Anatomy and innervation of the rhabdosphincter of the male urethra

The striated sphincter of the male urethra and its innervation are still a subject of controversy. Essentially, two concepts of its anatomy can be found in the literature. Some authors describe the rhabdosphincter as part of the urogenital diaphragm caudal to the prostate, others as a striated muscle which extends from the base of the bladder to the “urogenital diaphragm.” In a combined anatomic-histologic study the striated sphincter and the pudendal nerve were examined by means of anatomical dissections and serial anatomical as well as histological sections of 12 male pelves. Furthermore, radical prostatectomy was performed in a cadaver specimen; subsequently, the so-called “urogenital diaphragm” was excised and then examined histologically. The varying number of striated muscle fibers caudal to the prostate is of particular interest. In fetuses, there are abundant striated muscle fibers dorsal to the membranous urethra, where they are arranged as a circular collar around the urethra. In the adult male, hardly any striated muscle fibers can be found dorsal to the urethra; in a majority of cases this region is devoid of striated muscle fibers. Inserting dorsally in the perineal body, the fibers form an omega-shaped loop around the anterior and lateral aspects of the membranous urethra. The existence of a “urogenital diaphragm” and a strong, circular, striated “external sphincter urethrae” completely encircling the urethra caudal to the apex of the prostate could not be confirmed by our anatomical and histological investigations. Our study shows that the striated muscle fibers run in a cranial direction from the bulb of the penis to the base of the bladder along the anterior and lateral aspects of the prostate and the membranous urethra. Further dissection studies revealed that the rhabdosphincter is supplied by branches of the pudendal nerve after leaving the pudendal canal. © 1996 Wiley-Liss, Inc.     

Dynamic magnetic resonance imaging of the pelvic floor in patients with idiopathic combined fecal and urinary incontinence

The etiologies of combined fecal and urinary incontinence may be interrelated but remain poorly understood. A potential variable in this process is global pelvic floor dysfunction. The aim of this study was to prospectively assess the use of phased-array, body coil dynamic MRI in identifying pelvic floor abnormalities in patients with combined incontinence symptoms. Symptomatic patients were compared to asymptomatic control subjects and were selected from those referred to the pelvic physiology laboratory with complaints of combined urinary and fecal incontinence. All patients underwent standard urodynamic studies and anorectal physiologic assessment. Colonoscopy and endoanal ultrasonography were also performed. A standardized protocol was used for dynamic MRI, and the parameters were measured using workstation software (callipers, compass, and densitometer). In the incontinent group there was a significant difference, when compared to control subjects, in the angle of the levator ani muscle arch of the levator plate complex (3.0 ± 5 degrees vs. 14 ± 10 degrees; P = 0.004), the width of the levator hiatus (58.3 ± 8 mm vs. 46.5 ± 8 mm; P = 0.001), the area and tissue density of the levator ani muscle (19.5 ±1 mm² vs. 26.9 ±1 mm²; P = 0.001, and 157.3 ± 47 pixels vs. 126.1 ± 23 pixels; P ± 0.025, respectively), and in the length of the external anal sphincter (20.0 ± 5 mm vs. 26.6 ± 13 mm; P = 0.03). Body coil dynamic MRI is a noninvasive and well-tolerated imaging modality. Our data show that it can identify changes in pelvic muscle morphology in patients with disorders of incontinence, and this may help in planning better management strategies. Presented at the Forty-Fourth Annual Meeting of The Society for Surgery of the Alimentary Tract, Orlando, Florida, May 18–21, 2003 (oral presentation), and the Eighteenth Annual SSAT Residents and Fellows Research Conference, Orlando, Florida, May 17, 2003.     

