External Anal Sphincter Function Research Articles

Clinical utility of trans-sacral magnetic stimulation-evoked sphincter potentials and high-density electromyography in pelvic floor assessment: Technical evaluation.

Faecal incontinence is common and of multifactorial aetiologies, yet current diagnostic tools are unable to assess nerve and sphincter function objectively. We developed an anorectal high-density electromyography (HD-EMG) probe to evaluate motor-evoked potentials induced via trans-sacral magnetic stimulation (TSMS). Anorectal probes with an 8 × 8 array of electrodes spaced 1 cm apart were developed for recording HD-EMG of the external anal sphincter. These HD-EMG probes were used to map MEP amplitudes and latencies evoked via TSMS delivered through the Magstim Rapid2 (MagStim Company). Patients undergoing pelvic floor investigations were recruited for this IDEAL Stage 2a pilot study. Eight participants (median age 49 years; five female) were recruited. Methodological viability, safety and diagnostic workflow were established. The test was well tolerated with median discomfort scores ≤2.5/10, median pain scores ≤1/10 and no adverse events. Higher Faecal Incontinence Severity Index scores correlated with longer MEP latencies (r = 0.58, p < 0.001) and lower MEP amplitudes (r = -0.32, p = 0.046), as did St. Mark's Incontinence Scores with both MEP latencies (r = 0.49, p = 0.001) and MEP amplitudes (r = -0.47, p = 0.002). This HD-EMG probe in conjunction with TSMS presents a novel diagnostic tool for anorectal function assessment. Spatiotemporal assessment of magnetically stimulated MEPs correlated well with symptoms and offers a feasible, safe and patient-tolerable method of evaluating pudendal nerve and external anal sphincter function. Further clinical development and evaluation of these techniques is justified.

Fecal Incontinence as a Symptom of Myasthenia Gravis

I report three cases of fecal incontinence during the clinical course of myasthenia gravis. Fecal incontinence developed after withdrawal from the pyridostigmine and improved after re-administration of the pyridostigmine. Myasthenia gravis could affect external anal sphincter and puborectalis function. Myasthenia gravis is presumably one of the causes of fecal incontinence. We must check for fecal incontinence in the patients with myasthenia gravis.

Anoplasty Surgery in a Cat with Type I Atresia Ani

Atresia ani (AA) is a congenital defect that occurs when the anal membrane is not perforated and becomes permanent. However, it is worthwhile to note that it is not very common in cats. This case report consists of a 2 month old male Persian cat with Type I AA, who was brought to our clinic with the complaint of defecation from a very narrow opening since birth. In the clinical examination of the patient, abdominal distention and swelling around the anus were detected. The patient was constantly taking a defecation position and had difficulty defecating. Contrast radiography was taken with the retrograde method, and the obstruction in the anus was detected resulting in the decision of performing an operation. The aim of surgical intervention is to maintain anorectal continuity as well as preserving the external anal sphincter and colon function. Surgical treatment should be promptly performed before chronic and prolonged distention, colonic atony or megacolon associated with possible urinary tract infection occurs. The patient was placed on the table in the prone position and the narrowed part of the rectum was treated by resecting it with 3600 anoplasty. Having lowered the rectal mucosa distally, the mucosa and skin were brought together, and then sutured with synthetic non-absorbable monofilament 4/0 suture material. Extra care was taken to preserve the external anal sphincter and anal sacs during dissection.

Sphincter muscle activity before and after delivery: Does it depend on the type of birth?

