Question: Dr John Quintner, Consultant Physician in Rheumatology and Pain Medicine in Australia, has sent this very interesting article which I thought you would like to see. Thanks to Dr Quintner for sending the article. I will upload it to the website later today.
Answer 1: RSI IN THE Y2K
There is an entrenched belief in the Australian community that “RSI” in the 1980s was a mass psychogenic illness, particularly affecting women who had difficulty coping with the demands of their work. Having once acquired the label of “RSI” from sympathetic doctors, they then had an acceptable and compensable way out of their predicament.
There were vocal members of the medical profession, including some rheumatologists, who fostered this mythology and, as large sums of money were at stake, employers, insurers and Governments gratefully embraced it. Consequently, “RSI” as a diagnosis has disappeared but the problem of occupationally induced upper limb pain remains. It is now clear that the fundamental error made by the “psychalgic fundamentalists” (those doctors who believe that ideas per se can cause persistent pain) was their unwillingness to accept that the widespread pain and other sensory phenomena, such as tingling and numbness, that characterise “RSI”, could ever be xplained in terms of bodily dysfunction.[1,2] Hence the monumental leap they made into the minds of sufferers in their attempt to provide an explanation.
It is true that the pain syndrome “RSI” does not accord with the accepted “injury model” of disease (there being no objective evidence of tissue damage), but it also sits uneasily alongside contemporary psychiatric diagnoses for unexplained pain (eg. conversion or somatoform disorders).
That the criteria for diagnosis of these psychiatric conditions could not be met in most patients was not enough to save them. It is true that many were already distressed by their predicament, but the insinuation of imaginary pain (“it’s all in your mind, dear!”) was enough to complete their demoralisation.
There is a third explanatory model, wherein the clinical phenomena are seen as originating in the nervous system. This model was put forward late in the 19th century, but remained largely neglected until the time of the “RSI” epidemic. This neglect was due to poor understanding of the mechanisms responsible for chronic pain. Over the past two decades, neuroscientists have largely redressed this situation. Sadly for the “RSI” sufferers, these advances in knowledge came too late to prevent the ignominious treatment that Australian society meted out to them. “RSI” became a stigmatic label.
A considerable body of scientific evidence now supports the neurogenic model of “RSI”. A number of studies of the relationship between the characteristics or patterns of physical stimuli and the resultant sensation in these patients have provided valuable clues as to underlying pain mechanisms.
Under normal circumstances, feeling gently over peripheral nerve trunks is a painless examination technique. By contrast, in the painful upper limb(s) of “RSI” sufferers, this part of the physical examination is usually found to be painful. It appears that nerve trunks can become sensitive to mechanical forces when they have been exposed to a number of insults. These include their exposure to repeated increases in tension at specific anatomical sites (such as in the carpal tunnel at the wrist, the radial tunnel in the forearm, and the cubital tunnel at the elbow).
Upper limb tension tests, which were originally devised by Perth physiotherapist, Robert Elvey, are somewhat analogous to the straight-leg-raising tests long used in the diagnosis of lower limb pain. The tests are deemed positive when they are both limited in their range of excursion and do reproduce the patient’s pain.
In 1986, Elvey and his co-researchers in Perth reported that upper limb tension tests were usually positive in the symptomatic arms of their patients with “RSI”. Since then, others have confirmed this finding.[7,8] It appears to reflect the same state of increased mechanosensitivity of the nerves in the painful arm as is detectable when they are gently palpated.
Jesus Arroyo and Milton Cohen, from St Vincent’s Hospital, Darlinghurst, Sydney, showed that in patients with typical “RSI”, perception threshold and pain tolerance to non-noxious electrical stimulation of the skin in the unaffected limbs did not differ from those observed in normal subjects.
By contrast, in the affected limbs Arroyo and Cohen consistently noted reduction in pain tolerance to electrical stimulation, which was invariably accompanied by spread of arm pain and persistence of unpleasant abnormal sensations after cessation of the stimulus. From these results they inferred that dysfunction within the nervous system, either peripheral and/or central, may be involved in the development of “RSI”.
Jane Greening and Bruce Lynn, from the Department of Physiology, University College, London, found that detection thresholds for vibration were significantly raised in the distribution of the median and ulnar nerves in the symptomatic arms of these patients. This finding is consistent with there being a minor degree of nerve damage.
They also found that increased intensity of vibratory stimulation caused a painful response in 82% of subjects. As vibration is never a painful stimulus under normal circumstances, these findings suggest altered processing of non-noxious sensory information is occurring in these patients.
Stephen Gibson, Sandra LeVasseur, and Robert Helme from the National Institute of Gerontology and Geriatric Medicine, Mount Royal Hospital, Parkville, Victoria, measured the brain responses to potentially noxious thermal stimulation of the hands of those suffering unilateral cervicobrachial (neck and arm) pain.
When compared to controls, subjects showed both a reduced detection threshold activity and a reduction in amplitude of the positive waveform in the cerebral cortex on the affected side, but not on the unaffected side. Importantly, the alterations were restricted to pain perception and were more related to the severity of the reported pain than to the general mood state of the patients. These findings are consistent with an alteration of central nervous system processing, and subjective appraisal of acute experimental pain, in the painful limbs of “RSI” patients.
The Victorian researchers also found that the area of spreading flush or redness of the skin produced by injected chilli pepper (known as the flare response) was reduced in the pain-affected limbs of patients, whilst the unaffected limb showed increased size of the flare response when compared to controls.
The reported severity of cervicobrachial pain was significantly correlated with the reduction in flare size. The results were thought to signify a disturbance in function of the primary apparatus for the detection of tissue damage in the painful arms of these patients.
Taken together, the scientific evidence refutes the sole argument of the “psychalgic fundamentalists” – that the pain of “RSI” cannot be explained in terms of bodily dysfunction. The evidence points to there being significant alterations in the function of both nociceptive and non-nociceptive pathways related to the painful arms of patients. These alterations probably involve both peripheral and central neural processes connected with sensation, an explanation in accordance with current understanding of the neurobiology of chronic pain.[13,14]
The possibility that psychic trauma, strongly held personal beliefs, or even involvement in medico-legal systems can together or in part change the way in which the nervous system functions, resulting in persistent pain and other sensory phenomena, has yet to be addressed by the “psychalgic fundamentalists”.Will, or can, they respond, now that their own scientific credibility has been challenged?
John Quintner MRCP FFPMANZCA
Physician in Rheumatology and Pain Medicine.
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