Carpal Tunnel Syndrome

Transcription

1 Carpal Tunnel Syndrome Louis PATRY, Occupational Medecine Physician, Ergonomist Michel ROSSIGNOL, Occupational Medecine Physician, Epidemiologist Marie-Jeanne COSTA, Nurse, Ergonomist Martine BAILLARGEON, Plastic Surgeon 1 GUIDE TO THE DIAGNOSIS OF WORK-RELATED MUSCULOSKELETAL DISORDERS

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3 GUIDE TO THE DIAGNOSIS OF WORK-RELATED MUSCULOSKELETAL DISORDERS Carpal Tunnel Syndrome Louis PATRY, Occupational Medecine Physician, Ergonomist Michel ROSSIGNOL, Occupational Medecine Physician, Epidemiologist Marie-Jeanne COSTA, Nurse, Ergonomist Martine BAILLARGEON, Plastic Surgeon

4 Canadian Cataloguing in Publication Data Main entry under title: Guide to the diagnosis of work-related musculoskeletal injuries Translation of: Guide pour le diagnostic des lésions musculo-squelettiques attribuables au travail répétitif. Includes bibliographical references. Contents: 1. Carpal tunnel syndrome 2. De Quervain s tenosynovitis 3. Shoulder tendinitis. Co-published by: Institut de recherche en santé et en sécurité du travail du Québec. ISBN (v. 1) ISBN (v. 2) ISBN X (v. 3) 1. Musculoskeletal system Wounds and injuries Diagnosis. 2. Overuse injuries Diagnosis. 3. Carpal tunnel syndrome Diagnosis. 4. Tenosynovitis Diagnosis. 5. Tendinitis Diagnosis. 6. Occupational diseases Diagnosis. I. Patry, Louis. II. IRSST (Quebec). III. Workplace Safety & Insurance Board. RC925.7.G C Translation: Graphic design: Illustrations: Les Services Organon, Steven Sacks Gérard Beaudry Rear-cover photographs: Gil Jacques Marjolaine Rondeau, Medical Illustration Department of the Laval University Hospital Centre (CHUL) Max Stiebel, Instructional Communications Centre (ICC), McGill University Legal deposit Bibliothèque nationale du Québec, 1998 Legal deposit National Library of Canada, 1998 ISBN Éditions MultiMondes (Original edition: ISBN ) Éditions MultiMondes, 1998 Éditions MultiMondes Institut de recherche en santé 930, rue Pouliot et en sécurité du travail Sainte-Foy (Québec) 505, boul. de Maisonneuve Ouest Canada G1V 3N9 Montréal (Québec) Tel.: (418) Canada H3A 3C2 Fax: (418) Tel.: (514) Fax: (514) Régie régionale de la santé et des services sociaux Montréal-Centre Direction de la santé publique 1301, rue Sherbrooke Est Montréal (Québec) Canada H2L 1M3 Tel.: (514) Fax: (514)

5 PREFACE The diagnosis of cumulative trauma disorders (CTDs) presents many unique problems, especially for physicians. The absence of precise criteria upon which to establish a clinical diagnosis of CTD or decide whether a musculoskeletal injury is related to occupational factors was noted by several members of the advisory committee supporting an international expert group mandated by the IRSST to review the literature on CTDs*. To remedy this situation, in 1992 the IRSST asked a group of researchers to develop diagnostic guides for carpal tunnel syndrome, De Quervain s tenosynovitis, and tendinitis of the shoulder. The project team was initially composed of Louis Patry, occupational medecine physician and ergonomist, and Michel Rossignol, occupational medecine physician and epidemiologist, but quickly grew and increased the scope of its expertise through the addition of Marie-Jeanne Costa, a nurse with ergonomics training, and Martine Baillargeon, a plastic surgeon. All four team members participated in the drafting of the guides. These guides were designed to help physicians arrive at a clinical diagnosis and identify the most probable etiological agents. It should be noted that these guides were not designed for administrative or legal purposes and that their reliability has not been evaluated by the researchers. The publication of these guides designed specifically for physicians is one more advance in the IRSST s efforts to shed light on the phenomenon of cumulative trauma disorders and provide specialists with appropriate tools with which to prevent these injuries and reduce related risk factors. Jean Yves Savoie Director General Institut de recherche en santé et en sécurité du travail du Québec v * Hagberg, M., Silverstein, B., Wells, R., Smith, M.J., Hendrick, H.W., Carayon, P., Pérusse, M. (1995), Work related musculoskeletal disorders (WMSDs): a reference book for prevention, scientific editors: Kuorinka, I., Forcier, L., publishers Taylor and Francis, London, 421 pages.

