Sensory nerve endings in puborectalis and anal region: normal findings in the newborn and changes in anorectal anomalies

Electroacupuncture for postoperative pain in mixed hemorrhoids: A meta-analysis

BACKGROUND

To investigate the efficacy of electroacupuncture for postoperative pain in mixed hemorrhoids.

METHODS

Randomized controlled trials were searched in PubMed and Cochrane Library. The risk of bias assessment tool was used to assess methodological quality. Stata 14.0 software was used for meta-analysis. Weighted mean differences were calculated if all outcome variables were reported the same way, while standardized mean differences (SMD) were calculated if they were different.

RESULTS

From 27 identified studies, 5 Chinese studies (465 patients) were included in this meta-analysis. The electroacupuncture group had significantly lower postoperative pain scores compared with the control group at 6 hours postoperatively (SMD = -0.89, 95% CI: -1.091 to -0.692; P < .001), at 12 hours postoperatively (SMD = -1.089, 95% CI: -1.336 to -0.843; P < .001), at 24 hours postoperatively (SMD = -0.548, 95% CI: -0.721 to -0.374; P = .547), and 72 hours postoperatively (SMD = -1.089, 95% CI: -1.336 to -0.843; P < .001).

CONCLUSION

Electroacupuncture can improve pain after surgery for mixed hemorrhoids. It is an effective method to improve the pain after hemorrhoidectomy, which deserves further research and promotion.

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.

Laparoscopic surgical technique to enhance the management of anorectal malformations: 330 cases' experience in a single center

PURPOSE

Laparoscopic-assisted anorectoplasty (LAARP) is considered to benefit the patients with vesico-prostatic fistula. The aim of this study is to present the details of our LAARP technique for improving the short- and long-term outcomes in the patients with high and intermediate types of anorectal malformations (ARMs).

METHODS

330 patients with high-type (174 cases) and intermediate-type (156 cases) anorectal malformation (aged 8 days to 15 years) underwent LAARP from 2001 to 2019. LAARP was performed for full mobilization and resection of the dilated rectum, intra-rectal closure of the fistula, visualization, and enlargement of the center of the longitudinal muscle tube (LMT) from pelvic and perineal aspects.

RESULTS

LAARP was performed in all patients and no patient was converted to open procedure. The urethral diverticulum was found in three patients (1.02%, 3/294) according to postoperative protocol voiding cystourethrogram but was not associated with any symptoms such as urinary tract infection and dysuria. Rectal prolapse requiring surgical intervention developed in 25 (7.6%) of 330 patients. Anal stricture occurred in three patients and re-do anoplasty was performed 5 months after LAARP. Anal retraction occurred in two patients and re-pull-through was conducted at 5 and 6 days, respectively, after LAARP. 228 patients who were older than 3 years were followed up. The median follow-up period was 5.8 years (range 3-15 years). 217 patients (95.2%) had voluntary bowel movements; 202 patients (88.6%) were free from soiling or with grade 1 soiling; 30 patients (13.6%) and 25 patients (11.3%) suffered from grade 1 and grade 2 constipation, respectively, while no patient had grade 3 constipation.

CONCLUSION

Our experience demonstrates that the LAARP has advantages on rectal mobilization and resection, intra-rectal fistula closure and accurate tunnel formation in the LMT with minimal trauma. The improvement of the short-term and long-term outcomes after LAARP has been shown not only for high-type ARM but also for intermediate-type ARM.

Normal anorectal musculatures and changes in anorectal malformation

PURPOSE

We investigated the anorectal musclulature in normal children and anorectal malformations (ARM) to evaluate its role in bowel control mechanism.

METHODS

Pelves of 50 neonates died of ARM-unrelated diseases and 16 patients with anorectal malformations (8 high, 5 intermediate, and 3 low ARMs) were dissected and analyzed.

