Pain and its management

Abstract

The eighth annual day conference in the series 'Growing points in the treatment of rheumatic diseases', which was held at Harrogate on 7 May 1987, was devoted to 'Pain and its management'. An audience of 90 was made up of rheumatologists, anaesthetists with responsibility for pain clinics, representatives from industry, and representatives of the paramedical professions that have an interest in the control of pain. The enthusiasm of anaesthetists for this topic contrasted strongly with the low number of abstracts submitted by rheumatologists. The morning session opened with a review of the neurophysiology of pain by Dr A Harvey (Leeds). Anatomy was well defined in terms of histological tracts of myelinated and unmyelinated fibres. This basic anatomy could be modified in dynamic fashion both by the concept of neuroplasticity (alteration in the connection of the fibres concerned after unmyelinated C fibre activation) and by local humoral control, which was particularly pronounced in the dorsal horn of the spinal cord. The nervous system was biologically well adapted to the handling of acute pain but less so to the handling of chronic pain. Different levels of the nervous system at which intervention might be directed were defined. Dr J Dixon (Harrogate) reviewed the various descriptive scales available for the measurement of subjective pain. Novel semiobjective methods included videotaped recording of attitude, and conventional rheumatological assessments such as grip strength and joint tenderness also reflected an element of pain. The measurement of pain threshold produced a more finite end point, but this was not necessarily the same as pain perceived by the subject. In discussion it was agreed that daily diary card systems provided advantages in circumventing the atypical event of a special visit to clinic, and a plea was made for research on short pain questionnaires that were adapted to rheumatological problems and to modified articular indices that might reflect tenderness as well as synovial proliferation. It was not clear whether the problems inherent in visual analogue scales applied to rheumatology were also experienced when these scales were used for other symptoms such as breathlessness. Three short papers offered insight into different pharmacological approaches to the control of pain. Dr A Jones (St Bartholomew's Hospital) described work performed with the Hammersmith cyclotron in the investigation of opioid physiology in man. The investigation of an Indian fakir who lanced himself with needles showed that when he was not in a trance he had a normal response to pain. The induction of a state of intense concentration produced increased theta activity on EEG (of the sort that occurs during sleep), allowing him to lose awareness of his normal physiological response. Naturally occurring opioids were implicated and these might be manipulated pharmacologically. A technique had been devised using diphenorphine as a marker to identify those areas of the brain that had the highest concentration of opioid binding sites. An unexpected finding had been the change in distribution of such sites that occurred during sleep. A controlled trial of two psychotropic agents in osteoarthrosis was then described by Dr H Bird (Leeds). Prompted by the insistence of a drug abuser that amphetamines were the only drugs that completely relieved arthritic pain, an appetite suppressant with stimulant properties (diethylpropion) had been compared with an appetite suppressant with sedative properties (fenfluramine) and placebo in patients with osteoarthrosis. The stimulant drug relieved symptoms significantly more than the depressant drug, and this effect was independent of weight loss. Dr K Budd (Bradford), an anaesthetist, then reviewed a selection of novel drugs that had found favour with anaesthetists in the relief of many sorts of pain. These included cytotoxic agents, antidepressants, catecholamine antagonists, and amino acids, including D-phenylalanine and Ltryptophan. This last drug was originally marketed as an antidepressant. Patients with uncontrollable pain sometimes responded to these drugs used in combination. The afternoon session commenced with two papers on mechanical aspects of pain. Dr P Helliwell (Harrogate) using an arthrograph to measure joint stiffness had found, in agreement with other authors, that only a minority of patients with arthritis can distinguish pain from stiffness. Objective stiffness measured by a mechanical apparatus did not always correlate with the patients' subjective perception of discomfort. Objective stiffness was