Analysis of Fiber Type Transformation and Histology in Chronic Electrically Stimulated Canine Rectus Abdominis Muscle Island-Flap Stomal Sphincters:

Dynamic Penile Corpora Cavernosa Reconstruction Using Bilateral Innervated Gracilis Muscles: A Preclinical Investigation

Introduction

Prosthesis-assisted penile reconstruction has been performed extensively to restore a cosmetically acceptable phallus. However, a large number of patients will undergo revision surgery for various prosthesis-related complications.

Aim

To develop a 1-stage prosthesis-free dynamic cavernosa reconstruction method using bilateral innervated gracilis muscles and to investigate the feasibility and reliability of the surgical design.

Methods

10 fresh cadavers were dissected to assess the availability of bilateral gracilis muscles for functional cavernosa rebuilding. 11 mongrel female dogs were involved in the penile reconstruction surgery. The neophallus consisted of bilateral gracilis muscles as the neo-cavernosa, a right gracilis skin flap as the neourethra, and a lower abdominal flap with an anterior rectus sheath as the skin envelope and neo-tunica albuginea. The function and structure of the neo-phalli were assessed 7 months postoperatively.

Main Outcome Measures

The neurovascular pedicle length of the gracilis muscles and the volume of the gracilis venter musculi were measured in the cadaveric investigation. The average dimensions of the canine neo-phalli at rest and during electrostimulated erection were obtained and the muscular fatigue-resistant curve was drawn. Histologic evaluations also were performed.

Results

The neurovascular pedicle length and volume of the gracilis muscles were sufficient to yield a nearly normal appearance of the neo-cavernosa in the cadaveric and animal studies. The muscular fatigue-resistant curve demonstrated adequate length, stiffness, and duration of erection of the neo-phalli to accomplish normal coitus. Histologic evaluations showed an intact neourethra and nearly normal muscle structure in the inner layer of the canine neo-cavernosa, except for significantly increased amount of collagen fibers and type I/III collagen ratio in the outer layer of the neo-cavernosa. The percentage of type II (fatigue-prone) muscle fibers did not change significantly.

Conclusion

Our preclinical investigation proves that corpora cavernosa reconstruction using bilateral innervated gracilis muscles is technically feasible and functionally efficacious.

Yin Z, Liu L, Xue B, et al. Dynamic Penile Corpora Cavernosa Reconstruction Using Bilateral Innervated Gracilis Muscles: A Preclinical Investigation. Sex Med 2018;6:162–170.

Is it possible to use the rectus abdominis neo-sphincter as a continence mechanism for urinary catheterizable channels? A histologic and histochemical evaluation in an experimental study in rabbits

OBJECTIVE

To evaluate in a rabbit experimental model a mechanism of continence of catheterizable urinary conduits (CUC), focusing on the behavior of intersected rectal muscle fibers in relation to the channel by histological and histochemical analysis, and secondarily to register conduit continence rates from clinical and urodynamic data.

MATERIALS AND METHODS

12 rabbits were submitted to construction of a CUC from two abdominal skin flaps and divided into two groups: 8 with a urinary neo-sphincter created according to Yachia and 4 controls. We registered clinical outcome, urodynamic studies and microscopic analysis of CUC on the surface of the conduit, which was in direct contact with the mechanism of continence. We took muscle samples from the mechanisms of continence and performed histochemical evaluation by enzymatic reactions.

RESULTS

Histological evaluation of the CUC showed no difference between groups. Histology and immunohistochemistry of the muscle fibers showed that areas of necrosis, cell atrophy and motor neuron injury from the first eight weeks recovered by the end of 16th week. Conduit complications occurred in 4 animals (33%). The average detrusor leakage point pressure through the conduit was 90 cm H2O versus 39 cm H2O through the urethra.

CONCLUSION

The mechanism of continence did not promote ischemic stress on the conduit, was able to promote high pressure resistance and showed good recovery of intersected muscle fibers, after an initial slight atrophy, suggesting good durability of the neo-sphincter.

Electrically stimulated rectus abdominis muscle flap to achieve enterostomal continence: development of a functional canine model

BACKGROUND

Dynamic myoplasty has many clinical applications and has proven to be a versatile surgical procedure with great promise. This procedure has been used to achieve fecal/urinary continence, as in the dynamic graciloplasty, and to augment cardiac ventricular function, as is commonly seen with dynamic latissimus cardiomyoplasty. In the present study, the authors describe a functional innovative island flap sphincter created from the rectus abdominis muscle in a large-animal model to provide stomal continence for future clinical studies.

METHODS

The caudal region of the rectus abdominis muscle in eight mongrel canines (23 to 25 kg) was investigated through anatomical dissections during which the location of the neurovascular pedicles and the intersegmental muscle dimensions between the muscle inscriptions were noted. The rectus abdominis muscle was used to create functional dynamic stomal sphincters that were trained with subcutaneously implanted pulse stimulators.

RESULTS

The neurovascular pedicles were consistently found in similar locations along the posterior medial aspect of the caudal portion of the canine's rectus abdominis muscle. The vertical height of the deep inferior epigastric pedicle and caudal intercostal nerve muscular mean entry points were 6.75 +/- 1.89 cm and 7.44 +/- 0.86 cm, respectively. The mean caudal intersegmental muscle length of the rectus abdominis muscle used to create the sphincter was 9.69 +/- 1.81 cm.

CONCLUSIONS

The canine rectus abdominis muscle has reliable anatomical locations where the neurovascular pedicle may be found. This canine muscle may be used to create a continent island flap stomal sphincter. This large-animal sphincter model is versatile, durable, and easy to manipulate, with minimal morbidity to the animal.

A review of contemporary surgical alternatives to permanent colostomy

OBJECTIVES

To review the options available to patients with faecal incontinence with failed conservative treatment and/or failed anal sphincter repair and assessing the current indications and results of these options.

METHODS

A literature search of MEDLINE, EMBASE and Cochrane databases was performed using the relevant search terms.

RESULTS

Continent options for patients with severe or end stage faecal incontinence include the creation of a form of an anal neosphincter and more recently sacral nerve stimulation. Over half the patients, who are candidates, may benefit from these procedures, although long term results of sacral nerve stimulation are unknown. Dynamic graciloplasty improves the continence in 44-79% of the patients. The complications include frequent reoperations, high incidence of infection and obstructive defaecation. The success rates of artificial bowel sphincter vary between 24% and 79%. Once functional, the artificial bowel sphincter seems to improve the continence in the majority of the patients. Device removal due to infection, obstructive defaecation and pain is a frequent problem. Sacral nerve stimulation is claimed to result in improvement in continence in 35-100% of patients. The main risks in this procedure are infection, electrode displacement and pain.

CONCLUSIONS

All these procedures have high complication rates and have moderate success rates only. A major proportion of patients will need reoperations and hence high motivation is necessary for patients who undergo these procedures. A uniform standard for measurement of success is also necessary so that these procedures can be compared with each other.