Single potential analysis of cavernous electrical activity in impotent patients: a possible diagnostic method for autonomic cavernous dysfunction and cavernous smooth muscle degeneration

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.

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.

Relaxation degree of cavernous smooth muscle: a novel parameter to predict postoperative success in penile revascularization

OBJECTIVE

To investigate the role of a new preoperative parameter, relaxation degree (RD), in the prediction of postoperative success after deep dorsal vein arterialization operations.

PATIENTS AND METHODS

Chart reviews and electromyographic recordings were evaluated in 52 patients on whom deep dorsal vein arterialization was carried out for pure caverno-occlusive dysfunction. The efficiacy of the operation was assessed as improvement or failure according to the five-item version of international index of erectile function (IIEF). RD was defined as the percentage decrease in cavernous electrical activity (CEA) after intracavernous papaverine injection. Preoperative RD measurements were statistically compared between the improvement and the failure groups.

RESULTS

The mean age of patients was 34.2 +/- 8.1 years (range 25-49) with a mean follow-up of 32 +/- 8 months. Improvement was observed in 39 (75%) and failure in 13 (25%) patients. The mean RD values were 60% and 32% for surgical improvement and failure groups respectively (P < 0.01). In patients with mild ED, the mean RD value was 70.3% whereas it was 28.7% in patients with severe ED. The RD value of greater than 40% predicts surgical success with a specifity of 75% and a sensitivity of 90%.

CONCLUSION

The RD value of cavernous muscle seems to decrease as the severity of ED increases. In addition, RD may predict the outcome of penile revascularization operations and it may be a useful preoperative indicator for surgical success.

Effects of transanal pelvic plexus stimulation on penile erection: clinical implications

OBJECTIVE

To determine the ability of transanal pelvic plexus stimulation (TPPS) in inducing penile tumescence in patients with non-neurogenic erectile dysfunction (ED) and to compare the erection degree with papaverine-induced erection.

PATIENTS AND METHODS

The cavernous electrical activity (CEA) in 21 men with non-neurogenic erectile dysfunction was measured during TPPS by electromyography of corpus cavernosum and the erection degree of penis (flaccid, semi-rigid, rigid) was noted. The stimulation amplitude was increased from 20 to 100 mA. All patients also underwent intracavernous papaverine injection and further CEA recordings were obtained.

RESULTS

Twelve and nine patients were diagnosed with vasculogenic (VED) and non-vasculogenic ED (NVED), respectively. TPSS led to a penile erectile response in 12 patients (57%), whereas papaverine injection caused erection in 16 (76.2%) patients. The mean baseline CEA (16.9 +/- 9.1 mV) did not change with TPPS, but papaverine significantly decreased the mean CEA to 12.3 +/- 4.9 mV (P < 0.001). CEA recordings of 16 (76.2%) patients revealed a significant decrease after papaverine injection, however seven (33.3%) patients showed significant CEA decrease in response to TPPS. Both TPPS and papaverine were observed to have a higher effect in patients with NVED in terms of inducing penile erection and decreasing CEA compared to their effects in patients with VED.

CONCLUSION

TPPS induces penile erection and decreases CEA for some extent, but to a lesser degree compared to papaverine. As further improvements are achieved in the methodology of TPPS, it may be a valuable method in the evaluation patients with erectile dysfunction.

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.

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.

Physiology of penile erection and pathophysiology of erectile dysfunction

This article reviews the physiology of penile erection, the components of erectile function, and the pathophysiology of erectile dysfunction. The molecular and clinical under-standing of erectile function continues to gain ground at a particularly fast rate. Advances in gene discovery have aided greatly in working knowledge of smooth muscle relaxation/contraction pathways. The understanding of the nitric oxide pathway has aided not only in the molecular understanding of the tumescence but also greatly in the therapy of erectile dysfunction.

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.

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.

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.

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 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.

Autonomic nerve involvement and venous leakage in diabetic men with impotence

OBJECTIVE

To determine the neurophysiological and vascular factors in diabetic impotence, particularly the role of autonomic neuropathy on venous leakage and erectile impotence.

PATIENTS AND METHODS

Thirty-four diabetic men with impotence were investigated using various neurophysiological and radiological methods. The results were compared with those from patients with idiopathic penile venous leakage for autonomic neuropathy, especially for spontaneous cavernosal activity (SCA).

RESULTS

Of the neurophysiological tests, the SCA was most frequently abnormal, with the loss of normal periodic oscillations. Penile venous leakage, either alone or with arterial insufficiency, was the most frequent vascular problem (67%) in patients with diabetic impotence, in whom the SCA was absent in most (83%). Conversely, the SCA was normal in all impotent patients with idiopathic venous leakage.

CONCLUSION

Venous leakage in diabetic patients is probably produced by autonomic dysfunction of the penile vascular innervation or degeneration of penile smooth muscles, because the SCA was absent more often in these patients.

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.

Single potential analysis of corpus cavernosum electromyography for the assessment of erectile dysfunction: provocation, reproducibility and age dependence--findings in 36 healthy volunteers and 324 patients

PURPOSE

Corpus cavernosum electromyography is a controversial method for assessing erectile failure. For its application as a diagnostic tool with clinical relevance, intra-individual stability of the parameters in independent recordings as well as information about provocation and age dependence are required.

