Evaluation of anorectal function using real-time tissue elastography before and after preoperative chemoradiotherapy

PURPOSE

This study aimed to clarify the relationship between changes in elasticity and anorectal function before and after chemoradiotherapy.

METHODS

This is a single-center prospective cohort study (Department of Surgical Oncology, The University of Tokyo). We established a technique to quantify internal anal sphincter hardness as elasticity using transanal ultrasonography with real-time tissue elastography. Twenty-seven patients with post-chemoradiotherapy rectal cancer during 2019-2022 were included. Real-time tissue elastography with transanal ultrasonography was performed before and after chemoradiotherapy to measure internal anal sphincter hardness as "elasticity" (hardest (0) to softest (255); decreased elasticity indicated sclerotic changes). The relationship between the increase or decrease in elasticity pre- and post-chemoradiotherapy and the maximum resting pressure, maximum squeeze pressure, and Wexner score were the outcome measures.

RESULTS

A decrease in elasticity was observed in 16/27 (59.3%) patients after chemoradiotherapy. Patients with and without elasticity decrease after chemoradiotherapy comprised the internal anal sphincter sclerosis and non-sclerosis groups, respectively. The maximum resting pressure post-chemoradiotherapy was significantly high in the internal anal sphincter sclerosis group (63.0 mmHg vs. 47.0 mmHg), and a majority had a worsening Wexner score (60.0% vs. 18.2%) compared with that of the non-sclerosis group. Decreasing elasticity (internal anal sphincter sclerosis) correlated with a higher maximum resting pressure (r = 0.36); no correlation was observed between the degree of elasticity change and maximum squeeze pressure.

CONCLUSION

Internal anal sphincter sclerosis due to chemoradiotherapy may correlate to anorectal dysfunction.

Anatomic sphincteroplasty with combined reconstruction of internal and external anal muscles in the anal incontinence surgical treatment

Several groups studying the results of the classic sphincteroplasty show improvement of 75% of patients treated in a short-term follow-up, with a worsening of this data in the long-term follow-up down to an improvement of 50% of the patients. Some other groups published more optimistic results, showing an 80% success rate without any deterioration of the technique over time after introducing a separate repair of the internal and external muscles. We think that the introduction of some modifications in the classic technique, named "Anatomic sphincteroplasty with combined reconstruction of external and internal anal sphincter muscles" may obtain very good clinical and anorectal manometric results both in a short and mid-term follow-up. In addition, increasing the pressive length in the anal canal may contribute to maintain more stable results over time.

A systematic review of translation and experimental studies on internal anal sphincter for fecal incontinence

The complexity in the molecular mechanism of the internal anal sphincter (IAS) limits preclinical or clinical outcomes of fecal incontinence (FI) treatment. So far, there are no systematic reviews of IAS translation and experimental studies that have been reported. This systematic review aims to provide a comprehensive understanding of IAS critical role in FI. Previous studies revealed the key pathway for basal tone and relaxation of IAS in different properties as follows; calcium, Rho-associated, coiled-coil containing serine/threonine kinase, aging-associated IAS dysfunction, oxidative stress, renin-angiotensin-aldosterone, cyclooxygenase, and inhibitory neurotransmitters. Previous studies have reported improved functional outcomes of cellular treatment for regeneration of dysfunctional IAS, using various stem cells, but did not demonstrate the interrelationship between those results and basal tone or relaxation-related molecular pathway of IAS. Furthermore, these results have lower specificity for IAS-incontinence due to the included external anal sphincter or nerve injury regardless of the cell type. An acellular approach using bioengineered IAS showed a physiologic response of basal tone and relaxation response similar to human IAS. However, in both cellular and acellular approaches, the lack of human IAS data still hampers clinical application. Therefore, the IAS regeneration presents more challenges and warrants more advances.