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7 INTRODUCTION This guide is the first of a series of practical summaries of current medical knowledge on musculoskeletal injuries with well-documented occupational etiology, namely: carpal tunnel syndrome (CTS) De Quervain s tenosynovitis tendinitis of the shoulder When occupational in origin, these injuries are often referred to as CTDs, a term applicable to problems and diseases of the musculoskeletal system that include, among their causes, some factor related to work (Hagberg et al., 1995). Whatever term is used to designate them occupational overuse syndrome (OOS), repetitive strain injuries (RSI) or cumulative trauma disorders (CTDs) in English, troubles musculo-squelettiques (TMS), lésions musculo-squelettiques (LMS), lésions musculo-tendineuses (LMS), lésions musculo-tendineuses liées aux tâches répétitives, or pathologies d hyper-sollicitation in French their defining characteristic is the presence of an injury caused by biomechanical strain due to tension, pressure, or friction which is excessively forceful, repetitive, or prolonged. This guide is designed for physicians who are called upon in the course of their practice to diagnose musculoskeletal injuries and establish the extent to which these injuries are caused by their patient s work. Its goal is to help physicians arrive at clinical and etiological diagnoses. To this end, the guide first reviews the anatomical, physiopathological, and etiological knowledge upon which diagnosis depends. This is followed by guidelines for the evaluation of symptoms, the conduct of the clinical examination, and the control of potential risk factors related to the development of the injury. Musculoskeletal injuries may have many causes. For carpal tunnel syndrome (CTS), De Quervain s tenosynovitis, and tendinitis of the shoulder, these include not only occupational, sports-related, recreational, and household activities, but also specific health problems and conditions. This guide was prepared in response to requests from physicians, increasingly preoccupied by CTDs, for information and support on this subject. Although the approach taken emphasizes the documentation of potential occupational risk factors a subject little discussed in formal medical training it does not neglect the evaluation of other potential causes of carpal tunnel syndrome. This guide is meant to be used in a clinical setting. To help physicians collect the information they need to diagnosis the injury and establish its causes, it therefore includes a series of questions, presented in readily identifiable text boxes, for them to ask their patients. These questions were derived from psycho-physical scales used by ergonomists to subjectively evaluate workload (Sinclair, 1992) and medical questionnaires developed for the diagnosis of CTS and the evaluation of functional capacity (Katz et al., 1994; Levine et al., 1993; Rossignol et al., 1995). vii

8 Should however a physician remain unable to come to a definitive conclusion about the work-relatedness of an injury after consulting this guide, she or he should continue to seek information which will enable her or him to better evaluate the occupational musculoskeletal load to which her or his patient is subjected. Finally, it should be noted that this guide does not address the issues of multiple injuries and the psychosocial aspects of musculoskeletal injuries, important as they may be for the global evaluation of the patient. viii

9 TABLE OF CONTENTS Chapter 1 General Considerations Terminology... 1 Epidemiology... 1 Anatomical Review... 1 Pathophysiology... 3 Chapter 2 Etiology Pathologies that Modify the Shape of the Carpal Tunnel or Increase the Volume of its Contents... 5 Systemic Pathologies and Specific Conditions... 5 Work-Relatedness of Musculoskeletal Strain... 5 Compression of the Median Nerve in the Carpal Tunnel... 5 Compression of the Thenar Branch of the Median Nerve... 7 Chapter 3 Differential Diagnosis Disorders of the Central Nervous System... 9 Disorders of the Peripheral Nervous System... 9 Chapter 4 Clinical Considerations Symptoms Location of Symptoms (Where?) Onset of Symptoms (When?) Characteristics of Onset (How?) Impact on Activities of Daily Living Chapter 5 Recording of Information on Exposure Factors Occupational History Previous Work Current Work Current Work and Organisational Factors Sports-related, Recreational, and Household Activities Chapter 6 Clinical Examination Observation and Palpation Provocative Tests Evaluation of Sensitivity ix