RESULTS

Normal anorectal musculature was divided into three muscular tubes: the internal sphincter tube (IAST), longitudinal muscle tube (LMT) and transverse muscle tube (TMT). The LMT came from the outer longitudinal smooth muscle fiber of the rectum and the striated muscle fiber of the levator ani, and the TMT composed of the puborectalis and the external anal sphincter. However, in ARM, the IAST was absent and the LMT, the center of the sphincter muscle complex, was only from the levator ani and could be divided into the pelvic portion and the perineal portion. The former, from the upper rim of the puborectalis to the bulbar urethral, became narrowed and dislocated anteriorly near to the posterior urethra in high ARM and rectal pouch in intermediate ARM. The latter, below the bulbar urethra to the anal dimple, was fused to a column both in high and intermediate ARM. The columnar perineal LMT run downwards and then split, penetrated the superficial part of EAS and terminated at the deep aspect of the skin, to form the anal dimple, which represents the center of the perineal LMT from the perineal aspect. The length of the LMT was longer in high and intermediate ARM than the normal neonate. The columnar perineal LMT and narrowed pelvic LMT could be possibly identified by laparoscopic and perineal approaches retrospectively and widened to allow the passage of the rectum through.

CONCLUSIONS

The anorectal musculature in ARM is composed of agenesic LMT and TMT and the narrowed LMT gives anatomical evidence of the center, where the neorectum should pull through.

The Expression of Shh, Ptch1, and Gli1 in the Developing Caudal Spinal Cord of Fetal Rats With Anorectal Malformations

BACKGROUND

Postoperative incontinence and constipation still remain the major complications of anorectal malformations (ARMs), despite improvements in their treatment. One of the most important factors that affect postoperative anorectal function is malformations in the lumbosacral spinal cord. However, far too little attention has been paid to the underlying mechanism that produces these malformations.

MATERIALS AND METHODS

The levels of sonic hedgehog (Shh), patched homolog 1 (Ptch1), and zinc finger-containing transcription factors 1 (Gli1) expression were investigated in the lumbosacral spinal cord in ethylenethiourea-exposed rat fetus with ARMs, and Shh, Ptch1, and Gli1 expression was confirmed with immunohistochemical staining, quantitative real-time polymerase chain reaction, and western blot analyses during lumbosacral spinal cord development both in the ARMs and normal rat embryos.

RESULTS

Our results have shown that Shh, Ptch1, and Gli1 expression in the lumbosacral spinal cord of rat embryos with ARMs was decreased at both the messenger RNA and protein levels, when compared with their expression levels in normal tissues (P < 0.05).

CONCLUSIONS

This study demonstrated that the expression of Shh, Ptch1, and Gli1 in lumbosacral spinal cord was remarkably reduced during late developmental stages in fetal rats with ARMs. These findings offered some important insights into the involvement of the Shh-Ptch1-Gli1 signaling pathway in the pathogenesis of lumbosacral spinal cord maldevelopment in rat fetus with ARMs, which leads to complications after procedures for ARMs.

Pudendal afferent innervation of the guinea pig external anal sphincter

BACKGROUND

  Sensory nerves to the external anal sphincter (EAS) contribute to mechanisms promoting continence and defecation, yet we know little about their function. We investigated the function of pudendal mechanoreceptors to the guinea pig EAS.

METHODS

Extracellular recordings from pudendal nerve branches to 14 EAS preparations, in vitro, were used to characterize extrinsic primary afferent nerve endings activated by circumferential distension.

KEY RESULTS

All 42 pudendal nerve afferents were silent under non-distended conditions. Thirty-three of 42 afferents had slowly adapting, low-threshold responses to circumferential stretch that correlated with stretch length (R(2) = 0.40, P<0.001). Twenty of 20 slowly adapting afferents reduced firing when stretch was maintained for 60 s (P<0.0001). They had low thresholds to von Frey hairs (0.1-0.5mN). Firing frequency correlated with degree of compression (R(2) =0.40, P<0.0001). Nine of 42 afferents had rapidly adapting responses at the onset/offset of isometric stretch. During ramp stretch, small vibrations from the stepper motor evoked rapid bursts of firing at frequencies up to 200Hz. Instantaneous frequency was unrelated to either the rate or degree of stretch. Rapidly adapting units had low thresholds (0.1-0.2mN) to von Frey hairs and small punctate mechanotransduction sites. Responses to von Frey hair compression were also rapidly adapting, and instantaneous frequency was unrelated to the degree of compression.

