A comparison of pain measurement characteristics of mechanical visual analogue and simple numerical rating scales.

Numerical rating scales and mechanical visual analogue scales (M-VAS) were compared for their capacity to provide ratio scale measures of experimental pain. Separate estimates of experimental pain sensation intensity and pain unpleasantness were obtained by each method, as were estimates of clinical pain. Orofacial pain patients made numerical scale and VAS ratings in response to noxious thermal stimuli (45-51 degrees C) applied for 5 sec to the forearm by a contact thermode. The derived stimulus-response function was well fit as a power function only in the case of sensory M-VAS. The power function derived from sensory M-VAS ratings predicted temperatures chosen as twice as intense as standard temperatures of 47 degrees C and 48 degrees C, thereby providing evidence for ratio scale characteristics of M-VAS. The stimulus-response function derived from sensory numerical ratings differed from that obtained with M-VAS and did not provide accurate predictions of temperatures perceived as twice intense at 47 degrees C or 48 degrees C. Both M-VAS and numerical rating scales produced reliably different stimulus response functions for pain sensation intensity as compared to pain unpleasantness and both provided consistent measures of experimental and clinical pain intensity. Finally, both mechanical and pencil-and-paper VAS produced very similar stimulus-response functions. The ratio scale properties of M-VAS combined with its ease of administration and scoring in clinical settings offer the possibility of a simple yet powerful pain measurement technology in both research and health care settings.

Analysis of gender effects on pain perception and symptom presentation in temporomandibular pain.

Based on clinical populations, chronic orofacial pain of temporomandibular disorders (TMD) occurs more frequently (range: 2:1 to 9:1) in women than men. The reasons for this difference are not clear. The present study evaluated symptom presentation, sensitivity to pain, personality, and illness behavior in 2 samples of patients suffering with orofacial pain. Also, pain responses were studied in pain-free volunteers, controlling for experimenter-gender effects. The results showed few gender differences based on ratings of chronic or experimental pain, pain-related illness behavior, and personality. The higher ratio of women versus men seeking TMD care is consistent with greater health awareness or interest in symptoms by women than by men.

Effects of extraversion and neuroticism on experimental pain, clinical pain, and illness behavior.

The effects of 2 personality traits, extraversion and neuroticism, on experimental and clinical pain were characterized in a group of myofascial pain dysfunction (MPD) patients. Extraverts did not differ from introverts in visual analogue scale (VAS) sensory or VAS affective ratings of graded 5-sec nociceptive temperature stimuli (43-51 degrees C) nor in VAS sensory-VAS affective relationships related to their clinical pain. However, high extravert patients scored lower on affective inhibition (Pilowsky Illness Behavior Questionnaire; IBQ) compared to low extravert patients. This result is consistent with previous suggestions that extraverts inhibit overt expressions of suffering less than do introverts. High neurotic patients did not differ from low neurotic patients in their VAS sensory ratings of either experimental or clinical pain. Their VAS affective ratings of both types of pain were marginally higher as compared to low neurotic patients. As hypothesized, high neurotic score patients gave higher VAS ratings of emotions related to suffering and scored higher on items related to affective disturbance on the IBQ as compared to low neurotic score patients. Overall, the results indicate that the personality traits of neither extraversion nor neuroticism affect sensory mechanisms of nociceptive processing but appear to exert their influence by means of cognitive processes related to the ways in which people constitute the meanings and implications of pain.

A simultaneous comparison of fentanyl's analgesic effects on experimental and clinical pain.

Intravenous administration of 0.8 microgram/kg and 1.1 micrograms/kg fentanyl in low back pain patients reduced both sensory intensity and unpleasantness visual analogue scale (VAS) responses to experimental pain evoked by graded 5-sec nociceptive temperature stimuli (45-51 degrees C) as well as VAS-sensory and VAS-affective responses to clinical pain. Fentanyl produced similar decreases in VAS-sensory responses to experimental and clinical pain. Fentanyl produced nearly equal reductions in VAS-sensory and VAS-affective responses to experimental pain but greater reductions in clinical pain VAS-affective as compared to clinical pain VAS-sensory responses. This interaction of type of pain (experimental versus clinical) and pain dimension (sensory versus affective) results from either a steeper sensory intensity-unpleasantness relationship for clinical pain as compared to experimental pain or additional selective influences of opiates on affective factors uniquely related to clinical pain. These results indicate that low to moderate doses of opiates reduce both sensory and affective dimensions of pain and strongly suggest that changes in pain affect occur mainly as a direct consequence of reductions in pain sensation intensity.

Brain evoked potentials are functional correlates of induced pain in man.

Electrical potentials evoked by 5 intensities of painful dental stimulation were recorded at the scalp. During testing, volunteers indicated subjective painfulness by verbal pain ratings and visual analogue scales. Evoked potentials (EPs) to each intensity, observed between 50 and 400 msec, were characterized by 4 waveform components. The peak-to-peak amplitudes, but not the peak latencies, of all 4 EP components systematically increased with increased stimulation. The amplitudes of the two earlier components correlated with stimulus intensity when the effect of subjective painfulness was controlled, but this was not the case for the later components. In contrast, the amplitudes of the two later components were associated with subjective painfulness but not with stimulus intensity. A strong linear relationship was observed between subjective painfulness and peak-to-peak amplitude for the EP component observed between 175 and 260 msec. The data suggest that the earlier EP components may reflect sensory transmission processes while the later components indicate brain activity when pain is perceived.

Detection and decision factors in pain perception in young and elderly men.

The effect of age on ability to discriminate between levels of electrical stimulation of tooth pulp and willingness to report shocks as painful was evaluated using the Sensory Decision Theory. While threshold did not increase with age for tooth pulp stimulation as is often observed for thermal pain thresholds, a significant age deficit in ability to discriminate between suprathreshold shocks was observed. Significant changes with age in willingness to report the electrical shocks as painful were also observed. These results indicate that changes with age in pain perception are complex, involving not only possible discrimination deficits but also changes in bias for and against labeling noxious events as painful. These findings stress the need for within individual comparisons of laboratory techniques for evoking acute pain experiences where variables such as age are under consideration.