There are ongoing discussions whether cesarean section is the safest mode of childbirth to prevent pelvic floor disorders. Pelvic floor electromyography (EMG) allows the analysis of external anal sphincter (EAS) function during voluntary contractions. The primary objective of this study was the evaluation of EMG amplitude of external anal sphincter in women who had vaginal delivery, compared to women who had cesarean section. The secondary objective was to evaluate the anal incontinence score changes before and after delivery between the groups, and to look for any relationship between the clinical and EMG findings. Multichannel surface EMG was detected during maximal contractions in three sessions: (i) during pregnancy, (ii) 6 weeks after delivery and (iii) 1 year after delivery. Women were divided into two groups: cesarean section and vaginal delivery. External anal sphincter EMG amplitude decreases 6 weeks after vaginal deliveries from 10.1 to 8.6 μV with effect size of 0.4, but returns to baseline after 1 year. No differences were observed between groups in all other variables. No differences were observed after 1 year in EMG activity between the two groups; however, a slight decrease of sphincter muscle amplitude was noted 6 weeks after vaginal delivery. The delivery mode does not have effect on the EAS amplitude 1 year after delivery. Incontinence score slightly increased in both groups after delivery, with no significant differences between the two groups. No association was observed between the increase of incontinence score and the decrease of EMG signal amplitude.

Ipsilateral S2 nerve root transfer to pudendal nerve for restoration of external anal and urethral sphincter function: an anatomical study

Patients suffer bilateral sacral plexus injuries experience severe problems with incontinence. We performed a cadaveric study to explore the anatomical feasibility of transferring ipsilateral S2 nerve root combined with a sural nerve graft to pudendal nerve for restoration of external anal and urethral sphincter function. The sacral nerve roots and pudendal nerve roots on the right side were exposed in 10 cadavers. The length from S2 nerve root origin to pudendal nerve at inferior border of piriformis was measured. The sural nerve was used as nerve graft. The diameters and nerve cross-sectional areas of S2 nerve root, pudendal nerve and sural nerve were measured and calculated, so as the number of myelinated axons of three nerves on each cadaver specimen. The length from S2 nerve root to pudendal nerve was 10.69 ± 1.67 cm. The cross-sectional areas of the three nerves were 8.57 ± 3.03 mm2 for S2, 7.02 ± 2.04 mm2 for pudendal nerve and 6.33 ± 1.61 mm2 for sural nerve. The pudendal nerve contained approximately the same number of axons (5708 ± 1143) as the sural nerve (5607 ± 1305), which was a bit less than that of the S2 nerve root (6005 ± 1479). The S2 nerve root in combination with a sural nerve graft is surgically feasible to transfer to the pudendal nerve for return of external urethral and anal sphincter function, and may be suitable for clinical application in patients suffering from incontinence following sacral plexus injuries.

Manometric evaluation of anorectal function in patients treated with neoadjuvant chemoradiotherapy and total mesorectal excision for rectal cancer

BackgroundAn altered anorectal function is reported after chemoradiotherapy (CRT) and surgery for rectal cancer. AimThe aim of this study was to clarify the relative contribution of neoadjuvant chemoradiation and surgical resection on the impairment of anorectal function as evaluated by anorectal manometry. MethodsThirty-nine patients with rectal cancer, who underwent neoadjuvant CRT and laparoscopic rectal resection, were evaluated with the Pescatori Faecal Incontinence score, and with anorectal manometry: before neoadjuvant therapy (T0), after neoadjuvant therapy and before surgery (T1), 12 months after stoma closure (T2). ResultsResting and/or maximum squeeze pressure and/or volume thresholds for urgency were below the normal values in 12 (30%) patients at baseline. After CRT the mean resting pressure significantly decreased (p=0.007). Surgery determined a significantly decrease of the resting pressure (p=0.001), of the maximum squeeze pressure (p=0.001) and of the volume threshold for urgency (p=0.001). Impairment of continence was reported by 5, 11 and 18 patients at T0, T1 and T2, with a mean incontinence score of 3, 3.8 and 3.9 respectively. ConclusionsCRT is detrimental to the function of the internal anal sphincter. Rectal resection significantly affects both internal and external anal sphincter function and the maximum tolerated volume of the neo-rectum, particularly in patients with low rectal cancer, significantly impairing anal continence.

Management of patients with faecal incontinence.

