Gabriele Bammer editor and coordinator

The Neurogenic Hypothesis of RSI

John Quintner and Robert Elvey

WORKING PAPER NUMBER 24 Discussion Papers on the of Work-Related Neck and Upper Limb Disorders and the Implications for Diagnosis and Treatment

Gabriele Bammer editor and coordinator

The Neurogenic Hypothesis of RSI

John Quintner and Robert Elvey

WORKING PAPER NUMBER 24

Commentaries: Trevor Beswick and Annette Cursley David Champion Milton Cohen Malcolm Harrington and Paul Bacon Earl Owen Richard Pearson Campbell Semple Gisela Sj0gaard Eira Viikari-Juntura Patrick Wall Richard Wigley

May 1991

NATIONAL CENTRE FOR EPIDEMIOLOGY AND POPULATION HEALTH THE AUSTRALIAN NATIONAL UNIVERSITY

ISBN 0 7315 1197 2 ISSN 1033-1557 Contents

Introduction ...... i Gabriele Bammer

The Neurogenic Hypothesis of RSI ...... 1 John Quintner and Robert Elvey

Attachment I ...... 23

Attachment 11 ••••••••••••••••••••••••••••••••••••••.••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 26

Commentaries ...... 34 Trevor Beswick and Annette Cursley ...... 34 David Champion ...... 36 Milton Cohen ...... 38 Malcolm Harrington and Paul Bacon ...... 40 Earl Owen ...... 42 Richard Pearson ...... 43 Campbell Semple ...... 45 Gisela Sj0gaard ...... 4 7 Eira Viikari-Juntura ...... 48 Patrick Wall ...... 50 Richard Wigley ...... 50

Responses to Commentaries ...... 53 John Quintner and Robert Elvey INTRODUCTION

GABRIELE BAMMER BSc BA PhD Research Fellow National Centre for Epidemiology and Population Health Australian National University GPO Box 4 Canberra ACT 2601

Bernardino Ramazzini (1713) is generally pathology and consequent difficulties with credited with writing the first diagnosis and treatment. The disorders comprehensive treatise on occupational became responsible for a large portion of health. In it he made several references to the payouts for workers' compensation and what we now call work-related neck and the associated economic cost was a major upper limb disorders. Although there is factor in sparking an intense debate about still no standard definition for these whether or not the disorders have an disorders, they include 'myalgia, organic base. Protagonists in the debate peritendinitis, tenosynovitis, carpal tunnel played an important role in court cases to syndrome, thoracic outlet syndrome, determine whether or not compensation Guyon's canal syndrome, hypothenar should be awarded, and more importantly, hammer syndrome, vibration induced in defending or discrediting those who white finger, game keeper's thumb, claimed to be affected. osteoarthrosis of the CMC thumb , and fatigue. Numerous terms have been The underlying arguments were analysed introduced to refer to these disorders and by, among others, Brian Martin and myself include: occupational cervicobrachial (1988). Among the criticisms of what we disorders, repetitive trauma disorders, called the standard view, namely that there cumulative trauma disorders, repetitive is physical damage which is work-related, strain injuries and overuse syndrome' are that (Armstong et a!., 1988). • there are no objective signs on which Since the 1700s interest in these disorders diagnosis can be made, has fluctuated. The 1970s saw the • there is no underlying pathology, beginnings of a renewed upsurge in research particularly in the field of • the symptoms do not make clinical ergonomics. Consequently there is an sense, increasingly good understanding of the workplace factors, related both to • orthodox treatments, particularly rest, biomechanics and work organisation, which do not work, and are associated with these disorders: Clinical • there is no consistent relationship research has, however, lagged behind. between symptoms and work. This deficit became critically important in The critics generally have not argued their Australia in the mid-1980s, when there was a cases systematically or in detail and the marked increase in reporting of what were alternative explanations which they favour called repetition strain injuries or RSI. (By have even more problems than the the late 1980s similar upsurges were also standard view when examined with the reported in the USA and UK.) For many same rigour. Nevertheless, the five points workers the disorders produced severe mentioned above need to be dealt with by hardship and this was compounded by the any hypothesis proposing an organic basis lack of understanding of underlying for these disorders. ii Introduction

