Morphological analysis of the external anal sphincter motor nerve and its motoneurons in the cat

To investigate the spinal neural circuitry that controls the tonus of the external anal sphincter (EAS) in the cat, the size distribution of EAS motor fibers and their motoneurons (MN) was examined, and the presence of muscle spindles in EAS musculature was also tested for. The size distribution of EAS motor fibers was examined after degeneration of afferent fibers and that of their MN was measured, after labeling the cells with horseradish peroxidase. Both distributions were unimodal, thereby demonstrating the difficulty of distinguishing between alpha and potential gamma MN; but muscle spindles were not found in the musculature. Mechanisms underlying the spinally controlled tonus of the EAS remain unclear, including the nature and role of spinal reflexes. It is argued that non-spindle sensory receptors in the anal canal may provide the sensory component of a reflex circuit that contributes to this tonus.     

新型人工肛门括约肌系统的初步实验研究

目的观察自行研制的可用于治疗肛门失禁的新型植入式人工肛门括约肌系统（AASS）控制肠腔内容物的效果。方法 AASS由体内执行、体外控制和经皮能量传输3个模块构成,体内外通过无线模式通信。选择屠宰市场购买新鲜宰杀的猪结肠40 cm共4段,将其垂直固定放置,上端开放注入糊状内容物,下端套入AASS并关闭,向肠内缓慢注入糊状物,观察不渗漏所需注入AASS的液体量及囊内压力值;实验动物为贵州小型猪1只,体质量26.2 kg。肠道准备后麻醉开腹,距肛门8 cm处横断直肠套入AASS吻合,经皮能量接收线圈植入皮下,损坏动物肛门括约肌。术后1周开始AASS工作实验,1个月后麻醉开腹,观察AASS植入状态及工作状况。结果离体实验和活体实验均提示,在较少的注水量（9.0～10.5 mL）的情况下,AASS可产生对肠壁作用均匀的压力分布（3.34～7.26 kPa）,满意控制肠内容物渗漏。离体状态下4只AASS夹闭肠管所产生压力与空夹时有很好的相似性,植入活体猪体内1个月取出时系统功能完好,仍可满意夹闭肠管控制流质肠内容物,连续夹闭0.5 h无明显缺血改变。结论 AASS可以很好地模拟正常人体肛门括约肌功能,有望成为治疗肛门失禁和直肠癌术后原位肛门控便的一种新方法。     

Research on a novel artificial anal sphincter for human incontinence

This paper discusses a novel artificial anal sphincter with sensor feedback for controlling anal incontinence. The artificial anal sphincter system is a novel hydraulic-electric muscle which mainly comprises an artificial anal sphincter, a wireless power supply subsystem, and a communication subsystem. High integration of all functional components and no wire linking to the outer device make surgical implantation easier and lower risk. The wireless power supply subsystem employs a Class-E power amplifier based on adaptive control technique, and the electromagnetic compatibility in biological tissue is analysed. With the goal of designing a reliable and safe instrument, the models of human colonic blood flow and rectum motion are developed, the biomechanical material properties of human rectum and tissue ischaemia are analysed. The results show that the deformation of the artificial anal sphincter can be controlled by the press of reservoir below the upper limit of human tissue ischaemia. In vitro experiments demonstrate the artificial anal sphincter system is a good cure for human anal incontinence problems.     

Anatomic bases of graciloplasty using end-to-side nerve pudendal anastomosis

The objective of this study was to evaluate the possibilities of reinnervation of the gracilis muscle, transposed around the anus, by the pudendal nerve using an end-to-side nerve anastomosis. This study was carried out in 14 cases (7 adult human cadavers bilaterally). The gracilis muscle and its vascular-nervous bundle have been dissected and the nerve innervating the gracilis muscle has been cut at its origin. The gracilis muscle, accompanied by its nerve, has then been transposed around the anus. The pudendal nerve has been dissected from its extrapelvic part. The reinnervation using an end-to-side nerve anastomosis has been considered as feasible when the proximal ending of the nerve of the gracilis was put into a tension-free contact with the extrapelvic part of the pudendal nerve. The extrapelvic part of the pudendal nerve has a common trunk in 12 cases. The width of the extrapelvic part of the pudendal nerve was 2.6±0.7 mm, range 1–3.5. The width of the proximal endings of the nerve innervating the gracilis muscle was 2.3±0.5 mm, range 2–3. The reinnervation of the gracilis muscle by the pudendal nerve has been possible in 14 cases. An average supplementary length of 17.4±15.4 mm was available (range 5–52). These results suggest an eventual practical aspect of this technique for the reconstruction of a functional sphincter using the gracilis muscle transposed around the anus.     