Faecal incontinence, defined as the involuntary loss of solid or liquid stool, is a common problem affecting 0.8-8.3% of the adult population. Individuals suffering from faecal incontinence often live a restricted life with reduced quality of life. The present paper is a clinically oriented review of the pathophysiology, evaluation and treatment of faecal incontinence. First-line therapy should be conservative and usually include dietary adjustments, fibre supplement, constipating agents or mini enemas. Biofeedback therapy to improve external anal sphincter function can be offered but the evidence for long-term effect is poor. There is good evidence that colonic irrigation can reduce symptoms and improve quality of life, especially in patients with neurogenic faecal incontinence. Surgical interventions should only be considered if conservative measures fail. Sacral nerve stimulation is a minimally invasive procedure with high rate of success. Advanced surgical procedures should be restricted to highly selected patients and only performed at specialist centres. A stoma should be considered if other treatment modalities fail.

Two-dimensional Endoanal Ultrasound Scan Correlates with External Anal Sphincter Structure and Function, but not with Puborectalis

BackgroundTo investigate the relevance of two-dimensional (2D) endoanal ultrasonic (EAUS) assessment of anal sphincter and puborectalis morphology by comparison to functional measures derived from patient symptoms and anorectal physiology. MethodsThirty women (mean age 44 years, mean parity 2) with anal incontinence underwent 2D EAUS, anorectal pull-through manometry, anorectal electosensitivity and sensation to rectal distension, pelvic floor dynamometry, and completed Wexner incontinence scores. EAUS images were reported blind to physiological assessments by a single experienced observer. The external and internal sphincters, and puborectalis were measured and scored for integrity and atrophy, and correlated with symptom load (Wexner score) and physiological data. ResultsThe mean Wexner score was 10 (range 1–20). The puborectalis could not be accurately measured in 12 patients (44%) on EAUS. Anal squeeze pressure correlated with integrity of the external sphincter (r = −0.4, p = 0.02) but not integrity or atrophy of the puborectalis. There were no other significant correlations between EAUS features and patient symptom load or anorectal physiology (r range, −0.42–0.26, p > 0.05). ConclusionTwo-dimensional EAUS can define sphincter integrity, has a limited role for assessment of muscular quality but is not useful for assessment of the puborectalis.

Sa1370 Utility of MRI Defecography After Manometry in the Diagnosis and Management of Constipation and Fecal Incontinence

G A A b st ra ct s from 40.25 (SD 21.6) to 73.25 (SD 41.5) mmHg p=0.031, correspondingly (Graph 1 & Figure 1). Due to the physiologic improvement observed at the second ARM, in 4 (33%) cases the recommendation of the pelvic floor clinic was changed and vaginal delivery was considered as an acceptable option in subsequent deliveries. Conclusions: When there is discrepancy between severity of anal weakness on ARM and anatomy based on EAUS findings at three months postpartum, a second ARM within 6 months after pelvic floor physiotherapy may show significant improvement in external anal sphincter function. This repeated evaluation may alter the decision regarding future delivery mode, in up to one third of the patients.

Successful implantation of autologous muscle-derived stem cells in treatment of faecal incontinence due to external sphincter rupture