Oscillating calcium signals in smooth muscle cells underlie the persistent basal tone of internal anal sphincter

A persistent basal tone in the internal anal sphincter (IAS) is essential for keeping the anal canal closed and fecal continence; its inhibition via the rectoanal inhibitory reflex (RAIR) is required for successful defecation. However, cellular signals underlying the IAS basal tone remain enigmatic. Here we report the origin and molecular mechanisms of calcium signals that control the IAS basal tone, using a combination approach including a novel IAS slice preparation that retains cell arrangement and architecture as in vivo, 2-photon imaging, and cell-specific gene-modified mice. We found that IAS smooth muscle cells generate two forms of contractions (i.e., phasic and sustained contraction) and Ca2+ signals (i.e., synchronized Ca2+ oscillations [SCaOs] and asynchronized Ca2+ oscillations [ACaOs]) that last for hours. RyRs, TMEM16A, L-type Ca2+ channels, and gap junctions are required for SCaOs, which account for phasic contraction and 75% of sustained contraction. Nevertheless, only RyRs are required for ACaOs, which contribute 25% of sustained contraction. Nitric oxide, the primary neurotransmitter mediating the RAIR, blocks both types of Ca2+ signals, leading to IAS's full relaxation. Our results show that the oscillating nature of Ca2+ signals generates and maintains the basal tone without causing cytotoxicity to IAS. Our study provides insight into fecal continence and normal defecation.

Impact of Botulinum Toxin on Hirschsprung-Associated Enterocolitis After Primary Pull-Through

BACKGROUND

Hirschsprung-associated enterocolitis (HAEC) is a serious potential complication after primary pull-through surgery for Hirschsprung's disease (HSCR). Administration of anal botulinum toxin (BT) injection may improve obstructive symptoms at the internal anal sphincter, leading to improved fecal passage. The timing of administration and effects on delay or prevention of HAEC are unknown. We hypothesized that BT administration increased the postoperative time to HAEC and aimed to investigate whether anal BT administration after primary pull-through surgery for HSCR is associated with increased time to inpatient HAEC admission development.

METHODS

We performed a retrospective cohort study examining children with HSCR at US children's hospitals from 2008 to 2018 using the Pediatric Health Information System database with an associated primary pull-through operation performed before 60 d of age. The intervention assessed was the administration of BT concerning the timing of primary pull-through, and two groups were identified: PRO (received BT at or after primary pull-through, before HAEC) and NOT (never received BT, or received BT after HAEC). The primary outcome was time from pull-through to the first HAEC admission. The Cox proportional hazards model was developed to examine the BT administration effect on the primary outcome after controlling for patient-level covariates.

RESULTS

We examined a total of 1439 children (67 in the PRO and 1372 in the NOT groups). A total of 308 (21.4%) developed at least one episode of HAEC, including 76 (5.3%) who had two or more episodes. Between 2008 and 2018, the frequency of BT administration has increased from three to 20 hospitals with a frequency of administration between 2.2% and 16.2%. Prophylactic BT (PRO) was not associated with increased time to HAEC event on adjusted analysis.

CONCLUSIONS

Among children with HSCR undergoing primary pull-through surgery, prophylactic BT administration did not demonstrate increased time to first HAEC event. A better-powered study with prophylactic BT is required to determine the effect on HAEC occurrence and timing.

LEVEL OF EVIDENCE

Level II (retrospective cohort study).

Low Anterior Resection Syndrome

PURPOSE OF REVIEW

Low anterior resection syndrome is a highly prevalent condition that can develop after anal sphincter-sparing surgery for rectal cancer and impair quality of life. In this review, we summarize the major features and pathophysiology of this syndrome and discuss treatment approaches.

RECENT FINDINGS

Quality of life correlates significantly with severity of low anterior resection syndrome. Prompt assessment and initiation of therapy are essential to rehabilitating damaged mechanical and neural structures. Anorectal manometry demonstrates a global decrease in sphincteric function postoperatively, though in many patients, function does recover. Transanal irrigation, pelvic floor rehabilitation, and biofeedback are the mainstays of the treatment of major LARS. Definitive stoma can be considered in therapy refractory LARS > 2 years. The development of low anterior resection syndrome likely involves an interplay between mechanical and neural pathways. Clinically, patients present at varying levels of severity, and scoring systems are available to help assess patient symptoms and guide therapy. Treatment approaches range from conservative therapies to biofeedback and sacral nerve stimulation. Future randomized controlled trials aimed at risk stratification of patients and development of severity-based treatment algorithms are warranted.

Botulinum toxin injections after surgery for Hirschsprung disease: Systematic review and meta-analysis

BACKGROUND

A large proportion of patients with Hirschsprung disease experience persistent obstructive symptoms after corrective surgery. Persistent obstructive symptoms may result in faecal stasis that can develop into Hirschsprung-associated enterocolitis, a potential life-threatening condition. Important treatment to improve faecal passage is internal anal sphincter relaxation using botulinum toxin injections.

