Internal Anal Sphincter In Patients Research Articles

Thickened internal anal sphincter has been reported to be a typical finding in solitary rectal ulcer syndrome.

tion disorder among patients with solitary rectal ulcer syndrome (SRUS). The study showed that SRUS patients with abnormal balloon expulsion test had thicker internal anal sphincter (IAS), compared to those with normal tests. In fact, thickened IAS has been reported to be a typical endoanal sonographic finding in SRUS. 2,3 This finding could be associated with hypertrophy, possibly resulting from chronically increased work demand. A thickened IAS in patients with SRUS also is reported to be highly predictive of high-grade rectal intussusception. 4 Therefore, the result of Sharma et al’s study is not a novel finding but adds to the body of evidence demonstrating thickened anal sphincter as a typical endoanal feature in SRUS. As far as we know, several measuring points are required for the assessment of IAS thickness, since the thickness of IAS is not uniform. However, we could not find detailed methods for the measurement of IAS thickness in their article. We present typical endoscopic and sonographic findings of SRUS in a 59-year-old woman. She was referred to our constipation clinic for refractory constipation. Colonoscopy showed large ulcer with fold convergence (Figure A). The thickness of the IAS was measured at 4 different circumferential points. Endoanal sonography demonstrated thickened IAS irrespective of the level of anal canal (Figures B and C). Pathology showed fibrous obliteration and extension of smooth muscle fibers into the lamina propria. The confirmatory diagnosis of SRUS was made based on clinical presentation, endoscopic appearance and characteristic histologic features.

Distensibility of the anal canal in patients with systemic sclerosis: a study with the functional lumen imaging probe

Systemic sclerosis (SSc) is a generalized connective tissue disease that affects smooth muscle cells. Patients with SSc often have faecal incontinence caused by fibrotic degeneration of the internal anal sphincter (IAS). The functional lumen imaging probe (FLIP) is a novel method that allows the segmental biomechanical properties of the anal canal to be dynamically evaluated. The aim of the present study was to compare the segmental biomechanical properties of the anal canal in incontinent SSc patients and healthy controls. We hypothesized that the FLIP would reveal weaknesses of the IAS in the SSc patients. We performed FLIP distensions, endoanal ultrasonography and standard anal manometry on 14 incontinent SSc patients [11 women, median age 60 years (range 35-80)] and 15 healthy volunteers [12 women, median age 54 years (range 33-67)]. The anal canal was divided into three parts for the biomechanical analysis: upper (surrounded by the IAS and the puborectalis), middle (IAS and external anal sphincter) and lower (external sphincter only). The middle anal canal was the segment most resistant to distension in all of the subjects, but it was less resistant in the SSc patients than in the controls (P < 0.01). Correspondingly, the endoanal ultrasonography showed that the IAS of the SSc patients was thinner than normal (P < 0.05), and the anal resting and squeeze pressures were lower (P < 0.05). Only minor distensibility differences were found in the upper anal canal. No changes were found in the lower anal canal. Faecal incontinence in SSc patients is associated with poor IAS function, causing increased distensibility of the middle anal canal.

Analysis of mechanical response of fistula plug for structure optimization

Anal fistula is one of the three greatest anorectal diseases with a high prevalence. The traditional treatments(e.g., surgery) for fistula have limitations due to damage to the internal anal sphincter of patients. With recent advances in biomaterials, treatments based on biomaterial filling (e.g., scleraprotein injection, fistula plug) have emerged as novel therapies for fistula. The anal fistula plug (e.g., based on small intestinal submucosa (SIS)) has attracted increasing attention because of short term healing rate and biocompatibility. However, challenges remain for this method such as plug falling as observed in clinics. To address this, this paper analyzes the case of SIS falling under physiological condition from mechanical point of view using ANSYS simulation. It then proposes three new geometrical structures for fistula plug and compares their mechanical behavior (e.g., axial stress, reaction of constraint) with that of clinically used structure (cone shape). Based on the simulation, it optimizes the geometric parameters of fistula plug. The approach developed here can help to improve the design of fistula plug for better clinical treatments.