Dear Editor:The most common pathological mechanism of faecalincontinence is the insufficiency of the external anal sphinc-ter (EAS) caused by neurological or myogenic dysfunction.The myogenic mechanism of EAS insufficiency is usuallydue to direct mechanical damage during childbirth, traumaor surgery in anorectal region, whereas neurologicalaetiology involves either spinal or peripheral nerves disrup-tion—in most cases the pudendal nerve. Unfortunately, co-incidence of sphincter rupture with damage to pudendalnerves is quite common.Each skeletal muscle, including EAS, has the ability toregenerate to some degree and repair sustained damage. Inresponse to injury and/or muscle damage, so-called satellitecells are activated and become myoblasts—capable of in-tense proliferation. Myoblasts then differentiate and fusetogether to form new muscle fibres and connect withexisting ones, adding new portions of contractile tissue toexisting motoric units [1].Attempts of autotransplantation of myoblasts into dam-aged skeletal muscle were already made in animal models ofmuscular dystrophy, post-infarction myocardial dysfunctionand urethral sphincter insufficiency [2]. The results showedthat the transplanted myoblasts differentiate into musclefibres, connect with host motoric units, increase the amountof contractile elements in the muscle and improve its con-tractile activity. In 2001, Menasche et al. first transplantedautologous myoblasts into the post-infarction myocardialscar in human patients with cardiac failure, with significantimprovements in contractile function and clinical condition[3]. In Poland, the method of treating post-infarction heartfailure was performed for the first time a year later, withsimilar results [4].Basedonthose encouraging results,a pioneerexperimen-tal study was designed in attempt to enhance the function ofexternal anal sphincter using injections of autologousmuscle-derived stem cells. The study is designed as a pro-spective experimental study. It is being conducted by twocooperating research centres—the 3rd Department of Gen-eral Surgery, Jagiellonian University in Cracow and theDepartment of Reproductive Biology and Stem Cells, Insti-tute of Human Genetics, Polish Academy of Sciences inPoznan. We would like to present a case of the representa-tive patient enrolled to our study.A 20-year old male withfaecal incontinenceduetoanoldexternal anal sphincter rupture in a road accident was en-rolled to the study. Sphincter rupture had been repairedsurgically right after the accident (with an end-to-endsphincteroplasty). The patient underwent 6 months of bio-feedback training after the wounds were healed. At the timeof enrolment, he still complained of gas and loose stoolincontinence, daily soiling, with necessity to wear pads.Endoanal ultrasound showed a 8–10-mm scar on the leftcircumference of internal and external sphincter muscle,where anal canal was ruptured during the accident, andsurgically repaired afterwards. Anorectal manometryshowed decreased both mean resting and maximum squeezepressure, with short high pressure zone length. Endoanal

Increased rectal wall stiffness after prostate radiotherapy: relation with fecal urgency

Late anorectal toxicity is a frequent adverse event of external beam radiotherapy (EBRT) for prostate cancer. The pathophysiology of anorectal toxicity remains unknown, but we speculate that rectal distensibility is impaired due to fibrosis. Our goal was to determine whether EBRT induces changes of rectal distensibility as measured by an electronic barostat and to explore whether anorectal complaints are related to specific changes of anorectal function. Thirty-two men, irradiated for localized prostate carcinoma, underwent barostat measurements, anorectal manometry, and completed a questionnaire prior to and 1 year after radiotherapy. The primary outcome measure was rectal distensibility in response to stepwise isobaric distensions. In addition, we assessed sensory thresholds, anal pressures, and anorectal complaints. External beam radiotherapy reduced maximal rectal capacity (227 ± 14 mL vs 277 ± 15 mL; P < 0.001), area under the pressure-volume curve (3212 ± 352 mL mmHg vs 3969 ± 413 mL mmHg; P < 0.005), and rectal compliance (15.7 ± 1.2 mL mmHg(-1) vs 17.6 ± 0.9 mL mmHg(-1) ; P = 0.12). Sensory pressure thresholds did not significantly change. Sixteen of the 32 patients (50%) had one or more anorectal complaints. Patients with urgency (n = 10) had a more reduced anal squeeze and maximum pressure (decrease 29 ± 11 mmHg vs 1 ± 7 mmHg; P < 0.05 and 31 ± 12 mmHg vs 2 ± 8 mmHg; P < 0.05 respectively) compared with patients without complaints, indicating a deteriorated external anal sphincter function. Irradiation for prostate cancer leads to reduced rectal distensibility. In patients with urgency symptoms, anal sphincter function was also impaired.

