Comparison of pain scores and psychophysic functions for investigating the relation between experimental and clinical pain

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COMPARISON OF PAIN SCORES AND PSYCHOPHYSIC FUNCTIONS FOR Poster 56 INVESTIGATING THE RELATION BETWEEN EXPERIMENTAL AND GREY Th-Fri CLINICAL PAIN Exhibit Hall T. Wetinschtitz and H. Wbel Abs No 596 I Dep. of. Neurology, University of Kiel, Niemannsweg 147,D-2300 Kiel 1, FRG--------A

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AIM OF INVESTIGATION: We investigated whether simple pain scores determined in the algesimetric experiment were equally good criteria for describing the relation between experimental and clinical pain as the parameters of best-possibly fitted psychophysics functions. METHODS: In 44 neurology patients suprathreshold pain sensitivity was determined by appiying 12 different pressure stimuli to the middle finger on the day before diagnostic lumbar puncture. The intensity of the induced experimental pain and the clinical post-lumbar-puncture headache was measured using a verbal rating scale. The sum of induced pain intensities (Pain scores) and the individual psychophysic functions was computed as parameters for experimental pain sensitivity. RESULTS: Significant correlations could be established not only for the simple pain scores, but also for the parameters of psychophysic function and the clinical degree of post-lumbar-puncturesyndrome. The logarithmicpsychophysic function, in contrast to the pain intensity sum, however, proved to be a more discriminating criterion. CONCLUSION: The painstaking best-possible adaption of psychophysic functions decreases the error variance of the scaling procedure. The parameters of the psychophysic function are therewith more predictive with respect to experimentalpain sensitivity than simplepain scores and should be used in preference to these.

NOXIOUS ELECTRICAL STIMULATION ALTERS THE DIMENSIONS OF PAIN AND SUFFERING: MULTIDIMENSIONAL SCALING (MDS) ANALYSIS. W.C. Clark"', M.N. Janal' and J.D. Fletcher*', 'Columbia University, and 2New York State Psychiatric Institute, New York, NY, USA

Poster 57 GREEN Th-Fri Exhibit Hall Abs No

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AIM OF INVESTIGATION: To determine the effect of pain/anxiety on (a) the group stimulus pain/suffering space, and (b) the subject weight space (which locates each individual in the group space). METHODS: The 32 healthy male volunteers judged the similarity of all possible pairings of 12 descriptors of pain and suffering under two conditions: control, no electrical stimulation, and pain/anxiety, continuous plus random noxious electrical stimulation. The proximity matrices obtained were analyzed by individual differences scaling techniques (INDSCAL) to yield the two group stimulus spaces. The subject weights on the various dimensions under the two conditions were compared in a common space. RESULTS: For the separate group stimulus spaces, D-l, the pain/anxiety conditionleftthe generalhealth/illness dimension (arousal, somatosensory experiences, mood) unchanged. However, under the pain/anxiety condition the pain dimension was more salient than the nonpain dimension, while under the control condition, the nonpain dimension took precedence. In the joint subject weight space the pain/anxiety condition significantly increased the subject weights on D-l, the general health/illness dimension. CONCLUSION: The dimensions and subject weights of global pain and suffering are clearly influenced by laboratory pain/anxiety. The next step is to apply MDS to the measurement of clinical pain. Supported by USPHS grant NINCDS-20248