Browsing by Author "Riley, Joseph L."

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    Novel method for assessing age-related differences in the temporal summation of pain
    (Dove Medical Press, 2016) Naugle, Kelly M.; Cruz-Almeida, Yenisel; Fillingim, Roger B.; Staud, Roland; Riley, Joseph L.; Department of Kinesiology, School of Physical Education and Tourism Management
    Temporal summation (TS) of pain protocols typically involve the delivery of brief repetitive noxious stimuli held at a constant intensity and measuring the consequent increase in the perceived intensity of pain sensations. To date, no studies have examined the effect of a TS protocol on the perceived spatial dimensions of the pain experience and its interaction with age. This study used a new TS protocol that examined changes in the perceived size of the painful area in 22 younger adults and 20 older adults. Four trials of ten brief heat pulses delivered at a constant intensity were administered on the volar forearm. Interpulse intervals (IPIs) were 2.5 seconds or 3.5 seconds. Subjects rated the peak pain intensity (trials 1 and 3) or the size of the painful area (trials 2 and 4) after each pulse on a 0-100 scale. The magnitude of summation was calculated for each trial. Three seconds and 6 seconds after delivering the last heat pulse, the subjects rated the intensity or the size of any remaining pain (aftersensations). The results indicated that older adults compared to younger adults exhibited significantly greater summation of size ratings for the 2.5-second and 3.5-second IPI trials and size of pain aftersensations at 3 seconds following the 2.5-second IPI TS trial. These results suggest that aging is associated with enhanced endogenous facilitation of the perceived size of pain. The potential clinical and mechanistic implications of enhanced TS of size of pain remain unknown and warrant further investigation.
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    Reliability of pain intensity clamping using response-dependent thermal stimulation in healthy volunteers
    (Springer (Biomed Central Ltd.), 2015) Cruz-Almeida, Yenisel; Naugle, Kelly M.; Vierck, Charles J.; Fillingim, Roger B.; Riley, Joseph L.; Department of Kinesiology, School of Physical Education and Tourism Management
    BACKGROUND: Pain intensity clamping uses the REsponse-Dependent Stimulation (REDSTIM) methodology to automatically adjust stimulus intensity to maintain a desired pain rating set-point which is continuously monitored from a subject's real-time pain ratings. REDSTIM blinds subjects regarding the pain intensity set-point, supporting its use for assessing intervention efficacy. By maintaining the pain intensity at a constant level, a potential decrease in pain sensitivity can be detected by an increase in thermode temperature (unknown to the subject) and not by pain ratings alone. Further, previously described sensitizing and desensitizing trends within REDSTIM provide a novel insight into human pain mechanisms overcoming limitations of conventional testing methods. The purpose of the present study was to assess the test-retest reliability of pain intensity clamping using REDSTIM during three separate sessions. METHODS: We used a method for testing changes in pain sensitivity of human subjects (REDSTIM) where the stimulus temperature is modulated to clamp pain intensity near a desired set-point. Temperature serves as the response variable and is used to infer pain sensitivity. Several measures were analyzed for reliability including average temperature and area under the curve (AUC). Intraclass correlation coefficients were calculated for each measure at pain rating set-points of 20/100 and 35/100. RESULTS: Sixteen healthy individuals (mean age = 21.6 ± 3.9) participated in three experiments two days apart at both pain rating set-points. Most reliability coefficients were in the moderate to substantial range (r's = 0.79 to 0.94) except for the negative AUC (r = 0.52), but only at the 20/100 pain rating set-point. CONCLUSIONS: The present study supports the test-retest reliability of pain intensity clamping using the REDSTIM methodology while providing a novel tool to examine human pain modulatory mechanisms and overcoming common shortcomings of conventional quantitative sensory testing methods.