AIM

To give an overview of all empirical evidence on the effectiveness of botulinum toxin injections in patients with Hirschsprung disease.

METHODS

A systematic review and meta-analysis was done by searching PubMed, EMBASE and the Cochrane Library, using entry terms related to: (1) Hirschsprung disease; and (2) Botulinum toxin injections. 14 studies representing 278 patients met eligibility criteria. Data that were extracted were proportion of patients with improvement of obstructive symptoms or less enterocolitis after injection, proportion of patients with adverse effects and data on type botulinum toxin, mean dose, average age at first injection and patients with associated syndromes. Random-effects meta-analysis was used to aggregate effects and random-effects meta-regression was used to test for possible confounding factors.

RESULTS

Botulinum toxin injections are effective in treating obstructive symptoms in on average 66% of patients [event rate (ER) = 0.66, P = 0.004, I² = 49.5, n = 278 patients]. Type of botulinum toxin, average dose, average age at first injections and proportion of patients with associated syndromes were not predictive for this effect. Mean 7 duration of improvement after one botulinum toxin injections was 6.4 mo and patients needed on average 2.6 procedures. There was a significant higher response rate within one month after botulinum toxin injections compared to more than one month after Botulinum toxin injections (ER = 0.79, vs ER = 0.46, Q = 19.37, P < 0.001). Botulinum toxin injections were not effective in treating enterocolitis (ER 0.58, P = 0.65, I² = 71.0, n = 52 patients). There were adverse effects in on average 17% of patients (ER = 0.17, P < 0.001, I² = 52.1, n = 187 patients), varying from temporary incontinence to mild anal pain.

CONCLUSION

Findings from this systematic review and meta-analysis indicate that botulinum toxin injections are effective in treating obstructive symptoms and that adverse effects were present, but mild and temporary.

[Morphological characteristic of anal canal in patients with dyssynergic defecation and its correlation with anorectal manometry]

Objective: To evaluate the diagnostic value of three-dimensional endoanal ultrasound (3D-EAUS) for dyssynergic defecation (DD). Methods: A case-control study was performed to retrospectively collectclinical data of 46 DD patients, including 16 males and 30 females with median age of 51 (20 to 70) years, at Nanjing Hospital of Chinese Medicine from February 2012 to April 2015.All the patients met the diagnostic criteria of functional constipation of Rome III. The paradoxical contraction of puborectalis (PR) muscle was found by both rectal examination and anorectal manometry. In the same period,45 healthy volunteers, including 22 males and 23 females with median age of 48 (21 to 72) years, without pelvic operation history, and with normal defecation in recent 6 months, were enrolled as the control group. No significant differences were observed in age and gender between two groups (both P>0.05). Cleveland constipation score of DD group was higher than that of control group [15(8-24) vs. 5(1-9), t=15.720, P<0.001]. 3D-EAUS examination was performed in all the subjects. Thickness and length of internal anal sphincter (IAS) (anterior side and posterior side), thickness of PR muscle, length of external anal sphincter (EAS) plus PR muscle, and puborectalis angle were measured and compared by using student t test between two groups. Correlation between these ultrasound parameters and anorectal manometry was examined by Pearson correlation analysis. Results: Both male and female in the DD group had the greater thickness of IAS, as compared to those in the control group [male: (1.7±0.5) mm vs.(1.5±0.2) mm, t=2.516, P=0.016; female: (1.9±0.4) mm vs.(1.6±0.5) mm, t=2.034,P=0.047]. No significant differences between the two groups were observed with respect to the posterior length of IAS, length of EAS plus PR muscle, and thickness of PR muscle (all P>0.05). Compared to the control group, male in the DD group had smaller puborectalis angle during straining [(87.0±3.6)° vs. (90.5±1.8)°,t=3.502,P=0.002];female in the DD group had smaller puborectalis angle both in resting and straining [resting:(86.5±3.8)° vs. (90.1±2.1)°,t=4.047, P<0.001;straining: (84.1±4.5)° vs. (90.2±2.3)°, t=5.938, P<0.001]. Correlation analysis showed that anterior length of IAS was positively correlated with anal resting pressure (r=0.321, P=0.030); the length of EAS plus PR muscle was positively correlated with anal squeeze pressure (r=0.415, P=0.004). There were no correlations between the thickness and the posterior length of IAS and the anal resting pressure, or between the thickness of PR muscle and the anal squeeze pressure (all P>0.05). Conclusions: The 3D-EAUS can accurately assess the morphological features of anal canal in DD patients. There is a certain positive correlation between 3D-EAUS and anorectal manometry.