CONCLUSIONS & INFERENCES

The EAS has two functional classes of mechanoreceptors: slowly adapting low-threshold and rapidly adapting low-threshold mechanoreceptors. These two classes of afferents are likely to be involved in the maintenance of continence, and the process of defecation.

Anal mucosal electric sensation in postoperative patients with anorectal malformations

BACKGROUND

No previous report has, to our knowledge, been made on anal mucosal electric sensation in postoperative patients with anorectal malformations (ARMs). We studied the anal mucosal electric sensory threshold (AMEST) in comparison with clinical manifestation.

METHODS

The study included 25 patients with ARMs who underwent anorectoplasty (ARMs group) and 10 subjects (control group). Based on the type of ARMs, patients were divided into 3 subgroups: high type, n = 14; intermediate type, n = 6; low type, n = 5. The AMEST was measured at 3 positions, at the anal skin margin and 1 and 2 cm from the anal skin margin. The AMEST was analyzed compared with the type of ARMs and clinical manifestation.

RESULTS

The AMEST clearly increased at the 3 sites in patients with ARMs, especially those with high and intermediate types, compared with control subjects. The sensitivity threshold in the lower anal canal in the low-type subgroup was about the same as that in the control group. An analysis of clinical manifestations showed significantly increased thresholds in the upper and middle anal canal in the group of patients with difficulty in discriminating between gas and defecation and with fecal incontinence (P < .01 and P < .05).

CONCLUSIONS

The AMEST for the high-type and intermediate-type subgroups in the ARMs group was worse than that in the low-type subgroup and control group. The AMEST in the upper and middle anal canal was important for gas and defecation distinction and fecal maintenance.

Urinary control after the definitive reconstruction of cloacal anomaly

PURPOSE

Urinary control after definitive repair of a cloacal anomaly is difficult to achieve. The present report aims to describe the clinical course of urinary control, and the need for the management of bladder dysfunction after reconstruction.

METHODS

The present consecutive series consisted of 11 girls who underwent definitive repair of cloacal anomalies over a period of 11 years. Eight patients were associated with hydrocolpos. Radiological examination included a plain X-ray radiograph of the lumbosacral spine and a voiding cystourethrography with or without a urodynamic study.

RESULTS

Reconstruction of the cloaca was performed on patients aged between 1 and 3 years using a posterior sagittal approach. Vaginal reconstruction was carried out 13 times in 11 patients using tubularized vaginal flap, distal rectal segment, perineal skin flap, or total urogenital sinus mobilization. Cystostomy or vesicostomy was carried out in four newborns/infants. Another seven patients could void spontaneously but incompletely with residual urine. Occult spinal dysraphism was found in five patients and hemisacrum in two patients. After definitive reconstruction, most patients acquired an adequate to normal bladder volume for 1-year-olds. Normal detrusor-sphincter function was seen in three patients. Detrusor areflexia was seen in two patients who underwent in utero vesico-amniotic shunt. Detrusor underactivity was observed in six patients. Bladder compliance was good in all patients except for one. No patients in the present series showed persistent urinary incontinence from the bladder neck or urethral dysfunction.

CONCLUSION

It is postulated that wetting after definitive repair may be the result of overflow incontinence and poor bladder contractility rather than sphincter injury. The main clinical characteristic of bladder dysfunction was a failure to empty. We could not define the exact etiology, but iatrogenic injury from extensive dissection can lead to the higher risks of peripheral nerve damage. Accomplishment of definitive repair involves not only anatomical reconstruction, but also postoperative urinary control, including the initiation of clean intermittent catheterizations under repeated urodynamic evaluations.

Long-term outcomes of individualized biofeedback training based on the underlying dysfunction for patients with imperforate anus

BACKGROUND

The aim of this study was to design an individualized biofeedback program based on the underlying dysfunctions and to assess the short-term and long-term clinical and quality-of-life outcomes for patients with imperforate anus.

METHODS

Thirty-one patients were treated using an individualized biofeedback program according to their different dysfunctions after having completed the assessment of the anorectal function. Many special biofeedback training methods that consist of strengthening the perianal muscles biofeedback, sensory discrimination biofeedback, synchronizing external sphincter contraction biofeedback, and improving defecation dynamic biofeedback were selected to make up the individualized biofeedback training program. The clinical scores and quality-of-life scores were assessed in the short-term and long-term follow-up.