Endosonographic and manometric evaluation of internal anal sphincter in patients with chronic anal fissure and its correlation with clinical outcome after topical glyceryl trinitrate therapy

Anorectal pressure studies have demonstrated internal anal sphincter (IAS) hypertonia in patients with chronic anal fissure. It is unknown however, if these changes in IAS function are associated with any abnormality in sphincter morphology. The first aim was to investigate the clinical characteristics and the manometric and endosonographic findings of the IAS in a cohort of patients with chronic anal fissure. The second aim was to investigate the association between these findings and the outcome with topical Glyceryl trinitrate (GTN) therapy. All patients who presented with chronic anal fissure from November 1999 to May 2004 were included after failure of conservative therapy. Anorectal manometry and anal endosonography were performed before treatment with 0.2% GTN ointment twice daily was initiated. Patients were evaluated after 8 weeks. One hundred and twenty-four patients (66 women, mean age, 45.2 +/- 14.8 years) were included. Hypertonia of the IAS was found in 84 (68%) patients. The mean maximum IAS thickness was 3.6 +/- 0.76 mm (1.6-5.5). An abnormally thick IAS, adjusted by age, was observed in 113 (91.1%) patients. We found no correlation between resting pressure and IAS thickness (r = 0.074; p = 0.41). At 8 weeks, 52 patients (42%) had healed with complete symptoms resolution. No statistically significant differences were observed when clinical features and manometric and endosonographic findings were compared between healing and no-healing fissures. The majority of patients with chronic anal fissure present an abnormally thick IAS. Clinical, manometric and endosonographic features had no association with outcome after GTN treatment.

Decreased sensitivity of muscarinic but not 5-hydroxytryptamine receptors of the internal anal sphincter in neurogenic faecal incontinence.

Previous studies of the internal anal sphincter in patients with neurogenic faecal incontinence have indicated an abnormality of the adrenergic innervation, but little is known about the responsiveness of other receptors in the internal and sphincter in this condition. In this study the in vitro sensitivity to carbachol and 5-hydroxytryptamine (5-HT) of muscle strips from patients with neurogenic incontinence (n = 6 and n = 7) and from control patients (n = 9 and n = 10) was examined. Preparations of internal and sphincter from patients with incontinence were less sensitive to the relaxant actions of carbachol than preparations from the control group. The pD2 value for carbachol (i.e. the negative logarithm of the concentration for half-maximal response) was significantly greater in the controls than in the incontinent group (mean(s.e.m.) 6.03(0.15) versus 5.43(0.24), P < 0.05). There was no significant difference in the contractile responses to 5-HT, which had pD2 values of 6.93(0.13) and 6.63(0.27) for the control and incontinent groups respectively. The unaffected state of the 5-HT receptor and the subsensitivity of the muscarinic receptor are discussed in relation to intrinsic neural control of the internal and sphincter in neurogenic faecal incontinence.

The internal sphincter and anal fissure.

The activity of the internal anal sphincter in patients with fissure has been studied by measuring anal pressure and motility with a small balloon probe. The mean maximum anal pressure in 12 patients with fissure (116-8 +/- 21-8, s.d., cm H2O) was significantly higher than that in 40 control subjects (85-0 +/- 20-5 cm H2O; P less than 0-01). Ultra-slow pressure waves were present in 80 per cent of the patients and in 5 per cent of the controls. Both the high pressure of ultra-slow waves were due to abnormal activity of the internal sphincter. This could be corrected equally well by either dilatation or lateral subcutaneous sphincterotomy.

Pharmacological study of the internal and sphincter in patients with chronic anal fissure.

A pharmacological study of the internal anal sphincter (IAS) was undertaken in patients with chronic and fissure. The sensitivity of the IAS to the contractile effect of phenylephrine and potassium chloride and to relaxation by isoproterenol was evaluated. Supersensitivity of the IAS to relaxation by isoproterenol was noted. Further research is necessary to determine the pharmacological basis of such a disturbance.

