Sensory-affective relationships among different types of clinical and experimental pain.

Different types of pain patients used visual analogue scales (VAS) to rate their level of pain sensation intensity (VAS sensory) and degree of unpleasantness (VAS affective) associated with pain experienced at its maximum, usual, and minimum intensity. Women used the same VAS to rate their labor pain during early, active, and transition phases of stage I and in pushing (stage II). Consistent with the hypothesis that the affective dimension of clinical pain can be selectively augmented by perceived degree of threat to health or life, cancer pain patients and chronic pain patients gave higher VAS affective ratings as compared to VAS sensory ratings of their clinical pain, whereas labor patients and patients exposed to experimental pain gave lower VAS affective ratings compared to their VAS sensory ratings of pain. Affective VAS but not sensory VAS ratings of pain were considerably reduced when women in labor focused on the birth of the child as compared to when they focused on their pain. The results underscore the importance of utilizing separate measures of the sensory intensity versus the affective dimension of clinical pain and provide evidence that the affective dimension of different types of clinical pain is powerfully and differentially influenced by psychological contextual factors.