Basic Gastroenterology. Including Diseases of the Liver PDF
Preview Basic Gastroenterology. Including Diseases of the Liver
Basic Gastroenterology including Diseases of the Liver Alan E. Read MD FRCP Professor of Medicine, University of Bristol R. F. Harvey MD FRCP Consultant Physician, Frenchay Hospital, Bristol Lecturer in Medicine, University of Bristol and J. M. Naish MD FRCP Emeritus Consultant in Medicine, Avon Area Health Authority (T) with Chapters by L. R. Celestin FRCS Consultant Gastroenterological Surgeon, Frenchay Hospital, Bristol K. T. Evans FRCP DMRD FRCR Professor of Radiology, Welsh National School of Medicine, Cardiff and G. M. Roberts MD MRCP DMRD FRCR Consultant Radiologist, Welsh National School of Medicine, Cardiff THIRD EDITION BRISTOL: JOHN WRIGHT & SONS LTD © Alan E. Read, Richard F. Harvey and John M. Naish. 1981 Department of Medicine, Bristol Royal Infirmary, Bristol, BS2 8HW All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, photo- copying, recording, or otherwise, without the prior permission of the Copyright owner. Published by John Wright & Sons Ltd, 42-44 Triangle West, Bristol, BS8 1EX First edition 1965 Second edition 1974 Third edition 1981 British Library Cataloguing in Publication Data Read, Alan Ernest Basic gastroenterology. - 3rd ed. 1. Digestive organs - Diseases I. Title II. Harvey, R F III. Naish, John Michael 616.3 RC801 ISBN 0 7236 0551 3 Printed in Great Britain by John Wright & Sons Ltd, at The Stonebridge Press, Bristol, BS4 5NU PREFACE The practice of gastroenterology as a specialty has become widespread throughout the world since the first edition of this book appeared. At the same time there have been many major advances in our understanding of the workings of the gastrointestinal tract, both in normal circumstances and in disease states. Increasing numbers of physicians and basic scientists are making gastroenterology their special field of interest, as are many surgeons, radiologists and pathologists. National and international groups with a mutual interest in particular aspects of the subject, whether organs such as the liver or pancreas or functions such as motility or secretion, continue to proliferate. On the clinical side also there have been major advances. New types of diagnostic apparatus, often complex and costly, have appeared. New biochemical and radiological techniques have been developed. Powerful drugs, notably the histamine H-receptor blockers, have become available 2 for clinical use. Against this background of rapid advance, we have completely rewritten a large part of this book and introduced many new illustrations. As before, we have attempted to produce a volume which is an introduction to the fundamentals of gastroenterology, covering the field in a clinically- orientated and practical fashion. A.E.R. R.F.H. J.M.N. v Chapter 1 The Nervous System and the Gastrointestinal Tract This complex subject must be introduced early, because to understand the symptoms of particular diseases it is vital not only to appreciate the way in which the emotions may react upon those organs, but also to recognize the importance of the functional derangements to which the alimentary tube is prone. Each organic disease must always be differentiated from the functional disturbance which mimics it, and each patient, whether his affliction is mainly structural or mainly functional, must be treated as a whole. Many patients with an organic disease actually suffer from the functional disturbances triggered by the organic disease. Since patients do not die from them, the understanding of functional disorders is inhibited by the absence of pathological material. Knowledge is gained, not only from the experience of sufferers, but from animal experiments, the relevance of which may readily be doubted. The physio- logist usually designs his experiments with organs which purposely have been detached from their normal regulatory device, the emotions. Experi- ments on human volunteers, or on patients whose organs have been exposed at operation, often throw light on the disorders (as distinct from the diseases) of the gut, but it must be confessed that knowledge is derived mainly from clinical experience. For these reasons the subject is one which appeals more to the practising doctor than to the student. The latter, work- ing amongst the unrepresentative patient population of a hospital, is often unaware of the magnitude of the problem and the gaps in our knowledge, but later when his responsibilities are wide he will thirst to know more. This, therefore, must be a short introduction to a very big problem. AETIOLOGY To a large extent everyone is subject to nervous disorders of the gut. Few students can have escaped pre-examination nausea, few athletes pre-race diarrhoea. If