Innervation of the entire internal anal sphincter in a mouse model of Hirschsprung's disease: a first report

BACKGROUND

Impaired function of the internal anal sphincter (IAS) may be implicated in postoperative obstructed defecation (POD) that may complicate Hirschsprung's disease (HD) patients. While innervation of part of the IAS in HD has been reported, accurate details based on anatomic landmarks that can explain the clinical morbidity seen in POD are lacking, and there appear to be no studies that specifically document the innervation of the "entire" IAS in HD. We used endothelin receptor-B knockout mice to represent HD (HD-mice) and C57B6 wild mice as controls (C-mice) to investigate the innervation of the entire IAS to assess the pathophysiology of POD experimentally.

METHODS

The end-point of the longitudinal muscle layer was used to define the border between the IAS and the circular muscle layer (CML). Specimens of anorectum from HD- and C-mice were immunostained with PGP 9.5 and S100 as general nerve markers, nNOS and VIP as parasympathetic nerve markers, TH as a sympathetic nerve marker, and calretinin as a reliable diagnostic marker for HD. Immunostained cells/fibers were quantified using ImageJ.

RESULTS

On fluorescence microscopy, PGP 9.5, nNOS, and calretinin were significantly lower in the IAS of HD-mice than in C-mice (p < 0.05, respectively), while there were no significant differences between HD-mice and C-mice for S100, VIP, or TH.

CONCLUSION

We are the first to confirm that the expression of histochemical markers of innervation is abnormal throughout the "entire" IAS in HD-mice. Application of this finding may be beneficial for preventing POD and requires further research.

Internal anal sphincter nerves - a macroanatomical and microscopic description of the extrinsic autonomic nerve supply of the internal anal sphincter

AIM

The internal anal sphincter (IAS) contributes substantially to anorectal functions. While its autonomic nerve supply has been studied at the microscopic level, little information is available concerning the macroscopic topography of extrinsic nerve fibres. This study was designed to identify neural connections between the pelvic plexus and the IAS, provide a detailed topographical description, and give histological proof of autonomic nerve tissue.

METHODS

Macroscopic dissection of pelvic autonomic nerves was performed under magnification in seven (five male, two female) hemipelvises obtained from body donors (67-92 years). Candidate structures were investigated by histological and immunohistochemical staining protocols to visualize nerve tissue.

RESULTS

Nerve fibres could be traced from the anteroinferior edge of the pelvic plexus to the anorectal junction running along the neurovascular bundle anterolaterally to the rectum and posterolaterally to the prostate/vagina. Nerve fibres penetrated the longitudinal rectal muscle layer just above the fusion with the levator ani muscle (conjoint longitudinal muscle) and entered the intersphincteric space to reach the IAS. Histological and immunohistochemical findings confirmed the presence of nerve tissue.

CONCLUSIONS

Autonomic nerve fibres supplying the IAS emerge from the pelvic plexus and are distinct to nerves entering the rectum via the lateral pedicles. Thus, they should be classified as IAS nerves. The identification and precise topographical location described provides a basis for nerve-sparing rectal resection procedures and helps to prevent postoperative functional anorectal disorders.

Role of three-dimensional endoanal ultrasound in assessing the anal sphincter morphology of female patients with chronic proctalgia

AIM

To assess the role of three-dimensional endoanal ultrasound (3D-EAUS) for morphological assessment of the anal sphincter of female patients with chronic proctalgia (CP).

METHODS

In this unmatched case control study, 30 consecutive female patients with CP and 25 normal women (control group) were enrolled. 3D-EAUS was performed in all subjects. Thickness and length of internal anal sphincter (IAS), thickness of puborectalis muscle (PR), length of the external anal sphincter (EAS) plus PR, and puborectalis angle were measured and compared between the two groups.