RESULTS

The clinical scores and quality-of-life scores of patients before training, after biofeedback training, at short-term follow-up, and at long-term follow-up were 3.2 +/- 1.1 and 8.7 +/- 1.1, 5.2 +/- 0.6 and 11.0 +/- 0.8, 5.1 +/- 0.6 and 10.8 +/- 0.9, and 4.6 +/- 0.7 and 10.1 +/- 0.7, respectively. After biofeedback training, the strength of the perianal muscles were increased significantly, the abnormal rectal threshold sensation and defecation dynamic reverted to normal in all patients, and 82% patients who have no external anal sphincter reflex acquired the new reflex. In the short-term follow-up, 12 (57%) patients maintained the clinical outcome, and only 9 (43%) patients have regressions slightly. At long-term follow-up, 7 (33%) patients maintained the clinical outcome very well, and 14 (67%) patients had regressed. Although the clinical and quality-of-life scores have decreased slightly at follow-up, they were still significantly increased compared with those before biofeedback training.

CONCLUSIONS

The individualized biofeedback is more suitable for improvement of the clinical outcome and the quality of life, and maintained a good clinical outcome and quality of life on the short-term and long-term follow-ups.

Deficient motor innervation of the sphincter mechanism in fetal rats with anorectal malformation: a quantitative study by fluorogold retrograde tracing

BACKGROUND/PURPOSE

Deficiency of motoneuron innervation to the sphincter mechanism has been described in patients with anorectal malformation. Whether this event is primary or secondary remains unclear.

METHODS

The authors quantified the motoneuron innervation of the sphincter mechanism by Fluorogold (FG) retrograde tracing experiment in fetal rats with anorectal malformation. Anorectal malformation was induced in rat fetuses by ethylenethiourea (ETU). Serial longitudinal sections encompassing the whole width of lumbosacral spinal cord were examined. The number of FG-labelled motoneurons were scored and compared between male fetuses with or without malformation in the ETU-fed group and normal controls.

RESULTS

The number of FG-labelled motoneurons in the fetuses without defect, with imperforate anus (IA), with neural tube anomalies (NTA), with combined IA and NTA, and normal controls were determined to be (mean +/- SEM) 109.13 +/- 37.88, 55.05 +/- 25.85, 48.20 +/- 30.34, 54.43 +/- 28.55, and 135.22 +/- 28.78, respectively. FG-labelled motoneurons in the fetuses with IA, NTA, and combined IA and NTA are significantly fewer than that in fetuses without defects (P <.05) and in normal controls (P <.005).

CONCLUSIONS

These findings suggest that defective motoneuron innervation to the sphincter mechanism is a primary anomaly that coexists with the alimentary tract anomaly in anorectal malformation during fetal development. The intrinsic neural deficiency is an important factor likely to contribute to poor postoperative anorectal function despite surgical correction of anorectal malformation.

Assessment of sphincter muscle function before and after posterior sagittal anorectoplasty using a magnetic spinal stimulation technique

PURPOSE

The authors used a magnetic spinal stimulation technique to assess both the preoperative sphincter function and the effect of operative intervention on the sphincter muscle in patients with anorectal malformations.

METHODS

The authors examined 5 patients with an anorectal malformation consisting of 4 high-type cases and 1 intermediate-type case, that all had undergone posterior sagittal anorectoplasty during the previous 2-year period. Control data also were obtained from 11 age-matched healthy children. A contraction of the external anal sphincter (EAS) was evoked by magnetic stimulation of the sacral roots with a figure-of-eight coil at the level of the lumber and sacral segments. EAS electromyograms then were recorded at the anal verge.

RESULTS

The preoperative motor latencies at L4 stimulation increased significantly more in the patients than in the controls (5.9 +/- 0.5 msec v 4.1 +/- 0.7 msec during left side recording). In the postoperative examination (1 to 5 months after operation), the mean maximum amplitude decreased slightly without any significant difference, where as the latency was almost identical to the preoperative data.

CONCLUSION

These results suggest that the neurologic function of EAS was congenitally disturbed, and the current operative technique had no significant effect on the sphincter function.

