.

RESULTS

In the flaccid penis, the mean (+/- SD) amplitude of electrical activity of the corpus cavernosum was 17.42+/-2.05, 12.42+/-1.88, 9.71+/-1.59 and 5.85+/-0.96 microV in control rats, in unilaterally denervated rats (in which the cavernous nerve was intact on the left side), in unilaterally denervated rats in which the cavernous nerve was resected on the right side and in bilaterally denervated rats, respectively. In the flaccid state, EACC is lower in the bilaterally denervated group than in the control and unilaterally nerve-resected groups (P < or = 0.05). The recording of electrical activity of the corpus cavernosum was continued for 20 min after papaverine injection. In the control group and in both groups of unilaterally denervated rats, we observed a significant decrease in the electrical activity of the corpus cavernosum in the first 5 min after papaverine injection (P < or = 0.05). However, no difference was observed in bilaterally denervated rats after injection (P > or = 0.05).

CONCLUSIONS

We conclude that electrical activity of the corpus cavernosum continues after unilateral nerve injury in rats. Cross-innervation may play a role in penile innervation and corpus cavernosum electromyography shows electrical activity in denervated rats.

The nature of spontaneous cavernosal activity

OBJECTIVE

To determine the characteristics of spontaneous cavernosal activity (SCA) and to relate this to previous descriptions of spontaneous potentials from the cavernosum (single potential analysis of cavernosal activity, SPACE).

SUBJECTS AND METHODS

The SCA was recorded in 31 normal men with no sexual problems; various manipulations were applied using concentric-needle (CN), bipolar needle (BN) and surface electrodes. The electrical activity was compared with the observed slow retractile movements of the flaccid penis and with other assessments of electrical activity from skin.

RESULTS

SCA appeared synchronously from both sides of the cavernosal bodies in all normal subjects when detected by CN electrodes. The synchronous recordings both by CN and BN electrodes, or both by CN and surface electrodes registered similar oscillatory potentials. Slow retractile movements of the penis occurred synchronously with these potentials in all subjects and both were absent during erection.

CONCLUSION

SCA is apparently related to biomechanical slow movement artefacts of the flaccid penis: it may be a consequence of the summed contractions of smooth muscle groups in the cavernosum. Observing the small retractile slow movements of the flaccid penis and recording the SCA may be a useful indirect method to characterize cavernosal neural innervation and smooth muscle activity.

Evaluation of the role of corpus cavernosum electromyography as a noninvasive diagnostic tool in male erectile dysfunction

Corpus cavernosum electromyography (EMG) and its evolution: single potential analysis of cavernous electrical activity (SPACE) seem to be promising diagnostic methods in the evaluation of erectile dysfunction and smooth muscle integrity. Our study concentrates on the role of EMG in the evaluation of corpus cavernosum smooth muscles, using it as a noninvasive technique for demonstrating autonomic erectile dysfunction through their influence on recording SPACE and consequent proper selection of patients for different therapeutic modalities. A total of 80 male patients were examined for the feasibility of transcutaneous registration of cavernous electrical activity with a 2-channel electrophysiological unit (Evamatic 2000, Dantec) with two surface electrodes bilaterally placed on the penile shaft. Ten patients had normal erectile function, but complained of other urological symptoms. They served as the controls for normal electrical activity. Fifty patients with organic impotence of nonvascular (neurogenic) or vascular (venogenic, arteriogenic) aetiologies were subjected to EMG in both the flaccid and the erect state. On the basis of the EMG patterns the patients were divided into the following groups: 34 patients having normal tracing in both the flaccid and the erect state, and 21 patients showing abnormal patterns of waves with evidence of autonomic neurogenic dysfunction and incomplete smooth muscle relaxation. Of the latter 4 had long-standing diabetes mellitus and 4 had spinal injuries.

Comparative study between corpus cavernosum-electromyography findings and electron microscopy of cavernosal muscle biopsies in erectile dysfunction patients

BACKGROUND

Biopsy and electrical activity recordings of the corpus cavernosum are 2 new diagnostic methods for the evaluation of impotent men. We evaluated the corpus cavernosum ultrastructure and electromyography (EMG) recordings from patients with erectile dysfunction.

METHODS

Twenty erectile dysfunction patients with veno-occlusive dysfunction underwent a detailed history, physical examination, biochemical tests, hormonal analysis, injection of an intracavernous vasoactive agent (60 mg papaverine-HCl), color penile Doppler ultrasonography, cavernosometry/ cavernosography and corpus cavernosum electromyography (CC-EMG). Thirteen patients underwent total vein ligation and 7 had penile prosthesis implantations. Tissue samples were obtained during surgery from both corpora cavernosa and examined by transmission electron microscopy. Control corporal tissue samples were taken from 3 cadavers.

RESULTS

In 15 patients, CC-EMG recordings were 15.6 +/- 0.65 microV in the flaccid state, which decreased in 13 patients after papaverine (5.61 +/- 0.25 microV; P < 0.001). Five patients with diabetes mellitus had low amplitudes in the flaccid state (5.26 +/- 0.45 microV), which did not vary significantly after a papaverine injection (4.99 +/- 0.75 microV). The pathology of the corpus cavernosum biopsy specimens revealed a smooth muscle cell thickened basal membrane, dilated rough endoplasmic reticulum, and increased numbers of fibroblasts, but ultrastructurally normal endothelial cells lining the sinusoids. There was no difference between samples from diabetic or nondiabetic patients, or from either side of the corpora cavernosa. The only pathologic change observed in the controls was mitochondrial swelling.

CONCLUSION

CC-EMG is less invasive and a valuable method in patients with erectile dysfunction, whereas no specific findings were observed from penile biopsy specimens.

Smooth muscle electromyography from rat urethra

Electrical signals recorded from the penis have been suggested as reflecting electromyographic activity in the underlying smooth muscles. In order to verify this assertion, we manipulated the signal recorded from rat urethra surface. Stimulation of the pelvic nerve brought about a reduction of activity (965 +/- 826 to 166 +/- 143 microV, root mean square of the power at range 0.005-1 Hz, P = 0.008), with a significant frequency-response relationship (P = 0.0002). This effect was not altered by temporary closure of the aorta (P = 0.89), thus ruling out hemodynamic artifact as a possible cause of signal change during stimulation. Our findings support the assertion that the signal indeed reflects activity in smooth muscle.