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Slow temporal summation of pain for assessment of central pain sensitivity and clinical pain of fibromyalgia patients.

Staud R, Weyl EE, Riley JL, Fillingim RB - PLoS ONE (2014)

Bottom Line: Slope of WU-RF, which is representative of central pain sensitivity, was significantly steeper in FM patients than NC (p<.003).Compared to single WU series, WU-RFs integrate individuals' pain sensitivity as well as WU and WD.Slope of WU-RFs was significantly different between FM patients and NC.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Florida, Gainesville, Florida, United States of America.

ABSTRACT

Background: In healthy individuals slow temporal summation of pain or wind-up (WU) can be evoked by repetitive heat-pulses at frequencies of ≥.33 Hz. Previous WU studies have used various stimulus frequencies and intensities to characterize central sensitization of human subjects including fibromyalgia (FM) patients. However, many trials demonstrated considerable WU-variability including zero WU or even wind-down (WD) at stimulus intensities sufficient for activating C-nociceptors. Additionally, few WU-protocols have controlled for contributions of individual pain sensitivity to WU-magnitude, which is critical for WU-comparisons. We hypothesized that integration of 3 different WU-trains into a single WU-response function (WU-RF) would not only control for individuals' pain sensitivity but also better characterize their central pain responding including WU and WD.

Methods: 33 normal controls (NC) and 38 FM patients participated in a study of heat-WU. We systematically varied stimulus intensities of.4 Hz heat-pulse trains applied to the hands. Pain summation was calculated as difference scores of 1st and 5th heat-pulse ratings. WU-difference (WU-Δ) scores related to 3 heat-pulse trains (44°C, 46°C, 48°C) were integrated into WU-response functions whose slopes were used to assess group differences in central pain sensitivity. WU-aftersensations (WU-AS) at 15 s and 30 s were used to predict clinical FM pain intensity.

Results: WU-Δ scores linearly accelerated with increasing stimulus intensity (p<.001) in both groups of subjects (FM>NC) from WD to WU. Slope of WU-RF, which is representative of central pain sensitivity, was significantly steeper in FM patients than NC (p<.003). WU-AS predicted clinical FM pain intensity (Pearson's r = .4; p<.04).

Conclusions: Compared to single WU series, WU-RFs integrate individuals' pain sensitivity as well as WU and WD. Slope of WU-RFs was significantly different between FM patients and NC. Therefore WU-RF may be useful for assessing central sensitization of chronic pain patients in research and clinical practice.

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Average (SEM) WU-AS of NC and FM subjects at 15 s (A) and 30 s (B) after trains of 44°C, 46°C, and 48°C heat pulses to the hands.Ratings of WU-AS increased in NC (broken line) and FM subjects (solid line) with increasing WU heat stimulus intensity (all p<.001). WU-AS ratings at 15 s and 30 s increased significantly more with increasing temperatures in FM subjects than NC (all p<.04).
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pone-0089086-g003: Average (SEM) WU-AS of NC and FM subjects at 15 s (A) and 30 s (B) after trains of 44°C, 46°C, and 48°C heat pulses to the hands.Ratings of WU-AS increased in NC (broken line) and FM subjects (solid line) with increasing WU heat stimulus intensity (all p<.001). WU-AS ratings at 15 s and 30 s increased significantly more with increasing temperatures in FM subjects than NC (all p<.04).

Mentions: The mean ratings (SD) of WU- AS obtained 15 s and 30 s after each heat stimulus train for NC and FM subjects are shown in Figure 3a (15 s AS) and Figure 3b (30 s AS). 15 s WU- AS ratings of NC subjects after 44°C, 46°C, and 48°C heat pulse trains were.7 (2.9), 4.3 (8.0), and 10.2 (18.4) NPS units. The average 15 s AS ratings of FM subjects after 44°C, 46°C, and 48°C heat pulse trains were 14.3 (17.3), 22.4 (17.9), and 32.5 (17.9) NPS units, respectively. 30 s WU - AS ratings of NC subjects after 44°C, 46°C, and 48°C heat pulse trains were 1.7 (3.4), 6.0 (13.8), and 7.5 (14.9) NPS units and the average (SD) 30 s AS ratings of FM subjects after 44°C, 46°C, and 48°C heat pulse trains were 11.3 (17.9), 18.8 (17.9), and 27.4 (17.9) NPS units, respectively. A mixed model ANOVA with time (2) and WU temperature (3) as within and diagnostic group (2) as between subjects’ factors showed significant main effects for time (F(1,62) = 32.8; p<.001), WU temperature (F(1,62) = 41.6; p<.001), and diagnostic group (F(1,62) = 21.0; p<.001). Use of simple contrast demonstrated that all 15 s and 30 s WU-AS ratings of FM subjects were significantly greater than WU-AS ratings of NC (all p<.04). A significant time×diagnostic group interaction (F(1,62) = 8.0; p<.01) showed that the decay of 30 s AS across time was significantly slower in FM subjects compared to NC.


