Dynamic rectus abdominis muscle sphincter for stoma continence: an acute functional study in a dog model

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.

Practical and effective stomal sphincter creation: evaluation in pigs

PURPOSE

Stoma creation frequently presents complications for which there is no satisfactory surgical solution. We reexamined the feasibility of managing stoma continence with an artificial sphincter, addressing the outstanding issues of geometry, electrode disposition, and fatigue resistance.

METHODS

In 6 pigs, 1 rectus abdominis muscle was preconditioned with electric stimulation for 4 weeks by an implanted stimulator. A sphincter was then constructed and tested for its ability to provide continence against saline at a typical intestinal pressure. The result was compared with a sphincter fashioned from the unconditioned contralateral (control) muscle. In each case, stimulation was applied alternately to longitudinal segments.

RESULTS

A 2-layered wrap was required to achieve continence. Sphincters created from the preconditioned muscles could sustain continence continuously for at least 90 minutes.

CONCLUSION

This study establishes a practical approach to the creation of a sphincter from the rectus abdominis muscle in stoma patients. Continence can be achieved only with a double-layered wrap. Fatigue during long-term operation can be avoided by a combination of preconditioning and segmental stimulation of intramuscular nerve branches.

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.

Fecal incontinence: an up-to-date critical overview of surgical treatment options

BACKGROUND

Surgery is the last resort for patients suffering from severe fecal incontinence. The armamentarium of surgical options for this condition has increased impressively during the last decade. Nevertheless, this fact seems to make neither patients nor surgeons feel more comfortable. Treatment of fecal incontinence still remains a challenge to modern medicine due to many specific sides of this problem.

AIMS

This article gives an up-to-date overview of existing operative treatment options.

METHODS

An unbiased review of relevant literature was performed to assess the role of all methods of surgical treatment for fecal incontinence available nowadays.

RESULTS

Recent studies have shown poor late results after primary sphincter repair and low predictive value for most preoperative diagnostic tests. New surgical options such as artificial devices and electrically stimulated muscle transpositions are doomed by low success rates and unacceptably frequent complications. That is why current attention has focused on non- or minimally invasive therapies such as sacral nerve stimulation and temperature-controlled radio-frequency energy delivery to the anal canal. However, all these innovative techniques remain experimental till enough high-evidence data are gathered for their objective evaluation.

CONCLUSION

Careful and detailed preoperative assessment to exactly determine the etiology of incontinence and individual approach remain the cornerstones of surgical treatment of fecal incontinence nowadays.

Experimental model of continent colostomy using rectus abdominis neosphincteroplasty

Background

Use of dynamic myoplasty to create a continent stoma has produced promising results, but long-term stoma continence has not been achieved. The aim of the study was to establish and test a new model.

Methods

Three types of dynamic rectus abdominis sphincteroplasty around a colostomy and two conditioning protocols were tested in ten domestic pigs. Continence was assessed by means of conventional defaecography and neosphincter manometry after 8 and 12 weeks. The neosphincter muscle was studied histologically to assess the transformation of muscle type.

Results

Use of a distal rectus muscle sling surrounding the stoma by 270° with a low-frequency conditioning protocol achieved a continent colostomy for more than 12 h on each of 5 consecutive days. The neosphincter had a 40-mm high-pressure segment with mean pressure of 74 (range 67–82) mmHg. The proportion of type I muscle fibres increased from 38 (range 32–42) to 74 (range 66–78) per cent after 12 weeks of conditioning.

Conclusion

This pilot study demonstrated the feasibility of a continent stoma in an animal model with a dynamic rectus neosphincter. Long-term results should be confirmed in a larger series before use in humans can be considered.