Adrenergic control of the internal anal sphincter is abnormal in patients with idiopathic faecal incontinence

There is histological and functional evidence that the internal anal sphincter is abnormal in patients with idiopathic faecal incontinence. The in vitro responsiveness of the internal anal sphincter to noradrenaline (an important sympathetic neurotransmitter) and electrical field stimulation (known to stimulate the intrinsic innervation) has been studied. Muscle strips from eight patients with incontinence undergoing postanal repair and five controls undergoing resection for low rectal carcinoma were studied. The contraction-response curves for noradrenaline were significantly different, and the EC50, the concentration required to produce 50 per cent of maximum contraction, was higher in incontinent patients (P less than 0.001). Electrical field stimulation produced initial contractions in four of the control group which were blocked by phentolamine. This contraction was not present in the incontinent patients (P less than 0.01). These results indicate an abnormality in the adrenergic innervation of the internal anal sphincter in patients with idiopathic faecal incontinence.

Nitric oxide deficiency in the internal anal sphincter of patients with chronic anal fissure

Anal fissure is a common condition affecting young to middle-aged adults. It causes severe pain on defecation and rectal bleeding. The aetiology remains uncertain. Spasm of the internal anal sphincter is a constant feature. Nitric oxide (NO) is the major inhibitory neurotransmitter of the internal anal sphincter (IAS). In other spasmodic conditions of the GI tract a lack of normal nitric oxide synthase (NOS) activity has been reported. The aim of this preliminary study was to compare the presence of NOS in the internal sphincters of patients with and without chronic anal fissure. Internal anal sphincter biopsies were taken under general anaesthesia from patients having lateral internal sphincterotomy for chronic anal fissure and from sphincter of patients having abdominoperineal resections as controls. Sections of IAS were stained to show the presence of NADPH diaphorase (and hence presence of NOS). Internal anal sphincter was taken from 6 patients with chronic anal fissure and 6 controls. IAS taken from patients with chronic anal fissure showed little NOS presence compared with controls. It may be that there is an abnormal failure of relaxation of internal sphincter in those patients who develop chronic anal fissure caused by an intrinsic lack of neural NOS in the internal anal sphincter.

Endosonographic study of anal sphincters in patients after surgery for Hirschsprung's disease

Purpose: This study was performed to evaluate the relationship between endosonographic findings of anal sphincters and anorectal function in patients after surgery for Hirschsprung's disease. In addition, whether internal sphincterotomy or sphincterectomy was accomplished was examined in each procedure by anal endosonography. Methods: Fifteen patients, aged 11 to 20 years, were examined. Nine patients underwent modified Duhamel's operation, three underwent Rehbein's operation with anorectal myectomy, and three underwent modified Martin's operation. All 15 patients were examined by anal endosonography using a sonographic scanner (Aloka SSD 2000) with a 7.5-MHz radial rotating endoprobe, clinical bowel assessment, and manometric study. Results: After the modified Duhamel operation, anal endosonography showed an interruption of the external anal sphincter (EAS) in eight of the nine patients, as a high, mixed, or low echoic lesion in the hyperechoic band correlated to the EAS. The locations of the interruption were wide in patients with mild constipation. An interruption of the internal anal sphincter (IAS) was observed in all nine patients, as a hyperechoic lesion in the hypoechoic band correlated to IAS, which indicated internal sphincterotomy. After Rehbein's operation with anorectal myectomy, an interruption of EAS was observed in all three patients as a high or low echoic lesion in the hyperechoic band. An interruption of IAS was observed in all three patients. After the modified Martin's operation, an interruption of EAS was observed in two of the three patients as a high or low echoic lesion in the hyperechoic band. An interruption of IAS was observed in all three patients. Conclusion: Anal endosonography showed detailed distributions of EAS and IAS in patients after surgery for Hirschsprung's disease and complete internal sphincterotomy or sphincterectomy after these operations.

Internal anal sphincter: advances and insights.