the stimulus to gut disorder, whether it be fear, rage, or sexual excitement, is easily recognized by the sufferer, he will accept it. 1 2 BASIC GASTROENTEROLOGY But if the emotional cause of his discomforts is not obvious to him, and if it continues, then he will feel ill. This is the simplest concept, but behind environmental stress lies the constitution. Some people are born with such delicately tuned autonomic systems that 'the agitations of the soul communicate themselves directly to the body'. Alvarez (1956) tells the story of a man who dearly loved to play poker, but so intense were his reactions that when he drew a full house his face flushed and he often vomited. Another patient had diarrhoea not only after food but at the sight or sound of food. When walking in the town he had to cross the street to avoid restaurants, smells from which would provoke urgent defaecation. Yet another story concerns a girl, who, when a proposal of marriage was made to her in a restaurant, promptly vomited. Her would-be husband was so upset by this that he did not dare to mention the subject again for a year! Given, then, a finely adjusted nervous system and some physical or nervous stress, unpleasant symptoms rapidly assume the character of an illness. If, in addition, the patient becomes worried over the meaning of the symptoms, perhaps fearing cancer, the condition will become intract- able. Alternatively, the patient quite subconsciously may find in the symptoms and consequent invalidism a way of escape from an intolerable emotional situation, and then again chronicity ensues. There is certain experimental evidence which illustrates the workings of emotion of the gut. In animals under local anaesthesia, gut movements can be seen to be influenced by a variety of external stimuli, but section of the autonomic nerve supply abolishes these effects. In humans observed during radiological screening, gastric motility is inhibited and emptying of barium from the stomach is much slower if the patient is tense and anxious. Changes of mucosal colour and motility in response to emotion have been observed in the colon and stomach. Anxiety has been shown to produce strong non-propulsive contractions of the colon and may aggravate symp- toms in patients with the irritable bowel syndrome. It is easier to understand some of the mechanisms whereby disorders such as nausea, vomiting, abdominal cramps, diarrhoea and constipation are caused than it is to understand how stress may cause a peptic ulcer to bleed or colitis to 'flare up'. Aetiological concepts of psychosomatic disease are nebulous and rudimentary. CLINICAL PICTURE (Fig. 1.1) Some of the gastrointestinal manifestations of the neuroses can be summarized as follows: 1. Anxiety State due to: a. Simple anxiety over a situation THE NERVOUS SYSTEM AND THE GASTROINTESTINAL TRACT 3 Fig. 1.1. Gastrointestinal symptoms due to anxiety and depression. b. Neurotic or excessive anxiety c. Nosophobia (fear of certain diseases) Symptoms in Gastrointestinal Tract. Dry mouth and foul breath. Intest- inal colic and rumbling. Nausea and heartburn. Discomfort after food. Diarrhoea. 2. Depression due to: a. Undermining physical disease b. Emotional stress c. Endogenous Symptoms in Gastrointestinal Tract. Loss of appetite and resulting loss of weight. Nausea and discomfort after eating. Constipation. Conviction that serious organic disease is present. 4 BASIC GASTROENTEROLOGY 3. Obsessional States Symptoms. Worries about bad breath and dirty tongue. Food fads. Air swallowing and belching. Abdominal bloating and distension with consti- pation. Diarrhoea which prevents social activities. Fixed conviction about poisoning, 'germs', etc. In addition to the manifestations of fear, anxiety, depression and obsession, there are a number of other reasons for gastrointestinal distress which are not caused by structural disease. They can be grouped as follows: A. Constitutional Inadequacy There are patients who continually develop symptoms as a result of minor stresses and disappointments. They have an 'over-awareness' of their autonomic processes. Usually they are more comfortable when leading a quiet and restricted life. There is a continually changing pattern of symp- toms, amongst which feelings of distension, disorders of appetite and dietary fads are prominent. B. Habit Errors Food bolting and aerophagy cause belching and feelings of distension in the epigastrium. Over-purgation may cause cramps, rumblings, nausea and heartburn. Smoking may cause strong segmentation movements of the colon with reflex nausea, distension and heartburn. Eating in noisy or worrying surroundings may cause the same group of symptoms. C. Self-injury Patients often consciously or unconsciously manipulate their relatives, friends, or employers by utilizing the functional virtuosity of the gastro- intestinal tract. There are various clinical syndromes of this type, each of varying degrees of severity, in which the borderline between deliberate self-injury and a psychiatric disorder is often blurred. 