Interrater reliability and physical examination of the pubovisceral portion of the levator ani muscle, validity comparisons using MR imaging

AIMS: Defects in the pubovisceral portion of the levator ani muscle are seen with MR imaging. This study aims to determine interrater reliability of physical examination in detecting these defects, and to validate findings from physical examination using comparisons with MR images. METHODS: Two examiners palpated the pubovisceral muscles of 29 women to assess for defects in this muscle. Each examiner was blinded to the others findings. MR scans were acquired on a further 24 women after structured clinical examination by one examiner. These images were read to determine pubovisceral muscle defects, blinded to patient identifiers. Agreement between raters and between MR imaging and clinical examination were calculated. RESULTS: The two examiners had positive agreement (presence of a defect) of 72.7% and negative agreement (absence of a defect) of 83.3%. The positive agreement between physical examination and MR imaging was 27.3% and the negative agreement 86.5%. CONCLUSION: The structured physical examination to detect defects in the pubovisceral portion of the levator ani muscle can be learned as shown by good interrater agreement. However, examination alone underestimates these defects compared with MR imaging.     

Physiology: evacuation, pelvic floor and continence mechanisms

Faecal continence is defined by the ability to perceive, retain and evacuate bowel contents at socially convenient times. This is reliant upon normal function of the main involved organs (i.e. rectum, pelvic floor and anal sphincters) together with their associated sensorineural pathways. Incontinence may occur as a result of dysfunction in any one of these systems or due to factors such as systemic disease, emotion, bowel motility and stool consistency. The act of defaecation is a conscious process that involves interplay between motor and sensory elements, initiated by higher cortical function.Incontinence and evacuatory dysfunction are investigated using specialized tests that assess sphincter function and structure (anorectal manometry, endoanal ultrasound), anorectal and pelvic floor function (defaecating proctography, nerve conduction studies) and luminal integrity and colonic function (transit studies and endoscopy).     

Quantification of pelvic floor muscle strength in female urinary incontinence: A systematic review and comparison of contemporary methodologies

Aims

There remains no gold standard for quantification of voluntary pelvic floor muscle (PFM) strength, despite international guidelines that recommend PFM assessment in females with urinary incontinence (UI). Methods currently reported for quantification of skeletal muscle strength across disciplines are systematically reviewed and their relevance for clinical and academic use related to the pelvic floor are described.

Methods

A systematic review via Medline, PubMed, CINHAL, and the Cochrane database using key terms for pelvic floor anatomy and function were cross referenced with skeletal muscle strength quantification from 1946 to 2016. Full text peer‐reviewed articles in English having female subjects with incontinence were identified. Each study was analyzed for use of controls, type of methodology as direct or indirect measures, benefits, and limitations of the technique.

Results

A total of 1586 articles were identified of which 50 met the inclusion criteria. Nine methodologies of determining PFM strength were described including: digital palpation, perineometer, dynamometry, EMG, vaginal cones, ultrasonography, magnetic resonance imaging, urine stream interruption test, and the Colpexin pull test. Thirty‐two percent lacked a control group.

Conclusion

Technical refinements in both direct and indirect instrumentation for PFM strength measurement are allowing for sensitivity. However, the most common methods of quantification remain digital palpation and perineometry; techniques that pose limitations and yield subjective or indirect measures of muscular strength. Dynamometry has potential as an accurate and sensitive tool, but is limited by inability to assess PFM strength during dynamic movements.     

Reliability of speed of contraction and endurance dynamometric measurements of the pelvic floor musculature in stress incontinent parous women

AIMS: To evaluate the test-retest reliability of dynamometric measurements of the pelvic floor muscles (PFM) during speed and endurance tests. METHODS: Nineteen parous women suffering from stress urinary incontinence (SUI) participated in the study. Two PFM evaluation sessions were conducted using the dynamometric speculum. For the speed test, the women were instructed to contract maximally and relax as quickly as possible during a 15-s test period. The speed of contraction was quantified by the rate of force development of the first contraction and the number of contractions performed. The maximal strength value attained during the speed test was also extracted from the curves. For the endurance test, the subjects were asked to maintain a maximal contraction for 90 s. The normalized area under the force curve was utilized as the endurance parameter. The reliability of the data was evaluated using the generalizability theory. Two reliability estimates were calculated, the dependability indices (Phi) and the standard error of measurement (SEM), for one measurement session involving one trial. RESULTS: The indices of dependability obtained indicate that the reliability of the speed of contraction and endurance parameters are good (Phi=0.79-0.92). The corresponding SEMs were 1.39 N/s, 1 contraction, 1.00 N, and 298%*s for the rate of force development, number of contractions, maximal strength and normalized area, respectively. CONCLUSION: This study indicates that the speed of contraction and endurance parameters possess good test-retest reliability. The inclusion of these parameters in the PFM assessment is therefore highly recommended for assessing changes in PFM in incontinent women.     