The internal anal sphincter, the smooth muscle component of the anal sphincter complex, has an ambiguous role in maintaining anal continence. Despite its significant contribution to resting anal canal pressures, even total division of the internal anal sphincter in surgery for anal fistulas may fail to compromise continence in otherwise healthy subjects. However, recently reported abnormalities of the innervation and reflex response of the internal anal sphincter in patients with fecal incontinence indicate its significance in maintaining continence. The advent of sphincter-saving surgery and restorative proctocolectomy has re-emphasized the major contribution of the internal anal sphincter to resting pressure and its significance in preventing fecal leakage. The variable effect of rectal excision on rectoanal inhibitory reflex has led to a reappraisal of the significance of this reflex in discrimination of rectal contents and its impact on anal continence. Electromyographic, manometric, and ultrasonographic evaluation of the internal anal sphincter has provided new insights into its pathophysiology. This article reviews advances in our understanding of internal anal sphincter physiology in health and disease.

Abnormal internal anal sphincter innervation in patients with Hirschsprung's disease and allied disorders

The morphology of the intrinsic innervation of internal anal sphincter (IAS) in Hirschsprung's disease (HSCR) and allied disorders has not been clearly defined. At the time of IAS myectomy, specimens of the IAS were taken from four patients with HSCR, five patients with intestinal neuronal dysplasia (IND), five patients with IAS achalasia, and two patients with hypoganglionosis. Specimens also were taken from five normal controls. The specimens were examined using neural cell adhesion molecule (NCAM) immunohistochemistry, NADPH-diaphorase histochemistry, and acetylcholinesterase (AChE) histochemistry. The number of AChE-positive nerve fibers was markedly increased in the IAS of patients with HSCR, IND, and IAS achalasia compared with controls. NCAM and NADPH-diaphorase activity was absent or markedly reduced in the IAS of patients with HSCR, IND, and IAS achalasia. The IAS of patients with hypoganglionosis show markedly reduced NCAM and NADPH-diaphorase activity and occasional AChE-positive nerve fibers. These findings show that patients with HSCR, IND, hypoganglionosis, or IAS achalasia have abnormal innervation of the IAS and this may contribute to disturbances in gut motility in these conditions.

Effects of unilateral ovariectomy, gonadotropin stimulation and immunization against a synthetic peptide of the bovine inhibin [formula omitted] on oocyte recovery using transvaginal, ultrasound-guided aspiration

Purpose: This study was performed to evaluate the relationship between endosonographic findings of anal sphincters and anorectal function in patients after surgery for Hirschsprung's disease. In addition, whether internal sphincterotomy or sphincterectomy was accomplished was examined in each procedure by anal endosonography.Methods: Fifteen patients, aged 11 to 20 years, were examined. Nine patients underwent modified Duhamel's operation, three underwent Rehbein's operation with anorectal myectomy, and three underwent modified Martin's operation. All 15 patients were examined by anal endosonography using a sonographic scanner (Aloka SSD 2000) with a 7.5-MHz radial rotating endoprobe, clinical bowel assessment, and manometric study.Results: After the modified Duhamel operation, anal endosonography showed an interruption of the external anal sphincter (EAS) in eight of the nine patients, as a high, mixed, or low echoic lesion in the hyperechoic band correlated to the EAS. The locations of the interruption were wide in patients with mild constipation. An interruption of the internal anal sphincter (IAS) was observed in all nine patients, as a hyperechoic lesion in the hypoechoic band correlated to IAS, which indicated internal sphincterotomy. After Rehbein's operation with anorectal myectomy, an interruption of EAS was observed in all three patients as a high or low echoic lesion in the hyperechoic band. An interruption of IAS was observed in all three patients. After the modified Martin's operation, an interruption of EAS was observed in two of the three patients as a high or low echoic lesion in the hyperechoic band. An interruption of IAS was observed in all three patients.Conclusion: Anal endosonography showed detailed distributions of EAS and IAS in patients after surgery for Hirschsprung's disease and complete internal sphincterotomy or sphincterectomy after these operations.

