Neural correlates of fear of movement in high and low fear-avoidant chronic low back pain patients: an event-related fMRI study.

The fear-avoidance model postulates that in chronic low back pain (CLBP) a fear of movement is acquired in the acute phase, which leads to subsequent avoidance of physical activity and contributes to the pain syndrome's becoming chronic. In the present event-related functional magnetic resonance imaging (fMRI) study of the neural correlates of the fear of movement, 60 women (30 CLBP patients, 15 healthy controls, and 15 women with spider phobia; mean age 46.8±9.8 years) participated. The CLBP patients were divided into a high and low fear-avoidant group on the basis of the Tampa Scale of Kinesiophobia. The participants viewed photographs depicting neutral and aversive (back-stressing) movements, generally fear-inducing and neutral pictures from the International Affective Picture System, and pictures of spiders while fMRI data were acquired. It was hypothesized that the high fear-avoidant CLBP patients would show fear-related activations when viewing the aversive movements and that they would differ from CLBP patients with low fear-avoidance and controls in this regard. No such activations were found for high or low fear-avoidant CLBP patients. The random-effects analysis showed no differences between high and low fear-avoidant CLBP patients or high fear-avoidant CLBP patients and controls. Normal fear-related activations were present in the high fear-avoidant CLBP patients for the generally fear-inducing pictures, demonstrating the validity of the stimulation paradigm and a generally unimpaired fear processing of the high fear-avoidant CLBP patients. Our findings do not support the fear component of the fear avoidance model.