MATERIALS AND METHODS

We investigated reproducibility, provocation and age dependence of 11 parameters of single potential analysis of corpus cavernosum electromyography for 36 healthy volunteers in 2 independent recordings with surface electrodes using a visual evaluation technique. Recording 1 results were compared to findings for 324 men with erectile dysfunction.

RESULTS

In healthy subjects all parameters varied extremely among individuals and they were poorly reproducible at repetition. The definition of a normal range as mean plus or minus 2.5 standard deviations did not result in useful diagnostic criteria for individual cases. Activity was not age dependent. Significant differences between healthy and impotent men as defined groups were found in provocation (overall maximum likelihood chi-square 15.5, dF = 2, p < 0.0005).

CONCLUSIONS

Single potential analysis of corpus cavernosum electromyography seems to be appropriate for distinguishing potent volunteers from patients with erectile dysfunction. Provocation of slow cavernous electric activity seems to be a promising parameter that should be considered for ongoing studies. However, a high range of variation of findings even intra-individually does not currently qualify the method for routine clinical use. Further research will show whether different means of documentation or evaluation, that is corpus cavernosum electromyography pattern analysis at rest after audiovisual sexual stimulation, drug application or digital conversion of data, will lead to better results.

Application of factor analysis for the determination of specific frequency bands in corpus cavernosum EMG power density spectra

Corpus cavernosum electromyogram (CC-EMG) recording provides diagnostic information on cavernous autonomic innervation and the intact state of cavernous smooth muscle cells. Evaluation of these signals is time consuming and complex. Therefore, we attempted to facilitate their interpretation and to increase their objectivity by using computer-based digital signal processing. Spectral parameters were used as a starting point for this analysis, which were calculated from the Fourier-transformed time domain CC-EMGs. Factor analysis was applied to determine specific frequency bands in the CC-EMG power density. Two hundred power spectra, taken from normal subjects (n = 66) and from patients suffering from erectile dysfunction (n = 134), constituted the basic data. As a result of applying factor analysis, four specific frequency bands were depicted: 0.0-0.3, 0.3-3.5, 3.5-6.0 and 6.0-10.0 Hz. The results of this study form the basis for further mathematical evaluation and calculation of the CC-EMG for clinical and diagnostic purposes.

Intracavernous auto-injection of prostaglandin E1 for diagnostic evaluation and treatment of diabetic patients with erectile dysfunction

— In this paper we describe our experience in the treatment of impotence with intracavernous self-injection of prostaglandin E1 in 55 diabetic patients. Overall results show that 49 out of the 55 (89%) patients are satisfied with this method of treatment and have continued to use it for more than 3 years. Two thirds of the partners also reported an improvement in their sexual life. Complications were no more frequent than in non-diabetic men and were all of a minor nature.

Corpus cavernosum electromyography (CC-EMG): a new technique in the diagnostic work-up of impotence

We have studied cavernous electrical activity in 42 subjects, healthy volunteer controls and groups of impotent patients using a nonspecific electromyographic device (PICO-MENFIS) and a specific one, the SPACE-recorder 7500 designed to achieve electric recordings from the corpora cavernosa. In all of the patients, we detected under basal conditions a mean amplitude of 583 +/- 323 microV, a mean duration of 4.9 +/- 7 s, a mean polyphasicity of 3.5 +/- 1.4. It should be emphasized that a significant reduction of potential amplitudes was recorded after pharmacological stimulation in both the controls and the impotent patients. The healthy controls showed amplitudes significantly higher than the impotent patients after radical cystectomy (715 +/- 141 microV versus 381 +/- 227 microV, p < 0.01). The patients after a "nerve-sparing" radical cystectomy with a mean amplitude similar to the controls (500-700 microV) reacted well to the intracavernous drugs in a high percentage of cases. In our experience, CC-EMG seems to be a reliable method which can pinpoint directly lesions to the cavernous smooth muscle and penile autonomic nerves. It has also been able to assess the effects of stress, anxiety and pain on the erectile mechanisms.

Hand and genital sympathetic skin potentials in flaccid and erectile penile states in normal potent men and patients with premature ejaculation

Sympathetic skin potentials were recorded from the hand and genital region in 14 normal potent men and 18 patients with premature ejaculations. With the penis flaccid the sympathetic skin potentials obtained did not differ significantly in both groups. However, when erection was induced by 50 mg. intracavernous papaverine injection, the genital sympathetic skin potentials were significantly suppressed in all but 3 normal men, while the hand potentials did not change. In subjects with premature ejaculation genital and hand sympathetic skin potentials were suppressed during erection as a generalized bodily reaction except in 1 patient. This phenomenon may indicate that the specific and regional suppression of genital sympathetic activity during erection could not be properly adjusted in patients with premature ejaculation.

