Anatomic study of arterial and venous cavernospongious shunt in the human penis: surgical findings

The vascularization of the penis corpora cavernosa and the corpus spongiosum of foetus, children and adults was studied via intra-vascular injection with gelatenous india ink. The microscopic vision of sagittal and transvers sections of the penis showed perforate deep arterial system of the cavernosa directly anastomosed the urethral submucosal arteries in order to establish the shunt between the corpora cavernous arteries and spongious arterial network. Those vascular connection systems of the penis provided well diffusion of the drugs.     

Erectile dysfunction: anatomical parameters, etiology, diagnosis, and therapy

Functional anatomy of the human penis involves various parameters: cavernous tissue, covering integument, prepuce foreskin, corpora cavernosa, corpus spongiosum, glans, facia, arterial supply, venous drainage, lymph drainage, musculature, and nerve supply. Several factors affect the expression/degree of erectile dysfunction (ED) endocrine profile, aging/senescence, demyelinating diseases, and surgery. Risk factors of ED are: age, vascular factors, metabolic diseases (diabetes mellitus), neurologic diseases, and HIV/AIDS. Several drugs are associated with ED: antiandrogenic, anticholinergic, antidepressants, antihypertensive, major tranquilizers, anxiolytics, and certain medicines/metabolites. The International Index of Erectile Function (IIEF) is a multidimensional scale for assessment of erectile dysfunction. The main structures mediating erection are the corpora cavernosa or "erectile bodies," which are fused distally for approximately three-quarters of their length. They separate proximally to fuse with each ischial tuberosity of the pelvis. On their ventral surface lies the corpus spongiosum, which surrounds the urethra. Coital dysfunction is classified into "erectile dysfunction" (psychosexual and endocrine/neuro-endocrine) and "ejaculatory dysfunction" (psychosexual, and genitourinary surgery). Vasculogenic impotence was evaluated by high-resolution ultrasonography and pulsed Doppler spectrum analysis. Cavernosal, alpha-blockade is a technique used to evaluate and treat ED. Another diagnostic procedure for ED involves color floro and spectural Doppler imaging after papaverine-induced erection in impotent men. Color Doppler and duplex ultrasonography are used to evaluate Peyronie's disease. Sildenafil cilrate (Viagra) is an effective therapy of ED in men. Vardenavil is a highly selective phosphodiesterase 5 (PDE5) inhibitor which improved ED. Prostagland E1, vasoactive intestinal polypeptide (VIP), and phentolamine mesylate (administered by autoinjectors) have been applied to treat ED in patients resistant to other intracavernosal agents. Clinical trials were conducted on self-injection of vasoactive drugs, apomorphine SL, and tadalafil in diabetic men. Medical therapy of ED includes: medicated urethral system for erection (MUSE), intravenous pharmacotherapy, arterial revascularization, vacuum devices, two- and three-component inflatable penile prosthesis, semi-rigid penile prosthesis in situ, and inflatable one-piece penile prosthesis. Surgical therapy include procedures to correct Peyronie's penile deformity and penile deformity, procedures to avoid inevitable shortening accompanying Nesbit's disease, and for penile lengthening.     

Positive resection margins in partial penectomies: sites of involvement and proposal of local routes of spread of penile squamous cell carcinoma

Recurrence in patients with penile carcinoma occurs in about one third of cases, usually due to insufficient surgery or positive resection margins. An evaluation of surgical resection margins in penectomy specimens was performed to determine precise anatomic sites of tumor involvement, hoping to advance knowledge concerning the local routes of spread of penile carcinomas. A pathologic study of 80 partial penectomies revealed 14 positive margins. Margins were examined after their separation from the main specimen as follows: 1) proximal urethra and surrounding tissues consisting of urethral epithelium with Litree glands, lamina propria, corpus spongiosum, and penile fascia (periurethral cylinder); 2) proximal shaft with corresponding corpora cavernosa separated and surrounded by the tunica albuginea and penile fascia; and 3) skin of shaft with underlying corporal dartos. In 9 patients, only one site was involved by carcinoma, and in 5 there were multiple contiguous sites (for a total of 20 anatomic sites). The distribution of the various sites involved by carcinoma was as follows: urethral epithelium, 4 cases (2 in situ and 2 invasive carcinomas including intraluminal spread); lamina propria, 5 cases; corpus spongiosum, 3 cases; penile fascia, 6 cases; and corpora cavernosa and skin, 1 case each. One of the in situ lesions was discontinuous with the main glans tumor, and the other one was continuous with it. The penile fascia was the most commonly involved site followed by the urethral lamina propria and epithelium. Dissemination to outer skin, corpora cavernosa, and corpus spongiosum was less frequent. The highly vascularized and innervated loose connective tissue of the penile fascia appears to facilitate tumor spread. The urethra is either a pathway for in situ tumor progression from glans to urethra or part of a field prone to malignant transformation. The infrequent involvement of corpora cavernosa is probably due to the tunica albuginea acting as a barrier preventing tumor spread. Based on these observations and the examination of hundreds of penectomy specimens, we are proposing five probable routes of local spread for penile cancer: 1) horizontal and superficially spreading from one epithelial mucosal compartment (glans, coronal sulcus, and foreskin) to the other; 2) following the penile fascia; 3) through spaces created by feeding vessels in the tunica albuginea; 4) vertical spreading involving step-by-step different penile anatomic compartments; and 5) along the urethral epithelium.     

