Is pain-related fear a predictor of somatosensory hypervigilance in chronic low back pain patients?

Pain-related fear has been found to be associated with increased disability and increased pain perception in patients with chronic low back pain. A possible mechanism by which pain-related fear could lead to increased pain perception is heightened attention to somatosensory sensations. In the present study, chronic pain patients reporting either a high or low level of pain related fear and control participants performed an auditory reaction time task, while occasionally non-painful electrical stimuli - accompanied by threatening instructions - were given to the arm or back. In the primary task condition, participants had to perform the auditory task while ignoring the electrical stimuli. Next, the task was presented under dual task conditions in which participants had to respond both to tones as well as to detection of electrical stimuli. It was hypothesized that for the primary task, high fearful patients would show greater disruption of performance on the auditory task than low fearful patients and controls when stimuli were presented to the back. For the dual task, slower reaction times for the auditory task, in combination with faster detection of electrical stimuli was expected. The hypotheses were not confirmed but patients scoring high on pain-related fear did show an overall increase in reaction time for all conditions of the primary task, with or without simultaneous stimulation. Regression analyses demonstrated that high pain-related fear was associated with increased reaction time to tones both in patients and healthy controls, and that within patients pain-related fear was a better predictor of reaction time to tones than present pain intensity. The findings may be interpreted as showing that patients with elevated levels of pain-related fear habitually attend to somatic sensations, giving less priority to other attention-demanding tasks. (C) 2001 Elsevier Science Ltd. All rights reserved.