Purse-string Morphology of External Anal Sphincter Revealed by Novel Imaging Techniques

Overview

Journal Am J Physiol Gastrointest Liver Physiol

Publisher American Physiological Society

Specialties Gastroenterology
Physiology

Date 2014 Jan 25

PMID 24458022

Citations 13

Authors

Ravinder K Mittal

Valmik Bhargava

Geoff Sheean

Melissa Ledgerwood

Shantanu Sinha

Affiliations

Soon will be listed here.

Abstract

The external anal sphincter (EAS) may be injured in 25-35% of women during the first and subsequent vaginal childbirths and is likely the most common cause of anal incontinence. Since its first description almost 300 years ago, the EAS was believed to be a circular or a "donut-shaped" structure. Using three-dimensional transperineal ultrasound imaging, MRI, diffusion tensor imaging, and muscle fiber tracking, we delineated various components of the EAS and their muscle fiber directions. These novel imaging techniques suggest "purse-string" morphology, with "EAS muscles" crossing contralaterally in the perineal body to the contralateral transverse perineal (TP) and bulbospongiosus (BS) muscles, thus attaching the EAS to the pubic rami. Spin-tag MRI demonstrated purse-string action of the EAS muscle. Electromyography of TP/BS and EAS muscles revealed their simultaneous contraction and relaxation. Lidocaine injection into the TP/BS muscle significantly reduced anal canal pressure. These studies support purse-string morphology of the EAS to constrict/close the anal canal opening. Our findings have implications for the effect of episiotomy on anal closure function and the currently used surgical technique (overlapping sphincteroplasty) for EAS reconstructive surgery to treat anal incontinence.

Citing Articles

Pelvic floor and perineal muscles: a dynamic coordination between skeletal and smooth muscles on pelvic floor stabilization.

Muro S, Akita K Anat Sci Int. 2023; 98(3):407-425.

PMID: 36961619 PMC: 10256674. DOI: 10.1007/s12565-023-00717-7.

Understanding the physiology of human defaecation and disorders of continence and evacuation.

Heitmann P, Vollebregt P, Knowles C, Lunniss P, Dinning P, Scott S Nat Rev Gastroenterol Hepatol. 2021; 18(11):751-769.

PMID: 34373626 DOI: 10.1038/s41575-021-00487-5.

A missing distal complex of the external and internal anal sphincters: a macroscopic and histologic study using Japanese and German elderly cadavers.

Ishiyama G, Kim J, Chai O, Viebahn C, Wilting J, Murakami G Surg Radiol Anat. 2020; 43(5):775-784.

PMID: 33135107 DOI: 10.1007/s00276-020-02606-4.

Evaluation of Age- and Radical-Prostatectomy Related Changes in Male Pelvic Floor Anatomy Based on Magnetic Resonance Imaging and 3-Dimensional Reconstruction.

Tai J, Sorkhi S, Trivedi I, Sakamoto K, Albo M, Bhargava V World J Mens Health. 2020; 39(3):566-575.

PMID: 32648374 PMC: 8255398. DOI: 10.5534/wjmh.200021.

Loop analysis of the anal sphincter complex in fecal incontinent patients using functional luminal imaging probe.

Zifan A, Mittal R, Kunkel D, Swartz J, Barr G, Tuttle L Am J Physiol Gastrointest Liver Physiol. 2019; 318(1):G66-G76.

PMID: 31736339 PMC: 6985842. DOI: 10.1152/ajpgi.00164.2019.

References

Halverson A, Hull T . Long-term outcome of overlapping anal sphincter repair. Dis Colon Rectum. 2002; 45(3):345-8. DOI: 10.1007/s10350-004-6180-6. View

Bo K, Lilleas F, Talseth T, Hedland H . Dynamic MRI of the pelvic floor muscles in an upright sitting position. Neurourol Urodyn. 2001; 20(2):167-74. DOI: 10.1002/1520-6777(2001)20:2<167::aid-nau19>3.0.co;2-4. View

Heemskerk A, Strijkers G, Vilanova A, Drost M, Nicolay K . Determination of mouse skeletal muscle architecture using three-dimensional diffusion tensor imaging. Magn Reson Med. 2005; 53(6):1333-40. DOI: 10.1002/mrm.20476. View

Liu J, Guaderrama N, Nager C, Pretorius D, Master S, Mittal R . Functional correlates of anal canal anatomy: puborectalis muscle and anal canal pressure. Am J Gastroenterol. 2006; 101(5):1092-7. DOI: 10.1111/j.1572-0241.2006.00596.x. View