disorders, allowing those with 'RSI' to be The debate about whether or not these diagnosed more accurately and treated with disorders have a physical underpinning has more success. diverted attention and energy from another, and in my opinion more important, debate. This is a working paper destined for If most of these disorders do have an publication, along with the other papers in organic basis (and even the critics would this series, in a book. Further contributions agree that some do), what is it? Most to the debate, either commentaries on this practitioners have some notions about the paper or expositions of a particular underlying pathology; some emphasise hypothesis, are invited. Please contact me trigger points, others muscle fibre changes, for details. others irreversible irritability of and so on. In general these hypotheses have not been clearly expounded, let alone discussed, in an attempt to reach deeper understanding. An important caveat needs to be made REFERENCES here. In many, and perhaps even most, individuals with work-related neck and Armstrong T, B Silverstein, S Blair, P upper limb disorders, a number of Buckle, L Fine, M Hagberg, B Jonsson, A conditions with different underlying Kilborn, C Hogstedt, I Kuorinka, E Viikari­ probably co-exist. The Juntura and G Sjoegaard, 1988 'Work challenge is not only to establish clear related neck and upper limb disorders. A organic bases for different conditions, along discussion'. In Adams AS, RR Hall, BJ with diagnostic criteria and treatment McPhee and MS Oxen burgh (eds) strategies, but to define ways of identifying, Ergonomtcs Internattonal 88 (Proceedings in individual cases, co-existing conditions. of the Tenth Congress of the International In late 1989 I conceived the idea of inviting Ergonomics Association, 1-5 August 1988, Sydney Australia) 404-406. some of the leadirlg protagonists of different viewpoints to write detailed expositions of their hypotheses. These Bammer, G and B Martin, 1988 'The were to be circulated amongst a variety of arguments about RSI: an examination' people with different expertise, to Communtty Health Studtes 12 348-358. encourage discussion from a number of perspectives. The protagonists were also to be invited to respond to these Ramazzini, B, 1713 De Morbts Arttjicum. Second Edttton Translated by WC Wright, commentaries. Hafner Publishing Co, New York (1964 The following paper, The Neurogenic reprint). Hypotbests of 'RSI', by John Quintner and Robert Elvey is the first in this series. It provides an important overview of one explanation for these disorders and is an excellent starting paper for discussion. There are 11 commentaries, which highlight the most important points for debate and further work. A number of other expositions are being prepared. Along with John Quintner and Robert Elvey, the protagonists are clinicians and undertaking this task on top of heavy caseloads. I am grateful to them and to the commentators for generously devoting time to this project. This series of papers will be important in furthering understanding of the pathology of these Quintner and Elvey 1

THE NEUROGENIC HYPOTHESIS OF 'RSI'

JOHN QUINTNER MBBS MRCP Rheumatologist St John of God Medical Centre, 175 Cambridge Street, Wembley WA 6014 and ROBERT ELVEY BAppSc GradDipManipTher Manipulative Therapist South Perth Physiotherapy Centre, 152 Douglas Avenue, South Perth WA 6151

