The journal of pain : official journal of the American Pain Society
-
Anecdotally, orofacial pain patients sometimes report that the painful face area feels "swollen." Because there are no clinical signs of swelling, such illusions may represent perceptual distortions. In this study, we examine whether nociceptive stimulation can lead to perceptual distortion of the face in a way similar to that of local anesthesia. Sixteen healthy participants received injections of .4 mL hypertonic saline to induce short-term nociceptive stimulation, .4 mL mepivacaine (local anesthetic) to transiently block nerve transduction, and .4 mL isotonic saline as a control condition. Injections were administered in both the infraorbital and the mental nerve regions. Perceptual distortions were conceptualized as perceived changes in magnitude of the injected areas and the lips, and they were measured using 1) a verbal subjective rating scale and 2) a warping procedure. Prior to the study, participants filled in several psychological questionnaires. This study shows that both nociceptive stimulation (P < .05) and transient blocking of nerve transduction (P < .05) can lead to perceptual distortion of the face. A test-retest experiment including 9 new healthy subjects supported the results. Perceptual distortions were positively correlated with the psychological variable of dissociation in several conditions (P < .05). Perceptual distortions may therefore be influenced by somatosensory changes and psychological mechanisms. ⋯ Knowledge of the factors that influence the perception of the face is important to understand the possible implications of perceptual distortions in orofacial pain disorders (and possibly other chronic pain states). Such information may ultimately open up new avenues of treatment for persistent orofacial pain.
-
Review
Quality of pain intensity assessment reporting: ACTTION systematic review and recommendations.
Pain intensity assessments are used widely in human pain research, and their transparent reporting is crucial to interpreting study results. In this systematic review, we examined reporting of human pain intensity assessments and related elements (eg, administration frequency, time period assessed, type of pain) in all empirical pain studies with adult participants in 3 major pain journals (ie, European Journal of Pain, Journal of Pain, and Pain) between January 2011 and July 2012. Of the 262 articles identified, close to one-quarter (24%) ambiguously reported the pain intensity assessment. Elements related to the pain intensity assessment were frequently not reported: 31% did not identify the time period participants were asked to rate, 43% failed to report the type of pain intensity rated, and 58% did not report the specific location or pain condition rated. No differences were observed between randomized clinical trials and experimental (eg, studies involving experimental manipulation without random group assignment and blinding) and observational studies in reporting quality. The ability to understand study results, and to compare results between studies, is compromised when pain intensity assessments are not fully reported. Recommendations are presented regarding key details for investigators to consider when conducting and reporting pain intensity assessments in human adults. ⋯ This systematic review demonstrates that publications of pain research often incompletely report pain intensity assessments and their details (eg, administration frequency, type of pain). Failure to fully report details of pain intensity assessments creates ambiguity in interpreting research results. Recommendations are proposed to increase transparent reporting.
-
Vocalizing is a ubiquitous pain behavior. The present study investigated whether it helps alleviate pain and sought to discern potential underlying mechanisms. Participants were asked to immerse one hand in painfully cold water. On separate trials, they said "ow," heard a recording of them saying "ow," heard a recording of another person saying "ow," pressed a button, or sat passively. Compared to sitting passively, saying "ow" increased the duration of hand immersion. Although on average, participants predicted this effect, their expectations were uncorrelated with pain tolerance. Like vocalizing, button pressing increased the duration of hand immersion, and this increase was positively correlated with the vocalizing effect. Hearing one's own or another person's "ow" was not analgesic. Together, these results provide first evidence that vocalizing helps individuals cope with pain. Moreover, they suggest that motor more than other processes contribute to this effect. ⋯ Participants immersed their hand in painfully cold water longer when saying "ow" than when doing nothing. Whereas button pressing had a similar effect, hearing one's own or another person's "ow" did not. Thus, vocalizing in pain is not only communicative. Like other behaviors, it helps cope with pain.
-
Randomized Controlled Trial
Validation of the Short-form McGill Pain Questionnaire-2 (SF-MPQ-2) in acute low back pain.
The Short-form McGill Pain Questionnaire (SF-MPQ-2) assesses the major symptoms of both neuropathic and nonneuropathic pain and can be used in studies of epidemiology, natural history, pathophysiologic mechanisms, and treatment response. Previous research has demonstrated its reliability, validity, and responsiveness in diverse samples of patients with chronic pain. However, the SF-MPQ-2 has not been evaluated for use in patients with acute pain. Data were examined from a double-blind, randomized clinical trial of immediate-release tapentadol versus immediate-release oxycodone in patients with acute low back and associated radicular leg pain (N = 666). Analyses of internal consistency, convergent validity, and confirmatory factor structure were conducted using baseline data, and analyses of responsiveness were conducted using baseline and endpoint data. The SF-MPQ-2 total score and its 4 subscale scores (continuous pain, intermittent pain, predominantly neuropathic pain, and affective descriptors) generally showed good psychometric properties and 1) were internally consistent, 2) displayed good convergent validity, 3) fit the a priori factor structure, and 4) were highly responsive to analgesic treatment. These data extend previous evidence of the reliability, validity, and responsiveness of the SF-MPQ-2 in patients with chronic pain to those with acute low back and associated radicular leg pain. ⋯ Considered together with the results of other recent studies, the data suggest that the SF-MPQ-2 can provide a valid, responsive, and efficient assessment of both neuropathic and nonneuropathic pain qualities for clinical trials and other clinical research examining patients with various acute and chronic pain conditions.