Browsing by Author "Robinson, Michael E"

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Open Access
Relationship of intersession variation in negative pain-related affect and responses to thermally-evoked pain.
(J Pain, 2010-02) Bishop, Mark D; Craggs, Jason G; Horn, Maggie E; George, Steven Z; Robinson, Michael E
UNLABELLED: The purpose of this study was to determine whether session-specific measures of negative pain-related affect would account for longitudinal variability in the ratings of the evoked thermal pain. Pain-free subjects rated pain evoked on the posterior leg using thermal stimuli of 45 degrees , 47 degrees , 49 degrees , and 51 degrees C on 3 occasions, each separated by 2 weeks. Session-specific negative pain-related affect measures were also collected. Ratings of pain decreased significantly with repeated testing, demonstrating a systematic change in rating from the first to second sessions that ranged from a mean of 5.3 at 47 degrees C to 9.1 at 49 degrees C. In addition, large random variation occurred across all sessions, resulting in minimal detectable change ranging from 14 to 27. The least variability occurred when a mean rating of the 4 temperatures was used. Session-specific measures of pain-related affect decreased with repeated testing; however, the significant between-subject variability in both rating of pain and pain-related affect were not related to each other. No associations were identified between psychological measures and variability in rating of evoked pain. Future studies of the variability in ratings should consider other factors such as attentional focus. PERSPECTIVE: The individual variability in thermal rating was not explained by individual variation in session-specific measures of negative pain-related affect. The results of this study support the use of repeated baseline measures of thermal stimuli when feasible. When this is not possible, the variability in ratings of thermal stimuli over multiple sessions is reduced when the mean of multiple temperatures is used.
Open Access
Self-reported pain and disability outcomes from an endogenous model of muscular back pain.
(BMC Musculoskelet Disord, 2011-02-02) Bishop, Mark D; Horn, Maggie E; George, Steven Z; Robinson, Michael E
BACKGROUND: Our purpose was to develop an induced musculoskeletal pain model of acute low back pain and examine the relationship among pain, disability and fear in this model. METHODS: Delayed onset muscle soreness was induced in 52 healthy volunteers (23 women, 17 men; average age 22.4 years; average BMI 24.3) using fatiguing trunk extension exercise. Measures of pain intensity, unpleasantness, and location, and disability, were tracked for one week after exercise. RESULTS: Pain intensity ranged from 0 to 68 with 57.5% of participants reporting peak pain at 24 hours and 32.5% reporting this at 48 hours. The majority of participants reported pain in the low back with 33% also reporting pain in the legs. The ratio of unpleasantness to intensity indicated that the sensation was considered more unpleasant than intense. Statistical differences were noted in levels of reported disability between participants with and without leg pain. Pain intensity at 24 hours was correlated with pain unpleasantness, pain area and disability. Also, fear of pain was associated with pain intensity and unpleasantness. Disability was predicted by sex, presence of leg pain, and pain intensity; however, the largest amount of variance was explained by pain intensity (27% of a total 40%). The second model, predicting pain intensity only included fear of pain and explained less than 10% of the variance in pain intensity. CONCLUSIONS: Our results demonstrate a significant association between pain and disability in this model in young adults. However, the model is most applicable to patients with lower levels of pain and disability. Future work should include older adults to improve the external validity of this model.
Open Access
Spinal manipulative therapy-specific changes in pain sensitivity in individuals with low back pain (NCT01168999).
(J Pain, 2014-02) Bialosky, Joel E; George, Steven Z; Horn, Maggie E; Price, Donald D; Staud, Roland; Robinson, Michael E
UNLABELLED: Spinal manipulative therapy (SMT) is effective for some individuals experiencing low back pain; however, the mechanisms are not established regarding the role of placebo. SMT is associated with changes in pain sensitivity, suggesting related altered central nervous system response or processing of afferent nociceptive input. Placebo is also associated with changes in pain sensitivity, and the efficacy of SMT for changes in pain sensitivity beyond placebo has not been adequately considered. We randomly assigned 110 participants with low back pain to receive SMT, placebo SMT, placebo SMT with the instructional set "The manual therapy technique you will receive has been shown to significantly reduce low back pain in some people," or no intervention. Participants receiving the SMT and placebo SMT received their assigned intervention 6 times over 2 weeks. Pain sensitivity was assessed prior to and immediately following the assigned intervention during the first session. Clinical outcomes were assessed at baseline and following 2 weeks of participation in the study. Immediate attenuation of suprathreshold heat response was greatest following SMT (P = .05, partial η(2) = .07). Group-dependent differences were not observed for changes in pain intensity and disability at 2 weeks. Participant satisfaction was greatest following the enhanced placebo SMT. This study was registered at www.clinicaltrials.gov under the identifier NCT01168999. PERSPECTIVE: The results of this study indicate attenuation of pain sensitivity is greater in response to SMT than the expectation of receiving an SMT. These findings suggest a potential mechanism of SMT related to lessening of central sensitization and may indicate a preclinical effect beyond the expectations of receiving SMT.