Temporal summation in chronic pain patients: the impact of catastrophizing, distraction analgesia and opioid use

Catastrophizing has been shown to be greatly elevated in individuals with chronic pain. Previous studies have indicated that high catastrophizers have higher temporal summation of pain, and that this is likely due to supraspinal rather than spinal mechanisms. Similarly, distraction analgesia involves activation of a supraspinal centers. The ability of distraction to inhibit pain has been studied in healthy volunteers, revealing that high catastrophizers have a delayed analgesic response to distraction. In this study, we investigated the interaction of catastrophizing with distraction analgesia in chronic pain patients (n=149). Pain patients had a mean pain score of 5±2.4 out of 10, and half were chronically taking opioids to manage their pain. Patients underwent quantitative sensory testing (QST), including a pinprick train paradigm to measure temporal summation, both in the presence and absence of a distracting handgrip algometer task. Pain patients with high catastrophizing scores did not differ from low catastrophizers on most QST measures, but had significantly greater temporal summation. Interestingly, in the presence of a distraction task, the extent of temporal summation in high catastrophizers was reduced to the level of low catastrophizers. Moreover, distraction’s inhibitory effect on temporal summation in high catastrophizers was not altered by controlling for current pain scores or depression. When controlling for opioid use, however, chronic opioid users did not have the beneficial effect of distraction on temporal summation, while non-opioid users did. These data reconfirm previous findings that catastrophizing is associated with a greater tendency toward temporal summation, and that this may be attributable to increased attention to pain, as distraction is able to partially inhibit this. Furthermore, these data suggest that the inhibitory effect of distraction on pain may be altered by chronic opioid use.