(this document apparently began its life in something besides raw ASCII text and has suffered multiple generations of indenting and other errors. I've attempted to clean it up, but I may have missed something. -- dwallach) Date: Mon, 21 Mar 1994 05:18:58 GMT From: keith@actrix.gen.nz (Keith Stewart) Subject: Discussion on Pain Organization: Actrix Information Exchange Newsgroups: sci.med.occupational,sci.med This is an article written by an ergonomist who works for the Occupational Safety and Health Service of the Department of Labour in New Zealand The OOS he refers to is RSI ( we call it occupational overuse syndrome here ) So it's all in your mind . . . . A response to people who use this outdated expression. Contents 1 All health has a psychological component. 2 A definition of pain. 3 The gate-control theory of pain. 4 Some pain facts. 5 Stress and pain. 6 Sometimes the pain/nervous system malfunctions. 7 Where does the mind start and the body stop? 8 People with OOS have pain. 9 The state of the mind affects the way pain is perceived. 10 Therapeutic interventions. 11 People need to take charge of themselves. 12 Placebo is a valid treatment. 13 Malpractice 14 References and further reading 15 Other references. Appendix - controlling chronic pain - two approaches. So it's all in your mind . . . . Most safety and health practitioners will have heard this expression at one time or another. In our experience it is used by managers or doctors about people who have overuse syndrome. Is this approach valid? How should we respond to it? These notes suggest some answers. __________________________________________________________ 1 All health has a psychological component. All health and ill-health has an underlying psychological component. After all, we usually say "I feel better". Research estimates that about a third of all GP consultations have a major psychological imperative of some sort. And don't you feel better when you know a visit to the Doctor has been arranged? 2 A definition of pain. All of us would have an idea about how pain occurs. A common idea is that pain signals originate in body structures called nociceptors (or "structures that generate pain signals"), and that these signals travel along nerves to the brain where they are interpreted as pain. But it is not quite as simple as this. Pain is not easy to define. Here is the one used by pain specialists: "Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". These twenty two words define pain. More words are needed to understand its nature fully. "Pain is always subjective. Each individual learns the application of the word related to injury early in life. It is unquestionably a sensation in a part of the body but it is also un-pleasant and therefore an emotional reaction. Many people report pain in the absence of tissue damage or any likely pathophysiological cause. Usually this happens for psychological reasons. There is no way to distinguish their experience from that due to tissue damage, if we take the subjective report. If they regard their experience as pain and ifthey report it in the same way as pain caused by tissue damage, it should be accepted as pain. This definition avoids tying pain to the stimulus. Activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain, which is always a psychological state, even though we may well appreciate that pain most often has a proximate physical cause". So it's no good saying that "pain is a sensation produced byinjury" because this neglects the response of the brain. Nor can we say that pain is: "all in the mind" because this neglects the fact that pain signals originate in nociceptors. Nociceptors: Structures in the body that generate pain signals. 3 The gate control theory of pain. Back in 1965, Patrick Wall and Ronald Melzack suggested the "Gate Control" theory of pain. It goes like this: "Pain receptors (nociceptors) in the body send pain messages along small nerve fibres to a site in the spinal cord. The messages then travel up the nerves in the spinal cord to the brain where they are interpreted as pain. Near their point of entry into the spinal cord the messages pass through a "gate". This gate can be opened or closed. A diagram shows the theory as follows: The state of the gate is controlled by two types of (pain) messages: First, a second class of pain receptor in the body can send pain messages along larger nerve fibres. These tend to close the gate. Second, messages that flow down from the brain affect the state of the gate too. These messages come from four parts of the brain. Two are in the conscious area of the brain and two are in areas beyond conscious control. The point, of course, is that the state of the gate is affected by messages flowing down, from the brain, as well as up. There are feedback loops operating at various points also.You may be able to relate all this to common experience. If you gouge, sprig, thump or otherwise assault your rugby scrum opponent, little pain is felt. Pinch the same person off the field and it is quite different! The way our attention is engaged affects the way pain is perceived. It is well known that hospital patients require more pain killers at night. And when we experience emotional upset, we feel pain more acutely. Thus pain, by its very nature, is always subjective, and the higher parts of the brain play an integral role in the transmission of pain impulses from the body to their processing