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.

Neural electrophysiological studies on the external anal sphincter in children with anorectal malformation

BACKGROUND/PURPOSE

Abnormality of innervation of external anal sphincter is one of the most important factors affecting postoperative anorectal function. The abnormalities of lumbosacral nerves have been reported in many radiological and histopathologic studies. There are few reports on the neurophysiological changes in children with anoractal malformation. The aim of this study was to examine the functional changes of nerves to the external anal sphincter in anorectal malformation.

METHODS

Forty-five patients with anorectal malformation underwent studies of latencies of pudendo-anal reflex, spinoanal response, and evoked potential of cauda equine simultaneously. The conduction time of afferent nerve, efferent nerve, and sacral spinal center of pudendo-anal reflex arc were analyzed quantitatively.

RESULTS

The latencies of pudendo-anal reflex, spino-anal response, and conduction time of sacral spinal center significantly are prolonged in patients with anorectal malformation (P< .05). There was significant difference between rectourethral fistula group and vestibular fistula group as well as low-type deformity group. The patients with lumbosacral anomalies such as lumbosacral spinal bifida or absence of S4 or S5 had prolonged latencies, especially the pudendo-anal reflex latency. There was significant negative correlation between the latencies and clinical scores. Although pudendoanal reflex latency was longer in patients who had posterior sagittal anorectoplasty than those who had abdominoperineal pull-through procedure, the difference was not significant.

CONCLUSIONS

The abnormality of nerves to external anal sphincters is one of the important causes for clinical outcome. The neural lesions vary in each type of anal and lumbosacral deformity.

Anatomy of the nerve supply of the rectum, bladder, and internal genitalia in anorectal dysgenesis in the male

Using a posterior sagittal approach to expose retroperitoneal viscera and nerves, the anatomy of the pelvic autonomic nerve plexus was studied in normal and abnormal male cadaver specimens. This plexus is found on the anterolateral surface of the lower rectum surrounded by endopelvic fascia. The autonomic nerves that supply the plexus reach it from posterior, lateral to the midline by passing over the surface of the rectum. The nerves of this plexus are distributed with the terminal branches of the internal iliac arteries, mainly with the vessels of the inferior vesical plexus. The rectum receives its autonomic nerves with its arterial blood supply, the superior rectal artery. The nerves of the pelvic plexus supply the genitourinary viscera that lie anterior to the rectum and in front of the fascia of Denonvilliers. The named fascial layers of the pelvis play a major role in determining the anatomic plane of these structures. In anorectal agenesis the plexus becomes a more midline structure. Because the pelvic fascia is often deficient in these cases these nerves lie vulnerable to inappropriate midline dissection.

Damaging effects of anal stretching on the external anal sphincter

PURPOSE

This study was undertaken to investigate the effects of anal stretching on anal pressures and damage to the external anal sphincter.

METHODS

This study was performed on 37 guinea pigs. Animals were divided into three groups: control group, quick stretching group, and continuous overstretching group. Anal stretching was conducted by an 8-F Foley catheter balloon.

RESULTS

It was found that if the muscle was stretched from 100 to 300 percent of its original length, anal resting pressure (ARP) kept relatively steady, but anal contracting pressure (ACP) gradually increased; from 300 to 370 percent, a sharp ARP increase was developed, but ACP gradually decreased to zero; beyond 370 percent, ARP remained unchanged (plateau phase). By histologic examination, it was revealed that when the muscle was stretched at the ARP plateau phase, an ischemic zone of necrosis and an edematous zone of necrosis could be clearly identified in the muscle.

CONCLUSION

This study shows that length of the external anal sphincter definitively influences muscle strengths, and severe anal stretching will result in muscle damage. These results imply that the sphincteric muscle complex in high or intermediate anorectal anomalies may be injured during present conventional surgical approaches.