Artificial erection by perfusion of penile arteries

The dorsal and cavernous arteries of the penis in 14 cadavers and 4 surgical specimens were studied, and the role of these vessels in producing erection was evaluated. For the first time, erection was produced in a cadaver by the perfusion of the cavernous artery. Perfusing the dorsal artery resulted in distention but not erection, and the dorsal artery showed extensive anastomoses between all six arteries of the penis. The cavernous artery appears to be very important for erection, with the dorsal artery playing a relatively smaller role. Surgically, however, both vessels may lend themselves to vascular shunts in the treatment of vasculogenic impotence.     

Use of transurethral alprostadil (MUSE) (prostaglandin E1) for glans tumescence in a patient with penile prosthesis

The presence of communication between the emissary veins from the corpora cavernosa and the circumflex veins draining the corpus spongiosum makes it possible for the transfer of alprostadil (prostaglandin E1) in MUSE from the spongiosal compartment to the cavernosal compartment of the penis after its absorption through the urethral mucosa. This leads to engorgement and tumescence of the corpus spongiosum as well as the corpora cavernosa. Lack of tumescence of the glans penis and poor penile girth can be a cause for disappointment and frustration in patients following penile prosthetic surgery. MUSE was used successfully in a patient with a Dynaflex penile prosthesis to enhance the tumescence of the glans penis. It will be a useful adjunct for patients in similar circumstances.     

Technique of anterior urethra urethroplasty using tunica albuginea of corpora cavernosa

OBJECTIVE: Over previous years, urethral stricture has constantly created a great problem in efforts to find a permanent cure for it. We describe a technique of anterior urethroplasty using tunica albuginea of corpora cavernosa. METHODS: After a midline penoscrotal incision, the bulbar or penile urethra along with corpus spongiosum was dissected from the corpora cavernosa. Urethra was then rotated dorsally and the stricture was opened along its whole length. The walls of the slit urethra, along with the tunica albuginea of the corpus spongiosum, were sutured to the tunica albuginea of the corpora cavernosa at the 5 and 7 o'clock position after passing an all silicon catheter. We performed this technique on 79 male patients, having anterior urethral stricture, ranging 18-60 years of age (mean, 46 years). The etiology of stricture was trauma in 54, instrumentation in 12, infection in 10 and unknown in three. Follow ups were done at 4, 12 and 24 months by assessing patients' satisfaction rate along with a pre- and postoperative urethrogram, labeled as "good", "fair" and "poor". RESULTS: Good and fair results were considered as successful. The overall success rate was 94.9%. The success rate remained same at 4 months (64 + 11) and decreased to 93.7% (63 + 11) at 12 months and 89.9% (61 + 10) at 24 months. CONCLUSION: These observations show that anterior urethroplasty using tunica albuginea of corpora cavernosa have produced satisfactory results and are comparable with any other technique of urethroplasty. Thus, we strongly recommend the use of tunica albuginea of corpora cavernosa for anterior urethroplasty, which is histologically similar and anatomically located near the stricture.     