Effect of rectal distension on voluntary external anal sphincter function in healthy subjects

Quantification of the anorectal reflex function is critical for explaining the physiological control of continence. Reflex external anal sphincter activity increases with rectal distension in a dynamic response. We hypothesized that rectal distension would similarly augment voluntary external anal sphincter function, quantified by measuring the anal maximum squeeze pressure. Fifty-seven subjects (32 men, 25 women; median age 62 years), with normal anal canal manometry and endoanal ultrasound results, underwent a rectal barostat study with simultaneous anal manometry. Stepwise isovolumetric 50-ml distensions (n=35) or isobaric 4-mmHg distensions (n=22) above the minimum distending pressure were performed (up to 200 ml or 16 mmHg respectively), whilst anal resting pressure and maximum squeeze pressure were recorded and compared with the baseline pressure. The distension-induced squeeze increment was calculated as the maximum percentage increase in maximum squeeze pressure with progressive rectal distension. This was observed in 53 of the 57 subjects as a mean ± standard deviation (range) increase of 32.8 ± 24.1 (-5.5 to 97.7)%. The mean ± standard deviation (range) distension-induced squeeze increment in male subjects was 36.1 ± 25.7 (-5.5 to 97.7)% and in female subjects was 28.1 ± 20.1 (-3.8 to 70.2)%. There was no significant difference between the sexes (P=0.194). Rectal distension augments external anal sphincter function, confirming the existence of a dynamic rectoanal response. This may represent a quantifiable and important part of the continence mechanism.

Faecal incontinence in patients with systemic sclerosis: is an impaired internal anal sphincter the only cause?

Objectives: Faecal incontinence affects 40% of patients with systemic sclerosis (SSc). Several factors, including impaired anal sphincter function, reduced rectoanal sensation, abnormal rectoanal wall properties, and fast gastrointestinal transit, can cause faecal incontinence. Internal anal sphincter function is reduced in some patients with SSc, but other factors causing faecal incontinence remain to be studied in detail. Our aim was to compare tests of colorectal and anal physiology in patients with SSc suffering from faecal incontinence to those of SSc patients without faecal incontinence and healthy controls.Methods: Twenty SSc patients [18 women, mean age 58 (range 38–79) years] with bowel dysfunction were examined using rectoanal physiology tests, impedance planimetry, radiographic assessment of gastrointestinal transit time, and the Wexner incontinence score questionnaire. The results from SSc patients with faecal incontinence (n = 8) were compared to those from patients without faecal incontinence (n = 12) and healthy subjects [rectoanal physiology tests: 24 women, mean age 72 (range 65–83) years; impedance planimetry: 20 women, mean age 51 (range 40–80) years].Results: Anal resting pressure, which reflects internal anal sphincter function, was significantly reduced in SSc patients with faecal incontinence but not in those without. There were no significant differences in external anal sphincter function, rectoanal sensibility, rectal wall properties, or gastrointestinal transit time.Conclusion: The main cause of faecal incontinence in SSc is poor function of the internal anal sphincter smooth muscle.

Basal internal anal sphincter tone, inhibitory neurotransmission, and other factors contributing to the maintenance of high pressures in the anal canal

Maintenance of the basal tone in the internal anal sphincter (IAS) is critical for rectoanal continence. Effective evacuation requires a fully functional rectoanal inhibitory reflex (RAIR)-mediated relaxation of the IAS via inhibitory neurotransmission (INT). Systematic studies examining the nature of the INT in different species have identified nitric oxide (NO) as the major inhibitory neurotransmitter. However, other mediators such as vasoactive intestinal polypeptide (VIP), ATP, and carbon monoxide (CO) may also play species-specific role under certain experimental conditions. Measurements of the intraluminal pressures in the IAS along with the force of the isolated IAS tissues are the mainstay in the basic studies for the molecular mechanisms underlying the basal tone and in the nature of the INT. The identification of NO as the inhibitory neurotransmitter has led to major advances in the diagnosis and treatment of a number of rectoanal motility disorders associated with the IAS dysfunction. Besides the IAS, the high pressures in the anal canal are affected by the external anal sphincter (EAS) function, and its malfunction may also lead to rectoanal incontinence. Different approaches including biofeedback have been attempted to improve the EAS function, with variable outcomes. There is a dire need for the innovative ways to improve the week high pressures zone in the anal canal. This viewpoint focuses on two studies that extend the above concept of multiplicity of inhibitory neurotransmitters (Neurogastroenterol Motil 2011 23 e11–25), and that high pressures in the anal canal can be improved by the EAS plication (Neurogastroenterol Motil 2011 23 70–5).

