Occup. Med. 1992; 42: 167-168

BALANCE OF OPINION

Does RSI exist? S. T. Pheasant 81 Arlington Road, London, UK

Correspondence and reprint requests to: Dr S. Pheasant, Consulting Ergonomist, 81 Arlington Road, Southgate, London N14 5BA, UK.

© 1992 Butterworth-Heinemann for SOM 0962-7480/92/030167-02

pre-eminent among the WRULD in the UK; whereas in the USA, carpal tunnel syndrome seems to get more attention. The RSI controversy revolves however, not around discrete clinical entities like tenosynovitis and carpal tunnel syndrome; but around a more obscure class of conditions, often chronic and often involving pain and dysfunction at multiple sites, in which the examining physician is unable to detect any sufficiently clear combination of signs and symptoms which would enable him to allocate the patient to any specific clinical category of known pathology. By default therefore these are regarded as 'conditions of unknown pathology' with the possible implication that what is unknown is perhaps unreal. The inference that what is unknown does not exist, is both illogical and unscientific, but it could be tempting in the adversarial situation which, in practice, often pertains. And in the adversarial situation also, the work relatedness of a condition, involving chronic disability of unknown pathology, will of course be called into question. For present purposes we shall refer to these more obscure conditions as repetitive strain injuries of unknown pathology or RSI(UP). Do they exist, and are they work related? The fact that RSI (UP) often involves pain and dysfunction at multiple sites may be explained on both ergonomic and pathophysiological grounds. Jobs which involve repetitive motions of the hand, wrist or forearm also commonly involve static loading of the muslces of the neck and shoulder. This applies both to production line and to keyboard jobs11. Distal symptoms may be secondary to root entrapment, cervical dysfunction etc. and trigger points in muscles of the shoulder region may refer pain to distal sites as may forearm muscles refer pain to the wrist and hand12. To a considerable extent the controversial status of RSI (UP) hinges upon disputes concerning the relative importance of organic and psychological factors in the aetiology of these conditions. These disputes became particularly prominent in the context of the Australian 'epidemic', where the notion that some form of 'psychosocial contagion' might be involved was obviously a tempting one - again particularly in the adversarial context. For example, Lucire13 has argued that the symptoms of RSI result from the hysterical conversion of underlying psychological conflicts. Dennet and Fry14 however have taken biopsy specimens from the 1st dorsal interosseous muscles of subjects suffering from 'overuse syndrome' of various degrees of severity. They found clear signs of muscle fibre damage, the extent of which was related to the clinical severity of the condition. This finding would

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Does repetitive strain injury exist? Of itself, this is partly a scientific question and partly a semantic one. Its controversial nature is partly due to this confounding of the empirical with the semantic; but it is also (and probably more importantly) due to its socio-economic and legal implications. In the interests of clarity, we shall deal with the semantic issues first. The term repetitive (or repetition) strain injury (RSI) is used, somewhat loosely, to refer to a class of work-related musculoskeletal disorders affecting the hand, wrist and forearm and, to a lesser extent the upper arm, shoulder region and neck. These locations may be affected either singly or in various combinations. The term RSI originated in Australia, where in the 1980s there was something of an 'epidemic' of these conditions1'2. In the USA, a similar (but not necessarily identical) range of conditions are referred to as cumulative trauma disorders (CTD) 3 ' 4 ; and in Japan, the term occupational cervicobrachial disorder (OCD) is used 5. As a result of the considerable media attention which surrounded RSI at the time of the 'epidemic', some Australian authors now prefer to use the term overuse syndrome6'7. In the UK, the term RSI has been adopted by the media and the public at large; but in scientific and medical circles it is widely deprecated and the HSE 8 uses the term work related upper limb disorders (WRULD). The principal problem with collective terms of this kind is the diversity of clinical states to which they are applied. Some of these are discrete clinical entities of known pathology - such as the various forms of peritendinitis and tenosynovitis which affect the wrist extensors of people who do hand-intensive work. To ask the question 'does tenosynovitis exist' would be pointless, since in this day and age nobody would deny that it does. The fact that traumatic tenosynovitis is characteristically work-related is sufficiently undisputed that it is a prescribed industrial disease in the UK. The reality of carpal tunnel syndrome would be equally undisputed; but in this case the epidemiology indicates that although it may be work related9 it need not be since systemic risk factors may be present in up to 30 per cent of cases10. But even though tenosynovitis tends to occur in clusters (eg on a particular assembly line) not all of the individuals doing the kind of work concerned will be affected. So it would be logical to infer that some people are more at risk than others as a result of individual characteristics as yet unidentified. Curiously enough, tenosynovitis is usually regarded as

