5 E D IT O R IA L ISSN 2413-6077. IJMMR 2018 Vol. 4 Issue 1 International Journal of Medicine and Medical Research 2018, volume 4, Issue 1, p. 5-7 copyright © 2018, TSMU, All Rights Reserved Corresponding author: Janindra Warusavitarne, B Med FRACS Ph.D., Department of Surgery, St. Mark’s Hospital, London, United Kingdom E-mail: ccolorectal@btinternet.com Phone number: +07753061849 DOI 10.11603/IJMMR.2413-6077.2018.1.9198 ThE EvOLUTION Of ANOREcTAL mANOmETRy D. Wickramasinghe, J. Warusavitarne DEPARTMENT OF SURGERy, ST. MARK’S HOSPITAL, LONDON, UNITED KINGDOM The history of physiology testing The history of anorectal research can be dated back to 1200 BC to the Chester Beatty Medical Papyrus [1] which described anal diseases and contained scanty descriptions of the anal canal. This knowledge was further enhanced by the descriptions of Galen and illustrations of versalius and John Calcar. It was many centuries later that the physiology of the anal sphincter control was elucidated. In 1867, Masius identified the center of the lower spinal cord as being responsible for anal sphincter tone and reflex contractions in the dog and rabbit. During the same period, manometry studies were first carried out to study anorectal function. the first phenomenon to be described was the recto-anal inhibitory reflex reported by Gowers in 1877. This was followed by the observations of langley and Anderson where they demonstrated that in the cat, the stimulation of lumbar sympathetic nerves causes relaxation of the rectum and the contraction of the internal anal sphincter. Anorectal manometry Joltrain et al first described a method for measuring colorectal pressures in 1919. He used a rectal tube after rectal infusion to measure pressures of the lower gastro intestinal tract. this method was refined in 1940 by White et al [2] who developed the colonometrogram which was based on cystometry. This primitive device contained of a vertical glass tube ma- nometer connected in one side to an intravenous drip line and at the other end to a rectal tube (Figure 1). He used this to assess the colonic tone in patients with injuries in the brain, spinal cord, cauda equina or sacral nerves and noted that the compliance of the colon and rectum depended on the level of the lesion. Based on these initial maneuvers, Anorectal manometry (ARM) was developed. The pro- cedure involves insertion of a catheter into the anorectum and connecting it to a pressure recorder to measure the intraluminal pressure. it had first been used in assessing patients in the 1980s , although more complex procedures had been attempted several decades previously [3]. Transducers have often been developed first for oesophageal manometry and sub- sequently the same technology used to create devices for anorectal manometry. The initial devices had an intraluminal balloon. Sub- sequently water perfused and solid-state manometers had been used. Conventional manometry probes contained a few sensors that were spaced at 3-5 cm and incapable of acquiring the pressures the entire anal canal simultaneously. Therefore, they required pull- through manoeuvres or rotation to sample the entire area of interest. This prevented a con- tinuous measurement of pressures throughout the entire anal canal. Moreover, radial sensors required a pull through procedure that in- troduced motion artefacts. With the advancement of electronics and miniaturisation of sensors, more and more sensors could be fitted into the probes, and this resulted in the development of high-resolution anorectal manometry (HRARM) in 2007 [4]. In HRARM, the space between 2 adjacent sensors is less than 1 cm. Most systems have circum- ferential sensors, each with 12 pressure sensi- tive segments arranged radially. Ten of these sensors are fitted within 6 cm on the probe. the 12 sector pressures are averaged to obtain a single mean pressure value for each level. Three dimensional (3D) high definition anorectal manometry (3DHDM) was introduced in 2010 [5]. This uses 16 sensors, each with 16 radial pressure sensitive sectors, arranged over a space of 6.4 cm. This sensor arrangement for the first time provided sufficient radial re so- lution to allow accurate, simultaneous cir- cumferential assessment of the anal ASC. It is also a static test and therefore minimises motion artefacts and other confounders. Both these modern techniques are heavily dependent computer hardware and software for recording and interpolation of the data. There are several advantages and disadvantages in HRARM / 3DHDM when compared to con- ventional manometry [6] (see Table 1). D. Wickramasinghe et al. 6 E D IT O R IA L ISSN 2413-6077. IJMMR 2018 Vol. 4 Issue 1 Fig. 1. Colonometrogram, developed by White et al [2]. Table 1. Comparison of conventional manometry and HRARM / 3DHDM, From Lee et al [6] HRM / 3DHDM Conventional manometry More sensors at close intervals (continuum in space and time) E-sleeve for high-pressure zone Few sensors at wider intervals Dent sleeve for high-pressure zone Stationary examination, less discomfort Pull through, can be uncomfortable Color topographic display, better resolution allowing easier interpretation with less time lines display, poor anatomical resolution, less easy to interpret and time-consuming High resolution allows radial bedside pressure