Combined Use of Experimental Pain and Visual Analogue Scales in Providing Standardized Measurement of Clinical Pain

Myofascial pain dysfunction (MPD) patients, pain-free control subjects, and low back patients from a previous study were compared for visual analogue scale (VAS) responses to experimental pain (43–51°C temperatures) and clinical pain. MPD, low back pain, and control groups' nociceptive temperature-VAS response functions were all power functions with exponents of 2.1 for VAS-sensory-intensity responses, and 2.4–2.7 for VAS-affective responses. MPD patients' VAS-sensory responses to clinical pain, direct temperature matches to clinical pain, and temperature-VAS response function were internally consistent. The similar nociceptive stimulus-VAS response functions and consistent use of VAS to rate experimental and clinical pain provide a standardized procedure, whereby intensities of different types of pain can be accurately compared.