新型人工肛门括约肌系统及初步动物实验研究

目的研究可用于治疗肛门失禁的植入式人工肛门括约肌系统（artificial anal sphincter system,AASS）。方法系统由体内执行、体外控制和经皮能量传输3个模块构成,体内外通过无线模式通信。当体内直肠壁上压力超出阈值后,向体外发送排便报警信号,患者通过体外控制模块控制体内执行模块打开或关闭直肠,采用经皮能量传输模块为体内电池充电。通过1例猪的动物实验,评估在活体环境下系统各模块的可靠性和稳定性。15d后将动物解剖,观察组织变化并进行体内的腹泻实验和血供实验。结果植入体内后,体外控制模块可实时控制体内执行模块的各项操作,通过经皮能量传输充电3h,在体内可持续工作24h。拟腹泻状态下,对肠壁施加7．16kPa的压力（正常肛肠静息压为6．26～9．47kPa）,能有效抑制肠道内容物渗漏。结论AASS可以模拟正常人体肛门括约肌功能,为严重肛门失禁的患者提供了一种新的治疗方法。     

自体肌肉移植重建人工肛门括约肌

背景：有效的人工肛门括约肌重建能够改善肛门失禁患者的生存能力和生活质量。 目的：评价自体肌肉移植重建人工肛门括约肌的效果。 方法：分析自体臀大肌和股薄肌移植重建人工肛门括约肌的解剖学基础,并对应用自体臀大肌和股薄肌移植重建人工肛门括约肌的患者进行随访观察,通过评估人工肛门控便功能恢复情况以及相关并发症发生情况,明确自体臀大肌和股薄肌移植重建人工肛门括约肌的应用效果。 结果与结论：臀大肌和股薄肌均有丰富的血液供应,并且营养肌肉的动脉均有相应静脉和神经伴行。对应用自体臀大肌和股薄肌移植重建人工肛门括约肌的患者随访观察发现,患者多为直肠癌或者肛管癌,经过自体肌肉移植重建人工肛门括约肌后,均能获得较好的肛门排控便功能,较少发生肛门狭窄、肛周感染等并发症,无机体排斥反应的发生。     

The nerve branches to the external anal sphincter: the macroscopic supply and microscopic structure

The study was performed using 45 pelvic half section specimens (41 fetal ones and four adults). The macroscopic dissection followed the nerve branches from their spinal roots up to the external anal sphincter. Three nerve branches were found: the anterior ramus arising from the external perineal nerve, the inferior rectal nerve and an independent posterior branch. The anterior and the inferior rectal nerve branches always emerged from the pudendal plexus. The posterior branch arising either from S4 or from the inferior rectal nerve was only found in (31%) of our cases. Five anatomical distributions are described, percentages of every type notified. The fibre content of these nerve bundle branches was evaluated through histological sections using Heidenhain's azan stain and Luxol fast blue. The branches consisted of 2,896 to 2,137 fibres, 20% of them being unmyelinated and 80% containing various myelinated fibres. The nomenclature of these nerve branches has to be debated. The terms of anterior, middle and posterior anal nerves seem more suitable.     

国人肛门括约肌的数字化三维重建

目的通过人体连续横断面图像数据集和计算机三维重建形成数字化的肛门括约肌。方法将人体连续横断面图像数据集的括约肌部分,通过3D-MAX软件建立成数字立体的肛门括约肌三维图像。结果建立了我国第一份肛门括约肌的数字立体模型,并渲染、导出顶视图,前视图,侧视图及任意的剖面图。结论为研发集局部解剖学和肛肠科疾病于一体的教学软件及模拟手术程序,提供基础平台。     

Feedback control of TET system with variable coupling coefficients for a novel artificial anal sphincter

For treating severe faecal incontinence, the authors developed an intelligent artificial anal sphincter system (AASS) equipped with a feedback sensor that utilized a transcutaneous energy transfer system (TETS). To deliver the correct amount of power (i.e. to match the load demand under variable coupling conditions caused by changes in positioning between the coils due to fitting and changes in posture), a regulating method to stabilize output voltage with a closed loop variable-frequency controller was developed in this paper. The method via which the voltage gain characteristics of a voltage-fed series-tuned TETS were derived is also described. The theoretical analysis was verified by the results of the experiment. A numerical analysis method was used as a control rule with respect to the relationship between operating frequency and output voltage. To validate the feedback control rules, a prototype of the TET charging system was constructed, and its performance was validated with the coupling variation between 0.12–0.42. The results show that the output voltage of the secondary side can be maintained at a constant 7?V across the whole coupling coefficient range, with a switching frequency regulation range of 271.4–320.5?kHz, and the proposed controller has reached a maximal end-to-end power efficiency of 67.5% at 1?W.     

