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.     

Relaxation of isolated corpus cavernosum induced by smooth-muscle relaxant drugs

Summary Intracavernous injection of vasoactive substances are used in the treatment and investigation of impotence. We studied the effects induced by some pharmacological agents on strips of human erectile tissue. Specimens of corpus cavernosum were obtained from 16 men undergoing cystectomy or penectomy for bladder or penile malignancy. Strip preparations were mounted in thermostically controlled baths containing Krebs solution. Pharmacologic effects were monitored by means of an isotonic transducer. Papaverine was shown to be the substance able to cause the biggest relaxation effect. The authors compared the action of other drugs having a relaxant effect, studied the antagonist effects of epinephrine and dopamine on the pharmacologically relaxed preparations, and stressed that the relaxation of the erectile tissue has a determinant role in the appearance and maintenance of erection.     

Smooth muscle electromyography of the urinary bladder

To elucidate smooth muscle activity of the urinary bladder, we utilized an optimized animal model and a specially developed, computer-aided data acquisition and analysis system for bioelectrical signals. Twenty-five Wistar rats were pharmacologically paralyzed and artificially respirated. The urinary bladder was exposed by a suprapubic midabdominal incision, and both ureters were ligated to prevent physiological filling of the bladder. The bladder was initially emptied by slight manual pressure and was then filled via a transurethral catheter in 0.1-ml steps to a maximum of 0.45 ml with physiological saline. A custom-made, gold-plated needle electrode was tangentially guided by a micromanipulator to the smooth muscle of the bladder dome, and the recordings commenced. Furthermore, smooth muscle EMG recordings of the bladder were performed after pharmaco-stimulation of the detrusor with carbachol. Initial results demonstrate that, with the animal model presented here, it is possible to record reproducible and almost artifact-free smooth muscle activity from the urinary bladder. All experiments displayed a stochastic distribution of similar electrical events, increasing in appearance and amplitude with increased bladder volume and after pharmaco-stimulation with carbachol. Two-dimensional power spectrum analysis revealed a main signal frequency below 1 Hz. Neurourol. Urodynam. 17:71–83, 1998. © 1998 Wiley-Liss, Inc.     

Comparative studies on intracellular calcium and nadh fluorescence of the rabbit corpus cavernosum

Erectile function (erection and detumescence) involves the complex interaction of direct neuronal stimulation of corporal smooth muscle, neurohumoral release of specific endothelial contractile and relaxant factors, and secondary modulation by a variety of putative neuropeptides and vasoactive modulators. Using surface spectrofluorometry, we have correlated spontaneous contractile activity and the contractile response to field and pharmacological agents with intracellular calcium and NADH metabolism. The results demonstrate that the corpus cavernosal tissue has very unusual properties. Spontaneous contractile activity is correlated with a phasic increase in intracellular calcium. However, spontaneous contractile activity is most often correlated with a bi-phasic effect on the ratio of NADH/NAD. At the start of the spontaneous contraction, there is a sharp phasic increase in NADH/NAD; peak contractile force occurs simultaneous with a phasic decrease in this ratio showing that at peak force generation, there is a decrease in the level of intracellular energy. Phenylephrine stimulation results in an increase in intracellular calcium in proportion to the increase in tension; however, phenylephrine stimulation at low concentrations results in a net increase in the NADH/NAD ratio whereas high concentrations of phenylephrine result in a net decrease in the NADH/NAD ratio. In general, field stimulation results in a decrease in tension at low frequencies, a biphasic response at midfrequencies, and a contraction at high frequencies. These contractile responses are directly related to alterations in the intracellular concentration of calcium. That is, a decrease in tension is preceded by a decrease in intracellular calcium while an increase in tension is preceded by an increase in intracellular free calcium. Field stimulation results in a rapid and phasic alteration in the NADH/NAD ratio; however, the NADH/NAD response can be either an increase, decrease, or biphasic response. There does not appear to be a consistent relationship between the contractile/relaxant response to field stimulation and altered NADH/NAD ratio. Finally, ATP, bethanechol, and nitroprusside induce a decrease in the basal tension of the corpus cavernosal strips which corresponds with a decrease in the NADH/NAD ratio. However, whereas nitroprusside relaxation is correlated with a decreased intracellular calcium level, both ATP and bethanechol stimulate an increase in intracellular free calcium. These studies indicate that the response of the corpus cavernosal tissue to both field stimulation and pharmacological agents is complex and may involve both direct and indirect actions of a variety of cellular mediators on the corporal smooth muscle. © 1994 Wiley-Liss, Inc.     

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.     

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.     

Effects of partial bladder outlet obstruction on contraction and relaxation response of rabbit corpus cavernosum

It has been well established that erectile dysfunction (ED) is a common incident in patients with benign prostate hyperplasia. Animal models have been described to investigate the relationship between bladder obstruction and ED. In this study, we aimed to investigate whether partial bladder outlet obstruction (PBOO) induces changes in the contraction and relaxation response of corpus cavernosum smooth muscle (CCSM) of the penis in the rabbit model. Partial bladder obstruction was performed in rabbits as previously described. After 2 and 4 weeks of follow-up, control, sham-operated (2- and 4-week duration) and partial bladder outlet obstructed (obstruction of 2- and 4-week duration) rabbits were sacrificed and their bladder masses determined. Then CCSM tissue was obtained. Contraction responses induced by 124 mM KCl, phenylephrine (10(-6) to 10(-4)M) and relaxation responses induced by doxazosin (10(-7) to 10(-5)M) in CCSM of rabbits were determined. The obtained contraction and relaxation responses of all groups were compared. Bladder weight was significantly higher in PBOO groups than in control and sham-operated rabbits. Contraction responses induced by KCl and phenylephrine were statistically enhanced in the 4-week PBOO groups than controls. However, there was no statistically significant difference in any KCl, phenylephrine and doxazosin responses between 2- and 4-week sham-operated and PBOO groups. The rabbit model of PBOO described for the studies which examine bladder responses is useful for creating bladder outlet obstruction. However, this model is not suitable for the investigation of outlet obstruction-related ED.     