10 Strength Testing Electrophysiologic Tests Chapter 7 Summary of the Evaluation Chapter 8 Guidelines for Therapeutic and Preventive Interventions Therapeutic Guidelines Prevention Guidelines Conclusion Bibliography List of Figures Figure 1.1 Anatomy of the Carpal Tunnel... 2 Figure 1.2 Sensory Nerve Field... 2 Figure 1.3 Distal Branches of the Median Nerve (Sensory and Motor)... 2 Figure 2.1 Compression of the Thenar Branch... 7 Figure 3.1 Sites of Compression of the Median Nerve... 9 Figure 4.1 Hand and Upper Limb Diagram Figure 6.1 Bony Limits of the Carpal Tunnel Figure 6.2 Phalen s Test Figure 6.3 Tinel s Test Figure 6.4 Two-point Discrimination Test Figure 6.5 Semmes-Weinstein Test Figure 6.6 Abductor Pollicis Brevis Figure 6.7 Opponens Pollicis Figure 8.1 Therapeutic Intervention Flow-chart List of Tables Table 6.1 Clinical Provocation Tests Table 6.2 Tests of Sensory Function Table 6.3 Electrophysiologic Tests Table 8.1 Preventive Approach x List of Boxes Box 1.1 The Three Stages in the Evolution of the Progressive Form of Carpal Tunnel Syndrome... 3 Box 2.1 High-risk Activities, Movements, and Actions... 6 Box 4.1 Symptoms Reported by the Patient Box 4.2 Presentation and Clinical Severity of Symptoms... 13

11 Box 4.3 Questions about Activities of Daily Living Box 5.1 Questions about Previous Work Box 5.2 General Questions about Occupational Activities and Associated Symptoms Box 5.3 Questions about Activities that Cause Pain in the Hands or Wrist Box 5.4 Questions about Organizational Factors at Work Box 5.5 Questions about Sports-related, Recreational, and Household Activities Involving the Hands or Wrist Box 6.1 Appearance of the Arms, and State of the Wrist and Hand Tissues Box 7.1 Clinical Aspects xi

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13 1 General Considerations TERMINOLOGY The signs and symptoms of sensory and motor disorders of the hand in the median nerve field were first reported by Paget in 1854 in a patient having suffered a fracture of the wrist. The following terms were initially used to describe the observed problems: tardive paralysis of the median nerve, partial atrophy of the thenar eminence, and median neuritis. However, it was not until the work of Brain et al. in 1947 and of Phalen et al. in 1950 that the term carpal tunnel syndrome (CTS) was applied to these disorders. EPIDEMIOLOGY In Québec, the surgery rate in the general population for carpal tunnel syndrome is approximately 0.5 per men and 1.1 per women. The highest rate 2.2 per is observed among women aged 50 to 59 years. These rates are comparable to those reported by Vessey et al. (1990) for England ( ) and Liss et al. (1992) for Ontario ( ). The mean age of onset is 51 years in the general population, but only 37.4 years among individuals requesting workers compensation (Franklin et al., 1991). In 56.8% of cases, concomitant diseases or conditions are present (Stevens et al., 1992); the most common are hormonal disorders (6.1%), diabetes (6.1%), pregnancy (4.6%) and thyroid disorders (1.4%). Franklin et al. (1991) reported a CTS incidence rate of 1.74 per compensated workers in the state of Washington. The risk factors most commonly observed were repetitive wrist and forearm movements, holding the wrist at an angle (Armstrong et al., 1979), performing forceful movements (Silverstein et al., 1987), and exposure to segmental vibration and cold. Rossignol et al. s study (1990) of the occupational variation of the incidence of CTS on the island of Montreal reported that almost half of the cases (45%) of CTS occurring among manual workers are work-related. In seven occupational categories, this proportion ranged from 63% to 91%. ANATOMICAL REVIEW Anatomy of the Carpal Tunnel The carpal tunnel (Figure 1.1) is bounded posteriorly and medially by the carpal bones and anteriorly by the transverse carpal ligament. The median nerve and nine flexor tendons (four flexor digitorum superficialis, four flexor digitorum profundus tendons, and the flexor pollicis longus tendon) run through the tunnel. The pressure inside the tunnel varies as a function of the position of the wrist: it is 2.5 mm Hg when the wrist is in the neutral position, but rises to 30 mm Hg when it is completely flexed and 32 mm Hg when it is completely extended (Gelberman et al., 1981). 1