Sotiropoulos S, Bai L, Morgan P, Auer D, Constantinescu C, Tench C . A regularized two-tensor model fit to low angular resolution diffusion images using basis directions. J Magn Reson Imaging. 2008; 28(1):199-209. DOI: 10.1002/jmri.21380. View

Sinha S, Sinha U . In vivo diffusion tensor imaging of the human prostate. Magn Reson Med. 2004; 52(3):530-7. DOI: 10.1002/mrm.20190. View

Raj Rajasekaran M, Sohn D, Salehi M, Bhargava V, Fritsch H, Mittal R . Role of puborectalis muscle in the genesis of urethral pressure. J Urol. 2012; 188(4):1382-8. DOI: 10.1016/j.juro.2012.06.001. View

Kinugasa Y, Arakawa T, Abe H, Abe S, Cho B, Murakami G . Anococcygeal raphe revisited: a histological study using mid-term human fetuses and elderly cadavers. Yonsei Med J. 2012; 53(4):849-55. PMC: 3381476. DOI: 10.3349/ymj.2012.53.4.849. View

Raizada V, Bhargava V, KARSTEN A, Mittal R . Functional morphology of anal sphincter complex unveiled by high definition anal manometery and three dimensional ultrasound imaging. Neurogastroenterol Motil. 2011; 23(11):1013-9, e460. PMC: 3190080. DOI: 10.1111/j.1365-2982.2011.01782.x. View

10.

Peschers U, DeLancey J, Fritsch H, Quint L, Prince M . Cross-sectional imaging anatomy of the anal sphincters. Obstet Gynecol. 1997; 90(5):839-44. DOI: 10.1016/S0029-7844(97)00406-7. View

11.

Fritsch H, Brenner E, Lienemann A, Ludwikowski B . Anal sphincter complex: reinterpreted morphology and its clinical relevance. Dis Colon Rectum. 2002; 45(2):188-94. DOI: 10.1007/s10350-004-6144-x. View

12.

Bharucha A . Pelvic floor: anatomy and function. Neurogastroenterol Motil. 2006; 18(7):507-19. DOI: 10.1111/j.1365-2982.2006.00803.x. View

13.

Gaige T, Kwon H, Dai G, Cabral V, Wang R, Nam Y . Multiscale structural analysis of mouse lingual myoarchitecture employing diffusion spectrum magnetic resonance imaging and multiphoton microscopy. J Biomed Opt. 2009; 13(6):064005. DOI: 10.1117/1.3046724. View

14.

Goh V, Tam E, Taylor N, Stirling J, Simcock I, Jones R . Diffusion tensor imaging of the anal canal at 3 tesla: feasibility and reproducibility of anisotropy measures. J Magn Reson Imaging. 2011; 35(4):820-6. DOI: 10.1002/jmri.22873. View

15.

Lansdown D, Ding Z, Wadington M, Hornberger J, Damon B . Quantitative diffusion tensor MRI-based fiber tracking of human skeletal muscle. J Appl Physiol (1985). 2007; 103(2):673-81. PMC: 4440488. DOI: 10.1152/japplphysiol.00290.2007. View

16.

Hussain S, Stoker J, Lameris J . Anal sphincter complex: endoanal MR imaging of normal anatomy. Radiology. 1995; 197(3):671-7. DOI: 10.1148/radiology.197.3.7480737. View

17.

Cheeney G, Remes-Troche J, Attaluri A, Rao S . Investigation of anal motor characteristics of the sensorimotor response (SMR) using 3-D anorectal pressure topography. Am J Physiol Gastrointest Liver Physiol. 2010; 300(2):G236-40. PMC: 3043653. DOI: 10.1152/ajpgi.00348.2010. View

18.

Niitsu M, Campeau N, Riederer S, Ehman R . Tracking motion with tagged rapid gradient-echo magnetization-prepared MR imaging. J Magn Reson Imaging. 1992; 2(2):155-63. DOI: 10.1002/jmri.1880020208. View

19.

Arakawa T, Hayashi S, Kinugasa Y, Murakami G, Fujimiya M . Development of the external anal sphincter with special reference to intergender difference: observations of mid-term fetuses (15-30 weeks of gestation). Okajimas Folia Anat Jpn. 2010; 87(2):49-58. DOI: 10.2535/ofaj.87.49. View

20.

Whitehead W . Control groups appropriate for behavioral interventions. Gastroenterology. 2004; 126(1 Suppl 1):S159-63. DOI: 10.1053/j.gastro.2003.10.038. View