In this discussion paper we first briefly outline I. INTRODUCTION the clinical features of the 'RSI' pain syndrome and then propose a hypothesis for their The upsurge in cases of a syndrome known as development. This is followed by a detailed repetition strain injury (RSI) or occupational description of the supporting evidence. We overuse syndrome COOS) in the 1980s next discuss the differential diagnosis for this highlighted lack of precision in the medical condition and conclude by outlining some of diagnosis of work-related neck and upper limb the implications of our hypothesis for disorders. 80,81 Exemplifying the prevailing treatment. ignorance, Ferguson37 stated that 'the majority We also provide two attachments, the first of of cases of repetition strain injury are not which outlines a systematic approach to the localised syndromes, but of a more diffuse physical examination of upper limb tissues and disorder, apparently of muscles ... and ... little is the second deals with the concept, rationale known of its aetiology, pathogenesis and and methodology of brachial plexus tension pathology ... nor, if when established, why it appears to persist despite prolonged rest of testing. the patient.' We were impressed by the uniformity of 11. CLINICAL FEATURES OF 'RSI' 14,33,79,80,88 presenting clinical features in many of our 1. Common Symptoms patients, from diverse occupations, who had (a) pain'-initially localised to one anatomical been given (by others) a diagnosis of 'RSI' for site, either proximal (neck, upper back, compensation purposes. We were unable to shoulder) or distal (hand, wrist, forearm or detect recognisable upper limb elbow) musculoskeletal pathology in these patients. -subsequently becoming widespread in For reasons that will be explained in this one or both arms, upper back, neck and discussion paper, we considered that the head presence of a neurological disorder was a more -pain descriptors include aching, burning, likely explanation of their symptoms.33 electrical, sometimes sharp and shooting The stimulus to further investigate this -may follow course of major peripheral possibility was the previous original research nerves of arm of one of the authors in the area of differential (b) paraesthesiae' (includes dysaesthesiae) e.g. diagnosis of upper limb pain.30 The techrtique tingling, pins and needles, numbness, of physical examination which resulted from weakness, heaviness, fullness, fatigue this research (the brachial plexus tension test) (c) feeling of coldness of painful upper limb has proven valuable in the diagnosis of patients suffering from other conditions associated with widespread cervicobrachial pain. 89,90 * either induced by movement of the ann or occurring at rest 2 Quintner and Elvey

(d) sensation of swelling of the acral portion of (f) Vasomotor phenomena 14 limb [i] coldness of painful extremity79 (e) tenderness of tissues at site of pain [ii] cyanosis or pallor of painful (f) cramping sensation of muscles in the extremity79 affected arm (g) Overt signs of reflex sympathetic (g) painful limitation of movement dystrophy14"" [i] cervical spine [ii] shoulder (h) varying degrees of psychological distresS, Ill. THE HYPOTHESIS OF CAUSATION OF 'RSI' pain amplification phenomena or frank psychiatric illness may be present. This hypothesis relates to the majority of patients who present, as described by 2. Physical examination findings Ferguson,37 with a diffuse pain syndrome of (based both_ upon the authors' observations and the upper limb(s), often accompanied by pain published studies) (a) Tenderness on palpation of neural tissues in the neck and upper back. For the purposes related to the painful upper limb of this discussion paper, this syndrome will be [i] in upper limb, felt along the course of referred to as 'RSI'. Clinically identifiable nerves e.g. radial apterior to lateral musculoskeletal pathology causing upper limb epicondyle when pain involves radial pain may coexist with 'RSI', but is usually aspect of forearm; median nerve in the insufficient to explain the full clinical picture. cubital fossa when pain involves ventral In addition, non-occupational causes of diffuse · forearm; ulnar nerve in its groove behind upper limb pain (e.g. other causes of cervical medial epicondyle when pain involves radiculopathy, brachial plexopathy and upper medial aspect of forearm limb entrapment neuropathy) need to be [ii] over the anterior aspect of ipsilateral differentiated from 'RSI'. lower cervical transverse process, The hypothesis holds that: corresponding to spinal nerve (anterior 1. The clinical features of 'RSI' (as outlined primary ramus) in the gutter of the earlier) arise from irritable neural tissues transverse process.33 related to the upper limb. These tissues exhibit (b) Provocative tests positive for upper limb the properties of increased mechanosensitivity symptoms and ectopic impulse formation.97 Other [i] sustained cervical flexion/extension pathophysiological mechanisms relevant to postures33 neuropathic pain27,38,124 may be involved and [ii] brachial plexus tension test of Elvey33 are outlined in this discussion paper. (see also attachments 1 & 2) [iii] free arm hanging test 14 2. The sensori-neural tissues related to the [iv] forearm tension tests e.g. tethered painful arm have become irritable as a result of median nerve stretch test,64 radial nerve pathological changes induced by excessive stretch test24 mechanical tension and/or friction generated [v] false positive Finkelstein's test in radial during manual work of a repetitive nature, sensory nerve entrapment24 usually performed with postural fixity of the [vi] Phalen's test for carpal tunnel head and neckl4,33,88 syndrome.87 (c) Painful (+/-limited) range of movement 3. The neural tissues predominantly [i] cervical spine14 affected by these forces are proximally situated [ii] active abduction/elevation of shoulder (cervical spinal nerve, nerve root complex, (with elbow extended)l4,33 brachial plexus)14,33; however, an identical [iii] shoulder capsulitis. 14,119 clinical presentation (wide-spread neural pain) (d) Antalgic posture of the arm - shoulder may result from entrapment of distal upper adduction and internal rotation, elbow limb neural tissues.71 flexion, wrist and finger flexion. (e) Altered peripheral neural sensibility [i] hypoaesthesia 14' IV. EVIDENCE IN SUPPORT OF THE [ii] allodynia, hyperalgesia, hyperpathia 'NEUROGENIC' HYPOTHESIS syndrome.14