1. Psychogenic Vomiting. In this disorder the patient characteristically vomits at intervals, sometimes without preceding nausea, loss of appetite or weight. No organic disease is present, and usually despite prolonged or repeated vomiting the patient remains well. Some, however, develop profound electrolyte changes, predominantly a hypokalemic alkalosis. One such patient in Bristol has been admitted to hospital on 30 occasions over a period of 7 years with severe muscle weakness due to marked potassium loss in the vomited gastric juice. THE NERVOUS SYSTEM AND THE GASTROINTESTINAL TRACT 5 2. Anorexia Nervosa. This is potentially a more serious condition, seen predominantly, but not exclusively, in young women soon after the menarche. They are said often to be rebelling against dominant mothers, and they reject the female role. This leads them to a horror of growing round and plump, particularly if (as is often the case) they have previously been overweight, and they therefore starve themselves to maintain their juvenility. They develop a horror of food, especially carbohydrates. Pituitary function declines as a result of the starvation and they cease to menstruate. Secondary sex characteristics such as breast development and axillary and pubic hair are generally maintained, an important distinction from primary pituitary disease. Death may occur as a result of intercurrent infection such as gastroenteritis, but the prognosis is not so serious as it was in the past. Seventy per cent get better within three years, and progress is hastened if they can be removed from the anxiety-laden atmosphere of their own home. However, management is often difficult, requiring hospital admission and psychiatric help. As the condition is essentially one in which the patient is trying to manipulate or punish her parents, they usually tend to return to do so. In severe cases patients may pretend to eat when under observation, but either conceal the food or retire to the lavatory immediately after meals so that they can secretly vomit back the food eaten. Treatment with chlorpromazine, insulin, enteric feeding via a small bore nasojejunal tube or intravenous feeding may be tried in such circumstances, but are often of only temporary benefit and the mortality rate in such self- destructive patients is considerable. 3. Purgative Addiction. Some people develop the habit of regularly taking some form of laxative, often not because they are constipated, but for some irrational reason. This habit is usually harmless, but in some cases develops into a condition where the patient feels unable ever to open his or, more usually, her bowels without the help of one or more varieties of laxative. In severe cases of self-purgation hypokalemia may result, the cause of which may be missed if the patient does not admit to taking laxatives. Over-treatment with anthraquinones (e.g. senna) may perman- ently damage the myenteric plexus of the colon, and produce characteristic abnormalities on barium enema examination. Purgative addicts may complain of diarrhoea, of intractable (supposed) constipation, or of symptoms related to hypokalemia. Sigmoidoscopy may show brownish pigmentation of the mucosa 'melanosis coli', and on occasions the skin of such patients also may be pigmented, and there may be clubbing of the fingers. 4. Munchausen Syndrome. Some patients may pose a very difficult diagnostic problem by deliberately pretending to have non-existent symp- toms, which they describe with a wealth of corroborative detail. This will 6 BASIC GASTROENTEROLOGY often include a past history of various obscure illnesses and/or hospital admissions. Asher has described such patients as having Munchausen syndrome, after the literary Baron famous for his tall stories. The com- monest 'variety' of this syndrome seen in gastroenterological practice is a patient with recurrent abdominal pain who presents with the appearance of some intra-abdominal catastrophe and who may derive a morbid satis- faction from either (a) obtaining strong analgesics, e.g. pethidine injections, (b) being admitted to hospital amid scenes of drama and confusion, or even (c) undergoing completely unnecessary investigations or even opera- tion. Asher called this variant 'laparotomophilia migrans', and this possibility should be borne in mind in all patients where there is a conflict between the history of pain and the objective findings. A further type of patient may claim to have vomited blood or passed blood rectally ('haemorrhagica histrionica' of