mea- surement Only circular pressure measurement More fragile, shorter life span, greater maintenance required less susceptible to wear and tear, little maintenance and seldom malfunctions ARM provides information about the resting pressure (RP), squeeze pressure (SP) and length of the anal canal (anal high pressure zone length – HPZl) by direct measurement. A balloon attached to the tip of the catheter allows additional measurements such as rectal sensory thresholds and rectoanal inhibitory reflex to be elicited. The normal pressure values for a given age and gender varies significantly, depending on the technique and the type of catheter used and thus it is recommended that every laboratory establish its own normal values for every technique. Presently, there is a classi- fication system for anal incontinence based on anorectal manometry findings [7]. D. Wickramasinghe et al. 7 E D IT O R IA L ISSN 2413-6077. IJMMR 2018 Vol. 4 Issue 1 A group of patients who are incontinent will demonstrate normal anorectal manometry findings under static conditions. they require monitoring of anorectal motor events over a prolonged period and in the fully ambulatory state. The methods used utilise micro pressure transducers with or without simultaneous EMG recordings of the EAS. Ambulatory ARM was first used in patient evaluation in the last decade of the 20th century [8]. The study by Kumar et al [8] identified that spontaneous transient relaxations of the iaS were more frequent and of longer duration in patients with idiopathic anal incontinence. Furthermore, the motility index of the rectum and colon were lower in patients with slow transit constipation. Despite the promising results, the clinical role of ambulatory ARM has not yet been established. Traditional manometry assesses the pressure in the anal canal at each level as a single value and ignores the possibility of radial asymmetry. vector manometry assesses the radial and longitudinal pressure profile along the entire length of the anal sphincter. Radial asymmetry, which is expressed as a percentage calculates the degree to which the integrated cross sections deviate from a perfect circle. The Vector Symmetry index (VSi) on the other hand, is expressed as a value from 0 to 1 [9] with values closer to 0 indicate greater asymmetry. Despite being shown to have an accuracy comparable to endoanal ultrasound and needle eMg in some studies, Yang and Wexner found that the localisation of sphincter injuries with vector manometry is poor. The diagnostic utility of anorectal ma- nometry Anorectal manometry is useful in objectively evaluating a multitude of disorders. In patients with chronic constipation, ARM helps identify patients with defaecatory disorders [10]. However, there can be significant overlap between the subtypes. Manometry can help in distinguishing weaknesses in the internal and external anal sphincters in patients with anal incontinence [10]. The response to treatment can also be serially monitored using ARM. ARM is also useful in excluding dyssynergic defae ca- tion in patients with proctalgia. References 1. Banov Jl. the Chester Beatty Medical Papyrus: the earliest known treatise completely devoted to anorectal diseases. Surgery. 1965 Dec;58(6):1037-43. 2. White JC, verlot MG, Ehrentheil O. Neurogenic disturbances of the colon and their investigation by the colonmetrogram: a preliminary report. ann Surg. 1940 dec;112(6):1042-57. 3. Duthie Hl, Watts JM. Contribution of the external anal sphincter to the pressure zone in the anal canal. gut. 1965 feb;6(1):64-8. 4. Jones MP, Post J, Crowell MD. High-resolution m a n o m e t r y i n t h e e v a l u a t i o n o f a n o r e c t a l disorders: a simultaneous comparison with water- perfused ma nometry. Am J Gastroenterol. 2007 apr;102(4):850-5. 5. Rao SS. Advances in diagnostic assessment of fecal incontinence and dyssynergic defecation. Clinical Gastroenterology and Hepatology. 2010 Nov 1;8(11):910-919.e2. 6. lee yy, Erdogan A, Rao SS. High resolution and high definition anorectal manometry and pressure topography: diagnostic advance or a new kid on the block? Curr gastroenterol Rep. 2013 dec 1;15(12):360. 7. Thekkinkattil DK, lim M, Stojkovic SG, Finan PJ, Sagar PM, Burke d. a classification system for faecal incontinence based on anorectal investigations. Br J Surg. 2008 feb;95(2):222-8. 8. Kumar D, Waldron D, Williams NS, Browning C, Hutton MR, Wingate Dl. Prolonged anorectal manometry and external anal sphincter electro- myography in ambulant human subjects. Digestive diseases and Sciences. 1990 May 1;35(5):641-8. 9. Perry RE, Blatchford GJ, Christensen MA, Thorson AG, Attwood SE. Manometric diagnosis of anal sphincter injuries. The American Journal of Surgery. 1990 Jan 1;159(1):112-7; discussion 116-7. 10. Staller K. Role of Anorectal manometry in clinical practice. Current Treatment Options in gastroenterology. 2015 dec 1;13(4):418-31. Received: 2018-05-18 D. Wickramasinghe et al. ЕВОЛЮЦІЯ АНОРЕКТАЛЬНОЇ МАНОМЕТРІЇ D. Wickramasinghe, J. Warusavitarne ST. MARK’S HOSPITAL, LONDON, UNITED KINGDOM У статті розглянуто основні віхи розвитку методу аноректальної манометрії, який вико ристо вується для об’єктивної оцінки тонусу аноректальних м’язів і скоординованості скорочень прямої кишки та сфінктерів ануса шляхом прямого вимірювання.