Developmental processes and ectodermal contribution to the anal canal in mice

The anorectal canal has two origins; the upper part is derived from endoderm and the lower part is derived from ectoderm. The process of ectodermal contribution to the canal remains unclear. To understand the development of this area, serial sagittal sections of mouse embryos were made every 12 h from embryonic day 13.0 (E13.0) to E18.5. Three-dimensional (3-D) reconstructions were obtained from these sections. At the time of the disappearance of the cloacal membrane (E13.5), the endodermal lining reached the site of disintegrated membrane. Thus, the whole canal was of endodermal origin. The transitional zone between the dorsal end of the primary perineum and tail was thicker than other ectodermal epithelia. In this region, it changed from an acute to obtuse angle. After it straightened out and formed the canal, the secondary perineum appeared caudally. During these processes, the external sphincter appeared in the underlying mesenchyme of the thick ectoderm and functioned as a drawstring to form the ectodermal anal canal.     

A novel puborectalis muscle artificial anal sphincter system with the module of sensory perception

This article presents a novel puborectalis muscle artificial anal sphincter system (PM-AASS) with the module of sensory perception for treating severe faecal incontinence (FI). Due to the implantable feature of PM-AASS, this system applied low-power design and the total energy consumption could drop to 48.8 Ah/d. To reduce the injury of intestine and the pressure exerted on intestine, the actuator, including the structure of tings and the robot mechanism, of PM-AASS was presented and the middle ring was optimised. To realise the sensory perception, the intestinal flexible pressure sensors, comprising the radial sensors and the axial sensors, were designed. The sensors calibration showed the R-square of each fitting line were above 0.998, which presented a high goodness of fit and indicated we could figure out the pressure value with the analogue voltage captured by MCU. Through the in-vitro experiment, the results that the radial sensors were more relevant to the occlusion threshold while the axial sensors had more effect on the alarm threshold could be concluded. The practicability of the PM-AASS was verified by the results of the in-vivo experiment, which showed that the PM-AASS had the effect of improvement to the anorectal internal pressure.     

Origins and courses of the nervous branches to the male urethral sphincter

The striated sphincter of the male urethra, the so-called rhabdosphincter, contributes significantly to urethral closure pressure. It is generally agreed that the somatic nerve fibers from the pudendal nerve innervate the rhabdosphincter, and the autonomic nerve fibers innervate the smooth muscle of the urethra. Although it is difficult to clearly identify the rhabdosphincter macroscopically, we minutely investigated the nerve branches to the urethral sphincter muscle region in 10 male pelvic halves. In addition, the origins and courses of the pudendal plexus in 88 male pelvic halves were investigated. To this region were given branches of the pudendal nerve and the pelvic plexus. The branches from the pelvic plexus to the region generally originated from S4 as the lowest branch of the pelvic splanchnic nerve, and ran along the rectal attachment of the levator ani. The caudal root of the pelvic splanchnic nerve formed a common trunk with the nerve to the levator ani (94%). Various connections were sometimes observed between the pudendal nerve and the branches medial to the levator ani. It is suggested that the somatic nerve fibers from the nerve to the levator ani or from the pudendal nerve might also join the nerve branches to the region from the pelvic plexus.

---

Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at .