RESULTS

Patients with CP had significantly shorter IAS length and greater PR thickness, as compared to those in normal individuals (26.28 ± 3.59 mm vs 28.87 ± 4.84 mm, P < 0.05 and 9.67 ± 1.57 mm vs 8.85 ± 0.97 mm, P < 0.05, respectively). No significant between-group differences were observed with respect to IAS thickness and the EAS plus PR length (P > 0.05). Puborectalis angle in the CP group was significantly decreased, both in resting (88.23° ± 1.81° vs 89.94° ± 2.07° in control group, P < 0.05) and straining (88.47° ± 3.32° vs 90.72° ± 1.87° in control group, P < 0.05) phases, which suggest the presence of paradoxical contraction of PR in patients with CP. In the CP group, no significant difference in puborectalis angle was observed between the resting and straining phases (88.23° ± 1.81° vs 88.47° ± 3.32° respectively, P > 0.05).

CONCLUSION

The association of greater PR thickness and paradoxical contraction of PR with CP suggest their potential value as markers of CP.

Manometric findings in relation to functional outcomes in different types of anorectal malformations

AIMS

To compare anorectal manometry (AM) in patients with different types of anorectal malformations (ARMs) in relation to functional outcomes.

METHODS

A single-institution, cross-sectional study. After ethical approval, all patients ≥7years old treated for anterior anus (AA), perineal fistula (PF), vestibular fistula (VF), or rectourethral fistula (RUF) from 1983 onwards were invited to answer the Rintala bowel function score (BFS) questionnaire and to attend anorectal manometry (AM). Patients with mild ARMs (AA females and PF males) had been treated with minimally invasive perineal procedures. Females with VF/PF and males with RUF had undergone internal-sphincter saving sagittal repairs.

RESULTS

55 of 132 respondents (42%; median age 12 (7-29) years; 42% male) underwent AM. Patients with mild ARMs displayed good anorectal function after minimally invasive treatments. The median anal resting and squeeze pressures among patients with mild ARMs (60 cm H2O and 116 cm H2O respectively) were significantly higher than among patients with more severe ARMs (50 cm H2O, and 80cm H2O respectively; p≤0.002). The rectoanal inhibitory reflex was preserved in 100% of mild ARMs and 83% of patients with more severe malformations after IAS-saving sagittal repair. The functional outcome was poor in 4/5 patients with an absent RAIR (BFS≤11 or antegrade continence enema-dependence). Rectal sensation correlated significantly with the BFS.

CONCLUSIONS

Our findings support the appropriateness of our minimally invasive approaches to the management of mild ARMs, and IAS-saving anatomical repairs for patients with more severe malformations.

LEVEL OF EVIDENCE

III.

Chronic anal fissures: Open lateral internal sphincterotomy result; a case series study

Introduction

Anal fissure are defined as a tear in the skin of the anal canal distal to dentate line. Although still there are controversies about the exact management, lateral sphincterotomy is promising. The aim of this series is to present the outcome of lateral sphincterotomy for internal anal sphincter in term of patient satisfaction and complication.

Patient and methods

A prospective single cohort study, 190 patients, who were undergone lateral sphincterotomy for internal anal sphincter from 2010 to 2014, were analyzed. The operation was performed as a day case procedure. The median duration of follow up was 5 years (ranging from 3 to 6). The data were analyzed using the Statistical Package for Social sciences (SPSS) version 22. Descriptive statistic was used to describe findings.

Results

Forty three males (22.6%) and 147 females (77.4%) with a mean ± SD of age of 31.19 ± 7.78 years. Constipation was reported in 152 (80%) patients, bleeding in 131 (68.6%) cases, and pain in 142 (74.7%) patients. The median duration of the disease was 20 months (ranging from 1 to 30 months). Post-operatively, patient satisfaction was high (98.4%) with only 3 cases (1.6%) of recurrence.

Conclusion: lateral sphincterotomy for internal anal sphincter, along, is the procedure of choice for management of CAF because it is effective and it can cure the disease in nearly all patients with good patient satisfaction.

•

Anal fissures are defined as a tear in the skin of the anal canal distal to dentate line.

•

There are several modalities of management of anal fissure including anal dilatation and sphinerotomy.

•

The current study analyze the outcome of lateral sphenerotomy along in the management of chronic anal fissure.

Internal anal sphincter: Clinical perspective

OBJECTIVE

To summarise current knowledge of Internal anal sphincter.

BACKGROUND

The internal anal sphincter (IAS) is the involuntary ring of smooth muscle in the anal canal and is the major contributor to the resting pressure in the anus. Structural injury or functional weakness of the muscle results in passive incontinence of faeces and flatus. With advent of new assessment and treatment modalities IAS has become an important topic for surgeons. This review was undertaken to summarise our current knowledge of internal anal sphincter and highlight the areas that need further research.