Slow temporal summation of pain for assessment of central pain sensitivity and clinical pain of fibromyalgia patients.

Staud R, Weyl EE, Riley JL, Fillingim RB - PLoS ONE (2014)

Average (SEM) WU-AS of NC and FM subjects at 15 s (A) and 30 s (B) after trains of 44°C, 46°C, and 48°C heat pulses to the hands.Ratings of WU-AS increased in NC (broken line) and FM subjects (solid line) with increasing WU heat stimulus intensity (all p<.001). WU-AS ratings at 15 s and 30 s increased significantly more with increasing temperatures in FM subjects than NC (all p<.04).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928405&req=5

pone-0089086-g003: Average (SEM) WU-AS of NC and FM subjects at 15 s (A) and 30 s (B) after trains of 44°C, 46°C, and 48°C heat pulses to the hands.Ratings of WU-AS increased in NC (broken line) and FM subjects (solid line) with increasing WU heat stimulus intensity (all p<.001). WU-AS ratings at 15 s and 30 s increased significantly more with increasing temperatures in FM subjects than NC (all p<.04).
Mentions: The mean ratings (SD) of WU- AS obtained 15 s and 30 s after each heat stimulus train for NC and FM subjects are shown in Figure 3a (15 s AS) and Figure 3b (30 s AS). 15 s WU- AS ratings of NC subjects after 44°C, 46°C, and 48°C heat pulse trains were.7 (2.9), 4.3 (8.0), and 10.2 (18.4) NPS units. The average 15 s AS ratings of FM subjects after 44°C, 46°C, and 48°C heat pulse trains were 14.3 (17.3), 22.4 (17.9), and 32.5 (17.9) NPS units, respectively. 30 s WU - AS ratings of NC subjects after 44°C, 46°C, and 48°C heat pulse trains were 1.7 (3.4), 6.0 (13.8), and 7.5 (14.9) NPS units and the average (SD) 30 s AS ratings of FM subjects after 44°C, 46°C, and 48°C heat pulse trains were 11.3 (17.9), 18.8 (17.9), and 27.4 (17.9) NPS units, respectively. A mixed model ANOVA with time (2) and WU temperature (3) as within and diagnostic group (2) as between subjects’ factors showed significant main effects for time (F(1,62) = 32.8; p<.001), WU temperature (F(1,62) = 41.6; p<.001), and diagnostic group (F(1,62) = 21.0; p<.001). Use of simple contrast demonstrated that all 15 s and 30 s WU-AS ratings of FM subjects were significantly greater than WU-AS ratings of NC (all p<.04). A significant time×diagnostic group interaction (F(1,62) = 8.0; p<.01) showed that the decay of 30 s AS across time was significantly slower in FM subjects compared to NC.

Bottom Line: Slope of WU-RF, which is representative of central pain sensitivity, was significantly steeper in FM patients than NC (p<.003).Compared to single WU series, WU-RFs integrate individuals' pain sensitivity as well as WU and WD.Slope of WU-RFs was significantly different between FM patients and NC.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Florida, Gainesville, Florida, United States of America.

ABSTRACT

Background: In healthy individuals slow temporal summation of pain or wind-up (WU) can be evoked by repetitive heat-pulses at frequencies of ≥.33 Hz. Previous WU studies have used various stimulus frequencies and intensities to characterize central sensitization of human subjects including fibromyalgia (FM) patients. However, many trials demonstrated considerable WU-variability including zero WU or even wind-down (WD) at stimulus intensities sufficient for activating C-nociceptors. Additionally, few WU-protocols have controlled for contributions of individual pain sensitivity to WU-magnitude, which is critical for WU-comparisons. We hypothesized that integration of 3 different WU-trains into a single WU-response function (WU-RF) would not only control for individuals' pain sensitivity but also better characterize their central pain responding including WU and WD.

Methods: 33 normal controls (NC) and 38 FM patients participated in a study of heat-WU. We systematically varied stimulus intensities of.4 Hz heat-pulse trains applied to the hands. Pain summation was calculated as difference scores of 1st and 5th heat-pulse ratings. WU-difference (WU-Δ) scores related to 3 heat-pulse trains (44°C, 46°C, 48°C) were integrated into WU-response functions whose slopes were used to assess group differences in central pain sensitivity. WU-aftersensations (WU-AS) at 15 s and 30 s were used to predict clinical FM pain intensity.

Results: WU-Δ scores linearly accelerated with increasing stimulus intensity (p<.001) in both groups of subjects (FM>NC) from WD to WU. Slope of WU-RF, which is representative of central pain sensitivity, was significantly steeper in FM patients than NC (p<.003). WU-AS predicted clinical FM pain intensity (Pearson's r = .4; p<.04).

Conclusions: Compared to single WU series, WU-RFs integrate individuals' pain sensitivity as well as WU and WD. Slope of WU-RFs was significantly different between FM patients and NC. Therefore WU-RF may be useful for assessing central sensitization of chronic pain patients in research and clinical practice.

Show MeSH
Related in: MedlinePlus