• hypoalgesia deleted; see commentary by M i~on •• changed from f(iii) reflex sympathetic dYStrophy; see Cohen and response commentary by Milton Cohen and response. Quintner and Elvey 3

aching, boring quality, difficult to describe; it An understanding of the hypothesis requires a lies deep; it radiates for considerable distances; knowledge of anatomy and biomechanics of the area outlined by the patient does not the neural elements of both the spine and the correspond to peripheral nerve distribution upper limb, together with related aspects of or spinal nerve root distribution. There may neurophysiology, neuropathology, clinical be accompanying feelings of numbness; and occupational . feelings of heaviness; soreness of muscle The evidence will be presented under the (cramp); tenderness of muscle, and muscle following headings:- spasm at times; tenderness of bony 1. neuropathic pain prominences; secretomotor and vasomotor 2. case studies of patients with 'RSI' and changes (blanching, sweating).47 analogous conditions Referred pain of root involvement may be 3. human experimental studies difficult to diagnose in the absence of 4. occupational health field studies accompanying neurological deficit.47 In an 5. biomechanical studies of cervical and upper important hypothesis, Asbury and Fields3 limb neural tissues 6. response of neural tissues to stretch, tension proposed that pain due to peripheral nerve damage may be categorised as either · and friction 7. experimental studies of damaged spinal dysesthetic pain or nerve trunk pain. nerve root, dorsal root ganglion and peripheral Dysesthetic pain was d~cribed as burning, tingling, searing or raw, and was usually neural tissues 8. the brachial plexus (upper limb) tension test perceived in the cutaneous area innervated by of Elvey and other clinical tests of cervical the affected nerve. Nerve trunk pain was spine and/or brachial plexus neural irritability. described as a deep aching pain which extended along the course of the nerve. The 1. Neuropathic Pain involved nerve was often found to be tender. Both types of pain may be present in a patient First, the concept of referred pain needs to be with nerve dysfunction. briefly discussed. Kellgren,58,59 using chemical injection of muscles, deep fascia, , More is becoming known about the persistent periosteum, and interspinous as the pain states associated with traumatised or stimulus, was able to distinguish superfidal irritated peripheral nerves.27,38,124 Fielcts3B (skin) pain from deep pain. He found that local refers to this pain as neuropathic. Neuropathic pain arising from structures deep to the skin pain can be of extreme severity, can spread may be accompanied by referred pain. extensively and can be associated with muscle Referred pain was defined as pain falsely tenderness and cutaneous hypersensitivity in localised, and thus interpreted by the sufferer segmentally-related regions to the injured as arising from one deep tissue when, in fact, it neural tissue. Onset of pain may be delayed had originated in another. 58 Much of the pain following injury to nerve and may persist long arising from muscles and other soft tissues, after the original insult. Pain can be associated and can be misinterpreted in this with abnormal or unfamiliar unpleasant way and cause serious errors of medical sensations (dysaesthesiae), frequently having a diagnosis to be made. burning and/or electrical quality. A paroxysmal brief shooting or stabbing component is also Grieve47 has suggested the following described. Pain may be felt in a region of classification of pain states commonly sensory deficit, and, within this region, mild encountered in patients with musculoskeletal stimuli may be painful (allodynia); there may diseases: be an increased response to normally painful 1. local pain - pain perceived at the site of stimuli (hyperalgesia). The phenomena of tissue damage tempor:tl summation, spread of pain and after­ 2. referred pain without root involvement - reaction with repetitive stimuli may also be pain perceived in tissues which are not the site elicil:ed (hyperpathia);38 of tissue damage and whose afferent or efferent neurones are not involved in any way According to Devor27, 'a body of data ha& 3. referred