Effect of Myogenic Stem Cells on Contractile Properties of the Repaired and Unrepaired Transected External Anal Sphincter in an Animal Model

To estimate the effect of myogenic stem cells on contractile function of the external anal sphincter after transection with or without repair in an animal model. One hundred twenty virginal female rats were randomly assigned to repair (n=60) or no repair (n=60) after anal sphincter transection. Animals were further divided into two groups: 40-microliter injection at the transection site with either phosphate-buffered solution (control) or myogenic stem cells (3.2x10 cells). Animals were killed at 7, 21, or 90 days, and the anal sphincter complex dissected and analyzed for contractile function. Contractile function of the external anal sphincter was severely impaired 7 days after sphincter transection with or without repair. Twitch tension, maximal tetanic contraction, and maximal contractile force in response to electrical field stimulation improved significantly with time after sphincter repair. Injection of myogenic stem cells in the anal sphincter at the time of repair resulted in superior contractile function at both 7 days and 90 days compared with controls. Interestingly, contractile function of the nonrepaired external anal sphincter did not improve with time with or without myogenic stem cells. Indicators of denervation (fatigue and twitch or tetany ratios) did not change among groups. In this animal model, injection of myogenic stem cells at the time of external anal sphincter repair resulted in enhanced contractile function at 90 days compared with repair alone. Without repair, function of the external anal sphincter was not improved by stem cell therapy at any time point. These results suggest that addition of myogenic stem cells improves both acute and long-term function of the external anal sphincter after mechanical injury.

The role of Pudendal Nerve Terminal Motor Latency (PNTML) in the assessment of the external anal sphincter function

Objectives: The objective of our study was to analyse the impact of pudendal nerve terminal motor latency (PNTML) testing on the final treatment procedure in a group of patients who presented to us with anorectal disorders. Methods: The PNTML results and the final treatment procedure of 24 patients who attended the gastrointestinal physiology laboratory in the Department of Surgery at the University of Colombo was analysed. Results: Male to female ratio was 6 : 18 (1 : 3). The study population had a median age of 28 years with a range of 13 years to 69 years. The indications for the study were recurrent fistulain- ano 8 (33%), anal sphincter trauma 6 (25%), rectal prolapse 5 (21%), idiopathic incontinence 3 (13%) and miscellaneous 2 (8%). Twelve patients (50%) indicated bilateral or unilateral abnormality. Only in 4 (17%) patients, the final treatment modality was changed as a result of PNTML report. Conclusion: Although a significant number of patients (50%) indicated an abnormality in their PNTML values, it was of limited value in deciding the final treatment modality. doi: 10.4038/gmj.v11i1.1108 Galle Medical Journal Vol.11(1) 2006 3-6

Recovery of External Anal Sphincter Contractile Function After Prolonged Vaginal Distention or Sphincter Transection in an Animal Model