in the brain. So, from physiological evidence alone, it is obvious that the phrase: "It's all in the mind" is invalid. However, it is true to say: "The state of the mind can affect the waypain is perceived". This is not a subtle distinction - it is a major distinction - as we shall see. 4 Some pain facts. Identical injuries do not produce identical pain experiences. Melzack, Wall and Ty, for example, measured how pain felt to people who came to a hospital emergency centre with a variety of severe injuries. Wide individual variations, that were not explained by arguments of the "all in the mind" genre, were found: No acute pain 40% More pain than expected 40% Pain in the expected range 20% One underlying assumption about pain deserves particular mention: the fallacy of a simple "single cause/single diagnosis" relationship. The picture is rather as follows1: 1 No (pain) signal arrives in a blank, open, nervous system. Other types of signals are coming into the nervous system from the body all the time. The state of excitability of the nervous system therefore varies constantly. 2 These signals interact as they enter the central nervous system. The idea of a monopoly, the concept that each pain signal travels along its own dedicated and insulated wire is wrong - it is not like a telephone network. One nervous signal may inhibit or exaggerate the effects of other signals. 3 All known central nervous system pathways are subject to powerful controls originating from within the central nervous system. The progress of a pain signal in the central nervous system depends on these controls. An interesting (and unfortunate) discovery is evidence for the "transport" of chemicals along nerves. It seems that once a nociceptor has been stimulated for some time, (by an injury), the nociceptor may cause chemical changes in other parts of the nervous system. This may cause the nervous system to function as if it had a lower pain threshold. These points are illustrated in a finding about phantom limb pain. (This is the pain that is felt as if from a part of the body after it has been amputated.) When limbs are amputated in the operating theatre (i.e. not by accident) it has been found that phantom limb pain can be greatly reduced if the person is given a local anaesthetic before and during the operation. This prevents an enormous barrage of pain signals from arriving at the spinal cord as the amputation proceeds. A patient under general anaesthetic does not feel them, of course, but the non-arrival of these signals prevents them from changing the spinal cord in a way that leads to the phantom limb pain.5 Sometimes the pain/nervous system malfunctions. The pain system is part of the nervous system and, like any system in the body, it can malfunction, for a variety of reasons. In the view of Mike Butler, a Rheumatologist and Pain Specialist in Auckland, people with pain resulting from overuse syndrome are a small part of a wide spectrum of people with chronic musculoskeletal pain. This pain is two to three times more prevalent in women than men. Dr Butler observes that many doctors look for a "lesion" to explain pain and, when this is not found, seek a psychological explanation. If these are the only explanations considered a fundamental assumption is made: that the pain/nervous system is in perfect working order. This assumption is seldom stated to the patient, though comments might be made concerning a lack of evidence of any disease of the nervous system. From a physiological perspective, there is no reason why the pain/nervous system should always operate perfectly in every person. Dr. Butler says that comprehensive clinical questioning often reveals symptoms suggestive of nervous system dysfunction in people with chronic musculoskeletal pain. He often finds conditions such as menstrual irregularity and pain, tinnitus, Reynaud's disease, irritable bowel syndrome, sudden reddening and hot flushing and night sweating. That women with chronic pain conditions outnumber men by two to three times may be due to the lability of the nervous system control associated with hormonal cycling. While the brain uses electrical signals to effect its intentions, the operation of the nervous system, including the brain, is mediated by chemical messengers/ hormones. As Bergland says "The brain is a gland". Stress and Pain Stress results in increased "nervous traffic". More signals travel along the nerves when we exhibit the stress reaction. Sometimes, perhaps it is just that the volume of traffic can overwhelm the system. Using the analogy of a computer, perhaps these problems may be likened to a hard disc crash. In other words, these problems may be due to hardware malfunctions, not software problems that we might liken to psychological effects. The provocative agent , in the case of the person with OOS, may be called nervous traffic. Just as pollen is to hay fever, so the increased nervous function of the keyboard operator (possibly compounded by the stress reaction) may set off the nervous system dysfunction referred to. 7 Where does the mind stop and the body start - and vice versa? It should, by now, be obvious that this is a non - question. The gate control theory and the idea of chemical messengers mediating nervous transmission indicate that mind and body work together. 