Manipulation of pain catastrophizing: An experimental study of healthy participants

Pain catastrophizing is associated with the pain experience; however, causation has not been established. Studies which specifically manipulate catastrophizing are necessary to establish causation. The present study enrolled 100 healthy individuals. Participants were randomly assigned to repeat a positive, neutral, or one of three catastrophizing statements during a cold pressor task (CPT). Outcome measures of pain tolerance and pain intensity were recorded. No change was noted in catastrophizing immediately following the CPT (F(1,84) = 0.10, p = 0.75, partial η2 < 0.01) independent of group assignment (F(4,84) = 0.78, p = 0.54, partial η2 = 0.04). Pain tolerance (F(4) = 0.67, p = 0.62, partial η2 = 0.03) and pain intensity (F(4) = 0.73, p = 0.58, partial η2 = 0.03) did not differ by group. This study suggests catastrophizing may be difficult to manipulate through experimental pain procedures and repetition of specific catastrophizing statements was not sufficient to change levels of catastrophizing. Additionally, pain tolerance and pain intensity did not differ by group assignment. This study has implications for future studies attempting to experimentally manipulate pain catastrophizing

Stability of behavioral estimates of activity-dependent modulation of pain

Temporal sensory summation of pain (TSSP) is a proxy measure of windup in humans and results in increased ratings of pain caused by a repetitive, low-frequency noxious stimulus. Aftersensations (ASs) are pain sensations that remain after TSSP has been induced. We examined the within-session and across-session variability in TSSP and AS estimation in healthy participants and in participants with exercise-induced muscle pain in order to determine whether the presence of pain affected the stability of TSSP and ASs. TSSP was estimated by application of 10 repetitive, low-frequency (<0.33 Hz) thermal pulses and measured by the simple slope of pain ratings between the first and fifth pulses. ASs were measured by the presence of any remaining pain sensations up to 1 minute after TSSP was induced. TSSP estimation remained moderately stable in pain-free participants and in participants with pain within a single testing session but demonstrated low stability across sessions in pain-free participants. AS estimation was stable for all groups. Estimation of TSSP and ASs using these protocols appears to be a reliable single-session outcome measure in studies of interventions for acute muscle pain and in experimental studies with healthy participants. This article evaluates the reliability of a commonly used method of estimating TSSP and ASs in both healthy participants and in a clinically relevant model of acute pain. These protocols have the potential to be used as single-session outcome measures for interventional studies and in experimental studies

The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects

<p>Abstract</p> <p>Background</p> <p>The mechanisms thorough which spinal manipulative therapy (SMT) exerts clinical effects are not established. A prior study has suggested a dorsal horn modulated effect; however, the role of subject expectation was not considered. The purpose of the current study was to determine the effect of subject expectation on hypoalgesia associated with SMT.</p> <p>Methods</p> <p>Sixty healthy subjects agreed to participate and underwent quantitative sensory testing (QST) to their leg and low back. Next, participants were randomly assigned to receive a positive, negative, or neutral expectation instructional set regarding the effects of a specific SMT technique on pain perception. Following the instructional set, all subjects received SMT and underwent repeat QST.</p> <p>Results</p> <p>No interaction (p = 0.38) between group assignment and pain response was present in the lower extremity following SMT; however, a main effect (p < 0.01) for hypoalgesia was present. A significant interaction was present between change in pain perception and group assignment in the low back (p = 0.01) with participants receiving a negative expectation instructional set demonstrating significant hyperalgesia (p < 0.01).</p> <p>Conclusion</p> <p>The current study replicates prior findings of c- fiber mediated hypoalgesia in the lower extremity following SMT and this occurred regardless of expectation. A significant increase in pain perception occurred following SMT in the low back of participants receiving negative expectation suggesting a potential influence of expectation on SMT induced hypoalgesia in the body area to which the expectation is directed.</p

The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects-0

Pain. A statistical interaction occurred with participants receiving a positive expectation instructional set reporting expectations for less pain with quantitative sensory testing (QST) following spinal manipulative therapy (SMT) and those receiving a negative expectation instructional set reporting expectations for greater pain. Error bars represent 1 standard error of the mean (SEM). * indicates significant change at p ≤ 0.05.<p><b>Copyright information:</b></p><p>Taken from "The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects"</p><p>http://www.biomedcentral.com/1471-2474/9/19</p><p>BMC Musculoskeletal Disorders 2008;9():19-19.</p><p>Published online 11 Feb 2008</p><p>PMCID:PMC2270829.</p><p></p

The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects-1

E numbers indicate hypoalgesia, while negative numbers indicate hyperalgesia. A significant interaction was present in the low back suggesting that post SMT pain perception was dependent upon the group to which the participant was randomly assigned. Follow up pairwise comparison indicated a significant increase in pain perception in subjects receiving a negative expectation instructional set. No interaction was observed in the lower extremity of participants; however, a significant main effect occurred suggesting hypoalgesia regardless of group assignment. Error bars represent 1 standard error of the mean (SEM). * indicates a statistically significant change in pain perception in the low back following SMT at p ≤ 0.05.<p><b>Copyright information:</b></p><p>Taken from "The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects"</p><p>http://www.biomedcentral.com/1471-2474/9/19</p><p>BMC Musculoskeletal Disorders 2008;9():19-19.</p><p>Published online 11 Feb 2008</p><p>PMCID:PMC2270829.</p><p></p

The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects-2

Pain. A statistical interaction occurred with participants receiving a positive expectation instructional set reporting expectations for less pain with quantitative sensory testing (QST) following spinal manipulative therapy (SMT) and those receiving a negative expectation instructional set reporting expectations for greater pain. Error bars represent 1 standard error of the mean (SEM). * indicates significant change at p ≤ 0.05.<p><b>Copyright information:</b></p><p>Taken from "The influence of expectation on spinal manipulation induced hypoalgesia: An experimental study in normal subjects"</p><p>http://www.biomedcentral.com/1471-2474/9/19</p><p>BMC Musculoskeletal Disorders 2008;9():19-19.</p><p>Published online 11 Feb 2008</p><p>PMCID:PMC2270829.</p><p></p