Changes in brain activation related to pain relief in rheumatoid arthritis patients following the anti-TNF treatment
Wartolowska K., Schweinhardt P., Wordsworth P., Chizh BA., Tracey I.
Background and aims: Functional magnetic resonance imaging (fMRI) offers comprehensive information on brain function. The objective fMRI data can be correlated with behavioural and clinical measures to help dissect a subjective pain experience into its components. In this study we compared changes of experimental and clinical pain processing in rheumatoid arthritis (RA) before and after treatment with etanercept or infliximab; agents that block the action of proinflammatory cytokine, tumor necrosis factor (anti-TNF). Methods: We recruited 10 patients with active rheumatoid arthritis (RA) due to begin the anti-TNF treatment and 10 age and sex matched healthy volunteers. We used fMRI to investigate changes in brain activation patterns in response to clinically-relevant stimuli (joint squeeze and experimental heat pain stimulation) pre- and post-treatment. We collected also clinical and psychophysical information from each patient. Results: We observed robust activation in response to both clinical and experimental pain in all major pain processing areas. Preliminary analysis suggests that fMRI is able to detect differences in experimental pain processing between patients and healthy subjects, as well as differences between clinical and experimental pain in RA patients alone. We found significant (p<0.05) decreases in pain ratings for both kinds of stimuli, clinical markers of inflammation, disease activity score (DAS 28) and significant changes in fMRI signal in insula cortex post anti-TNF treatment. Conclusions: Our findings suggest that fMRI is a sensitive measure of pain experience and has the potential to become a useful tool in understanding pathophysiology of chronic pain as well as measuring treatment effects.