Concealed penis is a rare congenital abnormality in the children and has numerous and unclear etiology. Histological features of nerve ending especially dartos fascia in the CP have not been well explored in previous studies.
According to penile anatomy, the penile innervation consists of several branches of the pudendal nerve derived from S2–4, including the dorsal, cavernosal, and perineal nerves of the penis [15]. After branching from the pudendal nerve, the dorsal nerve traversed the dorsum of the penis deep to Buck's fascia. The dorsal nerve was superior to the cavernous bodies and together with the dorsal arteries and veins to supply sensation to penile skin, including the glans penis [16]. The fibers of the dorsal nerve of the penis penetrated the corpus spongiosum to innervate the urethral lumen as afferents and received input and relayed the information during micturition and ejaculation [17]. The perineal nerve also branched off the pudendal nerve and innervated the ventral shaft skin, the frenulum, and corpus cavernosum [18]. The cavernous nerve branched off the autonomic pelvic plexus, accompanying with the neurovascular plexus of the prostate, and carrying sympathetic and parasympathetic nerve fibers to the corpora cavernosa [19]. These nerves spreaded sensory signals to the central nervous system that was critical to achieve an erection and sexual function [20].
Common principles of surgical procedures for CP are complete degloving along Buck's fascia and correcting the deficiency of the penile shaft skin [21, 22] torestore the normal erectile and sexual function. Numerous techniques have been described to correct the CPwith various surgical outcomes, reflecting the different perceptions of etiology. In children, the CP is often caused by an inelasticity of the dartos fascia in infancy [23]. A review on comparison with current literature had reported that the dissection of the dartos and Buck’s fascia with division of chordee was commonly performed in children with CP [21]. Several studies also maintained that the key to correctionin children with the CP was the release of the abnormal dartos attachments and fixation of the penile skin to Buck’s fascia [14, 24]. However, in this study, we had observed that there were the abundant nerve plexuses on the dartos in CP children. Cold et al. [25] had also reported that the resection of dartos to correct CP may cause loss of sexual sensation, due to removal of abundant nerve endings. In addition, Wu, et al [26] had found that the concentration of substance P and calcitonin gene–related peptides on nerve terminals, which were associated with the afferent sensation of penises, were relatively high in the frenulum compared to other positions. Although the resection of the superficial fascia dartos has been proven to improve the cosmetically appearance in children, it may reduce the sensitivity of the penile skin after puberty.
For concealed penis repair, the first step is to make a circumcised incision and followed by degloving the foreskin, that is, releasing abnormal dartos. In this procedure, many surgeons choose to remove the abundant dartos which attached to Buck’s fascia to reduce the edema or hyperplasia of dartos which will reveal a poor cosmetic result, postoperatively. The purpose of this study is to find out whether this manipulate is harmless; if not, we have to modify the procedure to preserve the dartos. Also, the number of patients should be as few as possible to minimizing the ethical issues when we investigated if the manipulation was harmful. In this study, we obtained four samples from the children because many surgeons performed a surgical procedure for large-scale resection of the fascia under the penis in order to maintain the aesthetics of the penis after surgery, and reduce postoperative lymphatic drainage disorders and penile scar hyperplasia. We obtained a relative position specimen after the surgical removal of the fascia, without additionally increasing the damage of the child. This study was done for trying to minimize these injuries when the surgeon underwent the surgical removal of a large number of fascia tissue.
In this study, the nerve plexus distribution was more abundant on samples collected at 6 o’clock position than at other positions. The histology of penile anatomy in cross-section has indicated that there was a notable paucity of nerves at the 12 o’clock position while the most sensitive part of penis, the area around the frenulum, was located at the 6 o’clock position[27]. However, the study regarding the placement of sutures in reinforcement at the penoscrotal and penopubic angles had suggested the placement of three sutures at 120 degrees angles were sufficient for penile support and positioning [21], in which might cause the disruption of penile sensation. Liu et al. [22] had reported a surgical technique that the dartos facial bands were attached to the distal or middle shaft of the penis, it might be a better surgical procedure in preserving the nerve plexus in the dartos. The resection of the peripheral dartos, especially at the frenulum, might lead to postoperative complications such as the sexual dysfunction; however, the definite pathological mechanism should be further explored.
In the present study, the sample taken fromrelatively normal tissues at the periphery after the resection of black moles or hemangioma in other parts of the body was used as a normal control because it is impossible for us to take any samples from normal children. The "other part of the body" is the other regions on the body except penises. When the surgeon needs to remove the black sputum or hemangioma, the subcutaneous fascia tissue in other parts of the body can be obtained. The purpose of this study is to show that the subcutaneous nerves of the penis are richer than other parts, especially at 6 o’clock position, to illustrate the importance of this part of tissue.
For most hypospadias patients, their analgesia won't be complete unless an additional injection is made in the ventral part of the penis if only dorsal penile block is used for distal hypospadias. Patients usually feel pain if we do not make an additional injection to the ventral part. In this study, we have found the same phenomenon from circumcision and usually used caudal block and the phenomenon was not found for the hypospadias repair. Indeed, when doing a nerve block in penile surgery, there would be blockade during penile surgery if we did not take caudal anesthesia instead of simply using the nerve block on the dorsal side of the penis root. However, we usually achieved satisfactory results after undergoing the ventral block. We have not performed this study in children with hypospadias because the anesthesia of our penis surgery basically uses a caudal block. In theory, not only the penis is hidden, but also all penile nerves distribution should have the same condition. The future work for us would be doing further research on children with hypospadias.