---

Origine et trajet des branches nerveuses destinées au sphincter uréthral de l'homme

Résumé Le sphincter strié de l'urètre de l'homme, aussi appelé rhabdosphincter, contribue significativement a la pression de clôture de l'urètre. Il est généralement admis que les fibres somatiques du nerf pudendal innervent le sphincter strié, et que les fibres nerveuses autonomes innervent le muscle lisse de l'urètre. Ben qu'il soit difficile d'identifier macroscopiquement le sphincter strié, nous avons observé microscopiquement les branches nerveuses destinées aux muscle sphincter urétral sur dix hémi-pelvis masculins. De plus, l'origine et le trajet du plexus pudendal ont été explorés sur 88 hémi-pelvis masculins. Cette région recevait des branches du nerf pudendal et du plexus pelvien. Les branches du plexus pelvien pour cette zone provenaient en général de S4, sous la forme de la branche la plus distale du nerf splanchnique pelvien, et cheminaient le long de l'insertion rectale du muscle élévateur de l'anus. La racine caudale du nerf splanchnique pelvien formait un tronc commun avec le nerf du muscle élévateur de l'anus (94%). Des connexions variables ont parfois été observées entre le nerf pudendal et les branches médiales au muscle élévateur de l'anus. Ceci suggère que les fibres nerveuses somatiques du nerf du muscle élévateur de l'anus ou du nerf pudendal puissent rejoindre les branches nerveuses provenant du plexus pelvien.

     

Control of the internal anal sphincter (manometric study with human subjects)

Summary Manometric studies of the functions of the internal anal sphincter were performed in 73 children. Twenty-one out of these patients were normal subjects, the others had neurological lesions either central (sacral meningocele, dorsal cord transections) or peripheral (Hirschsprung's disease). It was found that the functions of the internal sphincter do not depend upon mechanical factors and are subject to nervous control. The pathways for control of the basal sphincteric tone are discussed. It is likely that this tone depends not only of the sympathetic pathways, but also of fibers of the sacral outflow. It is shown that the recto-anal inhibitory reflex is specific and independent of peristalsis. Arguments are given to prove that this reflex is an activity proper to the intra-mural plexus which is, however, subject to and regulated by the sacral cord.     

Histo-topographic study of the longitudinal anal muscle

The longitudinal anal muscle (LAM) has been described as a vertical layer of muscular tissue interposed between the circular layers of the internal (IAS) and external (EAS) anal sphincters. There is, however, no general agreement in the literature on its composition and attachments. The aim of this study was to investigate the histological structure, attachments, and topography of the LAM in order to evaluate its role in continence and defecation, thus enhancing knowledge of the surgical anatomy of this region. After in situ formalin fixation, the pelvic viscera were removed from eight male and eight female cadavers (age range: 52-72 years). Serial macrosections of the bladder base, lower rectum and anal canal, cervix and pelvic floor complex, cut in the transverse (six specimens) and coronal (six specimens) planes, underwent histological and immunohistochemical studies. Four specimens were studied using the E12 sheet plastination technique. The LAM was identified in 10/12 specimens (83%). Transverse and coronal sections made clear that it is a longitudinal layer of muscular tissue, marking the boundary between the internal and external anal sphincters. From the anorectal junction it extends along the anal canal, receives fibers from the innermost part of the puborectalis and the puboanalis muscles, and terminates with seven to nine fibro-elastic septa, which traverse the subcutaneous part of the external anal sphincter, reaching the perianal dermis. In the transverse plane, the mean thickness of the LAM was 1.68 +/- 0.27 mm. Immunohistochemical staining showed that the LAM consists of predominantly outer striated muscle fibers and smaller numbers of inner smooth muscle fibers, respectively coming from the levator ani muscle and from the longitudinal muscular layer of the rectum. The oblique fibers suggest that the LAM may represent the intermediate longitudinal course of small bridging muscle bundles going reciprocally from the striated EAS to the smooth IAS and vice versa. The spatial result is the helical course of striated and smooth muscle fibers between the EAS and IAS, which contribute not only to the narrowing but also to some shortening of the anal canal during sphincter contraction. Thus, rather than being a boundary, the LAM gives anatomical evidence of a functional connection between two muscle systems with different structures and topography.     

The ramifications of adrenergic nerve terminals in the rectum, anal sphincter and anal accessory muscles of the guinea-pig

Summary The anatomy and the adrenergic innervation of the rectum, internal anal sphincter and of accessory structures are described for the guinea-pig. The distribution of adrenergic nerves was examined using the fluorescence histochemical technique applied to both sections and whole mount preparations. The longitudinal and circular muscle of the rectum and the muscularis mucosae are all supplied by adrenergic nerve terminals. The density of the adrenergic innervation of the muscularis externa increases towards the anal sphincter. There is a very dense innervation of the internal anal sphincter, of the anal accessory muscles and of the corrugator ani. Non-fluorescent neurons in the ganglia of the myenteric plexus are supplied by adrenergic terminals. The ganglia become smaller and sparser towards the internal anal sphincter and non-ganglionated nerve strands containing adrenergic axons run from the plexus to the sphincter muscle. Adrenergic fibers innervate two interconnected ganglionated plexuses in the submucosa. Very few adrenergic nerve cells were found in the myenteric plexus and they were not found at all in the submucosa. The extrinsic arteries and veins of the pelvic region are heavily innervated by adrenergic nerves. Within the gut wall the arteries are densely innervated but there is little or no innervation of the veins.This work was supported by grants from the Australian Research Grants Committee and the National Health and Medical Research Council. We thank Professor G. Burnstock for his generous support.     

