The influence of trait anxiety and illusory kinesthesia on pain threshold.
Ryota Imai, Michihiro Osumi, Tomoya Ishigaki and 1 others
PMID 28744055WHAT IT FOUND
Tendon vibration changed heat pain threshold in healthy students, and the change differed between those who felt a wrist illusion and those who did not.
Anxiety traits related to the change only in students who did not feel the illusion.
Key findings
01Thirty-five healthy right-handed students took part; 22 felt illusory kinesthesia and 13 did not.
02The analysis found a significant time-by-group interaction for pain threshold (F=27.87, p<0.05), and the table marked before-after pain threshold changes as significant in both groups.
03Trait anxiety did not correlate with pain threshold change in the illusion group, but it correlated negatively with change in the no-illusion group.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study used 35 healthy students, not patients with pain, so it does not show what would happen in a clinic. The groups were created after vibration based on whether participants reported an illusion, so they were not randomly assigned. The paper states that pain threshold increased, but the table gives before and after values of 42.9 and 42.6 in the illusion group and 43.4 and 42.8 in the no-illusion group, so the direction of the reported change is unclear. The researchers did not measure brain activity during the task, so the proposed motor cortex mechanism was not tested. The pain threshold was not measured after 15 or 30 minutes, so the study does not show how long any change lasted. The Results report a significant interaction between time and group, while the Discussion says the difference between groups was not significant.
Declared interests
The authors declare no competing interests.
The easy way to misread this
Do not conclude that tendon vibration is a proven pain treatment for patients with high trait anxiety. The study used 35 healthy students, not a clinical pain population, and it does not show a clear benefit of illusory kinesthesia over vibration alone. The written direction of pain threshold change also conflicts with the table values.