pain of root (peripheral nerve) begun to emerge that indicates previously involvement - pain experienced in tissues unsuspected modes whereby nerve· trauma which are not the site of primary tissue and irritation could generate problematic pain damage, but are generally innervated by states by actions at the level of the damaged neurones involved in the tissue damage. nerYe itselP. Suggested mechanisms of neuropathic pain include ectopic impulse Referred pain of non-root musculoskeletal formation from a site of damage along the e origin has the following characteristics:- 'dull, course of a nerve, loss of afferent inhibition, 4 Quintner and iEl>-ey ephaptic transmission, and sympathetic tenosynm~ :.:-.£ er?'=dylitis were activation or facilitation of primary afferents.38 inad~ ~ t.r~ by :;;a:epted orthopaedic The dorsal root ganglion also becomes an aiteria fur ;[cese eag::oses.22 Their diagnostic ectopic generator when peripheral nerve is category of WRAP 1apetition injury suggested a damaged.125 Sensitization of C polymodal failure to distingti&'t J:>en>,-een true muscle nociceptors may explain hyperalgesia and injury and pam referred from elsewhere into other features of reflex sympathetic dystrophy muscle.59 It is likely that many of their patients which can accompany neuropathic pain_l5 . were experiencing pam of referred neural origin. One of the authors88 has argued on clinical grounds that the pain of 'RSI' resembles that Stonelll wrote of 100 patients with repetitive strain Injuries who presented to him over a 13 described in brachial neuropathy. 71 An obvious similarity can be seen between the week period. The more common components behaviour of the pain of 'RSI' (page 3) and of repetitive strain injuries were 'tendinitis, neuropathic pain. In addition, the associated tenosynovitis, peritendinitis, tenovaginitis, symptoms (paraesthesiae etc.) of both myositis or repetition muscle injury, conditions may be identicaL Further clinical epicondylitis, chronic muscle strain, ganglions evidence in support of the 'neurogenic' and neuritis ... reflex sympathetic hypothesis will be presented in the following dystrophy ... and thoracic outlet syndrome.' section. The diagnostic relevance of braclti:i.l Stone did not outline his criteria for the plexus tension testing will become obvious diagnosis of muscle strain or injury in his later in this discussion paper. However, it is original paper; in a later paper112 he inferred important at this stage to point out that such that muscle belly tenderness indicated muscle testing may provide the major means of injury and that tenderness over tendons determining clinically whether or not there is a denoted a pathological process involving significant neural pathology underlying the either the or its sheath. The possibility upper limb pain of a particular patient. of muscle tenderness being associated with referred pain from either somatic or neural 2. Case Studies of 'RSI' and Occupational structures was not discussed by Stone. Cervlcobrachlal Disorder Browne et aJ.10 proposed guidelines for both 1. The Australian experience of 'RSI' diagnosi5 ;r.d management of patients with In a study published in 1971, Ferguson36 occupational repetition strain injuries. The reviewed medical certificates issued to process frequency of semi-objective physical findings workers said to have suffered repetition such as local tenderness (in muscle, tendons, injuries. This was the first Australian study to ), pain on movement of joints, or on highlight the serious occup4tional health resisted contraction of muscles, and the problems of female workers. On the one reproduction of paraesthesia and numbness hand, he maintained that the ill-defined by evocative measures, was emphasised. symptom complexes, affecting the majority of Objective features (of inflammation) were said those studied, were 'probably most often to be unusual findings in chronic cases. simple muscle strains.' On the other hand, Symptoms in these cases could arise from after noting that a simple muscle strain should multiple sites (possibly caused by multiple recover in a week or two of removal from the pathologies). They attributed ongoing pain in source of strain, he speculated that brachial the muscles of the neck and shoulders to the plexus or cervical nerve root pressure or long-term effects of static muscle loading. traction may have been responsible for the Phenomena associated with referred pain were severe, prolonged and widespread pain not considered by these authors, but their syndromes of some workers. criteria for diagnosis are consistent with a neurogenic basis for the symptoms of many There were no other major studies until the patients. 