阴茎勃起机制的实验研究

为了进一步了解阴茎勃起机制，以３１条犬为对象，对阴茎海绵体的特征进行了研究。以２～１０Ｖ，１０～３０Ｈｚ的正方波刺激盆神经（ＰＮＳ），观察阴茎海绵体内压（ＩＣＰ）、动脉血流（Ａｆ）和静脉血流（Ｖｆ）的变化，以及阻断腹主动脉后ＰＮＳ时ＩＣＰ、Ａｆ和Ｖｆ的变化。结果发现ＩＣＰ在ＰＮＳ结束后的变化趋势是阴茎海绵体的本身特征。证明了阴茎海绵体是阴茎勃起的功能主体，并首次提出，在勃起过程中可能存在着动脉抗返流机制     

The hemodynamics of erection at the level of the penis and its local deterioration

We have studied penile structure in 300 specimens from cadavers, 3,000 patients undergoing general physical examination and more than 700 patients operated on for organic impotence. Special attention has been focused on the closure mechanism of the corpora cavernosa during erection. Venous outlets of the corpora cavernosa normally are situated only on the distal third of the ventral penile surface. A firm, lasting erection requires a tight albuginea of the corpora cavernosa, with perfect closure of the venous outlets. During life use of the penis or, eventually, misuse by repeated long-lasting, firm erections (high pressure in the corpora cavernosa) results in deterioration of the tightness of the albuginea, especially when the albuginea is thin (25 per cent of the cases). We have found that a leakage factor of the corpora cavernosa is the most frequent cause of organic impotence in aging men.     

Conjoint corpora cavernosa and its role in erection

The two penile corpora cavernosa (CC) remain as separate structures along the penile shaft. During our study of 28 cadavers, we came across three cadavers in which the two CCs were fused together forming a single tubular structure; this article discusses these three cadaveric specimens. The cadavers were aged 52, 36, and 12 years. After penile degloving, the dorsal groove on the penile shaft was absent. In two of the cadavers, multiple transverse cut-sections in the penile shaft showed that the two CCs were united into one single tubular structure that extended from the symphysis pubis to the glans penis. The cut section was kidney-shaped, with the corpus spongiosum lying under cover of the concave surface. No intercavernosal septum was identified. The transverse cut-section of the third cadaveric specimen revealed an incomplete fusion of the two CCs. An intercavernosal septum was present in its upper part, but absent in its lower part where the two CCs were fused together. In all three cadaveric specimens, the CCs showed a normal histologic pattern and the corpus spongiosum was morphologically normal. Based on biomechanical principles, we theorize that the blood volume occupying the two CCs would be greater, the penile rigidity stronger, and the penetration force more powerful in the two separate CCs as normal than in the two CCs if fused. However, further studies involving large number of cases are needed.     

Hemodynamics of erection in the monkey

Being able to induce controlled erection in dogs and monkeys, we investigated the hemodynamics and mechanism of penile erection. 'Chronic' monkey models, having had electrodes implanted around the cavernous nerves for electroerection, were studied to evaluate the details of the hemodynamic changes. The studies included: 1) arterial blood flow, 2) corporeal pressure, 3) blood gases, 4) venous flow and 5) radiography. Tumescence of the corpora cavernosa was found to be a result of: 1) active relaxation of the sinusoidal spaces, 2) active arteriolar dilatation and 3) active venous outflow constriction. At full erection there is adequate but reduced blood flow into and out of the corpora cavernosa for metabolic exchange.     

Maintenance of erection of penile glans, but not penile body, after transection of rat cavernous nerves

Two experiments tested the widely held assumption that the cavernous nerves (CN) are essential not only to erection of the penile body, via the corpora cavernosa, but also to erection of the glans penis, via the corpus spongiosum. In Experiment 1, the copulatory behavior and reflexive erections of male rats were studied before and after the CN were transected bilaterally (n = 8), unilaterally (n = 6), or sham-operated (n = 6). In postoperative tests, bilaterally operated males were severely impaired in their attempts to effect intromission, and they had the expected deficits in reflexive erections of the penile body, but their capacity for erection of the glans penis was only minimally impaired. Sham-operated males were unaffected by surgery, and unilaterally transected males had intermediate values. Experiment 2 tested the hypothesis that activity of the bulbospongiosus muscles was responsible for the residual erectile capacity of the glans after CN transection in Experiment 1. Males had bilateral sections of the CN (n = 9), or of the nerves innervating the bulbospongiosus muscles (n = 10), or of both of these nerves (n = 8), or sham surgery (n = 10). Relative to CN transection alone, the combined denervation further reduced glans penis erections, but did not eliminate them. These results suggest that the cavernous nerves of the rat are not the only peripheral nerves facilitating vascular engorgement of the corpus spongiosum.     

