Motor imagery in people with a history of back pain, current back pain, both, or neither.

INTRODUCTION: There is mounting evidence that cortical maps are disrupted in chronic limb pain and that these disruptions may contribute to the problem and be a viable target for treatment. Little is known as to whether this is also the case for the most common and costly chronic pain-back pain.
OBJECTIVES: To investigate the effects of back pain characteristics on the performance of left/right trunk judgment tasks, a method of testing the integrity of cortical maps.
METHODS: A total of 1008 volunteers completed an online left/right trunk judgment task in which they judged whether a model was rotated or laterally flexed to the left or right in a series of images.
RESULTS: Participants who had back pain at the time of testing were less accurate than pain-free controls (P=0.027), as were participants who were pain free but had a history of back pain (P<0.01). However, these results were driven by an interaction such that those with current back pain and a history of back pain were less accurate (mean [95% CI]=76% [74%-78%]) than all other groups (>84% [83%-85%]). DISCUSSION: Trunk motor imagery performance is reduced in people with a history of back pain when they are in a current episode. This is consistent with disruption of cortical proprioceptive representation of the trunk in this group. On the basis of this result, we propose a conceptual model speculating a role of this measure in understanding the development of chronic back pain, a model that can be tested in future studies.