1980s. Taylor et all19 studied 89 cases of 'process workers' arm', a syndrome which pry!O studied 379 musicians with painful encompassed 'a range of musculo-tendinous overuse syndrome of their upper limbs. He lesions' of the upper limb and neck Although assumed that their pain was due to a 6SO/o of their patients complained of numbness pathological process involving their painful of the affected limb, muscle repetition injury muscles, caused by overuse of these muscles. (91 %) and tenosynovitis (SZO/o) were the He based this opinion on tenderness found in commonest diagnoses made. Taylor et aJ.l6 muscle tissue at the site(s) of pain. Once explained numbness as due to neural tissue established, upper limb pain tended to spread compromised by swollen muscles. Their proximally and distally. FrylO made but brief minimal criteria for the diagnosis of mention of more complex spinal pain in some Quintner and Elvey 5 musicians. He later examined a larger group of may have been the major factor in the musicians with upper limb and/or spinal development of 'RSI' in our patients.33 pain.41 Upper limb pain was again attributed to overuse of the respective muscles whereas Miller and Topliss79 conducted a cross­ neck pain was attributed to asymmetrical sectional study of 229 consecutive patients loading (possibly of cervical musculature) in referred with chrome upper limb pain which the sitting posture. His reported examination had been labelled repettttve strain Injury or findings were said to have excluded nerve root overuse syndrome. Two hundred (87%) of lesions. Fry40 did not indicate how he was able these patients did not fulfil criteria for a to distinguish between pain arising from specific rheumatological diagnosis. However, overused muscles and pain referred into the as a group, their patients reported pain which muscles from painful cervical spinal tissues. had spread from an initial localised anatomical When Dennett and Fry25 reported minor and site to become widespread. Paraesthesiae were non-specific abnormalities in biopsy material reported in the painful upper limb by 91 o/o. from the first dorsal interosseous muscle of Their conclusion that there was no evidence of patients in whom they had made a diagnosis of physical injury in the majority of their patients overuse syndrome, they concluded that these was challenged in an editorial comment by changes supported their hypothesis of overuse Smythel05 on the grounds that a more careful injury. But as Cyriax21 warned, anatomical examination of the cervical region on the side diagnosis must precede pathological of the painful arm would have revealed investigation: 'until the tissue at fault has been unsuspected tenderness related to the anterior singled out, microscopy is out of place.' aspect of the lower transverse processes. Smythe105 deduced that 'RSI' in Australia was a Prominent involvement of the syndrome of arm pain referred from the neck. of female patients with 'RSI' was noted by Champion et at.14 Their evidence included a A population of 127 (62%) volunteers and 77 history of paraesthesiae to the fingers in 67%, (38%) patients, all with pain in the upper limb and referral for neurophysiological or neck and 'a highly stylized and repetitive' investigations of 38"/o of the women. Clinical occupation, were prospectively studied by examination revealed evidence suggesting Sikorski et at.l02 Most of their subjects proximal neural irritability in 59% and distal reported multiple areas of pain involvement neural irritabilty in 27%. They postulated and 122 ( 60%) reported a sensory disturbance irritability of cervical spinal nerve roots and/or of some form. They were able to make a brachial plexus as an important neurogenic diagnosis of a recognisable musculoskeletal mechanism in the 