Pathophysiology of erectile dysfunction

During the past decade, our knowledge of the hemodynamics, functional anatomy, neurophysiology, and neuropharmacology of erectile function has evolved substantially. The change of smooth muscle tone has emerged as a key factor in erection and detumescence. However, future studies are needed to elucidate the cellular and molecular basis of erectile physiology. With insight into normal physiology we will understand the pathologic process and be able to treat it.

Nitric oxide synthase: a new diagnostic tool for neurogenic impotence

Cavernosal biopsy specimens obtained from men undergoing penile surgery permitted determination of the diagnostic value of nitric oxide synthase in neurogenic impotence. In biopsy specimens obtained from 25 men, the presence of nitric oxide synthase (NOS), as shown by nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase staining, was determined in nerve fibers, smooth muscle, and sinusoidal endothelium. Positive staining for NOS correlated significantly (p < or = 0.001) with a clinical history of cavernous nerve integrity. In comparison, staining with protein gene product (PGP 9.5), an excellent general nerve stain, lacked any degree of specificity as an indicator of nerve status. NADPH diaphorase may provide important insight into the cavernous nerve integrity of the patient. This report is the first to describe histologic features of human cavernosal tissue biopsies that will allow the direct diagnosis of neurogenic impotence owing to cavernous nerve damage.

Electromyography of cavernous smooth muscle during flaccidity: evaluation of technique and normal values

Objective evaluation of the penile innervation in impotent patients is mostly restricted to examination of the somatic pudendal pathways. These tests provide little information on the pelvic-cavernous autonomic innervation of the corporeal bodies. Electromyography of the flaccid penile smooth muscle is a reproducible and non-invasive method of evaluating these autonomic pathways and the status of intrinsic smooth muscle. Examination techniques and normal values have been studied in 15 young and potent volunteers. Recordings in 13 patients with neuropathology and 57 impotent patients are discussed.

Gap junctions formed of connexin43 are found between smooth muscle cells of human corpus cavernosum

Despite sparse autonomic innervation, the smooth muscle cells of the corpus cavernosum relax and contract synchronously to achieve penile erection and flaccidity. As with other smooth muscle cell types, the excitation process in the corpora is presumably propagated through gap junctions to allow the diffusion of current-carrying ions and second messenger molecules from cell to cell. Using both molecular and immunocytochemical techniques, we have identified gap junctions between human corporal smooth muscle cells in situ and in culture. Northern analyses demonstrated that corporal smooth muscle cells express the gap junction protein connexin43, but not connexin26 mRNA. Immunoblots showed the presence of connexin43 isoforms, whereas connexin32 was not detected. Immunocytochemical studies in cultured cells identified prominent connexin43 immunoreactive puncta between cells, as well as within the cytoplasm. In addition, gap junction membranes both in situ and in culture were labelled in thin section by anti-connexin43 antibodies using the immunogold technique. We conclude that the presence and distribution of gap junctions in this sparsely innervated tissue may provide an important mechanism of intercellular communication among the smooth muscle cells, and thus play a major role in coordinating tissue contraction and relaxation.

Use of vacuum tumescence device for impotence secondary to venous leakage

The causes and treatment of venogenic impotence are still controversial. From September 1989 to April 1991, 317 men complaining of impotence were evaluated in our Erectile Dysfunction Clinic. Seventy patients were suspected of having venous leakage, and all men had dynamic cavernosography performed. Forty-seven of these 70 men (67%) had venous leakage, and a vacuum tumescence device was recommended as initial treatment for all of them. A questionnaire was later mailed to all 47 patients. A response to the questionnaire was obtained from 45 men (96%). Twenty-nine patients had purchased a vacuum tumescence device (Osbon ErecAid). A satisfactory result was obtained in 20 patients (69%) with venous leakage. Since the use of the vacuum tumescence device is relatively safe and noninvasive, and the results are as good as or better than venous ligation, we recommend its use as the initial treatment of venogenic impotence until a consistently reliable treatment for this condition is found.

Gap junction-mediated intercellular diffusion of Ca2+ in cultured human corporal smooth muscle cells

Ratio imaging using the calcium-sensitive probe fura-2 was employed to study intracellular calcium concentrations and intercellular calcium flux through gap junctions in homogeneous vascular smooth muscle cell cultures derived from the human corpora cavernosa. Microinjection techniques demonstrated that fura-2 free acid was freely diffusible through gap junctions between cultured cells. The resting intracellular calcium level in fura-2-loaded cells was 176.9 +/- 10.5. A robust increase in intracellular calcium was seen in response to both phenylephrine and the calcium ionophore A23187. Microinjection of Ca2+ into individual smooth muscle cells always resulted in significant, although temporally delayed, increases in intracellular calcium levels in adjacent cells; this intercellular calcium flux was reversibly blocked by inhibition of gap junctional communication with 2 mM heptanol. However, although microinjection of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] into individual smooth muscle cells always produced significant increases in intracellular calcium levels in the injected cell, the intercellular spread of Ca2+ in response to Ins(1,4,5)P3 was more variable than for Ca2+ injections. These studies demonstrate that Ca2+, and perhaps Ins(1,4,5)P3 as well, can diffuse between smooth muscle cells through gap junction channels.