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 [4]. 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.     

Traumatic rupture of the corpus cavernosum

Penile fracture is a rare entity. Twelve patients with penile fractures were treated surgically with a very low complication rate. Our results were compared with those reported in the literature.     

The veno-occlusive mechanism of the canine corpus cavernosum: angiographic and pharmacologic studies

Studies were designed to document the normal angiography and pressure-volume characteristics of the canine corpus cavernosum, evaluate the effects of various vasoactive agents, and characterize a veno-occlusive mechanism. In fourteen dogs, baseline cavernosography demonstrated venous drainage via six to ten tributaries arising from the crura and entering the deep penile veins. Control cavernosometry during infusion of saline at 0.33 ml./sec. led to a rise in intracavernosal pressure (ICP) from 24.9 +/- 7.9 mm. Hg to 68.4 +/- 21.1 mm. Hg. Intracavernosal injection of a number of vasodilators, including papaverine, nitroglycerin, acetylcholine, and prostaglandin E2, raised baseline ICP significantly, caused extreme elevation of pressure during saline infusion (greater than 450 mm. Hg), and narrowed or obliterated the venous lumena at the site of tunica perforation, as judged angiographically. These effects could be reversed with phenoxybenzamine or norepinephrine. Our results further support the current understanding of the canine veno-occlusive mechanism.     

Update on bladder smooth-muscle physiology

Summary The urinary bladder responds to distension induced by a number of different stresses with rapid and substantial increases in bladder mass and concomitant alterations in the contractile responses to neuronal stimulation, pharmacological simulation by autonomic agonists, and membrane depolarization. Furosemide, sucrose, or diabetes-induced diuresis, as well as outlet obstruction and overdistension all produce similar effects on the bladder. Accompanying the increases in bladder mass and contractile changes are increases in DNA synthesis and [³H]-thymidine uptake. Autoradiographic studies have localized the increased DNA synthesis following bladder distension initially to the urothelium, followed by slower increases in labelling of the lamina propria and extramural connective tissue. The net result of these compartmental differences in DNA synthesis is a reorganization of the structural relationships between smooth-muscle cells, the connective-tissue matrix, and the extrinsic connective-tissue lamina. This may contribute to the functional changes which occur after severe overdistension. Increases in the expression of heat-shock protein-70, basic fibroblast growth factor, N-ras, and c-myc, and decreases in transforming growth factor-beta occurred acutely after obstruction, suggesting that these changes may play a role in obstruction-induced bladder hypertrophy. Removal of the obstruction induces apoptosis of urothelial and connective tissue elements in the bladder, accompanied by increases in transforming growth factor-beta and decreases in basic fibroblast growth factor genes, and a reversal of the bladder dysfunction. Therefore the bladder hyperplasia after outlet obstruction and the regression following removal of the obstruction seem to be directly opposing processes governed by gene expression.This work was supported in part by grants from the Veterans Administration, NIH grants DK26508, DK33559, DK39740, DK44801, and DK40367, and Urological Research Associates.     

Abscess of corpus cavernosum.

A rare case of abscess of the corpus cavernosum is described. Culture of the abscess yielded beta-hemolytic streptococcus. Ultrasound scan and cavernosography confirmed the physical examination findings of involvement of the corpus cavernosum. The patient was treated successfully by percutaneous ultrasound-guided aspiration drainage and systemic antibiotic therapy.     

Traumatic rupture of corpus cavernosum

Fracture of the corpus cavernosum occurs when one or both corpora are ruptured usually during sexual intercourse and less often owing to blunt trauma. The injury may be associated with an urethral lesion and is easy to recognize; the treatment, however, remains controversial. 7/8 patients had primary or secondary surgical therapy, 1/8 was treated by conservative measures. The results after surgery were very satisfactory, with no immediate perioperative or postoperative complications. The success rate of the surgical management corresponds to a high degree with reports from the literature (complication rate is less than 10%). Based on literature review, conservative treatment is associated with a 25-30% complication rate. Early surgical repair might be the treatment of choice for rupture of the corpus cavernosum with and/or without concomitant lesion of the urethra.     

Traumatic rupture of corpus cavernosum

Penile fracture is a rare entity. Twelve patients with penile fractures were treated surgically with a very low complication rate. Our results were compared with those reported in the literature.     

Hemihypertrophy of the human corpus cavernosum.

Hemihypertrophy of the right corpus cavernosum and its accompanying thickened tunica albuginea are responsible for the left lateral deviation in congenital curvature of the penis. Surgical correction is more predictable when the lengths of the dorsal and ventral curvatures of the corpora cavernosa are known.     

Fine structure of the human corpus cavernosum

This paper demonstrates the ultrastructure of the human corpus cavernosum from eight male transexuals (aged 20 to 30 years) undergoing penectomy. The presence of collagen, smooth muscle, endothelial cells lining cavernous spaces, mast cells, and different types of nerve terminals, including those of a nonadrenergic and noncholinergic type, are illustrated.