Biochemical evaluation of an artificial anal sphincter made from shape memory alloys

Severe anal incontinence is a socially incapacitating disorder and a major unresolved clinical problem that has a considerable negative impact on quality of life. In this study, we developed a new artificial anal sphincter using shape memory alloys (SMAs) in order to improve the quality of life of such patients and evaluated the influence of this sphincter on blood serum chemistry in animal experiments. The artificial anal sphincter was driven by two Ti-Ni SMA actuators sandwiching the intestine and was implanted in three female goats. Blood was collected from the jugular vein on days 1 and 4; at weeks 1 and 2; and at months 1, 2, and 3, postoperatively. Biochemical parameters including total protein, albumin, total bilirubin, aspartate amino-transferase, blood urea nitrogen, creatinine, and C-reactive protein were examined. The time courses of total bilirubin and aspartate amino transferase of the three goats were within the baseline levels after 1 week of implantation and remained normal, demonstrating no liver function complications. The blood urea nitrogen and creatinine levels remained within the normal range, indicating no renal function complications. The total protein and albumin fluctuated within the normal range throughout the duration of this study. In these goats, it was also found that the level of C-reactive protein did not increase and that there was no stricture of the intestine where the artificial sphincter was attached. Our findings indicate that the artificial sphincter SMA demonstrated no adverse influence on blood serum chemistry and exhibited an effective system performance.     

Effects of peripheral nerve lesions during pregnancy on parturition in rats

Summary Bilateral section of either the sensory or motor branch of the pelvic nerve or pudendal nerve was performed in rats on days 8–10 of pregnancy, and the effects on delivery were observed. Bilateral resection of the sensory branch of the pelvic nerve reduced the number of live pups per litter, and increased the number of stillbirths and the number of fetuses retained in utero per litter at day 24. Sectioning motor components of the pelvic nerve, or both motor and sensory components of the pudendal nerve, had no effects on delivery in rats. We conclude that of the peripheral nerves evaluated in this study, only the sensory branch of the pelvic nerve is required for normal vaginal delivery in this species.     

Design and assessment of novel artificial anal sphincter with adaptive transcutaneous energy transfer system

Abstract

This paper presents the in vitro assessment of a novel elastic scaling artificial anal sphincter system (ES-AASS) with an adaptive transcutaneous energy transfer system (TETS) for treatment of severe faecal incontinence (FI). The proposed adaptive TETS has a phase control, which can maintain the output voltage at ～?7?V across the full range of the coupling coefficient variation (from 0.09–0.31) during the whole process of charging with a phase shift of 177.5° to 79.1°. A maximum surface temperature of 42.2?°C was measured above the secondary coil during an energy transmission of 3.5?W in air. The specific absorption rate (SAR) and current density analysis of the biological three-layers structure, including the skin, fat and muscle) surrounding the coil pair were analysed and the results of simulation analysis showed that the value of SAR and current density were very small at any given transmission condition compared with the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). In conclusion, in vitro experimental results showed that the ES-AASS can control simulated faecal behaviour effectively and the performance of TETS was validated.     

Excitability of the motor cortical representation of the external anal sphincter

This study was designed to assess the excitability of the motor cortical representation of the external anal sphincter by using transcranial magnetic stimulation (TMS). In six healthy volunteers, the rest motor threshold and the duration of the cortical silent period were determined with single TMS pulses, and the intracortical inhibition and facilitation were measured with paired TMS pulses. Values obtained from the anal sphincter were compared with those obtained from a muscle in the right hand. All subjects completed the study. Rest motor threshold and intracortical facilitation were similar in both muscles. In contrast, cortical silent period duration and intra-cortical inhibition were less for the anal sphincter than for hand muscle. This study has opened new perspectives for the investigation of anal sphincter cortical control in humans.