8 People with OOS have pain. The central feature of OOS is that people have pain. Usually this is poorly located in the muscles, and tends to come and go and to move about from place to place in the body. This pattern is often said to indicate malingering. However, it has become been recognised by so many physicians as typical of people with OOS that it cannot be regarded in this way. People with OOS are often said to have a psychological problem, and often this is taken to mean that it caused the OOS. Any psychological problems may be the result of the OOS. And it is quite clear that people with chronic severe pain often develop psychological symptoms - just like you or I would - and that these follow a more or less predictable pattern. This is a chicken and egg situation incapable of resolution. 9 The state of the mind affects the perception of pain. By now it should be obvious that the subdivision of pain into either physical or mental is outdated and dangerous . All pains with an overt physical cause have a mental component. On the other hand, pains with no physical lesions are rare. Note that these pains have characteristic properties that are not shown in the case of people who have OOS. Therefore, a therapist who tries the "all in the mind" will turn the patient off immediately. People generally know when they are not malingering! The all in the mind approach has equivalents such as "psychogenic", "psychological", "psychiatric" and "no physical reality". The use of these phrases will probably be equally non-therapeutic. However, we need to be careful in making blanket statements. It should be obvious that we cannot neglect the mental contribution. 10 Therapeutic interventions. Whatever we do when we are with a person with OOS is either therapeutic or non-therapeutic! Perhaps this is going a little far, but it conveys an important message. That is: we are going to have some sort of effect on the person. So we can't try to avoid making someone worse - we will have to take active steps to optimise the effect of our intervention. My own GP was instructive when I asked him "How do you deal with OOS?" His reply: "The first thing to do is to avoid making it worse". Hippocates lives again! 11 People need to take charge of themselves. These notes are from the OSH Treatment Guide. Consult the guide for more extensive hints. OOS is a truly (w)holistic disorder. Management must involve the entire person, with advice about the work and social environment. Social and work pressures, ergonomics and relaxation techniques are the important areas to concentrate on. The unpleasant supervisor or a catty workmate may be a prime cause. Successful management for diffuse muscle OOS depends on a do-it-yourself approach, in which the person and doctor form a partnership. Often, people with OOS turn from one method of treatment to another, including non-medical ones. They may become apprehensive at the escalation of symptoms, and the non-effect of any method of treatment. For example, one author reports that of 809 people who rang into an OOS "hotline" in Sydney, 301 reported that treatments such as physiotherapy, analgesics, rest and splints had been unsuccessful. It is vital that a single person co-ordinate the progress of the person with OOS and liaise with the supervisor. Usually the GP is best placed to do this, but someone closer to the workplace. (e.g. Occupational Health Nurse, Occupational Physician, Occupational Therapist) may be more suitable. Experience has shown that people who return to work promptly are likely to do better than the people who do not, as long as they do not return to the original provocative situation. 12 Placebo is a valid treatment. Paradoxically, all these observations have put the psychological factor in its proper light. Because of the involvement of the higher nervous system psychological therapy, even the placebo effect, has a primary role in management. When translated from the Latin, "placebo" means "I shall please". This is highly illuminating for the therapist. We need to aim to please people with pain from OOS. We need to give them some hope. Placebo is, of course, a valid treatment. It is implicit in any therapeutic endeavour. Placebo will generally produce a 60 to 80% relief of pain, but the effect is usually transient. If a form of treatment does not produce this degree of relief promptly it is not better than placebo and should be stopped. 13 Malpractice. When a medical practitioner disbelieves a patient's symptoms, it is called malpractice. 14 References and further reading. The following references will be useful as indicated. For a general understanding of pain: These are "must read" for all health professionals. 1. Defeating Pain: The War Against a Silent Epidemic. Patrick Wall, M Jones. Plenum Press. (1991). 2. The Fabric of Mind. Richard Bergland. Penguin. (1985). For the advanced reader. 3. The Challenge of Pain.Ronald Melzack & Patrick Wall Penguin 2nd ed. (1988). For people with particular problems. 1. Are You Sure It's Arthritis? Paul Davidson. Signet. (1987). 2. Chronic Muscle Pain Syndrome. Paul Davidson. Villard Books. (1990). 3. Migraine: Understanding The Common Disorder. Oliver Sacks. Pan. 2nd ed. (1985). For people who need help with chronic pain. See the appendix. 1. Controlling Chronic Pain. Connie Peck. Fontana/Collins. (1985). 2. Mastering Pain. Richard Sternbach. Ballantine Press. (1987). For general interest. 1. A Leg To Stand On. Oliver Sacks. Picador. (1986). 2 The man who mistook his wife for a hat. Oliver Sacks. 15 Other References