Ultrasound-guided blockade of the dorsal nerve of the penis in a Great Dane

This report describes an approach to regional anaesthesia of the dorsal nerves of the penis in a Great Dane, as part of an anaesthetic protocol for surgical urethral resection and anastomosis. Bupivacaine (0.5%) was infiltrated around the left and right dorsal nerves of the penis, with ultrasound guidance. The locoregional approach was trans-perineal, with the ultrasound probe orientated at a right angle to the anus, at the level of the ischial symphysis. The described technique provided good visualisation of the urethra and dorsal arteries of the penis. No adverse events relating to the nerve blockade were encountered and no additional analgesia, other than the methadone premedication, was required intra-operatively. The locoregional approach was subsequently repeated on a cadaver using the same technique and, on dissection, demonstrated deposition of injectate next to the target neurovascular bundles. The technique described may provide a simple method of distal penile anaesthesia in the dog, where ultrasound is available.

Anatomical Dissection of the Dorsal Nerve of the Clitoris

Background The clitoris is the primary somatosensory organ of female sexual response. Knowledge of its neural anatomy and related landmarks is essential for safe genital surgery. Objectives The aim of this study was to describe the distal course of the dorsal nerves of the clitoris and associated structures. Methods Clitorises of 10 fresh cadavers were dissected. Measurements of the dorsal nerves, suspensory ligament, clitoral body, clitoral hood, and clitoral glans were obtained. The course of the dorsal nerves was examined. Results The dorsal nerves of the clitoris were larger than expected, ranging from 2.0 to 3.2 mm in diameter, on average, along their course in the clitoral body. In 9 of 10 specimens, the dorsal nerves could be traced to within 6 mm of the glans. They traveled deep to a superficial clitoral fascia but superficial to the tunica albuginea, were variably located between 10 and 2 o’clock, and were separated by the deep suspensory ligament (DSL) of the clitoris. The mean length of the descending clitoral body, from the angle to the base of the glans, was 37.0 mm. The mean distance from the pubic rim to the DSL was 37.7 mm. Conclusions The clitoral body is substantial in length, mostly lying superficially under the clitoral hood and mons pubis. The dorsal nerves of the clitoris are large and superficial, terminating at or near the base of the clitoral glans. Knowledge of this anatomy is critical prior to performing surgery near the clitoris.

Autonomic Regulation of Penile Erection

Penile erection is a part of the human male sexual response, involving desire, excitation (erection), orgasm (ejaculation), and resolution, and autonomic nerves are involved in all phases. Autonomic innervation of smooth-muscle cells of the erectile tissue is provided by the cavernous nerve. Motor and sensory innervation is derived from the pudendal nerves and their terminal branches, that is, the dorsal nerves of the penis, which carry impulses from receptors harbored in the penile skin, prepuce, and glans. Erection begins with an increased flow in the pudendal arteries and dilatation of the cavernous arteries and helicine arterioles in association with relaxation of the smooth muscles of the trabecular network, causing engorgement of blood in the corpora. This leads to compression of subtunical venules by the resistant tunica albuginea and erection. During detumescence these events are reversed.

En Bloc Surgical Dissection for Penile Transplantation for Trans-Men: A Cadaveric Study

Introduction. The surgical techniques currently available for penile reconstruction for trans-men with gender dysphoria present with multiple drawbacks and often fail to meet patients’ expectations. Literature reports three cases where penile transplantation has been performed for cis-men, with the last two cases being considered successful. Aim. To determine whether an en bloc surgical dissection can be performed in a male cadaver, in order to include structures necessary for penile transplantation (from a deceased donor male) to a recipient with female genitalia in gender affirmation surgery. Method. The study was conducted in the form of explorative dissections of the genital and pelvic regions of three male cadavers preserved in phenol-ethanol solution. Results. The first two dissections failed to explant adequately all the relevant structures. The third dissection, which was performed along the pubic arch and through the perineum, succeeded in explanting the relevant structures: it, in fact, allowed for identification and adequate transection of urethra, vessels, dorsal nerves, crura of corpora cavernosa, and bulb of corpus spongiosum, in en bloc explantation of male genitalia. Conclusions. It is possible to explant the penis and associated vessels, nerves, and urethra en bloc from a cadaver. This study suggests a surgical technique for en bloc explantation aiming for transplantation of the penis from a cadaveric donor male to a recipient with female genitalia.

Penile Embryology and Anatomy

Knowledge of penile embryology and anatomy is essential to any pediatric urologist in order to fully understand and treat congenital anomalies. Sex differentiation of the external genitalia occurs between the 7thand 17thweeks of gestation. The Y chromosome initiates male differentiation through the SRY gene, which triggers testicular development. Under the influence of androgens produced by the testes, external genitalia then develop into the penis and scrotum. Dorsal nerves supply penile skin sensation and lie within Buck's fascia. These nerves are notably absent at the 12 o'clock position. Perineal nerves supply skin sensation to the ventral shaft skin and frenulum. Cavernosal nerves lie within the corpora cavernosa and are responsible for sexual function. Paired cavernosal, dorsal, and bulbourethral arteries have extensive anastomotic connections. During erection, the cavernosal artery causes engorgement of the cavernosa, while the deep dorsal artery leads to glans enlargement. The majority of venous drainage occurs through a single, deep dorsal vein into which multiple emissary veins from the corpora and circumflex veins from the spongiosum drain. The corpora cavernosa and spongiosum are all made of spongy erectile tissue. Buck's fascia circumferentially envelops all three structures, splitting into two leaves ventrally at the spongiosum. The male urethra is composed of six parts: bladder neck, prostatic, membranous, bulbous, penile, and fossa navicularis. The urethra receives its blood supply from both proximal and distal directions.

Physiologic studies of male sexual dysfunction in multiple sclerosis

Objective: We conducted this investigation to better define the neural disruptions that result in sexual dysfunction in men with multiple sclerosis (MS), using genital electrodiagnostic testing and nocturnal penile tumescence and rigidity monitoring. Methods: Thirteen men with MS and sexual dysfunction were recruited for the study. Twelve healthy, sexually potent men were enrolled as controls. All underwent pudendal somatosensory evoked potential (SEP) testing using standard methods, and a new modification to isolate the right and left dorsal nerves of the penis. RigiScan testing was performed on the MS subjects to assess nocturnal erectile function. Results: Unilateral and bilateral DNP SEPs were able to be performed on the control subjects. In all but one MS subjects, DNP SEP abnormalities were found. Three men had normal latency bilateral DNP SEP latencies, but on unilateral DNP testing, abnormalities were identified. Seven men, including those with abnormal or absent SEP latencies, had normal nocturnal erectile activity. There was no correlation between overall functional status, presence of abnormal or absent SEP, and quality of nocturnal erectile activity. Conclusions: Genital SEP abnormalities are common in men with MS and sexual dysfunction. Unilateral DNP SEP testing was more sensitive in identifying abnormalities than the standard method of pudendal SEP testing. One of the causes of sexual dysfunction in men with MS may be due to genital somatosensory pathway disruption, with sparing of the efferent tracts in some men.