METHOD

The PubMed database was used to identify relevant studies relating to internal anal sphincter.

RESULTS

The available evidence has been summarised and advantages and limitations highlighted for the different diagnostic and therapeutic techniques.

CONCLUSION

Our understanding of the physiology and pharmacology of IAS has increased greatly in the last three decades. Additionally, there has been a rise in diagnostic and therapeutic techniques specifically targeting the IAS. Although these are promising, future research is required before these can be incorporated into the management algorithm.

Endoanal ultrasonography in fecal incontinence: Current and future perspectives

Fecal incontinence has a profound impact in a patient’s life, impairing quality of life and carrying a substantial economic burden due to health costs. It is an underdiagnosed condition because many affected patients are reluctant to report it and also clinicians are usually not alert to it. Patient evaluation with a detailed clinical history and examination is very important to indicate the type of injury that is present. Endoanal ultrasonography is currently the gold standard for sphincter evaluation in fecal incontinence and is a simple, well-tolerated and non-expensive technique. Most studies revealed 100% sensitivity in identifying sphincter defect. It is better than endoanal magnetic resonance imaging for internal anal sphincter defects, equivalent for the diagnosis of external anal sphincter defects, but with a lower capacity for assessment of atrophy of this sphincter. The most common cause of fecal incontinence is anal sphincter injury related to obstetric trauma. Only a small percentage of women are diagnosed with sphincter tears immediately after vaginal delivery, but endoanal ultrasonography shows that one third of these women have occult sphincter defects. Furthermore, in patients submitted to primary repair of these tears, ultrasound revealed a high frequency of persistent sphincter defects after surgery. Three-dimensional endoanal ultrasonography is currently largely used and accepted for sphincter evaluation in fecal incontinence, improving diagnostic accuracy and our knowledge of physiologic and pathological sphincters alterations. Conversely, there is currently no evidence to support the use of elastography in fecal incontinence evaluation.

Transanal rectal mucosectomy and partial internal anal sphincterectomy for Hirschsprung's disease

PURPOSE

Hirschsprung-associated enterocolitis (HAEC) is a serious complication of Hirschsprung's disease (HD), with generalized sepsis and high mortality rate. Although the surgical correction of HD is mostly successful, challenges remain in the management of children with repeated episodes of enterocolitis. The authors describe a novel modification of transanal rectal mucosectomy and partial internal anal sphincterectomy (TRM-PIAS) for HD.

METHODS

One hundred twenty-seven HD children aged from 8 days to 16 years who successfully underwent TRM-PIAS were reviewed. TRM-PIAS was carried out circumferentially along the anorectal line. Anterior dissection was conducted between the rectal submuscosal layer and the rectal muscular sleeve. The posterior dissection was performed along the plane between internal and external anal sphincters. Normal colon was pulled through and anastomosed to anal mucosa. Aganglionic segment, rectal mucosa, part of internal anal sphincter and posterior rectal muscular cuff were removed. Twenty-five age-matched children without defecation dysfunction were used as the control group in the study of anal resting pressure.

RESULTS

Patients were followed up for 6-12 years (median: 8.2 years). The median age at last follow-up was 12.2 years (7.2-20.1 years). The incidence of enterocolitis decreased from 33.9% (43/127) preoperatively to 1.6% (2/127) postoperatively (P<0.01). The incidence of constipation decreased from 100% (127/127) preoperatively to 2.4% (3/127) postoperatively (P<0.01). Soiling rate on postoperative 1 month was 32.3%. It gradually decreased to 1.6% 6 months later. Anorectal manometries showed that mean anal resting pressure was significantly reduced from 37.9±12.5 mm Hg preoperatively to 20.2±6.4 mm Hg on postoperative 1 month and 24.8±9.9 mm Hg on postoperative 6 months, which were similar to age-matched normal controls (27.9±9.6 mm Hg, P>0.05).

CONCLUSIONS

TRM-PIAS is effective in treatment of HD. It is associated with low postoperative HD-associated enterocolitis.