'RSI' syndrome. This neural disorder in 118 (58%) 'without resorting to . irritability presumably resulted from their vague clinical terminology such as fibromyalgia, exposure to friction generated during fibrositis or regional pain syndrome.' Their repetitive movements of the arm and neck, clinical assessment was, in part, based on their and from traction or tension, a consequence of subjective judgement as to whether arm both forward bending of the neck and symptoms were compatible with a radicular or drooping of the shoulder girdle. peripheral nerve entrapment. Electrodiagnostic tests were performed on the Our own work also concluded that the upper 81 subjects thought on clinical assessment to limb symptoms of a group of severely affected have a rierve entrapment; they were positive in patients diagnosed by others as 'RSI' arose only 26. There were 86 (42%) subjects in whom from cervical or brachial plexus neural . a diagnosis could not be made. These subjects tissues.33 These symptoms were provoked by complained of poorly localised pain, diffuse the brachial plexus tension test devised by tenderness, easy fatiguability of upper limb Elvey.32 Symptoms in most patients were also muscles, and widespread upper limb reproduced during the sustained neck weakness. Sikorski et at.26 disc4ssed poss.ible postures of forward flexion and/ or backward explanations: that they were not fit enough for extension, performed with the patient the physical demands of their jobs, that they recumbent in the supine position. Abnormal were suffering from a di.screte physical disease tenderness of neural tissues on palpation over or disorder that has so far resisted definition, the gutters of the transverse processes of the that their problem was a psychosomatic related cervical levels on the side of the painful disorder, that they were suffering from an limb was elicited in· most patients. We iatrogenic disorder, oi: that their claims were hypothesised that maintenance of the forward fraudulent. They favoured the first of these, but flexed or 'poked forward' head/neck postures offered no explanation for tl;le persistence and during the performance of repetitive work severity of the reported symptoms of these patients. In many of their undiagnosed subjects, the symptoms appear compatible 6 Quintner and Elvey with our hypothesis but this cannot be fully coldness), and weakness of the painful arm. assessed as the authors did not use art Characteristic findings on physical examination examination technique to assess the were positive (symptom provoking) mechanosensitivity of neural tissues related to neurological tests (e.g. Adson's test), the upper limb. tenderness and/or enlargement of affected muscles, tenderness of nerves, (cervical) In summary, studies in· Australia of those paravertebral tenderness, percussion pain suffering from work-related neck and upper over (cervical) spinous processes and limb conditions have shown that the decreased muscle power. Autonomic commonest of these conditions is a syndrome, disturbances as well as mental symptoms were more frequent in females, characterised by fourid in patients who were severely affected. widespread·pain in' one or both arms, in the upper back, neck and head, often According to Jonsson et a!., 57 the clinical accompanied by complaints of paraesthesiae, manifestations ofOCD a:nd 'RSI' (OOS) are numbness, heaviness, weakness, or perceived identiCal; the emphasis in At;stralia being swelling of the painful arm. Tenderness of placed upon the repetitive nature of the work painful muscles, tendons and/or ligaments was performed whereas Japanese and Scandinavian a prominent finding. This was the syndrome studies tended to highlight constrained which became known as 'RSJ'.80.81 The working postures. For example, Kvarnstrom62 concept of repetition strain injury was studied musculoskeletal disorders of the originally based on the hypothesis that shoulder region in 112 workers employed by a performance of manual work of a repetitive large Swedish manufacturing company. They nature could injure the muscles involved. This fulfilled the following criteria: shoulder type of muscle injury was said to result in symptoms as the dominant reason for inability persistent and widespread