168 Occup. Med. 1992, Vol. 42, No 3

the concept of a chain of causation. Providing that this chain remains unbroken by any intervening act, then the cause of the original injury would normally be regarded as the 'cause at law' of any subsequent developments which might stem from it. Does RSI exist? In my view the answer is an unequivocal yes; notwithstanding that the term is in many respects unfortunate in that it is applied to a wide range of clinical states some of which are less well understood than others. Are these less well understood conditions work related? In my view, the answer again has to be yes; notwithstanding the complex interaction of organic and psychological factors in their aetiology particularly in the case of their chronic forms. REFERENCES 1. Ferguson DA. The 'new' industrial epidemic. Med J ' Aust 1984; 140: 318-9. 2. Ferguson DA. 'RSI': putting the epidemic to rest. Med J Aust 1987; 147:213-4. 3. Silverstein BA, Fine LJ, Armstrong TJ. Hand wrist cumulative trauma disorders in industry. Br J Indust Med 1986; 43: 779-84. 4. Putz-Anderson V. Cumulative Trauma Disorders. A Manual for Musculoskeletal Diseases of the Upper Limbs. London: Taylor and Francis, 1988. 5. Maeda K. Occupational cervicobrachial disorder and its causative factors. J Hum Ergol 1977; 6: 193-202. 6. Fry HJH. Overuse syndrome in musicians: prevention and management. Lancet September 27, 1986, 728-31. 7. NOSHC. The Prevention and Management of Occupational Overuse Syndrome. Sydney, Australia: National Occupational Safety and Health Commission, 1986. 8. Health and Safety Executive. Work Related Upper Limb Disorders. A Guide to Prevention. London: HMSO, 1990. 9. Silverstein BA, Fine LJ, Armstrong TJ. Occupational factors and carpal tunnel syndrome. Am J Indust Med 1987; 11:343-58. 10. Turner JP, Buckle PW. Carpal tunnel syndrome and associated risk factors - a review. In: Buckle P. ed. Musculoskeletal Disorders at Work. London: Taylor and Francis, pp. 124-32, 1987. 11. Pheasant S. Ergonomics, Work and Health London: Macmillan, 1991. 12. Travell JE, Simons DE. Myofascial Pain and Dysfunction : The Trigger Point Manual. Baltimore: Williams and Wilkins, 1983 13. Lucire Y. Neurosis in the workplace. Med J Aust 1986; 145:323-30. 14. Dennett X, Fry HJH. Overuse syndrome: a muscle biopsy study. Lancet April 23, 1988, 905-8. 15. Ryan GA, Bampton M. Comparison of data process operators with and without upper limb symptoms. Community Health Stud 1988; 12: 63-8. 16. Hopkins A. Stress, the quality of work, and repetition strain injury in Australia. Work and Stress 1990; 4: 129-38. 17. Melzack R, Wall P. The Challenge of Pain London: Penguin, 1988. 18. Littlejohn GO. Repetitive strain syndrome: an Australian experience. J Rheumatol 1986; 13: 1004-6. 19. Bennett RM. Current issues concerning management of fibrositis-fibromyalgia syndrome. Am J Med 1986; 81(suppl3A): 15-8. 20. Royal Australasian College of Physicians. Repetitive strain injury/occupational overuse syndrome. A statement by the Royal Australasian College of Physicians. RACP Fellowship Affairs, December 1988, 6-7.

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seem to give RSI (UP) a clear foundation in organic pathology. But the psychogenic component in the aetiology of these conditions cannot be ignored. Ryan and Bampton15 report a case-control study of data-entry workers, with and without upper limb symptoms. The cases had palpable tender points at various sites (clustering over the upper trapezius, forearm extensors, wrist and first interosseous space). More cases than controls described themselves as bored at work most or all of the time, felt the need to push themselves at work, and found work at least moderately stressful. They reported lower degrees of autonomy at work, peer group cohesion and role clarity. Do the musculoskeletal symptoms result from the high stress levels or vice versa? Is the reporting of both contingent upon an overall negative attitude towards working life? Or do certain objective features of working life (high workload, lack of task variety, etc.) lead to both musculoskeletal problems and the subjective experience of stress? To overcome these difficulties, Hopkins16 used only the responses of symptom-free workers in a comparative study of workplaces doing similar kinds of keyboard work but having high and low prevalences of musculoskeletal problems. The subjects in high prevalence workplaces reported higher levels of stress and boredom; and lower levels of autonomy, peer group cohesion job variety and job satisfaction. This finding would seem to place the psychological factors in the aetiology of RSI, in the external features of the workplace, rather than the internal makeup of the individuals concerned. As a working hypothesis it seems reasonable to propose that the conditions we have referred to as RSI (UP) are essentially myalgic states resulting from overuse (due to static muscle loading or repetitive motions) superimposed over which may be the localized or generalized muscle tensions which result from psychological stress''. The progression of these conditions to their chronic forms may involve some kind of neurological sensitization; see Melzack and Wa}l17 for the sorts of neural mechanisms which could be involved. There are strong points of resemblance between RSI(UP) and the condition (or conditions) which in recent years have come to be known as fibromyalgia18'19. It is widely recognized that fibromyalgia has a strong psychogenic component in its aetiology, but it is not in general thought of as being work related. This has led the Royal Australasian College of Physicians to deny categorically that RSI is work related20. As a conclusion this seems odd, since the fact that a particular syndrome is not always work related, does not in any sense prove that it is never work related. (Compare with the case of carpal tunnel syndrome above.) Supposing that the progression to its chronic state, of a condition which is initially work-related, is dominated by psychological factors, such that the pain and disability persist after the original injury has resolved. Would we be justified in regarding the long-term symptoms as work related? In problems of this kind English common law generally operates on

Does RSI exist?

Occup. Med. 1992; 42: 167-168 BALANCE OF OPINION Does RSI exist? S. T. Pheasant 81 Arlington Road, London, UK Correspondence and reprint requests t...
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