To estimate the effect of prolonged vaginal distention and anal sphincter transection on contractile properties of the external anal sphincter as a function of time. One hundred thirty-nine young female virginal rats were randomly assigned into four treatment groups (sham, vaginal distention, transection of anal sphincter plus repair, or combined distention and transection plus repair). After 3 days, 3 months, or 6 months, the anal sphincter complex was analyzed for peak force of twitch tension, peak tetanic force, fatigue, and maximal responses to electrical field stimulation. Statistical analysis was performed using analysis of variance (Student-Neuman-Keuls). After 3 days, vaginal balloon distention, anal sphincter transection with repair, and combined distention and transection plus repair resulted in compromise of maximal tetanic contraction and electrical field stimulated force generation. Twitch tension, and resistance to fatigue were also significantly decreased in animals with anal sphincter disruption and repair with and without vaginal distention at 3 days. Contractile function of the external anal sphincter, however, was fully recovered by 3 months and was sustained at 6 months in all treatment groups. The time course of repair was slower in animals with sphincter laceration. Anal sphincter transection with or without antecedent prolonged vaginal distention results in severe compromise of external anal sphincter function in the immediate period after injury. In this animal model, complete recovery of external anal sphincter function occurs 3 months after initial insult.

S1840 The Bowel Guarding Response As a Measure of External Anal Sphincter Function in Idiopathic Fecal Incontinence

S1840 The Bowel Guarding Response As a Measure of External Anal Sphincter Function in Idiopathic Fecal Incontinence

Significance of spina bifida occulta in non-retentive fecal incontinence in children

To explore the pathophysiological significance of spina bifida occulta (SBO) in non-retentive fecal incontinence (NRFI) in children. Twenty-seven children with NRFI diagnosed according to the Rome III criteria, 21 with SBO, aged (7.9 +/- 2.4) years, and 6 without SBO, aged (7.5 +/- 1.9) years, and 226 normal controls, aged (8.4 +/- 2.7) years, underwent plain X-ray photography, neurophysiological study, colonic transit test, electromyography (EMG), and anorectal manometry. The resting vector volume, squeezing vector volume, resting EMG amplitude, and squeezing EMG amplitude, which predominantly reflect internal and external anal sphincter function, were recorded. The prevalence rate of SBO in the children with NRFI was 78%, significantly higher than that of the normal controls (24%). The resting vector volume, squeezing vector volume, resting EMG amplitude, and squeezing EMG amplitude, of the children with NRFI were all significantly lower than those of the normal controls; however, there were no significant differences in these indexes between the NRFI children with and without SBO. The total colonic transit time of the NRFI children with SBO was (41 +/- 17) h, significantly longer than those of the children without SBO and normal controls (24 +/- 5) h and (29 +/- 8) h, both P < 0.05]. Neurophysiologic test showed that the latency of pudendi-anal reflex of the NRFI children with SBO was (52 +/- 20) ms, significant longer than those of the NRFI children without SBO and normal controls [(29 +/- 9) ms and (23 +/- 7) ms respectively, both P < 0.05]. SBO is a major cause of NRFI. Treatment should be focused on recovery of the functions of nervous system.

Effect of Prolonged Vaginal Distention and Sphincter Transection on Physiologic Function of the External Anal Sphincter in an Animal Model

To estimate the effect of prolonged vaginal distention and anal sphincter transection on contractile properties of the external anal sphincter. Young female virgin rats were randomly assigned to four treatment groups (sham, vaginal distention, transection of anal sphincter plus repair, or combined distention and transection plus repair). After 3 weeks, the anal sphincter complex was analyzed for twitch tension, maximal tetanic force, fatigue, and maximal responses to electrical field stimulation. Each sphincter was serially cross-sectioned and stained with hematoxylin and eosin to evaluate sphincter integrity. Statistical evaluation was performed using analysis of variance (Student-Newman-Keuls) and chi2 analysis. The function of a transected and repaired anal sphincter is compromised significantly after 3 weeks. Vaginal distention alone did not alter function of the sphincter. Further, prolonged vaginal distention together with sphincter transection did not result in statistically significant differences in sphincter function compared with transection alone. In an animal model, there is a major effect on external anal sphincter function in vitro 3 weeks after laceration with repair. Although prolonged vaginal distention had no significant effect alone and minimal adverse effects on the lacerated anal sphincter, laceration of the sphincter has major adverse effects on its morphology and function. II.