男性获得性尿失禁的治疗进展

男性获得性尿失禁发病率在近年来有所上升,严重影响患者的生活质量。依照尿失禁的轻重程度其治疗方法有不同的选择,中度尿失禁可以通过盆底锻炼、生物反馈以及药物治疗得以缓解;而重度尿失禁则需要一些积极治疗,如注射疗法、人工尿道括约肌以及球部尿道悬吊术等。本文对男性获得性尿失禁的主流治疗进展作一综述,但是对于新兴的干细胞治疗介绍较少。     

Magnetic resonance imaging of the pelvic floor in the postpartum patient

Magnetic resonance imaging (MRI) was used to assess anatomical changes in the pelvic floor after childbirth. Six women underwent serial MRI examination within 30 hours and at 1 week, 2 weeks, 6 weeks and 6 months after delivery; 8 additional women were studied only within 30 hours of delivery. T-1 and T-2-weighted images of the pelvis in the transverse and sagittal planes with a 1.5-T MR imager were obtained. In the sagittal section we assessed the urethrovesical angle, urethral length, distance from the symphysis to the proximal and distal vagina, vaginal length, width and length of the sphincters, and the presence of sphincter defects. Axial sections were assessed for sphincter defects for the distance between the symphysis and midurethra, vagina and rectum. Only one parameter (distance between symphysis and distal vagina) changed significantly over time, without a clear trend in direction. Interobserver variation was reasonable (<15%) except for anal canal length, urethral length and distance between symphysis and anus. There were no significant correlations between birthweight and MRI parameters. There was a non-significant association (P=0.09) between the sole combined sphincter defect and rectal injury, but not with episiotomy or parity. We concluded that it is feasible to determine multiple measurements on MR images to evaluate structures of the pelvic floor.EDITORIAL COMMENT: Although the presented study has multiple limitations — i.e. small sample size, no control group, static images, lack of correlated symptomatology — the investigators show that magnetic resonance imaging can be used to follow the natural course of pelvic floor changes after vaginal delivery. Hopefully this work will be continued and expanded, shedding more light on the effects of childbirth on pelvic floor anatomy and function.     

Static magnetic resonance imaging of the pelvic floor muscle morphology in women with stress urinary incontinence and pelvic prolapse

In a study, the magnetic resonance imaging (MRI) findings of 69 women were analyzed to define the typical MRI appearance of the pelvic floor musculature in healthy subjects (n = 20) and women with urinary incontinence (UI) and/or genitourinary prolapse (GP) (n = 49). The following parameters were determined: thickness and signal intensity of the levator muscles on each side, distance between the urethra and symphysis, diameter of the proximal urethra, and thickness and configuration of the anterior vaginal wall. These parameters were correlated with the patients' age and parity, urodynamic parameters, and the clinical assessment of the pelvic floor. In contrast to healthy subjects, the frequent findings in women with UI and/or GP are higher signal intensity of the levator muscles (p < 0.05) and loss of the hammock-like configuration of the vagina (p < 0.01). On static MRI, the morphometry of the levator musculature identified no findings typical of either UI or GP. Analysis of MRI combined with patients' parity suggests that the severity of damage to the pelvic floor at delivery is determined by the traumatic event as such and not by the number of deliveries. Urethral diameter, distance of the symphysis to the urethra, and vaginal wall thickness cannot distinguish between controls and women with UI and/or GP. Urodynamic and functional clinical parameters do not correlate with the changes in the pelvic floor musculature demonstrated by static MRI. Although morphological changes in UI and/or GP can be demonstrated by MRI, they can be assigned a pathogenic role only if clinical symptoms are present. Neurourol. Urodynam. 17:579–589, 1998. © 1998 Wiley-Liss, Inc.