arm pain. The to work, loss of more than 4 (continuous) diagnostic dictum of Cyriax21 that 'it is never weeks from work, shoulder pain and fatigue tenderness of a muscle, but pain elicited by the related to work and eased by rest and appropriate resisted movement that identifies tenderness of shoulder girdle musculature a muscle lesion' was apparently forgotten. That and/or rotator cuff tendon insertions. upper limb symptoms may have been Although Kvarnstrom62 grouped neck and referred from structures 'at fault' within the shoulder conditions together under the OCD neck or the brachial plexus of many patients diagnosis, he did not distinguish between was not discussed by the authors of most of cervical conditions referring pain into the the Australian studies, although the evidence shoulder girdle and shoulder conditions they presented is compatible with this causing local pain. The etiology which he explanation. favoured implied injury (microtrauma) to the cervical and/or shoulder girdle musculature 2. Overseas experience of 'RSI'. due to their repetitive contractions or to It is not feasible, within the constraints of this ischaemia resulting from their continuous static paper, to comprehensively review all overseas contraction involved in supporting the weight work related to these disorders. A recent of the arm. review has been carried out by Wallace and 3. Human Experimental Studies Buckle.126 Some key studies from Japan and Sweden are reviewed here. The field studies described above have highlighted the importance of work-related In the 1960s, the Japanese occupational health factors such as posture and repetition in became aware of pain syndromes causing these disorders. A number of related to the occupation of their keypunchers laboratory studies have looked carefully at the and other keyboard workers.76 Initially, postural side of causation and these are tenosynovitis was the diagnosis used to explain summarised here. In terms of the neurogenic forearm, wrist and hand symptoms. However, hypothesis, posture seems to be the most a growing awareness that pain was often more important causal consideration. widespread into the shoulder, neck and head led to the use of broader anatomical diagnoses Chaffinl3 reported a study of fiVe young such as cervicobrachial syndrome and, healthy women who were using microscopes. eventually, 'occupational cervicobrachial He studied the head tilt angles of each woman disorder' (OCD).77 Components of the OCD during her use of the microscope. He aimed to symptom complex included varying degrees determine the time taken to reach a state of of pain and stiffness in the neck, shoulder, fatigue, which he defined as the presence of arm, hand and fingers, paraesthesiae, functional continuous 'cramping' with deep 'hot' pain disturbance of the peripheral circulation (e.g. intermittently present, when the head was held Quintner and Elvey 7

at specific degrees of tilt for 50 minute from 2G-30kg with the head upright (e.g., intervals, with a 10 minute rest between looking at a VDU screen) to 30-40kg with the intervals. The results indicated that tilting the head bent forward (e.g., reading from notes head forward more than 30 degrees greatly flat <;>n a desk). These loads are concentrated in increased the neck extensor (sic) fatigue rates. a relatively small area of the spine and may be He noted that an angle of 15 degrees produced shared by other structures which include no subjective sensations after 6 hours. cervical spinal musculature, ligamentous structures and neural tissues. It is possible that In an important series of experimental studies some or all of the tissues which are exposed to using asymptomatic volunteers, Harrns­ loads of these magnitudes may become Ringdahl and Ekholm49 'aimed to see if pain symptomatic. could be felt after maintained experimentally­ controlled extreme positions of the lower Although not an experimental study, Levy69 neck, similar to common sitting work reported the case history of a man who had postures, and, if so, whether the extreme been tied up for 12 hours with his head forced position and/or pain induced changes in into and held in extreme forward flexion. This muscular activity.' They found that an extreme man developed