Functional evaluation of penile veins by cavernosography in papaverine-induced erection

Of 49 patients in whom cavernosography was performed after papaverine-induced erection 38 had abnormal venous leakage to various drainage systems (corpus spongiosum, cavernous vein or superficial and deep dorsal veins). Because the effect of papaverine on penile arteries, sinusoids and veins is similar to that caused by electrostimulation, we believe that this technique is better than other reported means of evaluating the functional status of the penile veins. However, we recommend that only patients with a normal arterial response but poor erection after papaverine injection be considered candidates for erection cavernosography, since they most likely will benefit.     

Venous surgery in erectile dysfunction: a critical report on 116 patients

From June, 1985, to December, 1987, we operated on 116 impotent patients suffering from venous incompetence of the cavernous bodies. A total of 115 patients underwent ligation of the deep dorsal vein of the penis. After a mean follow-up of 12.9 months, 67 patients (58.3%) were still able to obtain satisfactory erections. In 39 cases (33.9%), however, adjuvant corpus cavernosum autoinjection therapy was necessary. Eleven patients were submitted to spongiosolysis after ligation of the deep dorsal penile vein because of a distal venous leakage, consisting of venous shunts between the corpora cavernosa and the corpus spongiosum. After a mean follow-up of 14.2 months, 9 patients (81.8%) reported excellent penile rigidity; 5 of these patients, however, needed corpus cavernosum autoinjection therapy to maintain erectile function. One patient with ectopic veins emerging from the right crus of the penis was operated on successfully from a perineal approach. Serious complications did not occur in any of the patients. Despite the recurrence rate of 13 percent, venous surgery is an effective treatment for most patients concerned and offers a more physiologic erectile function than can be achieved by implantation of a penile prosthesis.     

Spongiosolysis: a new surgical treatment of impotence caused by distal venous leakage

Until recently ligation of the dorsal veins of the penis had been the only effective surgical treatment in cases of erectile dysfunction caused by venous insufficiency of the corpora cavernosa. Failure of this operation can be owing to persistent distal venous leakage consisting of venous shunts between the distal corpora cavernosa and corpus spongiosum, which can be demonstrated by cavernosography. These shunts can be closed successfully by spongiosolysis, that is by dissecting the distal half of the corpus spongiosum and by isolating the tips of the corpora cavernosa. Of 5 patients who underwent spongiosolysis after previous ligation of the dorsal vein of the penis 4 regained erectile ability with the help of intracavernous injection of a vasoactive drug mixture (15 mg. per ml. papaverine hydrochloride plus 0.5 mg. per ml. phentolamine mesylate, 0.5 to 2 ml. per injection), which was necessary because of concomitant arterial lesions demonstrated by arteriography. The only failure proved to be persistent venous insufficiency of the deep dorsal vein of the penis. Since none of the patients had any serious complication spongiosolysis seems to be a safe procedure in the treatment of distal venous leakage.     

Vascular impotence: focal or diffuse penile disease.

Using computerized image analysis the percentage of smooth muscle fibers was measured in several biopsies of the penis from 10 cadavers and 5 patients with vascular impotence. No significant difference was observed between the proximal and distal areas, and/or between the peripheral and central areas in 1 corpus cavernosum, and between the 2 corpora cavernosa for each patient or cadaver. The percentage of smooth muscle fibers was less in impotent patients in comparison with the cadavers, in which the erectile status was not known, and this reduction occurred throughout both cavernous bodies. Vascular impotence is a diffuse penile disease. Therefore, a cavernous body biopsy can be used to study the penile structure in the assessment of vascular impotence.     