Nerves and fasciae in and around the paracolpium or paravaginal tissue: an immunohistochemical study using elderly donated cadavers

The paracolpium or paravaginal tissue is surrounded by the vaginal wall, the pubocervical fascia and the rectovaginal septum (Denonvilliers' fascia). To clarify the configuration of nerves and fasciae in and around the paracolpium, we examined histological sections of 10 elderly cadavers. The paracolpium contained the distal part of the pelvic autonomic nerve plexus and its branches: the cavernous nerve, the nerves to the urethra and the nerves to the internal anal sphincter (NIAS). The NIAS ran postero-inferiorly along the superior fascia of the levator ani muscle to reach the longitudinal muscle layer of the rectum. In two nulliparous and one multiparous women, the pubocervical fascia and the rectovaginal septum were distinct and connected with the superior fascia of the levator at the tendinous arch of the pelvic fasciae. In these three cadavers, the pelvic plexus and its distal branches were distributed almost evenly in the paracolpium and sandwiched by the pubocervical and Denonvilliers' fasciae. By contrast, in five multiparous women, these nerves were divided into the anterosuperior group (bladder detrusor nerves) and the postero-inferior group (NIAS, cavernous and urethral nerves) by the well-developed venous plexus in combination with the fragmented or unclear fasciae. Although the small number of specimens was a major limitation of this study, we hypothesized that, in combination with destruction of the basic fascial architecture due to vaginal delivery and aging, the pelvic plexus is likely to change from a sheet-like configuration to several bundles.

Proteinase-activated receptor-1 (PAR1) and PAR2 mediate relaxation of guinea pig internal anal sphincter

Activation of proteinase-activated receptor-1 (PAR1) and PAR2 stimulates contraction of the rat but relaxation of the guinea pig colon. The aim of the present study was to investigate PAR effects on internal anal sphincter (IAS) motility. We measured relaxation of isolated muscle strips from the guinea pig IAS caused by PAR agonists using isometric transducers. Reverse transcription polymerase chain reaction (RT-PCR) was performed to determine the existence of PAR. In the IAS, thrombin and PAR1 peptide agonists TFLLR-NH2 and SFLLRN-NH2 evoked moderate to marked relaxation in a concentration-dependent manner. In addition, trypsin and PAR2 peptide agonists 2-furoyl-LIGRLO-NH2, SLIGRL-NH2 and SLIGKV-NH2 produced relaxation. In contrast, both PAR1 and PAR2 inactive control peptides did not elicit relaxation. Furthermore, the selective PAR1 antagonist vorapaxar and PAR2 antagonist GB 83 specifically inhibited thrombin and trypsin-induced relaxations, respectively. RT-PCR revealed the presence of PAR1 and PAR2 in the IAS. This indicates that PAR1 and PAR2 mediate the IAS relaxation. The relaxant responses of TFLLR-NH2 and trypsin were attenuated by N(omega)-Nitro-L-arginine (L-NNA), indicating involvement of NO. These responses were not affected by tetrodotoxin, implying that the PAR effects are not neurally mediated. On the other hand, PAR4 agonists GYPGKF-NH2, GYPGQV-NH2 and AYPGKF-NH2 did not cause relaxation or contraction, suggesting that PAR4 is not involved in the sphincter motility. Taken together, these results demonstrate that both PAR1 and PAR2 mediate relaxation of the guinea pig IAS through the NO pathway. PAR1 and PAR2 may regulate IAS tone and might be potential therapeutic targets for anal motility disorders.

Lack of nitrate tolerance in isosorbide dinitrate- and sodium nitroprusside-induced relaxation of rabbit internal anal sphincter

AIM: To investigate the tolerance development against the relaxant effect of nitric oxide donating drug isosorbide dinitrate (ISDN) and sodium nitroprusside (SNP) in internal anal sphincter (IAS) smooth muscle.

METHODS: Relaxation responses of ISDN, and electrical field stimulation (EFS) were obtained before and after tolerance induction by ISDN incubation.

RESULTS: ISDN (10^-7-10^-4 mol/L) and SNP (10^-8-10^-4 mol/L) caused a concentration-dependent relaxation on the basal tonus of the isolated rabbit IAS strips. After a period of 2 h incubation of the 6 x 10^-4 mol/L ISDN the relaxation effects of ISDN and SNP did not change compared to control strips. EFS evoked frequency-dependent relaxation in internal anal sphincter smooth muscle and E_max obtained from control strips were not changed in ISDN tolerance-inducing condition. In this study nitrate tolerance was not observed in rabbit IAS smooth muscle.

CONCLUSION: This result shows that nitric oxide donating drugs relaxes the internal anal sphincter of the rabbits without the development of tolerance.