Cyclic GMP relaxes the internal anal sphincter in Hirschsprung's disease

In Hirschsprung's disease (HD), the aganglionic colon and internal anal sphincter (IAS) fail to relax. Aganglionic colon of HD patients relaxes in response to exogenous nitric oxide (NO), whereas the IAS from HD patients does not relax. The authors hypothesized that the failure of IAS relaxation is caused by a local deficiency of cyclic guanosine monophosphate (cGMP), the final metabolite in NO-mediated smooth muscle relaxation. To test this hypothesis, the authors measured the isometric tension of smooth muscle strips taken from the IAS and aganglionic colon of patients with HD before and after exposure to cGMP and compared this with ganglionic colon and IAS from normal controls. In HD patients both the IAS and aganglionic colon relaxed in response to cGMP ( P < .05). The amount of relaxation observed in both the aganglionic colon and IAS was comparable to that measured in the normal controls. The observation that exogenous cGMP relaxes the IAS, whereas exogenous NO does not, suggests that mechanisms for relaxation may be different than those in the aganglionic colon and may explain persistent IAS dysfunction after resection of aganglionic colon. The defect of the IAS in HD may be the inability of the NO cGMP pathway to induce smooth muscle cell relaxation rather than a defect in the smooth muscle cell.

Abnormal internal anal sphincter fibrosis and elasticity in fecal incontinence.

We aimed to investigate the changes in the proportion of collagen and in the elasticity of the internal anal sphincter in patients with neurogenic fecal incontinence. Collagen content was studied in ten patients with neurogenic fecal incontinence (mean age, 51.5 years) and ten controls (age, 58.6 years) using histologic techniques to determine differences between incontinence and health and to determine the effect of aging. Changes in elasticity were also measured in 8 controls (mean age, 63 years) and 13 patients with neurogenic incontinence (mean age, 60 years) by recording the in vitro length-tension relationship of the freshly excised internal anal sphincter. Incontinent patients had a significantly higher collagen content than controls (55 percent vs. 33 percent; P = 0.013). In incontinent patients the amount of collagen and the patients' ages correlated significantly (P = 0.001). There was a greater increase in stable tension per increase in muscle length in the strips from incontinent patients compared with controls. Changes in fibrous tissue content are likely to influence muscle tone and responsiveness of the sphincter in fecal incontinence.

Effect of nitric oxide on the colonic smooth muscle of patients with Hirschsprung's disease

Hirschsprung's disease results in bowel obstruction because of a failure of smooth muscle relaxation in both the aganglionic segment of bowel and the internal anal sphincter (IAS). Nonadrenergic noncholinergic (NANC) nerves, which use nitric oxide (NO) as their chemical messenger, are responsible for relaxing smooth muscle in normal bowel and the IAS. Previous work indicates that the cause of the aganglionic colon's inability to relax may be a lack of NANC nerves. To test this hypothesis, the authors compared the effect of an exogenous source of NO, S-nitroso-N-acetylpenicillamine (SNAP), on the isometric tension of smooth muscle strips taken from the ganglionic colon, aganglionic colon, and IAS of patients with Hirschsprung's disease. Exposure of ganglionic and aganglionic colon specimens to SNAP (10 −3 to 10 −5 mol/L) resulted in up to 70% reduction of resting tension. This relaxation occurred in a dose-dependent fashion and could be promptly reversed by the addition of the NO antagonist methylene blue. However, SNAP had no demonstrable effect on the smooth muscle strips taken from the IAS of patients with Hirschsprung's disease. This finding suggests that, in the aganglionic colon, a deficiency of NANC nerves contributes to the development of bowel obstruction. However, the failure of the IAS to relax in Hirschsprung's disease appears to be unrelated to NO and the NANC nervous system.

Anal sphincteric pressure studies in complete rectal prolapse.

Anal sphincteric pressure studies of patients with complete rectal prolapse demonstrated that: 1) The resting yield pressure of the internal anal sphincter in patients with complete rectal prolapse was not significantly different from that of control subjects. Thus, it seems to have no role in the etiology of prolapse. 2) The maximal sphincteric pressure of the external anal sphincter was significantly less in patients with prolapse than in controls. This suggested weakness in the effective functional power of the external anal sphincter in complete prolapse. 3) Anal continence could be achieved by the ability to maintain full contraction of the external anal sphincter for more than 40 seconds, which was the minimum for control subjects. Incontinent patients could not do this.