Anal acoustic reflectometry in the evaluation of the anal sphincter and the response to treatment of faecal incontinence A thesis submitted to The University of Manchester for the degree of Doctor of Medicine in the Faculty of Medical and Human Sciences 2012 Benjamin Robert Hornung School of Medicine Table of Contents Table of Figures ........................................................................................................... 6 List of Tables ............................................................................................................... 7 List of Abbreviations ................................................................................................... 8 Abstract ........................................................................................................................ 9 Declaration ................................................................................................................. 10 Copyright Statement .................................................................................................. 11 Acknowledgements .................................................................................................... 12 Publications and Presentations ................................................................................... 13 Chapter 1 .................................................................................................................. 15 Introduction .............................................................................................................. 15 1.1 Anatomy ........................................................................................................... 16 1.1.1 Pelvis .......................................................................................................... 16 1.1.2 The Pelvic Floor ........................................................................................ 16 1.1.3 Rectum and Anal Canal ............................................................................. 17 1.1.3.1 The Internal Anal Sphincter ............................................................... 18 1.1.3.2 The External Anal Sphincter .............................................................. 19 1.1.3.3 The Conjoined Longitudinal Muscle ................................................. 21 1.2 Nerve Supply .................................................................................................... 22 1.2.1 Somatic Nervous System .......................................................................... 22 1.2.2 Autonomic Nervous System ...................................................................... 22 1.3 Physiology ........................................................................................................ 23 1.3.1 Anal Sphincter Tone .................................................................................. 23 1.3.2 Anal Motility ............................................................................................. 24 1.3.3 Anal Reflexes ............................................................................................. 25 1.3.3.1 The Recto-Anal Inhibitory Reflex ..................................................... 25 1.3.3.2 The Closing Reflex ............................................................................ 26 1.3.3.3 The Cough Reflex .............................................................................. 26 1.3.3.4 The Classical Anal Reflex .................................................................. 27 1.3.4 The Anal Stretch Receptor ......................................................................... 27 1.3.5 Maintenance of continence ........................................................................ 28 1.3.6 Defaecation ................................................................................................ 29 1.4 Faecal Incontinence ......................................................................................... 31 2 1.4.1 Definition and Prevalence .......................................................................... 31 1.4.2 Aetiology ................................................................................................... 32 1.4.3 Scoring Systems ......................................................................................... 33 1.4.4 Anorectal Investigations ............................................................................ 34 1.4.4.1 Anal Manometry ................................................................................ 34 1.4.4.2 Neurophysiological Investigations ..................................................... 34 1.4.4.3 Endoanal Ultrasonography ................................................................. 35 1.4.5 Management .............................................................................................. 36 1.4.5.1 Conservative Treatment ..................................................................... 37 1.4.5.2 Surgical Treatment ............................................................................. 37 1.4.6 Sacral Nerve Stimulation ........................................................................... 38 1.4.7 Faecal Incontinence in Males .................................................................... 40 1.5 Acoustic Reflectometry .................................................................................... 42 1.5.1 Background ................................................................................................ 42 1.5.2 Urethral Pressure Reflectometry ................................................................ 42 1.5.3 Anal Acoustic Reflectometry .................................................................... 47 1.6 Aims ................................................................................................................. 51 Chapter 2 .................................................................................................................. 52 Materials and Methods ............................................................................................ 52 2.1 Ethical Approval ............................................................................................... 53 2.2 Patients ............................................................................................................. 53 2.3 Anal Acoustic Reflectometry ........................................................................... 54 2.4 Anal Manometry ............................................................................................... 56 2.5 Experimental Learning Curve .......................................................................... 57 Chapter 3 .................................................................................................................. 58 A Comparative Study Of Anal Acoustic Reflectometry And Anal Manometry In The Assessment of Faecal Incontinence ................................................................. 58 3.1 Introduction ...................................................................................................... 59 3.2 Aims ................................................................................................................. 60 3.3 Methods ............................................................................................................ 60 3.4 Results .............................................................................................................. 62 3.5 Discussion ........................................................................................................ 68 3.6 Conclusions ...................................................................................................... 71 Chapter 4 .................................................................................................................. 73 3 Anal Acoustic Reflectometry – A Novel Method For Predicting Outcome Of Sacral Nerve Stimulation For Faecal Incontinence .............................................. 73 4.1 Introduction ...................................................................................................... 74 4.2 Aims ................................................................................................................. 75 4.3 Methods ............................................................................................................ 76 4.4 Results .............................................................................................................. 78 4.5 Discussion ........................................................................................................ 83 4.6 Conclusions ...................................................................................................... 88 Chapter 5 .................................................................................................................. 89 Anal Acoustic Reflectometry In The Evaluation Of Sacral Nerve Stimulation . 89 5.1 Introduction ...................................................................................................... 90 5.2 Aims ................................................................................................................. 91 5.3 Methods ............................................................................................................ 91 5.4 Results .............................................................................................................. 94 5.5 Discussion .......................................................................................................