Abstract
Aims
Stimulus intensity used for assessing temporal summation of pain (TSP) is commonly set at the participants’ pain tolerance. Yet pain ratings during TSP rarely reach that initial pain tolerance pain rating. This study aimed to explore the differences between baseline pain tolerance assessed by cuff algometry and subsequent pain ratings of the same stimulus intensity, and the reliability of these ratings over 2 sessions.
Methods
In two sessions, separated by one week, 24 healthy, pain-free males had their pressure pain detection (PDT) and tolerance threshold (PTT) recorded using a staircase inflation paradigm (5 kPa increments, 1sec-ON:4sec-OFF) with a cuff algometry system. The pain intensity was assessed during cuff stimulation using an electronic visual analogue scale (VAS, 0–10 cm). Three different inflation paradigms were then performed, using the PTT level as stimulation intensity, and a 1-s duration for each stimulus: PEAKS: 3 inflations at 0.17 Hz, SLOW: 10 inflations at 0.01 Hz, FAST: 10 inflations at 0.5 Hz). Approximately 5-min was kept between the staircase assessment and the first stimulation paradigm, and between each of the 3 inflation paradigms. The PTT and first inflation VAS rating from each paradigm was extracted.
Results
The VAS rating of PTT pressure was higher in the staircase (VAS: 8.5±2.1 cm) than the first PPT stimulus in any other paradigm (PEAKS: 5.4±2.0; SLOW: 4.6±2.1; FAST: 4.0±2.3, P < 0.05). VAS ratings were also lower in each subsequent paradigm (i.e. PEAKS > SLOW > FAST, P < 0.05). Intra-class coefficients demonstrated excellent reliability for each paradigm (all ICC > 0.79) between sessions.
Conclusions
PTT, as assessed with the staircase inflation paradigm, was rated more painful during baseline assessment than when the identical stimulus profile (PPT intensity for 1-s) was applied afterwards and this finding is considered reliable.