How important is the role of the internal anal sphincter in fecal continence? An experimental study in dogs

It is a generalized concept that the internal anal sphincter (IAS) plays a significant role in fecal continence by generating high pressure in the anal canal at rest and relaxation during rectal distention. Agreement also exists on the importance of internal sphincter-saving anoplasty on anorectal malformations in establishing anal continence. Twelve dogs were divided into four groups. Group 1, a control group, was subjected to a perirectal dissection only. Group 2 underwent the same perirectal dissection plus a 2-cm resection of the anal canal. Group 3 underwent the perirectal dissection plus a 4-cm resection of the anal canal, and group 4 underwent perirectal dissection and transposition of the anus to the posterolateral portion of the voluntary muscle mass. Clinical continence was evaluated, and manometric results were compared with preoperative measurements. All dogs in groups 1, 2, and 3 were clinically continent without soiling except one in group 3, and also manometric results showed minimal change between preoperative and postoperative anal pressure profiles. The transposed anus of group 4 showed continuous fecal soiling. The anal resting pressure (ARP) was also decreased but still existed in this group. This experimental study showed that the IAS contributes to the anal resting tone. However, resection of the IAS did not completely interfere with fecal continence. The smooth muscle of pulled-through rectum seemed to partly take over the function of the IAS.

The effect of posterior sagittal anorectoplasty and its variants on lower urinary tract function in children with anorectal malformations

The effect of posterior sagittal anorectoplasty (PSARP) and its variants on lower urinary tract function was investigated urodynamically in 32 patients with anorectal malformations. In 27 patients urodynamic evaluation was performed before and after surgery and in 4 it was done postoperatively only. One child was clinically assessed with no postoperative urodynamic study. Minor postoperative changes in the specific preoperative urodynamic pattern were observed in 4 cases but the changes did not seem to be related to surgery. In 3 boys with rectourethral fistulas detrusor failure consistent with autonomic denervation was noted postoperatively. Standard posterior sagittal anorectoplasty was performed in 1 of the 3 boys and posterior sagittal anorectoplasty combined with additional transabdominal procedures was done in the other 2. In general our findings suggest that posterior sagittal anorectoplasty and its variants do not affect lower urinary tract function unless these surgical techniques are combined with major transabdominal procedures and extensive retrovesical dissection.

Anorectal anomaly: neuropathological changes in the sacral spinal cord

The study was carried out on the bodies of five full-term newborn babies and 10 newborn patients with anorectal anomalies (four of whom had the high deformity, one had the intermediate, and five had the low). Serial transverse sections of the sacral spinal cords at 30 microns were made and stained with Nissle's. It was found that in the medial column of the sacral spinal cord there were two groups of motoneurons: posteriomedian group (group A) and anteriomedian group (group B). The former was found mainly in S3 and S4 and the latter extended from caudal S4 to caudal S2. In six of the 10 deformitive cases the cross-sections of the S5 showed a large diamond-shaped central canal and a thin conus medulla which could be distinguished as the basal and alar laminae; in one case, the lower part of the central canal and the anterior median fissure appeared undeveloped; in one case, the lower part of the central canal was divided into two large canals by a sagittal septum; and in the other two cases, their central canals appeared widened and flattened. Additionally, the average numbers of motoneurons in the group B of the high or intermediate deformity and the low deformity were 13.4% and 61.1%, respectively, of the normal number, and the corresponding numbers of group A were 61.3% and 77.7%, respectively, of the normal number. The observations suggest that sacral myelodysplasia is one of the neuropathological features in anorectal anomaly and may be responsible for the pathological changes in its peripheral nerve system.

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

The study was carried out in seven fetuses (ovulation ages were 16, 18, 20, 22, 26, 28, and 31 weeks, respectively) and in five full-term newborn babies. The modified Bielschowsky method and Barker's block silver impregnation were used. It was found that the muscle spindle was arranged in the puborectalis and the external sphincter muscles from the 20th week onward; the tendon organ was located in association with the musculo-tendinous junction of the puborectalis from the 20th week onward; the Pacinian corpuscle lay in the plane of cleavage between the internal anal sphincter and the external anal sphincter from the 22nd week onward, and in the presacral space from the 28th week onward, and the later lagged behind the former in development; the globular endings lay in the presacral space from the 28th week onward; and the free nerve ending was distributed in the epithelium of the anal mucosa and the epidermis around the anus from the 31st week onward. These sensory nerve endings tend to mature gradually with increasing age. It was concluded that these endings may be responsible for the reflex of the external anal sphincter and the anal sensation.