Asher's classification). Such claims are difficult to disprove when patients arrive with this story in the casualty department, and most are admitted to hospital for observa- tion, usually late at night, pending further and invariably negative investigations. When confronted the patient usually denies previous illnesses which are known to be associated with his activities — he becomes abusive and discharges himself to repeat the performance at another hospital. The danger is that on occasions organic disease may be present and will be wrongly ascribed to the underlying psychological problem. Most casualty departments have a 'black list' of the likely candidates for this diagnosis. D. Spasmodic Disorders Under this heading are included diseases which are essentially functional but which are not necessarily related to neurosis. Often there is a genetic predisposition, and organic changes may result from disordered motility patterns if they continue long enough. The best example of such a disease is the irritable colon syndrome, which is often linked to irritability and reflex disorders of other parts of the gastrointestinal tract. Some patients with this condition may ultimately develop a hypertrophy of the circular muscle of the sigmoid colon, and possibly diverticular disease (Chapter 20). Similar types of neuromuscular disorders are encountered in the oesopha- gus, and here also diverticula may develop in time (Chapter 3). It must be remembered that irritability and disordered muscular activity of one part of the gut is often associated with similar disturbances in another part. A good example of this is the heartburn which often accompanies irritable colon symptoms. DIAGNOSIS The experienced gastroenterologist may often suspect, after the patient's opening remarks, that his symptoms are due to a functional disturbance. THE NERVOUS SYSTEM AND THE GASTROINTESTINAL TRACT 7 From then on he will modify his interview technique, no longer relying on the straight answer to a question. The reason for this change of tactic is that the emotionally disturbed patient is often unable to give a coherent account of his symptoms; thus attempts to pressure him will only give a false picture in the mind of the physician and will effectively cut him off from the patient's inward fears which are the root cause of his abdominal distress. Interviews of such patients should be leisurely and permissive, with the physician relaxed as the patient talks. If he 'dries up', his last few words should be repeated with interest and curiosity; 'you were saying?' is a useful phrase. It must be remembered that the diagnostic interview is often the first step in therapy, and for this reason it must proceed gently and skilfully. Gradually a pattern will emerge which will suggest one or other of the groups of conditions mentioned earlier. There are two important guiding principles to be followed in the process of diagnosis. First, we should not make a firm diagnosis of a purely functional disorder until organic disease has been excluded. Secondly, we should not diagnose a condition as functional simply because we think that we have excluded organic disease. The diagnosis of a functional disorder must be firmly based on positive evidence which points to emotional involvement. For instance, we should look for: 1. A cause for anxiety or depression. 2. An insecure background with a history of nervous inadequacy. 3. A pattern of symptoms which suggests exaggeration or inhibition of normal function. 4. Symptoms too widespread to be accounted for by a structural disease. Lastly, though organic disease may exist, symptoms may be entirely due to functional disorders. The first general principle raises a difficult question — how far to carry the process of investigation to exclude organic disease. In some cases it may be unnecessary to do more than a thorough physical examination, in other cases simple screening tests such as a haemoglobin estimation, plasma viscosity or ESR, and faecal occult blood tests may be required. In all cases of dyspepsia with an element of cancerphobia it is best to have a barium meal done. The whole question must be decided on the index of clinical suspicion. Thus, if the diagnosis appears clear and positive, no investigations are necessary, but if the four criteria of a functional disorder are not present and if the trend of clinical suspicion is towards organic disease, then a very meticulous and thorough investigation may be demand- ed. It should not be forgotten, however, that repeated investigations in the milieu of a large hospital are damaging to the frightened or neurotic patient, who needs, above all, confident diagnosis and firm management, with as few investigations as possible.
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