Sensory nerve endings in the puborectalis and anal region of the fetus and newborn

Laparoscopic-assisted anorectoplasty for intermediate type rectovestibular fistula: a preliminary report

PURPOSE

Laparoscopic-assisted anorectoplasty (LAARP) is considered to benefit the male patients with anorectal malformation (ARM). This study evaluates LAARP management for intermediate type rectovestibular fistula (IRVF) in the female patient with ARM.

METHODS

Twelve patients with IRVF (aged 3-5 months) underwent LAARP from 2017 to 2019 in our institute. LAARP was performed for mobilization of the rectum, visualization and enlargement of the center of the sphincter muscle complex (SMC) from pelvic and perineal aspects, intra-fistula mucosectomy and rectal pull-through in the SMC with the fourchette and the perineal body unattached.

RESULTS

LARRP was performed in all patients without conversion to open procedure. No patient suffered from wound infection, vaginal injury, recurrent fistula and anal stenosis. The parents were satisfied with the appearance of the wound. Rectal prolapse developed in one patient and needed surgical correction. The patients were followed up for a mean of 19.7 months (ranged from 12 to 35 months).

CONCLUSION

Our preliminary experience shows that LAARP offers an alternative method of correction for the IRVF with good visualization of the SMC and may diminish the risks of wound dehiscence and vaginal injury.

Midline sensory nerve supply to the anoscrotal junction: a study using human male fetuses

The origin of the posterior scrotal nerve is considered to be the bilateral pudendal nerves but the course to the midline is still obscure. Using 5 late-stage human male fetuses, we identified the single nerve through the intramuscular midline septum of the bulbospongiosus and the bilateral nerves along the left and right sides of the septum. Thus, the posterior scrotal nerve showed a variation: a single midline trunk or bilateral nerves. Branches of the bilateral pudendal nerves ran medially between the muscle and Cowper's gland and, at the midline area, they joined or associated closely. During the proximal course, much or less, the nerve penetrated the superior part of the muscle. The nerve entered the subcutaneous tissue at and near the perineal raphe. The communication with intrapelvic autonomic nerves were suggested behind Cowper's gland. Notably, the midline skin immediately anterior to the anus carried a considerable dense supply of thin sensory nerves. However, these nerves seemed to come from a space between the rectal smooth muscle and the external anal sphincter, not from the posterior scrotal nerve. Therefore, surgical treatment of the intersphincteric layer was likely to injure the original sensory nerve supply to the anterior anal skin.

Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

In the intersphincteric space of the anal canal, nerves are thought to "change" from autonomic to somatic at the level of the squamous-columnar epithelial junction of the anal canal. To compare the nerve configuration in the intersphincteric space with the configuration in adjacent areas of the human rectum, we immunohistochemically assessed tissue samples from 12 donated cadavers, using antibodies to S100, neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH). Antibody to S100 revealed a clear difference in intramuscular nerve distribution patterns between the circular and longitudinal muscle layers of the most inferior part of the rectum, with the former having a plexus-like configuration, while the latter contained short, longitudinally running nerves. Most of the intramural ganglion cells in the anal canal were restricted to above the epithelial junction, but some were located just below that level. Near or at the level of the epithelial junction, the nerves along the rectal adventitia and Auerbach's nerve plexus joined to form intersphincteric nerves, with all these nerves containing both nNOS-positive parasympathetic and TH-positive sympathetic nerve fibers. Thus, it was histologically difficult to distinguish somatic intersphincteric nerves from the autonomic Auerbach's plexus. In the intersphincteric space, the autonomic nerve elements with intrapelvic courses seemed to "borrow" a nerve pathway in the peripheral branches of the pudendal nerve. Injury to the intersphincteric nerve during surgery may result in loss of innervation in the major part of the internal anal sphincter.

Defective development of sensory neurons innervating the levator ani muscle in fetal rats with anorectal malformation

BACKGROUND

Defects of the pelvic nerve innervation of levator ani muscle are associated with poor postoperative anorectal function in patients with anorectal malformation (ARM). We have previously shown deficient development of motoneurons innervating the levator ani muscle in rats with ARM. In this study we investigate whether there is a deficiency in the development of sensory neurons that innervate the levator ani muscle in rats with ARM.

