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

Colorectal and uterine movement and tension of the inferior hypogastric plexus in cadavers

Background: Hypotheses on somatovisceral dysfunction often assume interference by stretch or compression of the nerve supply to visceral structures. The purpose of this study is to examine the potential of pelvic visceral movement to create tension of the loose connective tissue that contains the fine branches of the inferior hypogastric nerve plexus. Methods: Twenty eight embalmed human cadavers were examined. Pelvic visceral structures were displaced by very gentle 5 N unidirectional tension and the associated movement of the endopelvic fascia containing the inferior hypogastric plexus that this caused was measured. Results: Most movement of the fascia containing the inferior hypogastric plexus was obtained by pulling the rectosigmoid junction or broad ligament of the uterus. The plexus did not cross any vertebral joints and the fascia containing it did not move on pulling the hypogastric nerve. Conclusions: Uterine and rectosigmoid displacement produce most movement of the fascia containing the hypogastric nerve plexus, potentially resulting in nerve tension. In the living this might occur as a consequence of menstruation, pregnancy or constipation. This may be relevant to somatovisceral reflex theories of the effects of manual therapy on visceral conditions.Ian P Johnso

The influence of clinical equipoise and patient preferences on outcomes of conservative manual interventions for spinal pain: an experimental study

Mark D Bishop,1,2 Joel E Bialosky,1&ndash;3 Charles W Penza,1,2 Jason M Beneciuk,1,3 Meryl J Alappattu1,2 1Department of Physical Therapy, University of Florida, 2Center for Pain Research and Behavioral Health, 3Brooks-PHHP Research Collaboration, Gainesville, FL, USA Background: Expected pain relief from treatment is associated with positive clinical outcomes in patients with musculoskeletal pain. Less studied is the influence on outcomes related to the preference of patients and providers for a specific treatment. Objectives: We sought to determine how provider and patient preferences for a manual therapy intervention influenced outcomes in individuals with acutely induced low back pain (LBP). Participants and methods: Pain-free participants were randomly assigned to one of two manual therapies (joint biased [JB] or constant touch [CT]) 48&nbsp;hours after completing an exercise protocol to induce LBP. Expectations for pain relief and preferences for treatment were collected at baseline, prior to randomization. Pain relief was assessed using a 100&nbsp;mm visual analog scale. All study procedures were conducted in a private testing laboratory at the University of Florida campus. Results: Sixty participants were included in this study. After controlling for preintervention pain intensity, the multivariate model included only preintervention pain (B=0.12, p=0.07) and provider preference (B=3.05, p&lt;0.0001) and explained 35.8% of the variance in postintervention pain. When determining whether a participant met his or her expected pain relief, receiving an intervention from a provider with a strong preference for that intervention increased the odds of meeting a participant&rsquo;s expected pain relief 68.3 times (p=0.013) compared to receiving any intervention from a provider with no preference. Receiving JB intervention from any provider increased the odds of meeting expected relief 29.7 times (p=0.023). The effect of a participant receiving an intervention they preferred was retained in the model but did not meet the criteria for a significant contribution. Conclusion: Our primary findings were that participant and provider preferences for treatment positively influence pain outcomes in individuals with acutely induced LBP, and joint-biased interventions resulted in a greater chance of meeting participants&rsquo; expected outcomes. This is contrary to our hypothesis that the interaction of receiving an intervention for which a participant had a preference would result in the best outcome. Keywords: equipoise, expectations, manual therapy, acute pai