阴茎体白膜两侧睾丸鞘膜移植阴茎增粗术实验研究

目的:探讨犬阴茎体白膜两侧自体睾丸鞘膜移植阴茎增粗术的治疗效果及手术并发症。方法:取5只雄性杂种狗自体睾丸鞘膜移植于阴茎白膜两侧的纵形切口,以扩大阴茎白膜腔、增大阴茎海绵体容积、增粗阴茎;手术前后进行疲软及勃起状态下阴茎海绵体周径的测量及两侧阴茎海绵体动态灌注测压(DIC);术后3个月行组织学检查。结果:施行5只10侧,术后3个月勃起状态下阴茎海绵体周径平均增加21.1%,疲软状态下增粗不明显,DIC参数与术前相比无统计学差异;无其他严重并发症;组织学检查移植物内轻度炎性反应和纤维化,其上有白膜的重新形成。结论:该手术方法使勃起状态下阴茎增粗效果显著,是一种安全的、真正针对勃起组织的阴茎增粗方法。     

Division of autonomic nerves within the neurovascular bundles distally into corpora cavernosa and corpus spongiosum components: immunohistochemical confirmation with three-dimensional reconstruction

Background

Detailed knowledge of the distribution and distal course of periprostatic nerves is essential to improve functional outcomes (erection and continence) after radical prostatectomy (RP).

Objective

To describe the location of nerve fibres within neurovascular bundles (NVBs) and around the prostate by three-dimensional (3D) computer-assisted anatomic dissection (CAAD) in human foetuses and adult cadavers.

Design, setting, and participants

Serial transverse sections of the pelvic portion were performed in seven human male foetuses and four male adult cadavers. Sections were treated by histologic coloration and neuronal immunolabelling of S100 protein. 3D pelvic reconstruction was achieved with digitised serial sections and WinSurf software.

Measurements

We evaluated the distribution of nerve fibres within the NVB qualitatively. The distribution of periprostatic nerves was also evaluated quantitatively in the adult specimens.

Results and limitations

Periprostatic nerve fibres were dispersed around the prostate on all sides with a significant percentage of these fibres present in the anterior and anterolateral sectors. At the prostate apex and the urethral levels, the NVBs have two divisions: cavernous nerves (CNs) and corpus spongiosum nerves (CSNs). The CNs were a continuation of the anterior and anterolateral fibres around the apex of the prostate, travelling towards the corpora cavernosa. The CSNs were a continuation of the posterolateral NVBs, and they eventually reached the corpus spongiosum. The limitations of this study were the small number of specimens available and the lack of functional information.

Conclusions

The anterolateral position of CNs at the apex of the prostate and the autonomic innervation towards the corpus spongiosum via CSNs indicate possible ways to minimise the effect of prostate surgery on sexual function. The ideal dissection plane should probably include the preservation of the anterolateral tissues and fascias to avoid CN lesions. Anatomic knowledge gained from CAAD pertains directly to proper surgical technique and subsequent recovery of erectile function after RP.     

Penile venous drainage in erectile dysfunction. Anatomical, radiological and functional considerations

To elucidate further the penile venous anatomy and its role in the haemodynamics of erection, we performed pharmacological cavernometry and cavernography in 95 patients with venogenic impotence and in 12 patients with psychogenic impotence. The findings were correlated with those of dissection in 10 adult male cadavers. Cavernography confirmed that the main venous drainage of the corpora cavernosa is via the cavernous veins, with additional drainage through the crural, circumflex and deep dorsal veins and demonstrated that, in patients with venogenic impotence, the cavernous veins are the common site of leakage. Cavernometry provided valuable parameters for the quantification of the degree of venous leakage. Detailed knowledge of the penile venous system and cavernometry and cavernography are essential for the proper diagnosis and treatment of patients with venogenic impotence.     

Congenital penile curvature (chordee without hypospadias)

We treated 30 patients aged six months to nine years with congenital penile curvature from 1988 to 1993. Twenty-four patients appeared to have a primary curvature with normal corpus spongiosum. In 12 of these 24 patients dissecting skin and dartos fascia were adequate to straighten the penis. In the other 12 patients, artificial erection demonstrated a varied degree of convexity of the penis after the skin and dartos fascia release, implying a disproportion of the corpora cavernosa bodies. We corrected this deformity using dorsal tunica albuginea plications (TAP). The remaining 6 patients presented with a primary curvature and hypoplastic urethra. In 5 of these patients we divided the hypoplastic midportion of the urethra leaving the meatus naturally on the glans and replaced the midurethral segment using a tubularized island flap. Of these 5 patients 2 required TAP for penile straightening. The final patient with a hypoplastic urethra was managed by preserving the urethral plate and applying an onlay island flap urethroplasty. Complications were one fistula and two mild ventral penile curvatures, presently not severe enough for reoperation (mean follow-up 2.6 years). We present a systematic approach for the repair of congenital penile curvature using intraoperative artificial erection, TAP, and the island flap urethroplasty when needed.