METHODS

ARM was induced by ethylenethiourea (ETU) in fetal rats. Retrograde tracer fluorogold (FG) was injected into the levator ani muscle. Serial transverse sections encompassing the entire length of the lumbosacral spinal cord were examined. The number of FG-labeled sensory neurons was scored and compared between fetuses with ARM and normal fetuses.

RESULTS

The number of FG-labeled sensory neurons innervating the levator ani muscle in normal control fetuses, ETU-fed fetuses with no malformation, low type of imperforate anus, high type of imperforate anus, and high type of imperforate anus combined with neural tube defects were determined to be (mean +/- SEM) 11,804 +/- 2362, 10,429 +/- 1708, 2886 +/- 705, 1026 +/- 425, and 964 +/- 445, respectively. FG-labeled sensory neurons in fetuses with imperforate anus with or without neural tube defects were significantly fewer than in control and ETU-fed fetuses without malformation (p < 0.05).

CONCLUSIONS

Defective sensory neurons innervating the levator ani muscle is a primary anomaly that coexists with the alimentary tract anomaly in ARM during fetal development. Nerve innervation deficiency of the pelvic muscles contributes to the poor postoperative anorectal functions in ARM patients.

Possible explanation of cephalic and noncephalic presentation during pregnancy: a theoretical approach

This paper is based on fact that the fetus is exposed to gravity. The hypothesis is that from the 24th week of gestation an increasing percentage of fetuses occupies an exclusively cephalic presentation, since it allows an uncompromised posture in the caudal direction of body segments whose muscles are first affected by the occurrence and progressive increase of tone. Being in cephalic presentation, in a caudal direction, the fetus relieves body segments of the weight of the hypotonic-atonic part of the body in the cranial direction. In other words, cephalic presentation presents a body axis posture along the line of gravity. When the body axis posture along gravity is absent, the fetus simply fills the intrauterine cavity. In many such cases, the results are transverse lie, breech presentation and also cephalic presentation.

Posterior sagittal approach: megasigmoid resection and anal reconstruction for severe constipation and fecal incontinence after anoplasty

PURPOSE

The aim of this study was to present the technique of megasigmoid resection and anal reconstruction by complete posterior sagittal approach for the children with severe constipation and fecal incontinence after anoplasty.

METHODS

Six patients (age, 2 to 18 years) born with imperforate anus and originally treated with perineal anoplasty suffered from intractable constipation and fecal incontinence. Contrast enema showed massive dilated and aperistaltic rectosigmoid colon with fecal impaction. Resection of the dilated bowel and anal reconstruction were completely performed by posterior sagittal approach.

RESULTS

The mean operating time was 205 minutes (range, 125 to 265 minutes) and the average length of resected colon was 23.3 cm (range, 10 to 40 cm). There were no intraoperative or postoperative complications. By 2 to 4 months after the operation, all patients obtained voluntary bowel movement. On follow-up at 6 to 24 months postoperative, no patient had constipation or required use of the laxatives again. Four of 6 patients suffered from grade 1 soiling, and the other 2 had grade greater than 1 soiling. None had urinary retention or incontinence after the procedure.

CONCLUSION

Resection of dilated rectosigmoid colon and anal reconstruction for the patients with severe constipation and fecal incontinence after anoplasty can be performed successfully using a posterior sagittal approach.

Sacral reflexes: physiology and clinical application

Sacral reflexes consist of motor responses in the pelvic floor and sphincter muscles evoked by stimulation of sensory receptors in pelvic skin, anus, rectum, or pelvic viscera. These responses may be elicited by physical or electrical stimuli. They have been used in research studies of the pathophysiology of pelvic floor and anorectal disorders and many have been recommended for diagnostic use. These reflexes are described and discussed in this review. More rigorous evaluation of their value in the clinical assessment and care of patients with pelvic floor and sphincter disorders is required. Currently direct comparisons of the value of particular responses are generally not available, and few of these reflexes have proven validity for use in clinical diagnosis.

Anorectal motor physiology and pathophysiology

Disorders of anorectal function are complex. A clear definition of the underlying pathophysiologic process is possible only with the use of the anal physiology laboratory. A reasonable treatment plan is then possible.