14 Guide To The Diagnosis Of Work-Related Musculoskeletal Disorders Figure 1.1 Anatomy of the Carpal Tunnel Figure 1.2 Sensory Nerve Field Median nerve Tendon of the flexor carpi radialis Transverse carpal ligament of the wrist Ulnar nerve Tendons of the flexor digitorum muscles Sensory Innervation The median nerve usually arises principally from the C6, C7, C8, and T1 nerve roots. Its sensory fibres innervate the palmar aspect of the thumb, index finger, middle finger and radial half of the ring finger, and the dorsal aspect of the tip of these fingers (Figure 1.2). The pad of the index and middle fingers constitutes its selective sensory nerve field. The palmar cutaneous branch of the median nerve innervates part of the palm and the thenar eminence of the hand; its innervation field is indicated by the shaded area in Figure 1.2. As it separates from the main body of the nerve 5-7 cm proximal to the anterior annular ligament of the wrist, it is not compressed in cases of carpal tunnel syndrome, and sensory function in the palm is usually preserved in cases of CTS (Tubiana, 1990; Dawson et al., 1990). Motor Innervation The motor branches of the median nerve innervate three muscles in the thenar eminence (the abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis) and the lumbricals of the index and middle finger (Figure 1.3). Because variant innervation patterns are common, the most reliable indicator of motor disorders of the median nerve is weakness of the abductor pollicis brevis (Dawson et al., 1990). Figure 1.3 Distal Branches of the Median Nerve (Sensory and Motor) Lumbricals 2 The autonomic nerve fibres of the median nerve control perspiration (Spinner, 1989) and innervate the superficial palmar arch and the digital vessels of the thumb, index finger, middle finger, and the radial half of the ring finger. Thenar muscles Transverse carpal ligament of the wrist

15 Work-related musculoskeletal injuries are one of the most common occupational health problems for which physicians are consulted. There is solid scientific evidence that these injuries may be occupational in origin. This guide was designed to help physicians interpret the results of a medical examination. By combining the standard clinical assessment procedure with guidelines concerning the identification of etiological factors, it helps physicians identify the cause of injury. AUTHORS Louis Patry holds a degree in medicine from Laval University and a diploma in ergonomics from the Conservatoire National des Arts et Metiers de Paris (CNAM). He is a specialist in occupational medicine, an associate member of the Royal College of Physicians and Surgeons of Canada, a professor in McGill University s Department of Epidemiology and Biostatistics and Occupational Health, and consulting physician to the Direction de la santé publique (Public Health Department), first in Québec City and currently at the MontréalCentre board. from the University of Sherbrooke, in epidemiology and community health from McGill University, and in occupational medicine from John Hopkins University. He is a professor in McGill University s Department of Epidemiology and Biostatistics and Occupational Health, co-director of the Centre for Clinical Epidemiology of the Jewish General Hospital of Montréal, and physician-epidemiologist at the Montréal-Centre board of the Direction de la santé publique (Public Health Department). Marie-Jeanne Costa holds a nursing degree from the Institut d études paramédicales de Liège and a degree in ergonomics from the École Pratique des Hautes Études de Paris. She is an ergonomics consultant and has collaborated on several studies of CTDs. She is particularly interested in the development of participatory ergonomics, specifically in the problem-resolution and diagnostic processes. Martine Baillargeon holds a degree in medicine from the Université de Montréal. She is a plastic surgeon and associate member of the Royal College of Physicians and Surgeons of Canada. After years of practising surgery she is now consulting physician, mainly in the field of musculoskeletal injuries affecting the upper limb, at the Montréal-Centre board of the Direction de la santé publique (Public Health Board). Michel Rossignol holds degrees in biochemistry and medicine